RED OPS, IPP2 Image Pipeline Stages 915 0190 Rev D

: Red 915-0190 Rev-D Red Ops, Ipp2 Image Pipeline Stages 915-0190 Rev-D RED OPS, IPP2 Image Pipeline Stages 915-0190

Open the PDF directly: View PDF .
Page Count: 2

RED DIGITAL CINEMA 34 Parker | Irvine, CA 92618 | 949.206.7900 | Red.com

1 | RED DIGITAL CINEMA Form 915-0190 Rev D – ECO 014096 (11/18)

IPP2: IMAGE PIPELINE STAGES

OVERVIEW

IPP2 (Image Processing Pipeline 2) is featured in RED® cameras with HELIUM®, MONSTRO®, GEMINI®, and

DRAGON-X™ sensors, although all RED customers can benefit in post-production with REDCINE-X PRO®

and the R3D® SDK. An image processing pipeline encompasses all the steps that take us from raw sensor

data through to a Standard Dynamic Range (“SDR”) or High Dynamic Range (“HDR”) output image.

All grading operations now occur in a single, well-defined, wide gamut log space—making them output

independent. Other image quality improvements have been made to improve the sharpness/resolution of the

demosaic and retention of highlight detail, among other enhancements.

IPP2 separates out the technical controls, which are standardized references that rarely change, from the

creative controls, which are unique to the colorist/production and often change with every shoot or clip.

Where possible, industry standard naming and specifications are also used throughout.

STAGES

STAGE

NAME

DESCRIPTION

CONTROLS

1

Primary Raw Development

Conversion to REDWideGamutRGB

Kelvin

Tint

Encode to Log3G10

ISO

Exposure Adjust

2

Grading

Grading via ASC CDL

CDL Slope, Offset, Power and

Saturation

Creative 3D LUT allows user to place creative

looks (that go beyond the scope of CDL).

Creative 3D LUT

Tools for fine-tuning existing CDL and 3D

LUT results within REDCINE-X PRO.

Contrast, Curves

3

Output Transform

Development to output color space via gamut

mapping algorithm to stop camera colors

going out-of-gamut.

Tone Map Curve (high, medium

and low contrast)

Output Color Space

Output encoding to SDR or HDR with

highlight roll-off and compression as

appropriate.

Highlight Roll-Off

HDR User Nits Limit

Output Gamma

1. PRIMARY R AW D EVELOPMENT

The primary raw development stage includes look-independent technical controls such as the demosaic,

exposure adjustments, and white balance. The first stage is the demosaic, which utilizes a new algorithm

that improves detail and sharpness, and also seeks not to exacerbate axial chromatic aberrations.

After demosaic, the camera data is still in the camera color space and is converted to REDWideGamutRGB

(RWG), a camera color space designed to encompass all colors a RED camera can generate without

clipping. To preserve camera dynamic range, the RWG image is encoded using Log3G10 which provides for

10 stops highlight extent above mid grey, which is more than sufficient for HDR output peaking at

10,000 nits or raw developments of ISO 12,800.

RED DIGITAL CINEMA 34 Parker | Irvine, CA 92618 | 949.206.7900 | Red.com

2 | RED DIGITAL CINEMA Form 915-0190 Rev D – ECO 014096 (11/18)

It is best to think of Log3G10 as a large container for image data over a very wide range of brightness levels.

The “size” of Log3G10 is large enough to avoid clipping under all reasonable circumstances, and thus it is

normal for the image to not use the entire Log3G10 range. In-camera, a log histogram would be tricky to

read as the image data would not spread across the entire width of the histogram. To avoid this issue, the

in-camera histogram is scaled so that the far right edge always represents sensor clip given the current ISO

and exposure gain settings in use.

2. GRADING

The second stage includes all the creative or stylistic adjustments to the image. CDL grading operations,

which are industry standard and well supported, form the core of this part of the pipeline. For more creative

looks than CDL can produce, a full creative 3D LUT is also supported. There are many ways this could be

used because it is placed in the pipeline at a point where the data is still RWG/Log3G10. For example:

 User curves (either luma, or R,G,B)

 Creative color transforms (like 3 strip film emulation)

 Film looks (either to match stock, or more extreme like bleach bypass)

 Secondary color correction like per-color saturation control

Although code is not provided for these 3D LUTs, they are relatively easy to create and examples of these

various looks can be provided. If additional grading needs to be performed after the CDL and 3D LUT, the

familiar Contrast and Curves tools are available in REDCINE-X PRO and applied at the end of the grading

stage.

The grading section is designed to function with both input and output data still in the RWG/Log3G10

format. This means that with careful design (if you’re making your own creative 3D LUTs) the grade will

function well for any of the Output Transform options across both SDR and HDR and the various output

color spaces.

3. OUTPUT TRANSFORM

The final stage comprises output or display-specific settings, and should therefore not be treated as part of

the creative process. The output transform converts the RWG/Log3G10 image into a standard color space

that is ready to be output through an encoding curve to a display. The first part of the transform process is

the use of a tone map curve to impart contrast to the image (this is automatically turned off for linear light

and log exports, and can be turned off if you want to do your own as part of the creative 3D LUT), followed

by the conversion of the color space with a gamut mapping process to stop out-of-gamut colors clipping

when converting to a smaller gamut.

At the end of the Output Transform, the image has highlight roll-off applied (for SDR and HDR outputs if

desired) and gamma, HDR or log encoding. For SDR, the roll-off is based on the full Log3G10 range and has

settings that allow for modifying the roll-off to work better with high key or low key scenes. For HDR, roll-off

is based upon the capabilities of the monitor. HDR highlights can be let through to the extent of the full

SMPTE2084 range of 10,000 nits, or rolled off to map in any brightness above a desired nit level.

The Output Transform stage can also be encapsulated into a 3D LUT for use in post grading applications.

When grading outside of the RED tools, the image is exported (or accessed from the R3D via the SDK, or

ProRes / DNxHD) using only the Primary Raw Development. All grading can now occur on the RWG/Log3G10

data, and the Output Transform cube can be selected to produce the desired output image.