ACES Computer Graphics

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ACEScg is the linear ACES variant for VFX and CGI, optimized for physically-correct rendering and compositing.

Definition

ACEScg (ACES Computer Graphics) is a linear encoding variant of ACES, specifically developed for visual effects, CGI rendering, and compositing. The linear color space allows for physically correct light calculations.

Why Linear for VFX?

Physical Correctness

Light behaves linearly in the real world
Double the amount of light = double the brightness value
Render engines calculate physically correctly

Compositing Precision

Additive blending works mathematically correctly
Motion blur, depth of field: precise results
No gamma artifacts

ACEScg in the VFX Workflow

Plate (LogC/S-Log)
 ↓ IDT → ACES
 ↓
ACEScg (linear working color space)
 ↓
 CGI Rendering in ACEScg
 ↓
 Compositing in ACEScg
 ↓
Export → Grading (ACEScct)

Comparison of ACES Variants for VFX

Task	Recommended Variant
Rendering	ACEScg
Compositing	ACEScg
Color Grading	ACEScct
Archiving	ACES2065-1

Practical Implementation

In Nuke

Read Node → OCIOColorSpace (Plate → ACEScg)
 ↓
Comp Work
 ↓
Write Node → OCIOColorSpace (ACEScg → Output)

In Maya/Houdini

Set Color Management to ACES
Rendering Space: ACEScg
Texture Input: Linearize

Challenges

Display: ACEScg looks "wrong" without a View Transform
Textures: Must be correctly linearized
Assets: All must be in the same color space

Related terms

Editing · Technique

Color Grading

Color Grading ist die kreative Farbgestaltung in der Postproduktion – der Prozess, der…

Secondary Color Correction / Selective Grading

The process of isolating and correcting specific color ranges, luminance ranges, or…

Editing · Terms

Power Window / Tracking Mask

Camera · Technique

Qualifier

Selection tool isolating image areas based on color, luminance, or saturation.

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