AgX vs. ACES 2.0 - Blender 5.0.0 Alpha (ACES issues still not resolved)
#ACES #AgX #blender5 #colormanagement
NOTE +++ Download links to the source files of the test are at the bottom +++
After Blender 5.0.0 Alpha (commit date: 2025-09-16 00:15, hash: `d26a79b14417`) integrated ACES 2.0 with ACEScg Color Space, I transferred an old test scene from Maya to Blender 1:1 to test the output transform protocols for AgX and ACES 2.0 with EXR images rendered in the ACEScg color space.
Left top: AgX
Left bottom: AgX Punchy
Right top: ACES 2.0
Right bottom: ACES 2.0 with Reference Gamut Compression
The scene elements use a simple Principled BSDF material with a reduced white value (Linear 0.8 for RGB) and a roughness value of 1.
The area light is set to a fixed power of 0.015 and exposure of 10. The light color animation runs over 350 frames at intervals of 50 frames from R - G - B - R - RG - RB - GB - R. Rendering was done in the ACEScg color space, which benefits AgX Punchy. The colors are more saturated than in the Rec.709 color space.
The transition from blue to red in particular remains critical under ACES. The transitions from red to green and red to yellow also do not show smooth grading, but rather distinct transitions due to collapsing colors. The new ACES 2.0 protocol transforms the higher color space significantly better than the old ACES 1.3, with the ACES 1.0 SDR-video (sRGB) View Transform protocol, but there are still significant issues compared to AgX. In particular, the color shift between blue and purple remains visible. The “Reference Gamut Compression” look can mitigate the visual issues, but cannot completely eliminate them. Overall, ACES 2.0 appears more saturated than AgX, but AgX remains stable in this test with very bright, colorful light. There are no color edges by collapsing colors in the transitions. The color transitions remain soft and even, except for blue to red, where a rapid transition from top to bottom can be seen.
Conclusion:
The developers of the ACES Transform protocol still have some serious work to do. Although it has been significantly improved and refined, the ACES 2.0 ODT protocol can still be described as “broken.” My test reveals weaknesses that may not be so obvious in “normal” images and can be eliminated by color grading, but ACES is an industry standard, and the developers need to fix these issues.
Sources for testing
Blender Scene: https://drive.google.com/file/d/1ePjA...
EXR DWAB Sequence: https://drive.google.com/file/d/1N5pq...
QuickTime ProRes 4444 QX: https://drive.google.com/file/d/1AFkZ...