Gamut Compression Implementation

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Document Workspace

Matthias Scharfenberg & Carol Payne - Working Group Co-Chairs

Alex Forsythe - ACES Technical Lead

Steve Tobenkin - ACES Adoption/Comms Lead

Discussion Area on ACESCentral Community Forum

Goals

The work completed by the Gamut Mapping Architecture group, which resulted in a scene-referred RGB Gamut Compression Algorithm, requires implementation of the algorithm in major software applications. The scope of work for the working group is as follows:

Outline baseline implementation standards and documentation

Work with software developers to ensure implementation across specialties such that productions can use the tool at scale

Our initial target software for implementation will be:

On Set: Pomfort LiveGrade

VFX: OpenColorIO

Grading/Finishing: Baselight, Resolve, Colorfront

Deliverables

Documentation detailing the implementation best practices and test materials (if applicable).

Reference implementations in at least one application for major production uses (on set, VFX, grading/finishing)

Workflow Stages

On Set

Should be tracked as an LMT in AMF

Should default to always on in on-set applications

Dailies

If used on set, should also be present in dailies media

VFX

Should not be baked into pulls

Should be treated in VFX as “pixel healing” in the comp, and should not be inverted out on return to DI

Grading/Finishing

Need a way to track VFX vs non-VFX shots, as VFX will have the gamut compression already applied

Gamut Mapping Image Submissions

Upload any image files that you think would be useful for this group to have access to for testing and development of gamut mapping solutions.

Upload link: Gamut Mapping Image Submission

Access/view the files: Gamut Mapping Image Submissions

Test images debayered to AP0 EXRS here

Documents

Working Group Proposal Form

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+ACES Gamut Compression Implementer’s Guide

+ACES 1.3 Reference Gamut Compression User Guide

Test Image

A Google Colab showing the generation of a proposed test image for implementers:

Google Colaboratory

Google Colaboratory •

Notice of Meeting - ACES Gamut Compression Implementation VWG - Meeting #17 - July 22, 2021

Here is a link to a Google Colab version of the code to generate (a slightly tweaked version of) the test pattern I showed in the meeting. It also includes CIExy plots of the original and compressed pattern. Because OpenImageIO is needed to write an ACES compliant EXR, and that will nor run in a Colab, I have commented out the OpenImageIO based lines, and added some code which uses ImageIO to write a 32-bit PIZ compressed EXR. Here is a proper ACES EXR of the test pattern, together with gamut...

community.acescentral.com

Notice of Meeting - ACES Gamut Compression Implementation VWG - Meeting #17 - July 22, 2021 • community.acescentral.com

ACES Central Post on the test image

Building on a test metric developed by the CLF VWG, the following OIIO command line will test for relative differences between unclamped linear scene-referred images:

oiiotool gc_test_image_v006_comp_ctl.exr --dup gc_test_image_v006_comp_blink.exr --absdiff --swap --abs --maxc 0.1 --div --rangecheck 0,0,0 .002,.002,.002 -o /tmp/tmp.exr

which will produce the following output if the images match:

0 < 0,0,0

0 > .002,.002,.002

2073600 within range

Past Meetings

Past meeting notes and recordings can be found below, in reverse chronological order.

Meeting #36 - 17th March 2022

​​(ARCHIVED - This group has concluded and is no longer active. This page remains here for reference only.)

​​Document Workspace

​​Goals

​​Deliverables

​​Workflow Stages

​​On Set

​​Dailies

​​VFX

​​Grading/Finishing

​​Gamut Mapping Image Submissions

​​Documents

​​Working Group Proposal Form

​​Test Image

​​Past Meetings

​​Group Norms

​​How the ACES VWG Process Works