pixtreme-aces

ACES Color Management for pixtreme (OCIO ACES 1.2 Compliant)

Overview

pixtreme-aces provides professional ACES color management functionality for VFX and color grading workflows. It implements the Academy Color Encoding System (ACES) 1.2 standard with full GPU acceleration.

Features

• ACES 1.2 Compliance: Matrix values match OpenColorIO-Config-ACES standard
• Industry Standard Workflow: Compatible with Nuke, Houdini, Maya color pipelines
• GPU Accelerated: All operations run on CUDA-enabled GPUs via CuPy
• Type Preservation: Seamlessly works with both NumPy and CuPy arrays

Installation

Requirements:

• Python >= 3.12
• CUDA Toolkit 12.x
• NVIDIA GPU with compute capability >= 6.0

pip install pixtreme-aces

Requires pixtreme-core and CUDA Toolkit 12.x.

Quick Start

import pixtreme_aces as aces
import pixtreme_core as px

# Read display-referred image (Rec.709/sRGB)
img = px.imread("input.jpg")

# Convert to ACES2065-1 (scene-referred, linear AP0)
aces_img = aces.rec709_to_aces2065_1(img)

# Work in ACES color space
# ... color grading, compositing, etc.

# Convert back to Rec.709 for display
output = aces.aces2065_1_to_rec709(aces_img)

px.imwrite("output.jpg", output)

Color Space Conversions

ACES Working Spaces

• ACES2065-1: Archive format (linear AP0, wide gamut)
• ACEScg: CG/VFX working space (linear AP1)
• ACEScct: Grading space (log-encoded AP1)

# ACES2065-1 ↔ ACEScg
acescg = aces.aces2065_1_to_acescg(aces_img)
aces_img = aces.acescg_to_aces2065_1(acescg)

# ACES2065-1 ↔ ACEScct
acescct = aces.aces2065_1_to_acescct(aces_img)
aces_img = aces.acescct_to_aces2065_1(acescct)

Transfer Functions

The IEC 61966-2-1 sRGB and ITU-R BT.1886 transfer functions are available as independent building blocks. BT.1886 supports configurable display white and black luminance through L_w and L_b.

# sRGB signal ↔ linear light
linear = aces.srgb_eotf(img)
encoded = aces.srgb_inverse_eotf(linear)

# BT.1886 signal ↔ normalized display luminance
linear = aces.bt1886_eotf(img, L_w=100.0, L_b=0.1)
encoded = aces.bt1886_inverse_eotf(linear, L_w=100.0, L_b=0.1)

ACES AP0 and CIE XYZ

Low-level matrix transforms convert between ACES2065-1 AP0 and CIE XYZ with a D60 white point.

xyz_d60 = aces.ap0_to_xyz_d60(aces_img)
aces_img = aces.xyz_d60_to_ap0(xyz_d60)

All conversions above accept NumPy and CuPy arrays, preserve the input array kind and shape, and normalize computation to float32 without clipping scene-referred values.

References

• ACES Central
• ACES Technical Documentation
• OpenColorIO-Config-ACES
• SMPTE ST 2065-1: ACES2065-1 specification

License

MIT License - see LICENSE file for details.

ACES® is a trademark of the Academy of Motion Picture Arts and Sciences (A.M.P.A.S.). This software is not endorsed by A.M.P.A.S.

Links

• Repository: https://github.com/sync-dev-org/pixtreme