Users of ACES are experiencing problems with clipping of colors and the resulting artifacts(loss of texture, intensification of color fringes). This clipping occurs at two stages in the pipeline.
Conversion from camera raw RGB or from the manufacturer’s encoding space into ACES AP0
Conversion from ACES AP0 into the working color space ACES AP1
Scope
The scope of work for the working group is as follows:
Propose transforms between color spaces that avoid or reduce color clipping. Solutions for this may include:
Proposing a suitable color encoding space for digital motion-picture cameras.
Proposing a suitable working color space.
Propose a suitable gamut mapping/compression algorithm that performs well with wide gamut, high dynamic range, scene referred content that is robust and invertible.
Anticipated Deliverable(s)
Documentation detailing the group’s research and findings around gamut recommendations, based on real-world and CG content.
New proposed gamut standards(if changing)
New recommendation for a gamut mapping algorithm(if applicable)
Contains 5 different compression function methods: log, reinhard, exp, arctan, tanh
. Here is a comparison plotting the difference of the curve shoulder with a threshold at 0.7 and the y=1 intersect at 1.5. In the user interface these options are sorted by how aggressive the curve is starting with the lowest.
atan - Arc tangent compression curve. Has C2 continuity(that is, the 2nd derivative of the curve is smooth
tanh - Hyperbolic tangent compression curve. Has C2 continuity. Very aggressive slope, has issues with inverse transform the farther the max distance limit is set.
Document Workspace
Problem
Scope
Anticipated Deliverable(s)
Documents
+Progress Report, ACES Gamut Mapping Virtual Working Group
Gamut Mapping Image Submissions
Gamut Mapping Algorithm WIPs