CHM Photo Grav 3 User Guide

User Manual: CHM PhotoGrav 3 - User Guide

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The Power Tool for Laser Engraving Photographs

PhotoGraV
User Guide

Version 3.0

PhotoGrav
Version 3.0

User Guide
Revision 3.0.1

© 2007 ImageLaz, LLC. All rights reserved.
This document is for information purposes only. ImageLaz, LLC makes no warranties, expressed
or implied.
Other brand and product names are trademarks or registered trademarks of the respective holders.
Microsoft is a registered trademark and Windows is a registered trademark of the Microsoft
Corporation.
The characteristics of the laser engravers modeled by PhotoGrav were taken from published
specifications and review articles. The use of these characteristics does not represent an endorsement
of Photograv by the respective laser engraver manufacturers nor a commitment to the specifications
on the part of the manufacturers.
Information in this document is subject to change without notice and does not represent a
commitment on the part of ImageLaz, LLC. The software described in this document is furnished
under a license agreement. It is against the law to copy the software on any medium except as
specifically allowed in the license or nondisclosure agreement. No part of this manual may be
reproduced or retransmitted in any form or by any means, electronically or mechanically, including
photocopying, recording, or information recording and retrieval systems, for any purpose other than
the purchaser’s personal use, without the express written permission of ImageLaz, LLC.

Table of Contents
Introduction

Chapter 1: Getting Started
1.0
1.1
1.2
1.3
1.4
1.5
1.6

1-1

Using this Document
System Requirements
Preliminaries
Installation / Setup
Activation System & Licensing
Quick Start Scenarios
Additional Tutorial Scenarios

1-1
1-1
1-2
1-3
1-3
1-5
1-7

Chapter 2: Operational Overview
2.0
2.1
2.2
2.3

2-1

Introduction
Functional Flow of Events
Basic PhotoGrav Concepts
Important PhotoGrav Information

2-1
2-1
2-3
2-4

Chapter 3: PhotoGrav Application
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7

3-1

Introduction
PhotoGrav Sessions
Primary Toolbar
Viewing Panes and Panels
Interactive Mode
Cloning—Comparison of Results
Machine Properties
Automatic Updates

3-1
3-1
3-3
3-7
3-8
3-15
3-16
3-17

Chapter 4: Troubleshooting

4-1

4.0 Introduction
4.1 Solutions to PhotoGrav Problems
4.2 Technical Support

4-1
4-1
4-3

iii

Appendices
Appendix 1:
Appendix 2:
Appendix 3:
Appendix 4:
Appendix 5:

A1-1
Engraving Tips
Calculational Procedure for “Turn Time”
PhotoGrav and Clip Art
PhotoGrav Concepts and Design
PhotoGrav License Agreement

A2-1
A3-1
A4-1
A5-1
A6-1

PhotoGrav has been designed specifically for Laser Engravers. The objective of the program is to
efficiently process digitized photographs so they can be engraved on a variety of common engraving
materials with a high degree of confidence that the engraved photographs will be acceptable products.
Traditionally, the engraving of photographs has been difficult and has been a hit or miss endeavor
resulting in many discarded objects. The process has been so difficult and costly, in fact, that many
Engraving shops simply do not offer engraved photographs as one of their standard products.
PhotoGrav has been designed to address this problem and does so in three ways:
1. It provides a set of powerful tools that have been found effective in
processing photos for engraving.
2. It provides an automated application of these tools to the subject photo.
3. It provides a simulation of the engraving process for many common
materials so the “engraved product” can be inspected before it is actually
engraved.
Currently, PhotoGrav simulates more than 25 engraving materials including: cherry and walnut
wood; clear and black-painted acrylic; black laser brass and anodized aluminum; a variety of generic
leather materials; and many plastics with either a white or black core and with a variety of caps
including brushed gold and most solid colors. PhotoGrav’s processing functions have been tuned and
optimized for each of these materials and the appropriate optimized parameters are automatically
loaded whenever a new material is selected. Further, PhotoGrav automatically compensates for the
engraving peculiarities of each material in the process of creating the “engraver-ready” processed
image. For example, photos to be engraved on clear acrylic are automatically mirror-imaged and
produced at a “negative” polarity. Of course, you can override these automatic features at any time to
produce special effects if so desired.
The PhotoGrav process is very simple: (1) You select the digitized image that you want to
engrave, (2) You select the engraving material, and (3) You choose the Final Processing option
within PhotoGrav. The next thing you see on your computer monitor is a simulation of what the
image will look like when it is actually engraved on the material you have chosen. You can then save
the image on disk and use your favorite image processing program, e.g., CorelDraw, to send the image
to the engraver.
Of course, the simulated engraving might not look quite like you wanted so instead of saving the
image on disk you can reprocess the image by “tweaking” the parameters that PhotoGrav had
v

originally chosen for the image. Most of the time, however, the automated processing in PhotoGrav is
so good that you won’t be able to improve on the automated rendition no matter how long you tweak.
Using an energy and lens model, PhotoGrav has been calibrated for many laser engravers from
the major manufacturers. However, PhotoGrav goes one step further in that it provides the capability
that allows you to customize and automate PhotoGrav’s processing for your particular machine and
for the particular materials that you use.
As a final note, we would like to point out that PhotoGrav has NOT been designed in a vacuum
by computer scientists who have merely a passing acquaintance with a laser engraver. Rather, it has
been designed by a team of engravers, physicists, and computer scientists who have pooled their
experience, knowledge, and talents to result in a truly unique and remarkable product for the laser
engraving community. This team wishes you all possible success in using PhotoGrav and welcomes
your comments for improvements to future PhotoGrav versions.

Getting Started

1.0 Using this Document
This document has two objectives: (1) To acquaint you with PhotoGrav so you can be
productively using the program as rapidly as possible and (2) To serve as a complete reference source
for all of PhotoGrav's components and operational characteristics.
To satisfy the first objective, chapters 1 and 2 have been written to present essential information and
concepts in as concise a manner as possible. Chapter 1 provides the information necessary to install
PhotoGrav and to begin using it almost immediately. A series of logically-connected scenarios, with
screen shots, provides immediate hands-on experience and should give you a good idea of PhotoGrav's
basic operational characteristics. Chapter 2 presents an overview of the flow of events within
PhotoGrav, discusses some basic PhotoGrav concepts and rationale, and presents a summary of
important information that you should know about the program.
The remainder of the chapters, especially chapters 3 and 4, provides a detailed reference source for
all of PhotoGrav's features. Chapters 3 and 4 present detailed descriptions of PhotoGrav's Primary and
Support windows, respectively. Chapter 5 describes how to use the program's Help capability and
Chapter 6 explains what to do if you have any difficulties in using PhotoGrav. The Appendices present
supplemental information in specialized areas.
At a minimum, after installing the program, you should read Sec. 1.4 and step through the scenario
presented in that section. You should also definitely read Sec. 2.3, Important PhotoGrav
Information. Preferably, to really understand and fully use PhotoGrav's extensive capabilities, you
should read Chapters 1 and 2 in their entirety.

1.1 System Requirements
To use PhotoGrav, you need the following hardware and software:

1-1

Hardware
Minimum Configuration
500 MHz Intel or AMD processor or better
128 megabytes (MB) of RAM
CD-ROM or DVD-ROM drive
Hard disk with at least 50 MB of free space (see Notes below)
Keyboard & Mouse
1024 x 768 SVGA Video Card
Recommended Configuration
2 GHz multicore or faster Intel or AMD processor
At least 1 to 2 GB of RAM
CD-ROM/DVD-ROM drive
Hard disk with 100 MB of free space (see Notes below)
Keyboard & Mouse
At least 32 MB SVGA Video card

Software
Windows 2000, Windows XP, Windows Vista

Notes on Hardware Requirements:
PhotoGrav itself requires less than 30 MB of hard disk space for program and data files. However,
several temporary disk files are created during PhotoGrav execution on the disk where you installed
PhotoGrav. These files are used as temporary storage for some of the images which are generated
during execution. The sizes of these temporary files are proportional to the size of the digitized photo
which is to be engraved and thus the required hard disk space is a “soft” number which depends on your
operational scenario. All PhotoGrav temporary files are deleted when PhotoGrav terminates
execution.

1.2 Preliminaries
PhotoGrav requires that your computer monitor be set up to display a pixel depth of at least 32 bits
per pixel. It is also desirable that the display resolution (desktop area) be set to at least 1024 x 768, but
it is recommended to be set at a larger size.

1-2

1.3 Installation / Setup

1. Log in to Windows if you have not already done so.
2. Insert the CD into your CD-ROM drive.
3. If Autorun is enabled on your system, installation will start automatically.
Otherwise, click Start, then Run and enter X:\setup.exe where X is your CDROM drive.
4. Click OK.
5. Follow the instructions on the screen.
Note: During installation you will be asked to enter your PhotoGrav serial
number. It is located on page i (first page) of this document, printed directly
on the PhotoGrav CD, and in Help→About PhotoGrav… menu item.
6. After Installation and until PhotoGrav is activated a Product Activation Screen
will give the remaining days left to activate the PhotoGrav product. PhotoGrav
allows up to 15 days to activate the software. For further information refer to Sec
1.4 on Activation.
7. After Installation and on the first time PhotoGrav is launched a Select Machine
Type window will appear. Select the appropriate laser machine type from the list
of available laser machine manufacturers and model types. For further
information refer to Sec 3.6 on Machine Properties.

The installation process will create an icon for PhotoGrav and place that on your desktop as a
shortcut and will also create a new Program Group under “PhotoGrav”. In all cases, the installation
process will also create an Uninstall icon that allows you to easily remove PhotoGrav from your
system. You may also use the “Add/Remove Programs” capability in the Control Panel to uninstall
the program.

1.4 PhotoGrav Activation System and Licensing
When PhotoGrav is launched it checks to see if the software has been activated and authenticated
for full use. PhotoGrav will permit full usage with an activation reminder up to 15 days from initial
installation in order to give adequate time for the user to activate the software. No registration is
required to activate the software and no personal information is transmitted across the internet.

1-3

Fig. 1.4.1
Fig. 1.4.2

PhotoGrav Licensing and Activation System permits activations on two separate computer
machines and reactivation as many times as needed. This policy allows PhotoGrav to be installed on
any combination of two computers such as office/laptop, home/office, machine/office, etc.
There are four different methods of activation provided to conveniently assist in activating the
PhotoGrav software product. These four methods of activation are via the Web, Email, Postal Mail,
and Phone (see Fig. 1.4.1). The quickest method to activate the PhotoGrav software, assuming efficient
internet capabilities, is to use the online PhotoGrav Activation System (see Fig. 1.4.2).
To activate the software and display the activation screen in Fig 1.4.1, open PhotoGrav and click
Help→Activate PhotoGrav on the main menu bar. If an active internet connection is available then it
is suggested to click the Get Activation Key (Web)… button for the quickest way to activate the
software. If you prefer to use email then simply click on the Get Activation Key (Email)… button and
on most computers your default email client will pop up and be filled in with the appropriate
information. If the computer system is configured in such a way that the relevant information is already
filled in then just click the Send button to send an activation request email and allow 24 hours for the
Activation Key to be emailed back to the sending email address. The third method is to call ImageLaz
Sales Dept and we will be happy to provide an Activation Key. The fourth and most inefficient
method of activation is to send an activation request via postal mail to ImageLaz with the appropriate
information and wait for the Activation Key to be sent back.

1-4

1.5 Quick Start Scenarios
This section provides a “Quick Start” to using PhotoGrav by presenting a simple, but typical,
engraving scenario. It introduces PhotoGrav’s major features and controls and how they are used
within the context of an actual engraving scenario. To successfully use this section you should have a
basic understanding of Windows features and techniques. If you’re anxious to try PhotoGrav and you
don’t like to read, then this section is for you. However, even if you consider yourself a PhotoGrav
expert after completing this section, it is highly recommended that you step through the additional
scenarios in Section 1.6 and then read Chapter 2 for a more complete understanding of how PhotoGrav
works.
There are several definitions that one should have firmly in mind before tackling the Quick Start
scenario. These definitions are listed below:

Original Image
(Gray or Color)

The image, in jpg, tif, png or bmp format, that is the input image to
PhotoGrav. This image is the digitized photograph (either in color or
grayscale) that you want to engrave.

Engraved Image
(Binary)

This is the processed image that PhotoGrav produces that should be sent
to your laser engraver. This image is a binary image (black & white) and
can be saved in either tif, png, or bmp format.

Simulation Image

This is a simulation, produced by PhotoGrav, of what the engraved
image will look like when engraved on the selected engraving material.
This image is a 24-bit, true color image and can be saved in either jpg,
tif, png or bmp format. This image is useful for customer proofs and for
reference BUT is NOT the image to be sent to the laser engraver.

Scenario 1: Engrave a man’s photograph on cherry wood.
It is assumed that the man’s photograph has been previously digitized and stored as either a color or
grayshaded image (in one of the supported image formats) on disk. This scenario will use the image
“Image250.bmp” which has been furnished with PhotoGrav. This image should reside in the directory
C:\[PhotoGrav Installation Directory]\SAMPLES.
Note: The image “Image250.bmp” has a dpi of 250. In general, the ratio of engraver dpi to image
dpi should be an integer factor. So if your engraver has dpi’s like 150, 300, 600, . . , then in the
following scenario you should use the image “Image300.dpi” which has a dpi of 300.

1-5

1. Start PhotoGrav by double clicking its icon
The opening “Splash” screen appears.

or by choosing it from the Start menu.

2. Click anywhere at any time on the opening screen or press any key to continue with
PhotoGrav execution which always begins with a blank Session Window.
3. However, the very first time you run PhotoGrav, a “Select Machine Type” Window is
automatically displayed. In that window, select your engraver type by clicking one of the
option buttons. If you cannot find your engraver in the list of machines just Select “User
Defined→Custom” and type in the relevant information. Then click OK to close the
window.
4. Click Open Image and use the standard Windows dialog box to choose the image
“Image250.bmp” which resides in the \SAMPLES subdirectory of the directory in which
you installed PhotoGrav. The image should be displayed.
5. Click Select Material. (A list of engraving materials appears).
6. Scroll down the list and select “Cherry with light vertical grain” and click OK. (“Cherry
with light vertical grain” shows up in the status bar pane at the bottom of the PhotoGrav
application window).
7. Click Final Process. (A status message informs you of PhotoGrav’s progress permitting
you to CANCEL the operation if needed at the first available point in the processing
algorithm).
8. When processing is complete, a simulation of the engraving is displayed while permitting
one to cycle through the various images by clicking on the appropriate buttons:
O = Original, G = Grayscale, E = Engraved, S = Simulated
9. Click on the Save Image button. At this point, if you wished to save the engraved image to
disk in order to later send it to your engraver, you would select the “Engraved” option in
the Export Image window that appears. A standard Windows dialog box would then appear
in which you could specify the file name of the engraved (binary) image in the usual manner.
10. That’s all there is to it! You have created an image, the engraved image, which is ready to
be sent to your laser engraver via your print software such as CorelDraw or your laser
driver. You may now save the PhotoGrav Session if desired which will save the original
image and all the appropriate material, machine, and session parameters in one PhotoGrav
Session File (.pgs) .
At this point, either continue with scenario 2 (in Section 1.6) or click Exit to exit the
PhotoGrav program.

1-6

1.6 Additional Tutorial Scenarios
This section presents five additional scenarios which further illustrate PhotoGrav’s features. Each
scenario is a logical follow-on to Scenario 1 presented in the preceding section.

Scenario 2: Compare the original, grayscale, engraved, & simulated images.
This scenario will demonstrate how easy it is to evaluate the engraved (binary) image by comparing
it and the simulated engraving to the original (input) or grayscale image. The scenario will also
demonstrate some of PhotoGrav’s supporting features. PhotoGrav has a “Split Screen” feature which
can be used to more efficiently compare the various images (i.e. grayscale vs. simulated).

1. If you are continuing here from Scenario 1, then go to the next step. Otherwise, repeat the
first eight steps of Scenario 1.
2. Left click on the Split Window

button. This will provide two separate viewing

windows to facilitate in the comparison of results.
3. Now click the Cycle Images button in either viewing pane to successively display the
original, grayscale, engraved, and simulated images. Note that the four images have been
enlarged by the same amount and are in synchronization to facilitate comparisons among
the images.
4. Left click at a position between the man’s eyes on whichever image is displayed. The
image will be magnified. Left click again at approximately the same point. The image will
be enlarged more. (Note the scale factor in the lower right corner of the window).
5. Click with either mouse button anywhere on the gray area surrounding the displayed image.
The display should now show the entire image. (The image can also be de-magnified in
steps by clicking on the image with the right mouse button).
6. “Click and drag” on the image to define a rectangular area that you want magnified. After
releasing the mouse button, the selected portion of the image will be magnified to fill the
image area.
7. The simulation image and the ability to magnify and to cycle among the original, grayscale,
engraved, and simulated images has been designed to help you decide whether or not the
engraved image is a good representation of the original (input) or grayscale image on the
engraving material you have chosen (cherry wood in this scenario).
At this point, either continue with scenario 3 or click Exit to exit the PhotoGrav program.

1-7

Scenario 3: Generating a PhotoGrav Session Information Report
This scenario will demonstrate how to generate a PhotoGrav Session Information Report that
completely describes the current engraving session. The scenario will also demonstrate several other
PhotoGrav features.

1. If you are continuing here from Scenario 1 or Scenario 2, then go to the next step.
Otherwise, repeat the first eight steps of Scenario 1.
2. Click the Display Info

button located on the Primary Functions Toolbar.

The Session Info Report window should open and display all the relevant session
information including an estimate of engraving time.
3. Click on the lightest-gray box titled Engraver’s Comments.
Type in a comment such as: This session used the standard parameters for cherry wood.
4. Click the Print Report button near the bottom of the window. A standard Windows dialog
box should appear allowing you to select a printer (if you have more than one) and to set
the options for the selected printer. Your report should be printed after clicking OK in the
standard dialog box.
5. Click the Close button next to the Engraver’s Comments button and the PhotoGrav
Session Info Report window should disappear.
6. Refer to Figure 1.6.1 on the next page for the entire display of the PhotoGrav Session Info
Report screen.
At this point, either continue with Scenario 4 or click Exit to exit the PhotoGrav program.

Notes:

1-8

Fig. 1.6.1
1-9

Scenario 4: Adjusting Parameters in the “Interactive Mode” Panel.
This scenario will demonstrate how to adjust the parameters used in creating the engraved and
simulation images. The Interactive Mode panel is extremely powerful, but also a little complicated so
this scenario will just demonstrate some, not all, of the features available when Interactive Mode is
selected. This scenario will also demonstrate how to export the Parameters.

1. If you are continuing here from Scenario 1, 2, or 3, then go to the next step. Otherwise,
repeat the first eight steps of Scenario 1.
2. Click the Interactive Mode
button located on the Primary Functions Toolbar.
The Interactive Mode button should change to indicate that it is selected and the Parameter
Adjustment view is displayed in the lower panel of the Session Window (see Fig. 1.6.2).
3. Components of the Interactive Mode panel:
is selected (two viewing windows) and the input image is
If Split Window
displayed in the left image pane and the output image (usually the simulated image) is
displayed in the right image pane.
The seven green/red ON/OFF buttons represent the various processing functions that are
applied to the input image. If a button is green, that function is “ON”. If the button is red,
that function is “OFF”. There are also 8 sliders with corresponding text boxes for manual
entry of the various parameters along with slider controls that adjust the histogram clipping
region and the viewing range.
4. Within the “Simulate Engraving” panel, click the “Power” scroll bar (in the light gray area
under the scroll box) until its value is 20%. Now click the
button (also on the
session toolbar see Fig 1.6.3) and note that the simulated image has gotten much lighter
reflecting the lower power setting for the engraving.
5. In a similar fashion, click the “Speed” scroll bar until its value is 30% followed by the
button. Again note that the simulation image is now about the same darkness
as was the case when Power was 70% and Speed was 100%.
6. Now, uncheck the
check box and click the Reset
button next to the
Power control then click the
button. Note how much faster the simulated image
is displayed. If it is significantly faster then you may want to consider leaving this
unchecked unless you are working with a rather large image.

1 - 10

7. You may have noticed that every change you make requires you to click one of the Preview
buttons to view the changes. To see the changes in almost real time after every change
ensure that the
checkbox is checked and the
checkbox is unchecked.
Now change the Power back to 20% by either typing “20” into the textbox for the Power
parameter followed by pressing the [Enter] key or move the slider bar until the textbox
reads 20% followed by releasing the mouse button. Note in either case how the simulated
image is changed almost instantly. These options are included to provide some flexibility in
previewing efficiency based on the speed of your computer and the size of the image.
8. Once you have adjusted the parameters to your satisfaction press the
button to
hold the parameter changes and process the image in its entirety. The engraved/binary
image is now ready to be saved for engraving.
9. There are many other functions and features available when in Interactive Mode. See
Section 3.2 of this PhotoGrav User Guide for a complete description of each of these
functions.
At this point you can click Exit to exit the PhotoGrav program if you so choose.

Fig. 1.6.2

Fig. 1.6.3

1 - 11

Notes:

1 - 12

Operational Overview
2.0 Introduction
The objective of this chapter is to present the essential information that you need to know in order
to effectively use PhotoGrav. Section 2.1 briefly describes PhotoGrav's primary functions and flow of
events that those functions support during a typical PhotoGrav session. Beginning with PhotoGrav
version 3.0 multiple simultaneous PhotoGrav sessions can be opened, modified, and independently
saved. Section 2.2 provides a concise, high-level description of the program's concepts and the rationale
for those concepts. Finally, section 2.3 presents a list of items that summarize the important
information about PhotoGrav.

2.1 Functional Flow of Events
PhotoGrav employs a small number of primary toolbar buttons to functionally organize the major
steps involved in engraving a photograph. Each functional button has one or more major functions to
accomplish and, upon completion of those functions, control passes back to the main session window.
Figure 2.1.1 illustrates the normal flow of events in PhotoGrav processing.

Fig. 2.1.1: PhotoGrav Functional Flow

The Open Image Button provides the capability to select the image that you want to engrave while
the Select Material Button selects the engraving material that you want to use. PhotoGrav stores a set
of processing parameters with each material that it models. These processing parameters are optimized
for each particular material to ensure excellent engraving results without any user intervention. These
optimized parameters make possible the “Final Process” path indicated in Fig 2.1-1.
2-1

The Resize Image Button provides the capability for you to resize/resample the input image
without having to rely on another software application to perform this task. PhotoGrav will NOT resize
or even modify the original image in any way because PhotoGrav makes a working copy of the original
file. Also, on every resize/resample operation PhotoGrav uses the original image to perform the resize
operation in order to maintain the highest degree of quality.
The Interactive Mode Button provides the capability to individually specify parameters for all of
PhotoGrav’s processing functions and to view the result in near real time. Most importantly, one can
view a simulation of what the engraving would actually look like on the material that you have selected.
Although the Interactive Mode provides complete access to PhotoGrav’s functions that have been
tuned specifically for Laser Engravers, you will probably find that you can seldom do better than
PhotoGrav’s Automatic Final Processing option.
The Final Process Button (Auto Process in previous versions) allows the input image to be
processed and finalized in the proper format for the laser engraver. To ensure that the image is
processed and finalized with the latest modifications of the parameters this operation should ALWAYS
be performed whether in Interactive Mode or otherwise prior to saving the image to disk.
The Viewing Panes (Figure 2.1.2), whether in split mode or otherwise, displays the Original
(Input) image, the Grayscale image, the Engraved (Binary) image (the image that is to be used for
engraving), and the Simulated image (what the engraving will look like on the selected material). The
images appear on the screen one or two (if in split mode) at a time. One can, however, click a button to
rapidly cycle through the various images for comparison purposes or view the images side by side when
in split view mode. You can also magnify the images by clicking near the center of the area you want
magnified or by defining a rectangular area to be enlarged to fill the screen. All three images are
magnified by the same amount so comparisons are still easy to do even after magnification. Once the
processed image is acceptable the various images can be save to disk for storing and to transfer to your
engraver.
The Save Image Button allows the various images (Original, Grayscale, Engraved, Simulated) to
be saved to disk (when appropriate) in the supported file formats i.e. jpg, tif, bmp, png. When saving
the Engraved image the jpg file format is NOT permitted due to the fact that in most cases it would ruin
the engraved image information which would not be suitable for engraving.

Fig. 2.1.2: Viewing Panes

Single Viewing Pane

Split Viewing Pane
2-2

2.2 Basic PhotoGrav Concepts
The objective of the PhotoGrav program is to efficiently process digitized photographs so they can
be engraved on a variety of common engraving materials with a high degree of confidence that the
engraved photographs will be acceptable products. This objective is achieved via two basic PhotoGrav
concepts:
1. Processing operations that are "tuned" for each engraving material, and
2. A simulation of the engraved image
The intent of this section of the user guide is to provide a concise, high-level description of these
two concepts and their underlying rationale. A more detailed description can be found in "Appendix 5:
PhotoGrav Concepts and Design".
PhotoGrav's processing operations were designed and developed specifically to process images for
laser engraving and were parameterized so that a wide range of effects could be achieved by adjustment
of the parameters. Then the parameters were individually "tuned" for each of the engraving materials
supported by the program. This "tuning" was accomplished experimentally, using several test images,
by specifying several sets of parameters for each engraving material, actually engraving the images on
the material, and evaluating the resulting engravings. This process was repeated until the resultant
engravings appeared to be near optimal for the subject material. The parameters that produced the final,
"near optimal' engraving were then recorded and a data set was created for the material. These data sets
are stored as part of the description of each engraving material and are automatically retrieved whenever
a material is selected as the current engraving material within PhotoGrav.
Although the tuning process described above results in "near optimal" parameter settings for each
engraving material, engraving results are still often somewhat image dependent. In other words, the
settings that produce an excellent engraving for one image on a specific material might result in an
engraving that is less satisfactory for another image using the same engraving material. Further, it is
very difficult to view the raw processed image on a computer monitor and to judge from that display
whether or not the final engraving will be satisfactory. To overcome these difficulties, PhotoGrav
provides, optionally, a simulation of what the processed image will look like once it is actually engraved
on the selected material and the ability to modify the parameters as needed.
PhotoGrav's simulation capability is intended to provide a WYSIWYG (What You See Is What
You Get) capability. In other words, the appearance of the simulated image on your computer monitor
should be close to the appearance of the actual engraving produced from the processed image for most
of the included materials. The simulated image is not merely an overlay of "dots" on top of a
representation of the engraving material, but rather a convolution of the various parameters and images.
In other words, it is a full-fledged simulation wherein a lens-power model, calibrated for each material,
is used to calculate an effective laser spot size which is then "burned" into a representation of the
engraving material. Further details about the simulation and model can be found in Appendix 5.
The Simulation Image produced by PhotoGrav should always be a representation of the final
engraving. For example, for "Black Laser Brass", the Simulation Image should appear with proper
polarity even though the processed image, if displayed in its "raw" form, would appear to have a
"negative" polarity. There is one special case of this WYSIWYG capability that should be noted. For
acrylics, which are normally engraved on the "back" of the material, the Simulation Image produced by
2-3

PhotoGrav is the view from the "front" of the material, i.e., the normal viewing perspective. So, even in
this special case, the Simulation Image produced by PhotoGrav is a true WYSIWYG representation,
i.e., the simulated engraving is presented as it would normally be viewed by your customers as a finished
product. Although the primary utility of the Simulation Image is to help you make fine adjustments to
create a more satisfactory engraving, it can also be printed and used for customer proofs or as
supplements to file copies of your shop's projects. The prints are especially effective if you have a color
printer attached to your computer.
Although the simulation model has been calibrated for a variety of laser engravers and for many
common engraving materials, there are bound to be variables that at times cause noticeable differences
between PhotoGrav's Simulation Image and the actual engraving. For example, black laser brass from
different manufacturers, or even different "batches" from the same manufacturer, will sometimes
engrave somewhat differently under identical engraver settings. Also, variables in the laser engraver
itself, e.g., dirty lenses or mirrors, can cause variations in the engraving performance. You should try to
control these variables to the degree possible and also realize that PhotoGrav, like any other tool,
requires some practice and skill on your part to adapt its capabilities to your particular environment and
requirements. It is also important to remember that, for engraved photographs, "beauty is in the eye of
the beholder", i.e., the perceived goodness of an engraving is a very subjective measure. You might
therefore find that PhotoGrav's processing parameters for a particular material do not result in
engravings that match your tastes. If so, use PhotoGrav's interactive processing capabilities (see Sec.
3.4) and its Named Parameter Sets to define things the way you want them to be.
One other aspect of PhotoGrav's operational characteristics requires some discussion before
concluding this section. In the Image Viewing Panes (see Fig. 2.1.2), PhotoGrav displays the Original
Image, the Grayscale Image, the Engraved Image, and the Simulation Image for comparison purposes.
The Grayscale Image is the input image and the Engraved Image is the processed binary image that is to
be sent to the engraver. The Engraved Image is normally displayed in the same polarity and the same
left-to-right orientation as the Grayscale Image even though those characteristics might be automatically
changed by PhotoGrav when the image is saved on disk for transfer to your engraver. The reason for
displaying the Engraved Image in this fashion is merely to facilitate the comparison to the input image.
If this is a bit confusing, just remember that the Simulated Image always represents what will be
engraved if you save the processed image (Engraved Image in PhotoGrav's terminology) to disk and
transfer it to the engraver with no changes.

2.3 Important PhotoGrav Information
The following is a collection of important things that you should know about PhotoGrav. Some of
the items have already been discussed in previous sections and some of them will be covered in later
sections. However, since much of the information following Chapter 2 is very detailed and is intended
as reference material, the essential elements of that information are summarized below so you can begin
using PhotoGrav with confidence after reading this section. If an item is discussed elsewhere in this
document, then a reference to the appropriate section is included below.
2-4

1. PhotoGrav has been designed for compatibility with a display screen color pixel depth of
32-bit and a resolution of 1024 x 768 or larger.
(Reference: Sec. 3.3)
2. The input image ("Original/Grayscale Image") for PhotoGrav can be any image type in the
following format: tif, bmp, jpg, png.
(Reference: Sec. 3.2.2)
3. The input image to PhotoGrav should be scanned in some image processing program such
as CorelDraw or Adobe PhotoShop, so that its size and resolution (dpi) are "correct". If the
image is already in a digital format then PhotoGrav is able to resample the image to the
desired size and resolution (dpi). Most images taken with a digital camera have an arbitrary
resolution of either 72 or 96 dpi. In most engraving cases a dpi of 72 or 96 must be altered
for best results.
The dpi (dots per inch) for the image should be the same, or an integer factor or divisor, of
the dpi at which you intend to engrave the image. For example, if you intend to engrave at
250 or 500 dpi, then the image should be scanned at 250 dpi. If you intend to engrave at 300
or 600 dpi, then the image should be scanned at 300 dpi. Engraving results can often be very
disappointing otherwise. The size of the image, at the scanned resolution (dpi), should be
the desired size of the final engraved image.
4. Processed photographs (PhotoGrav's "Engraved Image") should be engraved using the
highest resolution lens (smallest spot size) that you have available. If you do not own your
manufacturer's "high-resolution lens" and if you intend to engrave a lot of photographs, then
you might consider obtaining such a lens.
5. Use PhotoGrav's “Machine Properties” or “Select Machine” dialog window to set the
parameters and characteristics for your specific laser engraver. The “Machine Properties”
window is accessible from the File→System Defaults→Select Machine menu item. The
session “Machine Properties” can be modified by selecting Session→Select Machine from
the menu bar.
(Reference: Sec. 3.6)
Although you specified your Laser Engraver model and its maximum power on your very
first PhotoGrav execution, there are other parameters that further define your specific
machine. In particular, within the “Machine Properties” window, you should add and/or
delete lenses from the “Lenses” list to match your set of lenses. Similarly, the list of “dpi's”
should be edited to reflect the dpi settings available on your machine. Also, if your laser
engraver’s maximum wattage is not listed under “Watts” then add it to the list as well.
6. PhotoGrav is not designed to "Print" directly to laser engravers. To engrave a PhotoGrav
processed image (the "Engraved Image"), save the "Engraved Image" to disk and use your
standard program, e.g., CorelDraw, to send the image to the engraver.
(Reference: Sec. 4.1.2.1)
7.

DO NOT RESIZE NOR ROTATE the "Engraved Image" (the image to be sent to the
engraver) in CorelDraw, or any other image processing program, before sending it to your
engraver. The "Engraved Image" is a binary image, as it must be for laser engraving, and
resizing and rotation operations in general do not work well for binary images.
2-5

PhotoGrav's “Sessions” provide a powerful mechanism whereby you can customize
PhotoGrav's parameters to achieve the results you want and can be assured that those
results are repeatable in the future. If PhotoGrav's default parameter settings do not
provide a satisfactory result for a specific material after the “Final Process” button is
pressed, then select the “Interactive Mode” button to create "Engraved Images" at several
parameter settings that you suspect might be better. Save the various “Session’s” with
different names and then actually engrave the images. Choose the engraving you prefer
and then delete the “Session’s” that do not correspond to that “best” engraving. If
satisfied with the “best” engraving, note which session was used and/or rename it so you
can readily access it in the future for similar engraving projects. Otherwise, repeat the
process until the results are satisfactory. You can now use this “Session” as a template to
begin other similar “Session” types.
(Reference: Sec. 3.1)

The engraving material to be modeled is selected via the “Material Properties” dialog
window. The “Material Properties” dialog window can be accessed by selecting the
File→System Defaults→Select Material menu item. The session “Material Properties”
can be modified by selecting Session→Select Material from the menu bar.
(Reference: Sec. 3.2.3)

10. The leather materials included with PhotoGrav, unlike most of the other furnished
engraving materials, are not standardized materials. Further, the engraving behavior of
leather depends very much on the tanning process, whether the leather is oiled or not, etc.
therefore, PhotoGrav's Simulation Image for any specific leather material might not be a
good representation relative to the specific leather material that you want to use.
However, you can use the furnished material as a starting point for your own calibration
process wherein you save your final, calibrated parameters as a PhotoGrav “Session File”
Template.
11. The list of engraving materials includes two plastic materials that are “User-Defined
Caps” with white or black cores. These materials can be used to model just about any
plastic with a solid-color cap and with either a black or white core. Some calibration and
parameter adjustment, as described in item 8 above, might be necessary for certain plastics
(Reference: Sec. A1.1, Tip 5)
and colors.
12. Two copies of PhotoGrav cannot be running at the same time. If PhotoGrav refuses to
start, there is probably another copy of PhotoGrav running in a minimized window.
13. PhotoGrav produces temporary image files during its execution that can become quite
large if the input image is large. Try to maintain a reasonable quantity of free disk space on
the hard disk where you installed PhotoGrav (200 MB should be more than adequate for
most purposes).
14. PhotoGrav is a Windows 32-bit program which runs equally well under 2000, XP, and
Vista. A 64-bit version is planned to be released and it is recommended that you call
PhotoGrav or check online at www.photograv.com for the latest information.

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PhotoGrav Application

3.0 Introduction
Chapter Two described PhotoGrav’s operational overview and how PhotoGrav uses these to
provide a smooth flow of events within a PhotoGrav Session. This chapter, Chapter Three, provides
a detailed description of each of those primary functional blocks as well as describing a PhotoGrav
Session and the essentials of the PhotoGrav Application. The description with appropriate graphics
include: (1) PhotoGrav Sessions, (2) The Primary Toolbar and its operations, (3) Viewing Panes and
Panels, (4) Interactive Mode, (5) Cloning—Comparison of Results, (6) Machine Selection, and
(7) Automatic Updates. It is especially recommended to become familiar with these primary
functional blocks located on the Primary Toolbar and the respective operations since these are vital in
producing a digital image for laser engraving.

3.1 PhotoGrav Sessions
One of PhotoGrav’s primary design concepts is the notion of a “PhotoGrav Session” and its
respective “Session File” (*.pgs). A “Session File” is a file that is designed to save the current state of
ones work including all parameter settings, user preferences, machine and material info, as well as the
source image. By permitting the source image to be saved with the session alleviates the need to
remember where the “original” image file is located. One can simply reopen the “Session File” and
perform any necessary modifications and/or adjustments without having to relocate the original image.
The machine information will be stored in the “Session File” which is helpful, for example, if
PhotoGrav is used with multiple engravers. This permits one to save machine/material “templates”
such that the user can just open up the session “template” pertaining to that particular machine/material
and begin using PhotoGrav with the machine and material info already selected and defined.
Whenever an image is opened, PhotoGrav will automatically insert that image into either a new
session OR an existing active session. Either way there will always be only one image associated with
a PhotoGrav Session.
Due to the “Session File” format, however, one must keep in mind that there are two modes of
selecting a machine and/or material. These two modes are selecting the “Session” machine/material
(Figure 3.1.1) and setting the “system” material/machine (Figure 3.1.2). The “Session” selection stays
with that particular session and the “System Default” selection sets the default material/machine type
3-1

so that any new session that is created will default to the machine/material type that is selected in the
“System Default” settings.
Session files can be very useful when becoming proficient with PhotoGrav in the following ways;
when working with a difficult image, if multiple engraving machines are used, when working with
multiple concurrent jobs, and in many other cases as well. PhotoGrav allows multiple session files to
be opened simultaneously and offers some functions specifically related to Session files such as
Cloning (Figure 3.1.3). For further instruction on cloning refer to Section 3.5 on Cloning—
Comparison of Results .
PhotoGrav has the capability to email Session files for easier review. For example PhotoGrav
Session Files can be emailed to PhotoGrav Technical Support or to another office location for review
simply by clicking on the Session→Email Session… menu item (Fig 3.1.4).
From this point forward the majority of this section is in the context of a “PhotoGrav Session” file
(.pgs files).

Fig. 3.1.1: Session
Fig. 3.1.2: System Default

Fig. 3.1.3: Session Functions

Fig. 3.1.4: Email Session

3- 2

3.2 Primary Toolbar
3.2.1 Overview
PhotoGrav is designed for simplicity, therefore, all of the primary functions necessary to prepare
an image for laser engraving are grouped together and displayed in the “Primary Toolbar” (Fig 3.2.1).
The Primary Toolbar provides quick access to the most commonly used functions.

Fig. 3.2.1: Primary Toolbar

The Primary Toolbar has 5 basic functions that perform the minimum requirement operations to
successfully laser engrave an image or photograph. As noted in Section 2.1 of this manual these 5
minimal steps are as follows:

1.
2.
3.
4.
5.
3.2.2 Open Image

Open an Image (Input Image).
Select the engraving material.
Resize the image to the desired size.
Process the image.
Save the image to disk.

The Open Image button simply displays a dialog window that allows an image in any PhotoGrav
supported file type (bmp, jpg, tif, png) to be opened and inserted into either a new or existing session
window. While the open file dialog filters the listed items to only show PhotoGrav supported image
types. If the “All files (*.*)” option is selected any PhotoGrav file type can be opened such as
PhotoGrav Session Files (pgs), PhotoGrav Parameter Files (prm, pgp), or PhotoGrav Supported
Image Files (bmp, jpg, tif, png).
The image that is initially opened is considered the “Original Image”. The image can be either
color or grayscale. PhotoGrav then automatically converts the original image if necessary to a
“Grayscale Image”. PhotoGrav considers the grayscale image because it is often much more reliable
to compare the grayscale image (rather than the color image) to the engraved image.

3-3

3.2.3 Select Material

The “Select Material” button displays a dialog window listing all the available materials sorted by
the various categories (see Fig 3.2.2). Remember that this material selection only changes the material
for the “active” session. Refer to Section 3.1, Fig 3.1.2 to see how to change the default material
setting. This list will be altered by the “Auto Update” feature (see Section 3.7) as more materials
become available for download. PhotoGrav does not permit the user to modify this list due to the fact
that many materials individually and specifically tested and fine tuned for the best results. While some
material parameters are modifiable by the user there are a number of parameters that are fixed during
the design and testing phase of that material. The material can also be chosen by double-clicking an
item in the list or by highlighting the material and clicking the “OK” button. The selected material will
then be displayed in the status bar at the bottom of the main application window.

Fig. 3.2.2: Material Selection Dialog

Fig. 3.2.3: Modify Material Color

The Modify Material Color dialog window (Fig. 3.2.3) can only be invoked from the Select
Material dialog window and provides the capability to the appearance of an engraving material. The
capability to modify the engraving material’s appearance enhances PhotoGrav’s usefulness in two
ways. The more important of the two ways is that it allows a broad range of solid-color plastics to be
effectively modeled by PhotoGrav. This is achieved by providing two materials both of which have a
User-Defined Cap but one of which has a white core and the other has a black core. These userdefined caps can be modified to have any solid color as will be described below. The other way that
the capability to modify the engraving material’s appearance can be useful results from the fact that
many engraving materials, although similar to those provided by PhotoGrav, might differ somewhat in
color and brightness. The capability to alter their appearance might improve the fidelity of the
simulated engravings produced by PhotoGrav.

3- 4

The material to be modified can be chosen by clicking a material item in the list in Fig. 3.2.2 and
then clicking the “Modify” button. Pressing the “Modify” button causes the Modify Material dialog
window to appear.
The controls in the “Color Adjustments” frame are used to modify the appearance of the engraving
material. The “Brightness” and “Contrast” controls affect the overall brightness and contrast of the
material for all colors equally. The “Brightness” modification can range from -100 to +100 and the
“Contrast” modification can range from -1.00 To + 1.00. The modification values can be changed only
by clicking the scrollbars, not by direct numerical entries in the textboxes.
The “Red Tint”, “Green Tint”, and “Blue Tint” scrollbars change the contrast of the respective
colors. The tint modifications can range from -1.00 to +1.00 and can be changed only by clicking the
scrollbars, not by direct numerical entries in the text boxes.
Modifications caused by the adjustments are immediately visible in the material image view
window. The “Reset” command button resets all of the scroll bars to the “no adjustment” state since
the last time this material was modified. The “Reset to Default” button resets the adjustments to the
default setting of the material, in other words to the settings of the material when originally shipped.
As an example try selecting the “User-Defined Cap/White Core” material type under plastics. And
click “Modify”. Then adjust the “Green Tint” and “Blue Tint” slider bars so that both have a value of
-1.00. Note that the effect of these values is that the material image view window turns from white to
bright red. That red color could be further adjusted by changes in the “Brightness”, “Contrast”, and
“Red Tint” scroll bars. The net result is that one can create almost any desired color for the cap of a
solid-color plastic for which the core color can be either white (in the example) or black.
3.2.4 Resize/Resample Image

Resizing and/or Resampling the original input image
(Fig 3.2.4) is almost always a requirement because one
rarely receives the image in the actual size needed for
engraving (this does vary some depending on the
engravers policies). PhotoGrav offers the ability to
resize/resample an image to the desired size without
having to depend on other outside methods. PhotoGrav
will raise a notification if it detects a discrepancy between
the selected machine resolution (dpi) and the resolution
(dpi) of the image. The image should be resampled to the
same resolution (or an integer multiple of) as the desired
engraving resolution (machine dpi setting). PhotoGrav
uses the machine settings extensively to prepare and
Fig. 3.2.4: Resize Image
simulate the image to give the user an idea, estimate, or
relative difference of what to expect when the actual
engraving is performed. Therefore, PhotoGrav does not adjust the “actual engraver” setting, which is
usually modified through the software driver that comes with the engraver, but rather only adjusts the
“machine setting” in PhotoGrav which is then used to prepare the image for engraving.

3-5

3.2.5 Final Process

The “Final Process” command button performs the actual processing necessary to produce an
image ready for the laser engraver. This button should be pressed in every case prior to saving the
image to disk. Once the “Final Process” button is clicked PhotoGrav will process the image using the
current parameter settings. After the processing is complete PhotoGrav will switch the image viewing
pane to either the “Engraved” image or the “Simulated” image determined by which image is selected
in the viewing pane toolbar (see Section 3.3, Fig 3.3.2). There will now be a total of three or four
images to use for comparison purposes in order to further fine tune the results if needed.

3.2.6 Save Image

Now that the material has been selected and the image
has been opened, resized, and processed it is ready to be
saved to disk for engraving (Fig 3.2.5). To do this simply
select the “Save Images” button on the Primary Toolbar
and save the appropriate images to disk in any of the
PhotoGrav supported file formats. The only exception is
the “Engraved” image which cannot be saved as a jpeg
Fig. 3.2.5: Save Image
due to the fact this format usually uses a lossy
compression type scheme which would create dire effects
on the engraved image. One can elect to save the images while flipping either horizontally,
vertically or both. One may find the “Flip Horizontal” check box to be turned on depending on the
material type selected due to the fact that some material types such as acrylic engrave better on the
back side, therefore requiring the image to be flipped or mirrored. This can be altered, however, by
modifying the parameters when in Interactive Mode and then saving the session as a Template Session.
After the “Save Images” dialog is opened one must select the “Exit” button to close out of this
dialog screen. The reason for this is that often it may be desirable to save more than just the
“Engraved” image so this goes into a continuous loop until all images are saved as needed.

3.2.7 Display Info

The remaining buttons on the Primary Toolbar have to do with the way information is handled and
viewed (see Fig 3.2.6). After pressing the “Display Info” button the “PhotoGrav Session Report”
window will be displayed (Fig 1.6.1). This is a formatted report, that can be viewed or printed, of the
parameter, machine, and image settings for a particular session. This report also includes thumbnail
images of the original and simulated image types. This provides an opportunity to print and file every
job performed while having quick access to all the data that was used for that job. One can also use it
to quickly view all the relevant settings for a session in a neatly organized fashion. The PhotoGrav
Session Report is also where an estimate of the engraving time can be located and any comments that
might be helpful relating to the active session.

3- 6

Fig. 3.2.6: Primary Toolbar

3.2.8 Size to Fit

The “Size to Fit” button zooms all the images to fit within the viewing panes (see Section 3.3 for
further information on Viewing Panes and Panels).

3.2.9 Split Window

The “Split Window” button toggles between viewing the images in a single or double viewing
mode (see Section 3.3 for further information on Viewing Panes and Panels).

3.3 Viewing Panes and Panels
PhotoGrav provides a few options for displaying
information about the image, session, machine,
parameter, etc. The session window is divided up into
2 primary views. The first is the “Image” view. This is
where the images are displayed and image commands
such as zoom in, zoom out, pan, etc. are performed.
Due to the numerous sizes and resolutions of existing
monitors PhotoGrav offers the ability to view the
images in either single or “split window” mode. This
allows for a larger viewing area where the images can
be cycled one at a time in single view mode or
individually selectable by pressing the corresponding
toolbar button. On the other hand it also permits one to
compare side-by-side the resulting images in split screen
mode (Fig 3.3.1).

3-7

Image View
Panel View
Fig. 3.3.1: Primary Toolbar

Fig. 3.3.3: Parameter Info

Fig. 3.3.2: Image Info

The second view that provides information is called the “Panel”
view. The “Panel” view is further divided into two subsequent
views named “Image Info” and “Parameter Info” (Fig 3.3.1). The
“Image Info” panel (Fig 3.3.2) shows basic information about the
image and the currently selected machine. The next sub panel is the
“Parameter Info” panel (Fig 3.3.3) which displays a fixed summary
of the current parameter settings. This “Parameter Info” view
changes to permit adjustments and modifications to the parameters
when in “Interactive Mode” which is discussed in Section 3.4.

Fig. 3.3.4: Hide/Show

These panel views can be hidden to again provide for larger
viewing areas as needed by selecting the appropriate toolbar button
from the PhotoGrav Session Toolbar (Fig 3.3.4).
There are four images that one can select for viewing namely
Original input, Grayscale, Engraved/binary, and the Simulated
images (Fig 3.3.5). If one has “Split Screen” selected then these
images can be selected independently per image view. To open an
image one can select the “Open Image” button on the primary
command bar. This button can be selected even if there is no
session window open in which case a new session window will be
created and the respective image inserted into that session. If, on
the other hand, an existing session is open then the selected image
will be inserted over the existing image if an image exists. In
other words, if the user already has a session open then he or she
should create a “New” session prior to opening the image to
prevent the replacement of the existing session’s image.
By left or right clicking of the mouse button in either one of
the two Image View Windows one can incrementally zoom in or
out respectively. It is also possible to drag a zoom “box” or
rectangle around the desired area for closer inspection of the
images. Another image command is the “pan” command. This
command centers the image at the point where the mouse button
was clicked. Holding down the [Space Bar] will activate this
command (Fig 3.3.6).

3- 8

Fig. 3.3.5: Image Selection

Fig. 3.3.6: Image Selection

3.4 Interactive Mode
The Interactive Mode
Fig. 3.4.1: Primary Toolbar
Button toggles between two
modes of operation. When in
“Interactive Mode” the Interactive Mode Button will show a green “i” icon indicating that
PhotoGrav is in “Interactive Mode”. Similarly when PhotoGrav is NOT in “Interactive Mode” the
button will display a red “i”.
The “Interactive Mode” is designed for the primary purpose of providing a quick and efficient
preview of the final image, since with average size images it would simply take too long to run through
the entire PhotoGrav processing pipeline every time a small change is made to a parameter. With this
in mind PhotoGrav distinguishes between “Preview” and “Final Process”. The “Final Process” button
(formerly called “Auto Process” in previous versions) takes the raw image data along with the current
material, parameter, and machine settings and completely processes the image producing the binary or
engraved image ready to be saved and engraved. On the other hand the “Preview” buttons (only
available in “Interactive Mode” - Fig 3.4.2) process a scaled version of the image (NOT THE
ORIGINAL IMAGE) suitable for rapid viewing as one adjusts and modifies the parameters in almost if
not real time.
PhotoGrav does not restrict the image view display size therefore providing a larger viewing area
for a more accurate representation of the resulting image. A larger viewing area does require more
processing speed in order to maintain real time performance. The real time performance of
interactively adjusting the parameter settings is a direct correlation to the size of the image and the size
of the display screens viewing area. Since PhotoGrav permits arbitrary screen sizes it is better
prepared to adapt to the increasing speeds of modern computers. Assuming 17” to 24” computer
monitors and current average to high end computers one can expect almost real time performance when
interacting with the parameters while in “Interactive Mode”.
Due to the plethora of monitor and
display types, resolutions, and sizes that
exist in the market place today
PhotoGrav offers a couple of options to
facilitate the advanced user who relies on
the “Interactive Mode” in their production
cycle. The first option is the “Auto
Preview” checkbox (Fig 3.4.2). This is
provided to give the user the ability to
regenerate the preview image
automatically after each parameter
adjustment without the user having to
manually click on the “Preview” buttons.
The user may select to turn this on or off
depending on the image size and/or
display screen size to increase
performance.

Fig. 3.4.2: Preview Buttons
3-9

Fig. 3.4.3: Parameter Adjustment Panel
The second option is the “Progress Bar On” checkbox (Fig 3.4.2). This checkbox offers the user the
option of increasing performance by turning this off. When the progress bar is turned off PhotoGrav
will process the “Preview” image slightly faster, however, with larger images and depending on the
speed of the users’ computer one may want to turn this on. By turning this on it gives a “heads up” as
to what PhotoGrav is doing followed by an indication when the “Preview” image is ready for display.
Once the image and parameters are determined either in “Interactive Mode” or otherwise then the user
can select the “Final Process” button to process the image. Clicking on the “Final Process” button
inherently assumes that the user is now ready to prepare and process the image for engraving and
exporting. Once the final processing is complete one can export/save the images or compare the
images to other sessions (see Section 3.5 on Cloning—Comparison of Results later on).
While working in “Interactive Mode” the user may want to restore the parameters to a previous
value. PhotoGrav provides parameter restoration at 3 different levels (Fig 3.4.3). The first is
“Restore” which restores the parameter settings of the current session to the values it carried along the
last time that the image was processed using the “Final Process” button. The second method of
restoration is “Reset To System”. This resets the parameters to the default settings of the base material
selected for that session. And finally the third level of restoring the parameters is “Reset To Last
Saved”. When one clicks this button it resets the parameters back to the settings since the PhotoGrav
Session was last saved.
It may be desirable to export or import (Fig 3.4.3) some parameter settings while in Interactive
Mode” and therefore PhotoGrav offers these capabilities through the selection of the respective
buttons. PhotoGrav allows the user to import parameter settings from version 2.xx (.prm files) or
version 3.xx and later (.pgp files), however, one can only export parameter settings in version 3.xx and
above “pgp” format. The parameters can also be exported or imported via the menu bar at the top of
the PhotoGrav Application Window.
The remaining comments in this section describe the various parameter settings and the respective
controls. PhotoGrav has five major processing functions whereby it transforms the original input
image into the Engraved and Simulated images. All processing function can be toggled on or off by
clicking on the small green or red lights beside each processing function turning the functions on or off
respectively. Furthermore, all processing functions can be quickly reset by pressing the small blue
“Reset” arrow beside each control function.
3- 10

3.4.1 Adjust Grayshade
Figure 3.4.4 displays a histogram, or distribution, of
the gray shades in the Original (input) image. The
horizontal axis ranges from zero (black) on the left to
255 (white) on the right. The height of the distribution
indicates the relative number of image elements (pixels)
that have the gray shade indicated by the corresponding
point on the horizontal axis. (If a distribution is very
“peaked” at certain gray shades, then the peaks are
truncated and other heights scaled to prevent the peaks
from totally dominating the distribution).
As an
example, for the distribution displayed in Fig. 3.4.4,
there are many more values of “white” in the image
compared to any other gray shade producing a large
spike at the very far right of the histogram. The rest of
the histogram looks to have a higher concentration of
values near the middle of the gray shaded spectrum.

Fig. 3.4.4: Adjust Grayshade Function

The left (black) and right (red) triangles below the horizontal axis specify the black and white
clipping values, respectively, for the “Adjust Grayshade” function, i.e., all grayshades to the left of the
left triangle are set to black (zero) and all grayshades to the right of the right triangle are set to white
(255) and the grayshades between are linearly scaled. The “Black” and “White” labels to the left of the
distribution specify quantitatively the black and white clipping values (45 and 255, respectively, for the
distribution in Fig. 3.4.4). The clipping values can be changed by “clicking and dragging” the
triangles. As a result, the “Black” and/or “White” quantitative values will change and the effect will
show up as a change in the Processed and simulated Image. The clipping values can also, of course, be
reset by clicking the small blue “Reset” arrow. (Note: All the engraving materials delivered with
PhotoGrav calculate the “1%” clipping values for the grayshade distribution).
The middle (yellow) triangle below the horizontal axis is the “gamma” for the gray shade transfer
function. Changing the gamma value, by clicking and dragging the triangle, has the effect of
simultaneously changing the brightness and contrast of the image. Moving the triangle to the right will
generally make the Processed Image brighter and
moving it to the left will generally make it darker.
The blue triangle (Fig 3.4.5) that slides in the
vertical direction located on the left side of the
histogram provides a scaling function so that a few
values do not dominate the graph. Note that in Figure
3.4.5 the histogram shows a much more evenly
distributed display thus far more readable. Both Figure
3.4.4 and Figure 3.4.5 are the exact same histogram but
note how the two blue vertical triangles have different
locations. By adjusting this vertical scaling triangle a
much more readable view of the image distribution is
achieved.

3 - 11

Fig. 3.4.5: Vertical Scaling

3.4.2 Enhance Edges
The “Enhance Edges” function provides the capability to
both “smooth” the image and to enhance the image’s edges.
As with the “Adjust Grayshade” function, if the green “On”
button is checked, then the function affects the image data;
otherwise, if unchecked (red), there is NO effect regardless of
the parameter settings.

Fig. 3.4.6: Enhance Edges

The “Extent” parameter pictured in Fig. 3.4.6 can be modified by entering a value directly in the
appropriate textbox (contains “9” in Fig. 3.4.6) or by clicking the associated horizontal scrollbar. The
extent parameter specifies the relative size of the area around each pixel which is then smoothed.
Small values indicate relatively little smoothing whereas large values specify relatively large
smoothing.
The “Strength” parameter specifies the degree to which edges are enhanced or emphasized . The
“Strength” parameter is controlled in a manner similar to the “Extent” parameter except that its values
range from -100% to +100% rather than 0% to 100%. Almost all of the useful settings for the
“Strength” parameter are positive but interesting effects can sometimes be achieved with negative
settings.
Although PhotoGrav automatically sets parameter values appropriate to each engraving material,
it is a good idea for you to experiment with the “Extent” and “Strength” parameter settings to get a
feel for their effect which at times can be rather dramatic. An interesting way to do this is to have the
“Simulation” ON and to turn the “Enhance Edges” function alternately ON and OFF to observe the
effect.
3.4.3 Apply Screen
The “Apply Screen” function (Fig. 3.4.7) provides the
capability to “screen” the image in preparation for
thresholding which follows this function.
Fig. 3.4.7: Apply Screen
The “Apply Screen” function actually performs a
Diffusion Dithering. Diffusion Dithering is a technique to
convert a grayshade image to a binary image (black & white only, no shades of gray) wherein the
shades of gray in the original image are represented in the processed binary image by differing
densities of black and/or white dots. Diffusion Dithering accomplishes this by converting each gray
shade in the original image to either a black or white value depending on its value relative to a
predetermined “threshold” value. The error in making this assignment is then “diffused” to
neighboring pixels which eventually are also thresholded (and then error diffused) and so forth and so
on throughout the entire image.
The Diffusion Dithering within PhotoGrav has been designed and optimized specifically for laser
engraving and is controlled by the two parameters indicated in Fig. 3.4.7: (1) ED Density and (2)
Noise Gain. (The ED stands for Error Diffusion). The “ED Density” parameter can be used to darken

3- 12

lighter areas of the processed image without substantially affecting areas that are already dark and, vice
versa, can be used to lighten darker areas of the image without substantially affecting areas that are
already light. The “Noise Gain” parameter can be used to add noise to the image to reduce
“contouring”, "repetitive pattern", or “jpeg artifacts” effects that often occur when grayshade images
are converted to binary images.
Both parameter values can be modified by clicking the scroll bars or by entering numeric values in
the white text boxes directly above each scroll bar. Relative values for the “ED Density” parameter
range from -100 (darken) to +100 (lighten). Relative values for the “Noise Gain” parameter range
from 0% (no noise) to 100% (maximum noise).
3.4.4 Apply Threshold
The “Apply Threshold” function (Fig 3.4.8) linearly
combines the last two control functions (Enhance and Screen),
pixel by pixel and with variable weights, before thresholding
the result to create an “Engraver-ready” binary image.

Fig. 3.4.8: Apply Threshold

There are two parameters associated with the “Threshold” function: (1) the “Screen %” and (2)
the “Output Threshold Level”. The first parameter, the “Screen %”, specifies how the two inputs to
the function are combined by specifying the weighting factor assigned to the input from the “Screen”
function. The weighting factor assigned to the image coming from the “Enhance” function is then equal
to (100 - Screen %) . A value of zero for this parameter specifies that the resulting data, before
thresholding, is totally from the “Enhance” function. A value of “100” for this parameter specifies that
the data, before thresholding, is totally from the “Screen” function. A value of “50” for this parameter
specifies that the two inputs are equally weighted and then combined. The “combine” portion of the
“Threshold” function is always ON, i.e., the two inputs are ALWAYS combined, before thresholding,
using the weighting factors specified by the “Screen %” factor.
The second parameter, the “Threshold Level”, specifies a threshold value which ranges from zero
to 255. The threshold value is applied to the combined output of the “Enhance” and “Screen”
functions, weighted as described above. If a combined value is less than the threshold value, then it is
assigned a zero (black). If a combined value is greater than the threshold value, then it is assigned a
one (white). The “threshold” portion of this function, unlike the “combine” portion, can be turned ON
or OFF by checking, or not checking, the green/red checkbox located to the left of the label “Threshold
Level”. If the thresholding is OFF, then the simulation function, described in the next section, cannot
be turned ON and an engraver-ready (binary) image is not produced.
Either parameter for this function can be modified by clicking the horizontal scroll bars or by
entering a numeric value in the white text boxes immediately below the scroll bars.
3.4.5 Speed and Power
The vertical scroll bars labeled “Power” and “Speed” (Fig 3.4.9) specify the percentage of
maximum power and the percentage of the maximum speed for the laser engraver currently being

3 - 13

modeled (You can change the laser engraver being modeled as well
as the specifications for any laser engraver by selecting a different
machine see Section 3.6). The “Power” and “Speed” controls
should be very similar to the controls which actually exist on your
laser engraver and should behave in the same fashion.

Fig. 3.4.9: Speed and Power

The “Maximize Power” and “Maximize Speed” (Fig 3.4.9)
checkboxes determine whether the Power setting or Speed setting
for your machine is maximized when it is necessary to modify
these settings. The necessity for modifying these settings occurs since PhotoGrav’s engraving
materials were calibrated using a specific machine; therefore the power, speed, resolution, etc. of your
machine may not match those of the “calibration” machine. PhotoGrav strives to deliver the
appropriate quantity of energy to each laser spot, based on the settings for your machine, and in so
doing has a choice of what values to use for the Power and Speed settings (generally a large number of
settings will all satisfy the energy requirement). If you are interested in engraving as fast as possible,
then the “Maximize Speed” box should be checked. If you are more comfortable with a higher Power
setting, then the “Maximize Power” box should be checked. These two boxes cannot both be checked
or unchecked at the same time so the boxes also act as toggles, i.e., if you check the “Maximize
Power” box, then the “Maximize Speed” box will automatically become unchecked and vice versa.
(Note: The effect of these checkboxes may at times appear confusing and it may at first appear to you
that they are not working properly. It is important to remember that “Maximize” is used for both
boxes to mean the maximum value for that parameter that will still result in the proper energy being
delivered to the laser spot and that maximum value may not be 100%. For example, if the “Maximize
Speed” box is checked, then it would be possible for the Power and Speed settings to be, e.g., 100%
and 65%, respectively, which might at first seem incorrect since “Speed” was to have been maximized.
However, in the example given, if the Speed is more than 65%, then inadequate energy will be
delivered to the laser spot since the Power setting cannot be more than 100% (Speeding the engraver
up delivers less energy to each spot). So, in this case, 65% is indeed the “maximum” value for the
Speed setting subject to the constraint that the proper quantity of energy is delivered to the laser spot).
3.4.6 Other Parameters
The remaining parameter settings and various other
functions are located under the “Other Parameters” group
box.
The text box labeled “Machine DPI”, containing the
value 300 in Fig 3.4.10, specifies the Engraver resolution,
NOT the image resolution, in dots per inch. The value in
this textbox is initially taken from the dpi value selected
Fig. 3.4.10: Other Parameters
from the “Machine Preferences” dialog box. It should be
noted that when changing the “Machine DPI” will only
cause the DPI setting to become the Engraver resolution for the current session. The textbox labeled
“Image DPI” is for reference only and thus cannot be altered by the user.
The “Reverse Polarity” checkbox provides the capability to set the polarity of the Engraved and
Simulation images. Positive polarity materials are those for which the laser, when on, causes the
3- 14

engraving material to become darker, e.g., most woods. Negative polarity materials are those for
which the laser, when on, causes the engraving material to become lighter, e.g., black laser brass and
acrylics. The “Mirror Image” checkbox provides the capability to “mirror-the-image” (flip left to
right) the Engraved and Simulation images. This feature is useful for materials like acrylic which are
engraved on the “back” of the engraving material but viewed from the front. For various reasons the
processed image is not shown “mirrored” in the Image Viewing Windows, but rather the Engraved and
Simulated images are flipped (by user selection) only when written to disk.
A few other options are also available such as turning the Simulation on or off as well as exporting
or importing parameters either from the current or previous versions of PhotoGrav. Refer to the
beginning of this Section (3.4) for further information on most of these settings and functions.
See Section 2.2 for a more complete discussion of the underlying rationale for the simulation
capability and how it can be an extraordinarily useful tool.

Fig. 3.5.1: Other Parameters

Fig. 3.5.2: Other Parameters

3.5 Cloning—Comparison of Results
The comparison of images whether simulated or otherwise can be an efficient time saving
procedure when it comes to preparing the image for engraving. PhotoGrav offers two different
methods by which one can compare the processed image. The first is to compare the various images
solely within a particular session (Fig 3.5.1) and second is to compare the results of two sessions with
each other (Fig 3.5.2).
3 - 15

Learning how to use the “Cloning—Image Comparison” features along with the simulation of
results should again increase productivity. While the simulation is attempting to get as close as
possible to the final results there are many variables that affect the results of the actual vs. the
simulated images. Therefore, the simulation can be thought of as a relative comparison of the
simulated images rather than an absolute final result. This essentially means that once one learns how
a particular “simulated” image compares to the actual engraved image for a specific material and
machine type; then a “relative” difference or pattern should emerge giving the user a sense of how to
adjust the parameters to improve the actual engraving. This simulation feature was significantly relied
on during the design of PhotoGrav to improve performance and efficiency.
PhotoGrav has a “Clone” function (Fig 3.5.2) to further assist in comparing processed results.
This “Clone” feature assumes that the user wants to spin off or clone another session based on the
current active session. This provides an exact duplicate of the current selected session or active
session. This provides an efficient method to quickly process another session and compare the two (if
desired) without having to go through the whole process of reopening the same image in another
session. For example, it can be helpful to compare one simulated or engraved image (session X),
where the parameters have been adjusted, with a second image (session Y) where the parameters have
NOT been modified (i.e. default material settings).

3.6 Machine Properties
The “Machine Properties” dialog
window (Fig. 3.6.1) can only be invoked
from the main application menu bar and is
used to select and modify the laser
engraver and associated parameters which
PhotoGrav is currently modeling. The
“Machine Make” frame provides the
capability for you to select your laser
engraver manufacturer and model type.
The “Machine Properties”, “Machine
Resolution”, “Machine Lens Spot Size”,
and “Machine Watts” frames provide the
capability for you to modify, add to, or
specify completely, the parameters that
essentially define the laser engraver
model.

Fig. 3.6.1: Machine Properties

The list at the top of the “Machine Model” frame displays the laser engraver machines currently
modeled by PhotoGrav including a “User Defined” machine for which you can completely specify the
engraver parameters from scratch. Each machine manufacturer in the list also provides a “Custom”
laser model type in the case where the specific model type is not known but the manufacturer is known.
In the case of the “Custom” model type all the machine properties can be defined just as in the “User
Defined Laser” case.

3- 16

Selecting a machine from the list will enter the machine’s name into the text box directly to the
right of the list along with the machine model type. It will also change all the settings to reflect which
machine type is selected.
Clicking the “Reset to Default” button will restore a machine’s parameters, to the values they had
when PhotoGrav was first installed, for whatever machine is currently selected. Any machine’s
parameters can be modified using the controls in the “Machine Properties” dialog window and, once
the “OK” button is pressed, the modified parameters become the current parameters for the machine
and are stored to disk as such when the current PhotoGrav session terminates).
The first two textboxes at the top of the “Machine Properties” frame specify the maximum power
(in watts) and the maximum speed (in inches/second) for the current laser engraver. These two values
obviously have a big influence on how PhotoGrav produces the Simulated Image. The third textbox
from the top specifies the time, in seconds, for the laser to slow down, stop, and reverse direction for
each scan line. This parameter is used only for calculating estimates of the engraving time, which are
displayed in the PhotoGrav Session Report (see Section 3.2.7). A procedure for calculating this
parameter for your particular machine is presented in Appendix 3: Calculational Procedure for
“Turn Time”.
The list displayed in the “Machine Lens Spot Size” frame contains a list of the effective laser spot
sizes (diameters in inches) for the lenses available to the simulated Laser Engraver. These are the
values that are available to PhotoGrav for creating the Simulated Image. A single click of an item in
the list only locally selects the item. When an item in the property listbox is selected two functions can
be performed, namely “Del” or “Use”. The “Del” button deletes the item from the list while the “Use”
button places that value into the associated text under the “Machine Properties” frame. Double
clicking on a list item will behave just as if the “Use” button was pressed. Also, values in the list
textbox can be Added to the list by clicking the “Add” button.
PhotoGrav adjusts itself appropriately so that the simulated engraving is as realistic as possible.
The lens that is installed on the laser engraver is the lens that should be specified in this textbox.
Generally, for photographs, the spot size corresponding to the highest-resolution is the best lens to use,
if that lens is available for your machine.
The second list is the “Machine Resolution” frame which contains a list of the resolutions (dots per
inch) available to the simulated Laser Engraver. The controls in this frame behave identically to the
controls in the “Machine Lens Spot Size” frame as
described in the paragraph above. Similarly, the
“Machine Watts” frame behaves just as the other two
similar frames.
It is important to remember that there are two
locations where the “Machine Properties” can be
selected.
The first one is located under the
File→System Defaults→Select Machine… menu
item (Fig 3.6.2). When this option is selected ONLY
THE DEFAULT MACHINE TYPE IS CHOSEN
which means that any new session that is created will

3 - 17

Fig. 3.6.2: Default Machine

use this machine type. The second method of opening
the “Machine Properties” dialog window is located in
the Session→Select Machine… menu item (Fig 3.6.3).
When this method is used ONLY THE ACTIVE
SESSION MACHINE PROPERTIES ARE MODIFIED.

Fig. 3.6.3: Select Machine

3.7 Automatic Updates
Another feature that can be very useful in
PhotoGrav is the ability for additional materials and
machine types (when available) to be added
automatically via an internet connection on any
computer that has PhotoGrav installed (Fig 3.7.1). This
does not prevent one from still saving/exporting and
loading/importing parameter files and PhotoGrav
Sessions (pgp files) for both current and previous
versions of PhotoGrav and custom configuring the
machine settings as required.
The available method to check for updates is
through the Help menu item as shown in Figure 3.7.1.
There are three main items that PhotoGrav checks for
when performing a “Check for Update” function. The
first and second are to check for any new Materials and
Machines. The third is to check for any updates to the
application. If any one of these three checks indicates a
need to update then a message listing the current vs.
latest versions available (Fig 3.7.2) appears. The updates
can then be selected to “Yes” go ahead and download or
“No” just leave it as it is.

Notes

3- 18

Fig. 3.7.1: Updates

Fig. 3.7.2: Update Notification

Troubleshooting

4.0 Introduction
This chapter consists of two parts. Section 4.1 presents solutions to problems you might
occasionally encounter when using PhotoGrav. Section 4.2 specifies how to get technical support for
any further difficulties you might have with PhotoGrav.

4.1 Solutions to PhotoGrav Problems

4.1.1.1 Problem
I click the PhotoGrav icon (the twirled star) to start PhotoGrav and absolutely nothing happens.
4.1.1.2 Solution
There is probably another copy of PhotoGrav currently running in a minimized window. Check
the Windows TaskBar for any minimized PhotoGrav icons and close any running versions that you
find. Then try again to start PhotoGrav. If this does not solve the problem, seek technical support as
specified in Sec. 4.2.

4-1

4.1.2.1 Problem
I tried to "Print" directly to my engraver from the PhotoGrav program and it did not work. Why
not?
4.1.2.2 Solution
PhotoGrav does not currently recommend trying to print directly to the specific "Printer" drivers
supplied with most laser engravers. To engrave, save PhotoGrav's "Engraved Image" to disk and use
the program that you normally use for engraving (for example, CorelDraw), to send that image to the
engraver. The "Engraved Image" produced by PhotoGrav is a binary image and should NOT be
resized nor rotated once produced.

4.1.3.1 Problem
Occasionally one of my engraved images from PhotoGrav has a funny checked pattern.
4.1.3.2 Solution
This problem is probably caused by one of two conditions: (1) Your image dpi does not match
your engraver dpi, or (2) Your image has areas of solid gray tones, a common occurrence for exported
clip art, and PhotoGrav's processing causes repetitive patterns in these solid areas.
To correct the problem: (1) Change the dpi of the input image and/or make sure the machine dpi is
set correctly OR, (2) Use the PhotoGrav "Noise Gain" function (see Sec. 3.4.3) to break up any
patterns.

4.1.4.1 Problem
The PhotoGrav installation program will not run to completion. It complains about some file not
available because it is currently being used by some other program.
4.1.4.2 Solution
Make sure that you have closed all running programs before attempting to install PhotoGrav. If
you are on a network, log off the network before beginning the installation. Novell networks in
particular seem to cause installation problems for some programs.

4-2

4.2 Technical Support
Before requesting technical support, please:

•

Check the preceding section, Sec. 4.1, for the possibility that your problem is already
addressed in that section.
Check the appropriate section of the user guide for detailed information about the
PhotoGrav component that is causing you difficulty. Chapters 2 and 3 are essentially
reference chapters and contain very detailed information that you might have overlooked
in your first perusal of the document.

•

When you have determined that you definitely need technical support, the most efficient manner in
which to receive that support is via email. The next most efficient means of requesting support is by
FAX. However, if you need an immediate response, or if the email or FAX response is for any reason
inadequate, then call one of the appropriate numbers listed below. Technical support is available
Monday through Friday, 9:00 a.m.. to 5:00 p.m. (Eastern Standard Time).
When requesting technical support, whether by email, FAX, or phone, please have available the
following information:


Your full name and the name of the registered user, if different.



Your street address, phone and fax number, and email address.



The version number and the serial number of your copy of PhotoGrav.
Both of these numbers should be available in the "About PhotoGrav" dialog box
accessible on the Help menus while executing the program. The serial number
should also be available at the bottom of page i of the PhotoGrav User Guide.



As much of the following system information for the computer you are using as
possible:
- Make and model of the machine
- Operating system
- Quantity of memory



If you are have difficulty getting good engraving results then also have your laser
engraver information ready as well (i.e. make, model, max speed, max power and the
resolution (dpi) that you are engraving). Refer to Appendix 1—Engraving Tips.



A detailed description of the problem. Please try to list the steps and conditions
which led to the problem and any error messages that were encountered.

4-3

For support with the PhotoGrav program itself, e.g., something doesn't seem to work right when
PhotoGrav is executed or some sort of error is reported during execution, contact:
Email:
Web:
FAX:
Phone:
Address:

support@imagelaz.com
www.photograv.com
(574) 534-5047
(574) 534-0906
See our web site for current address

Comments about PhotoGrav's current performance and suggestions for improvements and
additions to future versions would be appreciated and can be emailed or mailed to the address provided
on our web site at www.photograv.com.

4-4

Engraving Tips

A1.0 Introduction
This Appendix consists of Engraving "tips" which should assist you when you are ready to actually
engrave the photographs that you have processed in PhotoGrav. The tips are provided for a variety of
the most common engraving materials that are suitable for engraving photographs. The tips are
primarily "finishing tips" that should enhance the appearance of the engraved photos.

A1.1 Engraving Tips
1. Increasing the contrast on Cherry (or Maple) wood plaques.
After engraving, the use of liquid shoe polish will darken the engraved areas thus
increasing the contrast. Care must be taken to prevent dye from bleeding under the plaque
surface into the pores of the wood, permanently damaging the plaque. You will need the
following supplies:
Brown & Neutral Kiwi brand liquid shoe polish with foam applicator top
paper towels
leather chamois
water
Follow these steps for best results (first you seal it, then you dye it):
a. The cherry plaque should have a lacquered finish; it should NOT be raw wood.
b. Laser engrave the plaque dry and unmasked.
c. Wet the chamois and fold it to result in a pad that is several layers thick and about
4"x4" in size. Wring out the chamois so it is well soaked but not dripping.
d. Smooth out the chamois so it is a nice flat pad.
A1-1

e. Seal the engraving by using the NEUTRAL polish. Using the foam applicator,
liberally dab the polish on the engraving and brush around to cover all engraved
areas.
f. Immediately wipe off the excess polish with a clean pad of paper towel, quickly
followed by the wet chamois. Wipe lightly and briskly to clean the surface without
pulling lots of dye from the engraved recesses. You may need to re-fold your
chamois pad several times to maintain a clean wiping surface.
g. Let the neutral dye dry for 10 min. to seal the wood pores.
h. Repeat the same procedure with the BROWN dye to darken the photo.
Shoe dye dries quickly and it is difficult or impossible to remove stains if you go too
slowly and let it dry unevenly. Rubbing alcohol will clean some stains, but use sparingly
as it can attack some wood finishes.

2. Engraving photos on Walnut wood plaques.

Walnut is a traditional wood in the industry but it surely does not work well for photo
laser engraving since it tends to be quite dark and therefore results in very little contrast. If
your customer insists on using walnut for a photo engraving, first try to convince him/her to
let you put the photo on a separate plate like black brass or, better yet, the new Spectrum
Lights ultra thin engraving material - it works fantastically well for photo engraving. If you
do need to laser the photo into walnut, then use PhotoGrav settings for walnut that result in
higher contrast and very little, or no, dot-dither shading so the processed image looks
similar to a line drawing . Then, after engraving, use the dye procedure described in tip #1
above to attempt to get more contrast. However, use BLACK dye instead of the brown.
Also, it is not necessary to seal the engraving first (with the neutral polish) because the
walnut wood grain is tighter than cherry or maple so the polish won't bleed into the grain.

3. Engraving photos on Oak wood plaques.

Don't even waste your time trying it. Oak is very porous and has an uneven grain
hardness. These characteristics result in a very inconsistent and uneven engraving. Also, if
you try to increase contrast using the dye technique of tip #1, then the dye bleeds like crazy
under the plaque surface. Oak is light colored but the laser engraving is light also so your
photo will not show up well at all.

A1-2

4. Engraving photos on Acrylic.

Engraving on the back of the plaque, with the photo flipped left-to-right, always looks
better than engraving on the face of the plaque. (PhotoGrav automatically processes photos
for "back" engraving on acrylics unless you override the default).
Cast type acrylics produce a nice white frosty cut, but extruded acrylics (usually 1/4" and
thinner) result in engravings that are mostly clear which is usually not very good for photos.
To engrave an acrylic plaque, use very low power settings - just enough to frost the
surface on clear acrylic or remove the paint on painted acrylic (PhotoGrav automatically
sets an appropriate power value when acrylic is the selected material). Engrave the plaque
after removing the paper mask and let it dry. After it is dry, gently wipe any white dusty
residue off with a clean, dry cloth. Then polish with a different clean, dry cloth using
Novus #1 plastic polish. Spray the polish sparingly on the product and clean with the cloth.
Use a dry spot on the cloth to buff dry.

5. More ideas for engraving photos on Acrylic.

Vector cut shapes or silhouettes from clear 1/8" acrylic and then engrave portraits, or
other photographs, on the cutouts..
Laser engrave the photo, wipe it clean, and color it with permanent markers or spray
paint. Let the paint dry and then sand off the back, leaving a frosted looking background
with a color filled photo. (Note: With this technique, you would PhotoGrav-process the
image in positive polarity, not negative. PhotoGrav's default polarity for acrylic is
negative so you must override this default)
Spray paint the back of an extruded acrylic plaque before engraving. (We recommend
Krylon brand spray paint.) Laser engrave the photo through the paint. Since it is extruded
acrylic the engraving should be fairly transparent, so paint it again with another color, or
back up with a shiny piece of gold, silver, or colored metal to show through the photo.

A1-3

6. Engraving photos on Black Anodized Aluminum.

If , after engraving, the engraved areas are not very white looking, you might be using
too much power, not too little. Try a lower laser power setting. Aluminum tends to have a
narrow power response band for which the material turns nice and white. Too much power
turns the aluminum a light yellowish color. Too little power does not remove all of the
black anodized coating.
No clean up is normally needed but window cleaner works well if any is needed.

7. Engraving photos on Corian brand solid surfacing materials.
This material engraves nicely and is easy to color fill.
a. Engrave your photo.
b. Scrub out the engraving with hot soapy water and a toothbrush. Rinse thoroughly
and blow out with compressed air.
c. Let dry.
d. Dab enamel paint into the engraved areas.
e. Using a piece of card stock, squeegee the excess paint off. This action also forces
paint into the little dots in the photo.
f. Let the paint dry.
g. Wet sand with a block using 220 grit wet-dry sandpaper to remove the rest of the
paint from the face of the plaque.
h. Buff with a very fine scotch brite pad.
i. Rinse the plaque off and let it dry.
j. Polish the plaque with automotive wax or a good counter top polish like Hope's
brand polish.
This type of plaque holds up well outdoors. It provides a great alternative to cast bronze and
works well with photos also!
Alternative, indoor use only:
a. Use solid white Corian and engrave a photo or clip art
b. Use Permanent Markers to color the engraving in a rainbow of colors.
c. After the plaque is dry, it can be sanded. An easier method, however, is to wipe the
surface with a block wrapped in a paper towel that has been dampened with
rubbing alcohol.

A1-4

8. Engraving photos on Spectrum Lights marking material.

This is a newer material, with a satin brass appearance, that works exceptionally well
with PhotoGrav processed images. It is very thin, about .004", and comes with adhesive
already on the back. Engrave the material dry and unmasked at very low power.
(PhotoGrav defaults to a very low power setting for this material). No clean up is needed
after engraving.
Then, using your laser vector cutting capability, cut out the picture as an oval frame or
some other interesting shape. Then you just peel off the backing and stick it on your plaque
or anywhere. Great stuff!

9. Engraving photos on coated Laser Brass, black or colors.

Only use brass that is specifically made for laser engraving. This brass is shiny under
the coating unlike the traditional black brass that is dull gold under the surface. Engrave the
material dry and unmasked at just enough power to cleanly remove the coating and expose
the brass. A larger power setting will wash out the detail in your image because brass does
not absorb CO2 laser energy and therefore the excess energy is simply "spread" out, blowing
away the details. It is best to not polish the engraved plate very much. However, you might
want to shine the plate up using a little Pledge furniture polish on a soft, clean cloth. Most
paper towels can scratch brass plates, so it is best not to use them. If you do use paper
towels, the only ones to use are Bounty brand towels since they tend to scratch less.

10. Reducing the white/frosty appearance of some wood engravings.

This "frosted" effect is caused by the laser not fully penetrating the clear finish on a
plaque, especially in areas where there are few dithering dots. This effect can be reduced
with a product know as "Almond Stick" which can be ordered from the Fuller Brush
Company or can be found in some woodworking supply catalogs, furniture stores, or
hardware stores. After engraving, you simply dab some of this product on the plaque
surface and buff off with the palm of your hand. Most of the "white stuff" is subsequently
hidden. Almond stick also hides small nicks and dings on wood plaques.

A1-5

11. Engraving photos on Vinyl wrapped particle board plaques.
Most light colored plaques of this type are okay for engraving photos. After engraving,
the "Black dye" procedure described in tip #1 works quite well.
The melamine type laminated plaques like PDU brand Spectra-Lights work exceptionally
well for photo engraving. They accept dye and color fill readily and their surface is much
more durable than most. Quail brand melamine plaques also work quite well.
One note of caution: Some of the cheaper plaques of this type may swell up around the
engraved areas after you get them wet using the "Black dye" method. It is always wise to
test your own suppliers' plaques before you commit to any job.

We hope these finishing tips are helpful and profitable to your business. It has taken years of trial
and error, wasted materials, seminars, and talking to others at trade shows to develop these techniques
for engraving photos that work well in our shop. The tips described above are techniques we really use
in our daily production, and they do work. We continue to refine and test new ideas, but hopefully this
existing information will already save you lots of time and money. Have fun.

A1-6

Calculational Procedure for “Turn Time”

A2.0 Introduction
This Appendix presents a procedure for calculating the “Turn Time” parameter which is used in
the algorithm which estimates the time in seconds for an image to be engraved on your machine. See
Section 3.6 for a brief description of the parameter and how it should be specified in the Machine
Properties dialog window of the PhotoGrav program.
Section A2.1 describes a simple procedure which you can use to calculate the “Turn Time”.
Section A2.2 describes a somewhat more complex procedure which you can use to calculate the “Turn
Time” under more varied conditions so that you can perform some consistency checks on the
calculational procedure. Section A2.3 then presents the model used to derive the calculational
procedure and the rationale behind that model.

A2.1 Simple Procedure
This section describes a relatively simple procedure for calculating the “Turn Time” parameter.

Procedure
1. Prepare two grayshade images in a format that is acceptable for sending to your laser engraver.
Make the first image a black square that is 1" wide (along scan) by 1" high (across scan). Make the
other image a black rectangle that is 2" wide (along scan) by 1" high (across scan). Produce the
images at the same resolution that you intend to use on the laser engraver, e.g., 250 dpi would probably
be a good choice for a ULS machine and 300 dpi would probably be a good choice for an Epilog or
LMI machine.
A2-1

A. To accomplish this in CorelDraw, start CorelDraw and create a new blank page as
you would for any engraving job. Select the rectangle tool and draw a rectangle exactly
1.00” tall x 1.00” wide, approximately centered on the page (turning the snap to grid on
will make this easier). Select the pick tool and select the rectangle you just drew. Fill
the rectangle with solid black by using the paint bucket tool. Set the outline to none by
using the outline tool. Save this file as 1X1.CDR. Repeat the procedure and create a
1.00” tall x 2.00” wide image and save it as 1X2.CDR.
B. To accomplish this in Adobe PhotoShop, start PhotoShop and set the Background
color to black. Then, from the File menu, select New. In the dialog box that appears,
set the Width to 1", the Height to 1", the Resolution to 250 or 300 pixels per inch, the
Mode to Grayscale, and for the Contents select the option for "Background Color".
Then click the "OK" command button. Save the image in any format that you can send
to your engraver and give it a name so you can remember it as the 1" square. Repeat
this process to create the 2" x 1" black image.
The images you have produced should appear as depicted in Fig. A2.1.1.

Along Scan
1"

2"
Across Scan

Fig. A2.1.1: Test Images

2. Engrave each of the two images making sure that your engraver is in raster mode, not vector mode,
and that the speed is set to its maximum value (100%). Also, set the engraver resolution, r, to the same
value as that used to create both images, e.g., r = 250 dpi or r = 300 dpi. Record the time in seconds
that it takes, as measured by your engraver, to complete the engraving. Designate the time to engrave
the 1" x 1" square as T1 and the time to engrave the 2" x 1" rectangle as T2.
3. Calculate the "Turn Time" parameter, t, using the following formula:
t = (2T1 - T2) / r
where

t
T1
T2
r

=
=
=
=

"Turn Time" parameter in seconds
Time (in seconds) to engrave the 1" x 1" square
Time (in seconds) to engrave the 2" x 1" rectangle
Engraver & image resolution in dots per inch

A2-2

For example, if T1= 46 seconds, T2 = 56 seconds, and r = 250 dots per inch, then t = 0.144 seconds
and that is the number (0.144) which should be entered for the "Turn Time" parameter in the Machine
Properties dialog window as specified in Section 3.6.
4. Perform the following check to see if the measured numbers make sense. Calculate, from the
measured numbers, the maximum speed, s, for your engraver using the following formula:
s = r / (T2 - T1)

where s is measured in inches per second.

Using the same example numbers as those used in step 3, we get s = 25 inches per second for the
maximum speed of the laser engraver used to generate the samples.
If, using the numbers you have measured, the value of s is not close to the maximum speed of your
engraver as specified in your engraver documentation, then the value for the "Turn Time" parameter, t,
as calculated in Step 3 is probably not reliable and any engraving time estimates which PhotoGrav
produces are also not reliable. If engraving time estimates are important to you, then request assistance
as specified in Chapter 4.

A2.2 More Complex Procedure
The procedure described in this section is actually not any more complex than the procedure
described in Sec. A2.1 but it does require a few more variables for its specification. However, as a
result, it is considerably more general than the previous procedure and will allow you to calculate the
"Turn Time" parameter with higher precision and to perform consistency checks by measuring the
parameter under several conditions.
Procedure
1. Prepare two grayshade images in a format that is acceptable for sending to your laser engraver.
Make the first image a black rectangle that is w1 inches wide (along scan) by h1 inches high (across
scan). Make the other image a black rectangle that is w2 inches wide (along scan) by h2 inches high
(across scan). Produce the images at the same resolution that you intend to use on the laser engraver,
e.g., 250 dpi would probably be a good choice for a ULS machine and 300 dpi would probably be a
good choice for an Epilog or LMI machine. The images can be produced in CorelDraw or PhotoShop
by small modifications to the procedures described in Sec. A3.1, Steps 1A and 1B. The images you
have produced should appear as depicted in Fig. A2.2.1.

A2-3

Along Scan
w1"

w2"
Across Scan
h2"

Fig. A2.2.1: Test Images
2. Engrave each of the two images making sure that your engraver is in raster mode, not vector mode,
and that the speed is set to its maximum value (100%). Also, set the engraver resolution, r, to the same
value as that used to create both images, e.g., r = 250 dpi or r = 300 dpi. Record the time in seconds
that it takes, as measured by your engraver, to complete the engraving. Designate the time to engrave
the the first rectangle as T1 and the time to engrave the second rectangle as T2.
3. Calculate the "Turn Time" parameter, t, using the following formula:
t = (h1 x w1 x T2 - w2 x h2 x T1) / ( (w1 - w2) x r x h1 x h2 )
where

t
T1
T2
r

=
=
=
=

"Turn Time" parameter in seconds
Time (in seconds) to engrave the first rectangle
Time (in seconds) to engrave the second rectangle
Engraver & image resolution in dots per inch

For example, if w1 = 1", h1 = 2", w2 = 4", h2 = 1", T1= 90 seconds, T2 = 75 seconds, and r = 250
dots per inch, then t = 0.140 seconds and that is the number (0.140) which should be entered for the
"Turn Time" parameter in the Machine Properties dialog window as specified in Section 2.6.
4. Perform the following check to see if the measured numbers make sense. Calculate, from the
measured numbers, the maximum speed, s, for your engraver using the following formula:
s = ( r x (w2 - w1) x h1 x h2 ) / ( h1 x T2 - h2 x T1 )
where s is measured in inches per second.
Using the same example numbers as those used in step 3, we again get s = 25 inches per second for
the maximum speed of the laser engraver used to generate the samples.
If, using the numbers you have measured, the value of s is not close to the maximum speed of your
engraver as specified in your engraver documentation, then the value for the "Turn Time" parameter, t,
A2-4

as calculated in Step 3 is probably not reliable and any engraving time estimates which PhotoGrav
produces are also not reliable.
The procedure described in this section provides much more flexibility than the simple procedure
described in Sec A2.1. For example, one can use larger rectangles and/or a larger value for the
engraver and image resolutions to increase the precision of the calculated "Turn Time" parameter. Or
one can use several pairs of different-sized rectangles, calculating the parameter independently from
each pair, to determine the consistency of the calculated values. If you get inconsistent numbers for the
parameter, or if the maximum speed, s, calculated above is not close to the manufacturer's published
value, then request assistance as specified in Chapter 4.

A2.3 Calculational Model
Consider the rectangular black object in Fig. A2.3.1 which is an image which is to be engraved.

Line 1 "Turnaround" region

Line 2 "Turnaround" region

w
Fig. A2.3.1: Image to be Engraved

The width of the rectangle is "w" inches and the height of the rectangle is "h" inches. The "along
scan" direction is horizontal in Fig. A2.3.1 and the cross scan direction is vertical. Assume that the
image was created with a resolution of "r" dots per inch (dpi) and that it will be engraved at that same
resolution. The region designated "Line 1 Turnaround region" in Fig A2.3.1 is the distance that the
engraver requires, after scanning Line 1, to decelerate, move down (1/r) inches, and to then accelerate
to begin the scan for Line 2. There is one such region associated with every scan line to be engraved.
A2-5

Assume that the time, "t", that the engraver spends in this region is independent of the engraving
speed, "s", and is the same for every scan line. Then the time spent on each scan line is (w/s + t)
seconds where s is specified in inches per second, w is specified in inches, and t is given in seconds.
The number of scan lines in the rectangle of Fig. A2.3.1 is (r x h) where r is given in dots per inch and
h is measured in inches. Thus, the total time, T, to engrave the rectangle is:
T = (r x h) x (w/s + t)
Now assume that we have two rectangles to be engraved, one of dimensions w1 x h1 and the other
of dimensions w2 x h2. The total times, T1 and T2, to engrave these rectangles are given by:
T1 = (r x h1) x (w1/s + t) and
T2 = (r x h2) x (w2/s + t)
These two equations can be regarded as two equations in two unknowns, s and t (although s is
"known" from the manufacturer's literature, it provides a convenient check to regard it as an unknown).
The two equations can be solved for t and s with the following solutions:
t = (h1 x w1 x T2 - w2 x h2 x T1) / ( (w1 - w2) x r x h1 x h2 )
s = ( r x (w2 - w1) x h1 x h2 ) / (h1 x T2 - h2 x T1)
which are exactly the formulas used in Sec. A2.2. Note that the speed, s, in these equations need not be
the maximum speed of the engraver. That assumption was made in the preceding sections to simplify
the procedures and explanations.
Obviously, the "Simple Procedure" described in Section A2.1 could be simplified even more by
assuming that one does indeed know the speed of the engraver and then substituting that value of s
directly in one of the two equations and solving for t directly. In that case, one need only make and
engrave one rectangular image to determine t but this ultra simple procedure provides no consistency
check at all.
The algorithm within PhotoGrav that calculates estimated engraving times is reasonably
sophisticated in that it knows and uses the actual length of each line to be engraved (first "burn" to last
"burn") and will not "time" regions for which no engraving is to be done. However, there is a risk in
that sophistication in that, if the "printer" drivers used by a manufacturer are less sophisticated in
controlling the engraver, then PhotoGrav's time estimates could differ substantially from actual
engraving times for that particular engraver.

A2-6

PhotoGrav and Clip Art

A3.0 Introduction
This appendix describes how PhotoGrav can process clip art to create engravable images that are
really quite amazing. Although the procedure is described for color clip art from the extensive
CorelDraw collection, the procedure should be applicable to other clip art collections after appropriate
modifications.

A3.1 Procedure for CorelDraw Color Clip Art
Laser engraving the clip art from the CorelDraw collection 'as is' often produces less than
desirable results. In fact, many times the engravings are totally unacceptable. On the other hand,
following a rather simple procedure and then processing with PhotoGrav will yield reliable results
that are often quite spectacular. Adhering to this procedure, you can now offer any of the thousands of
Corel images to your customers with confidence that the final engraving will be not only acceptable
but highly appreciated as well. In addition, you will not have to spend hours tweaking the art and
possibly scrapping a lot of material in the process. If you have tried lasering some of the Corel art, you
are probably aware of some of the problems: "hidden" lines appearing in surprising areas, poor
contrast between different-colored areas, poorly defined edges, loss of detail, coarse dithering, funny
checked patterns, unpredictable shading and depth, etc. The procedure described below, using
PhotoGrav for the processing, solves all of these problems and more.
1.
2.
3.
4.
5.

Start CorelDraw and create a new blank page.
Import the desired clip art from the Corel CD. (or any other clip art source)
Resize the art to the size you want it to be for the engraving.
Draw a rectangle slightly larger than the art and center it over the art.
Select only the rectangle and set it's fill and outline to NONE.
A3-1

However, if you intend to engrave the clip art on a negative polarity material like black
brass or black painted acrylic, then it is best to fill the padding rectangle with black so that
only the clip art is engraved, not a rectangle cutout frame. Also, in this case, the rectangle
must be put BEHIND the clip art. To accomplish this:
A. Select the rectangle and fill it with solid black, no outline.
B. From the "Arrange" menu, choose "Order" and then "To Back"
(or press Shift+PgDn).
6. From the Edit menu choose "Select All" - this should select your art AND the invisible
(or black) rectangle. (the rectangle is important because it forces Corel to pad your clip
art export with a white, or black, border). If there are any other objects, or possibly a
page frame, make SURE only your art and rectangle are selected.
7. With both the art and the rectangle still selected, choose "Export" from the File menu.
8. Select the "File Type" as "Windows Bitmap (.BMP)" (or jpg, tif, png file type).
9. Give the file a name of your choice.
10. IMPORTANT: Make sure you check the "Selected Only" checkbox.
11. Click on "Export" and you will be presented with a dialog of choices for your .bmp
export. Select the following options:
Color = 256 shades of gray
Size = 1 to 1
Resolution = Custom (250 dpi for ULS machines; 300 dpi for Epilog and LMI)
Anti-aliasing = (If available in your version of Corel,
choose one of the following):
Super sampling
Normal sampling
No Anti-aliasing
"Super sampling" is the best choice since it retains more fine lines and
results in smoother details. "Normal sampling" results in good edge
smoothing but tends to fatten up fine details which are subsequently
sometimes lost. "No Anti-aliasing" is not used for most art since it often
results in jaggy edges.
12.
13.
14.
15.

Click on "OK" and a grayscale version of your clip art will be created.
Start PhotoGrav and load the .bmp image you just created.
Process the image with PhotoGrav and save the "Engraved Image".
Import this processed .bmp image back into your Corel layout and engrave it.
(IT IS VERY IMPORTANT, that you do NOT resize or rotate the processed image
after you import it back into Corel. Doing so would destroy the special dithering pattern
created by PhotoGrav.)

A3-2

Additional Tip:
Try importing a photo into CorelDraw and adding a fancy border or oval frame from the clip art
collection. Select all of this, export it as a .bmp file, and process with PhotoGrav as described above.
We have used this technique to create some really cool engravings - customers love them and will pay
top dollar for them.

Use your imagination and PhotoGrav's processing power! We would love to hear about your
creative tricks.

A3-3

A3-4

PhotoGrav Concepts and Design

A4.0 Introduction
This appendix presents the rationale behind several of PhotoGrav's concepts and, at a high level,
the design necessary to realize those concepts. The information duplicates some of the material
presented in Sec. 2.2 but provides more detail about PhotoGrav's model and about the procedures
used to tune the parameterized processing algorithms for the engraving materials.

A4.1 PhotoGrav Concepts
The objective of the PhotoGrav program is to efficiently process digitized photographs so they
can be engraved on a variety of common engraving materials with a high degree of confidence that the
engraved photographs will be acceptable products. PhotoGrav achieves this objective in the
following way:
1. It provides parameterized algorithms that have been found effective in processing photos
for engraving.
2. It provides, for many common engraving materials, the algorithm parameters that result
in near-optimal engraving for each material.
3. It provides an automated, or interactive, application of the algorithms to the subject photo
for the currently-specified engraving material.
4. It provides a simulation of the engraving process so the "engraved product" can be
inspected before it is actually engraved.
This section addresses "Basic PhotoGrav Concepts" as two major subtopics: (1) "Parameterized
Algorithms and Engraving Materials" and (2) "PhotoGrav Simulation".

A4-1

A4.1.1 Parameterized Algorithms and Engraving Materials
PhotoGrav provides four major algorithms for processing digitized photos into engravable
(binary) images: (1) Grayshade Adjustments, (2) Smoothing and Edge Enhancements, (3)
"Screening" Operations, and (4) Image/Screen Combinations and Thresholding. Each of these
algorithms has several functional components and each component is parameterized to provide a broad
range of possible effects. It is not the intent of this section to describe each algorithm and its
components (see Sec. 3.4 for detailed algorithm descriptions) but rather to describe how the algorithms
are "tuned" for each engraving material.
Basically, PhotoGrav's algorithms are "tuned" for a specific material by an iterative process
utilizing a combination of: (1) PhotoGrav's simulation capabilities (described in the next section)
and (2) experimental engravings on the specified material. An initial estimate is made, for the subject
material, of what the parameters should be for each of PhotoGrav's processing algorithms. The initial
estimate is then specified to the PhotoGrav simulation capability and the result is inspected on the
computer monitor. Adjustments are then made to the initial parameters until the simulation appears to
be near optimal for several digitized photos. The "Engraved Image" produced by PhotoGrav is then
actually engraved on the subject material and inspected. Based on the inspection, further adjustments
are made to the parameters, the simulation is repeated, and further engravings are produced. This
process is repeated until further iterations produce no perceptible improvements in the engravings.
The overall "tuning" process, although simple, is rather tedious and would be extremely difficult
without PhotoGrav's simulation capabilities.
The derived parameters for the subject material are then stored as a data set specific to that
material. When the engraving material is subsequently selected during a normal PhotoGrav session,
these parameters are accessed and loaded as the current processing parameters. The stored parameters
include flags that indicate whether or not certain special operations should be performed for the
material. For example, for black brass, a flag indicates that this is a negative-polarity material and that
the "Engraved Image" should be inverted from normal engraving polarity. Or, for black painted
acrylic, flags indicate that this is not only a negative polarity material but also that the image should be
mirrored horizontally before engraving. Any of the parameters specifying the processing for a specific
material can be readily adjusted in PhotoGrav's Interactive Process window. Adjustments can then
be saved as a "PhotoGrav Session" and used as a template as needed.

A4.1.2 PhotoGrav Simulation
Although the tuning process described above results in "near optimal" parameter settings for each
engraving material, engraving results are still often somewhat image dependent. In other words, the
settings that produce an excellent engraving for one image on a specific material might result in an
engraving that is less satisfactory for another image using the same engraving material. Further, it is
very difficult to view the raw processed image on a computer monitor and to judge from that display
whether or not the final engraving will be satisfactory. To overcome these difficulties, PhotoGrav
provides, optionally, a simulation of what the processed image will look like once it is actually
engraved on the selected material.
A4-2

PhotoGrav's simulation capability is intended to provide a WYSIWYG (What You See Is What
You Get) capability. In other words, the appearance of the simulated image on your computer monitor
should be very close to the appearance of the actual engraving produced from the processed image
(subject to some of the qualifying factors mentioned in Sec. 2.2). The simulated image is not merely an
overlay of "dots" on top of a representation of the engraving material. Rather, it is a full-fledged
simulation wherein a lens-power model, calibrated for each material, is used to calculate an effective
spot size which is then "burned" into a representation of the engraving material. The word "effective"
is emphasized in the preceding statement because the spot size that PhotoGrav uses for the simulation
is the size of the spot that the laser creates on the subject material, not just the geometric cross section
of the laser beam at the focal plane. The "effective spot size" is modeled as a two-dimensional
Gaussian curve whose height (degree of burn) and width (area of burn) are dependent on the laser's
power and speed settings, the lens, and the engraver's dpi setting relative to the image dpi. The
effective spot size is calibrated for each material by engraving test images at several power settings and
then matching the engravings to PhotoGrav's Simulated Image by adjusting the effective spot size as a
function of the previously-mentioned variables.
All simulation models contain some approximations and PhotoGrav's model is no exception.
Most of these approximations are very straightforward and require no explanation since they adhere
very closely to reality.
However, one approximation does require some explanation and that
approximation occurs when the engraver dpi does not match the image dpi. For example, suppose that
an image is digitized at 250 dpi but is to be engraved at 500 dpi. If PhotoGrav's simulated image were
to be produced at 500 dpi, then it would be four times larger than if it were produced at 250 dpi and
would take approximately four times longer to produce. So, in order to save both disk space and
execution time, PhotoGrav produces the simulated image at 250 dpi but modifies the "effective spot
size and power" so that an engraving dpi of 500 dpi is approximated. To see this effect, start
PhotoGrav, select an input image of 250 dpi (or 300 dpi), choose Black Laser Brass as the engraving
material , and "Interactive Mode" the image. Within the Interactive Mode control panel change the
Power setting to 15%. Type a value of 250 (or 300) into the “Machine DPI” and hit the “Preview”
button. Note the laser spot size in the Simulated or Engraved image. Then choose 500 (or 600) DPI
from the list and note that the spot has gotten much brighter and larger, especially in the cross scan
(vertical) dimension. These differences in the effective spot size are indicators of the approximation
that PhotoGrav uses when the engraver dpi does not match the image dpi.
As noted in Sec. 2.2, the Simulation Image might not always be a good representation of the actual
engraving produced from the processed image due to factors that vary in an unknown way. However,
if you take steps to minimize these variations and take the time to develop some skill in interpreting
PhotoGrav's Simulated image relative to your particular materials and engraver, then the simulation
can be a powerful tool in reliably creating excellent photographic engravings. This notion is what is
previously referred to as a “Relative” simulation.

A4-3

A4-4

PhotoGrav License Agreement
IMPORTANT
READ CAREFULLY BEFORE INSTALLING THE SOFTWARE. When you enter your name as required
during installation, you indicate your acceptance of the following PhotoGrav License Agreement.

This is a legal agreement between you (either an individual or an entity) and IMAGELAZ, LLC. Use of this software
constitutes acceptance of the terms of this agreement. If you do not agree to the terms of this agreement, contact
IMAGELAZ, LLC for other licensing options or promptly return the software and the accompanying items (including
written materials and binders or other containers) to IMAGELAZ, LLC or its authorized distributor from which you
received the software for a full refund.
1. GRANT OF LICENSE
The enclosed IMAGELAZ, LLC software program (the "Licensed Software") may be used only by the registered owner.
You may use one copy of the IMAGELAZ, LLC software product identified above, which includes "online" or electronic
documents (the "SOFTWARE") on a single computer. The SOFTWARE is in "use" on a computer when it is loaded into
temporary memory (i.e. RAM) or installed into permanent memory (e.g., hard disk, CD-ROM, or other storage device) of
that computer.
2. COPYRIGHT
The Licensed Software is owned by IMAGELAZ, LLC and is protected by United States copyright laws and
international treaty provisions. Therefore, you must treat the Licensed Software like any other copyrighted material (e.g., a
book or musical recording), except that you may either (i) make one copy of the Licensed Software solely for backup or
archival purposes, provided you reproduce and include IMAGELAZ, LLC's copyright and trademark notices contained on
the original disk labels on such backup copy, or (ii) transfer the Licensed Software to a single hard disk, provided you keep
the original solely for backup or archival purposes. You may not copy the written materials accompanying the Licensed
Software.
3. OTHER RESTRICTIONS
a.

You may not use, copy, or modify the files containing the licensed software, or any backup copy, in whole or in part,
or translate such files into any other file format or language, except as expressly provided for in this agreement. You
may not rent, lease or sublicense the Licensed Software, but you may transfer the Licensed Software and
accompanying written materials on a permanent basis, provided you retain no copies, the recipient agrees to the terms
of this License Agreement, immediately contacts IMAGELAZ, LLC to inform IMAGELAZ, LLC of such transfer and
pays to IMAGELAZ, LLC a transfer fee in an amount to be determined by IMAGELAZ, LLC and in effect at the time
in question. Upon such transfer, your license under this License Agreement is automatically terminated.

b. You may not reverse engineer, decompile or disassemble the Licensed Software for any purpose whatsoever.
4. TERM
Your license is effective upon payment for and the opening of the package containing the Licensed Software. You may

A5-1

terminate it at any time by destroying the Licensed Software together with all copies. It will also terminate upon conditions
set forth elsewhere in this Agreement or if you fail to comply with any term or condition of this Agreement. You agree
upon such termination to destroy all copies of the Licensed Software in any form in your possession or under your control.
5. LIMITED WARRANTY
IMAGELAZ, LLC warrants that for a period of ninety (90) days from the date of receipt, the Licensed Software will
perform substantially in accordance with the accompanying written materials. THE FOREGOING IS THE SOLE AND
EXCLUSIVE WARRANTY OFFERED BY IMAGELAZ, LLC. IMAGELAZ, LLC DISCLAIMS ALL OTHER
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH REGARD TO THE LICENSED
SOFTWARE AND ALL ACCOMPANYING MATERIALS.
6. CUSTOMER REMEDY
IMAGELAZ, LLC's entire liability and your exclusive remedy shall be, at IMAGELAZ, LLC's option, either (a) return
of the price paid, or (b) repair or replacement of the Licensed Software that does not meet IMAGELAZ, LLC's Limited
Warranty and which is returned to IMAGELAZ, LLC within the warranty period. The Limited Warranty is void if failure of
the Licensed Software has resulted from accident, abuse or misapplication. Any replacement of Licensed Software will be
warranted for the remainder of the original warranty period or thirty (30) days, whichever is longer.
7. DISCLAIMER OF DAMAGES
You assume responsibility for, among other things, (i) the selection of the Licensed Software to achieve your intended
results, (ii) the acquisition of other software (including any programming or operating system software) and/or equipment
compatible with the Licensed Software, and (iii) the installation, use and results obtained from the Licensed Software.
Further, inasmuch as the price paid for the license rights granted to you to use the Licensed Software may be substantially
disproportionate to the value of products to be used in conjunction with, or produced by, the Licensed Software, and for the
express purpose of limiting the liability against IMAGELAZ, LLC to an extent which is reasonably proportionate to the
commercial value of this transaction, you agree that, to the maximum extent permitted by law, IMAGELAZ, LLC shall in
no event be liable for any damages whatsoever (including without limitation, damages for loss of business profits, business
interruption, loss of business information, or any other pecuniary loss) arising out of the use or inability to use the Licensed
Software, whether direct, indirect, incidental, consequential, special or otherwise, REGARDLESS OF THE FORM OF
ACTION, even if IMAGELAZ, LLC has been advised of the possibility of such damages.
8. UPDATES & TECHNICAL SUPPORT
For a period of one year from the date of your receipt of the Licensed Software, IMAGELAZ, LLC will make available
to you Technical Support in the manner and under the guidelines set forth in the Licensed Software user documentation,
which may be modified from time to time by IMAGELAZ, LLC at its discretion without notice. IMAGELAZ, LLC may,
from time to time, revise or update the Licensed Software. In so doing, IMAGELAZ, LLC incurs no obligation to furnish
such revision or updates to you. Updates and further support terms are available to you on the same basis as IMAGELAZ,
LLC makes them available to its other licensees at then current prices.
9. GENERAL
a.

This License is personal between you and IMAGELAZ, LLC. It is not transferable and any attempt by you to rent,
lease, sublicense, assign or transfer any of the rights, duties or obligations hereunder, except as provided in Section 3,
above, is void. This Agreement and the conduct of the parties hereto shall be governed by the laws of the State of
Indiana.
YOU ACKNOWLEDGE THAT YOU HAVE READ THIS AGREEMENT, UNDERSTAND IT AND AGREE TO
BE BOUND BY ITS TERMS AND CONDITIONS. YOU FURTHER AGREE THAT IT IS THE COMPLETE AND
EXCLUSIVE STATEMENT OF THE AGREEMENT BETWEEN YOU AND IMAGELAZ, LLC WHICH
SUPERSEDES ANY PROPOSAL OR PRIOR AGREEMENT, ORAL OR WRITTEN, AND ANY OTHER
COMMUNICATIONS BETWEEN YOU AND IMAGELAZ, LLC OR IMAGELAZ, LLC'S AGENT(S) RELATING
TO THE LICENSED SOFTWARE.

A5-2

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