1. The Hollywood Standard: What is the Academy Color Encoding System?
Created by the Academy of Motion Picture Arts and Sciences (AMPAS), the Academy Color Encoding System (ACES) is the universal color management framework used in major motion pictures, streaming originals (Netflix, Amazon Prime, Apple TV+), and AAA visual effects.
ACES solves the multi-camera matching challenge. In a high-budget production mixing ARRI Alexa 35, RED V-Raptor, Sony FX9, and drone cameras, each sensor captures light using unique spectral sensitivities. ACES transforms each camera's proprietary raw log output into a shared 32-bit floating-point color space using mathematical Input Device Transforms (IDTs).
2. ACEScc vs. ACEScct: The Mathematical Distinction
Colorists working inside ACES encounter two logarithmic working spaces: ACEScc (Colorist Current) and ACEScct (Colorist Current with Toe). Choosing the correct working space is fundamental to wheel grading behavior:
| Parameter | ACEScc (Pure Log) | ACEScct (Log with Toe) | Industry Application |
|---|---|---|---|
| Curve Behavior | Pure logarithmic across all stops | Logarithmic with shadow toe below -4.5 stops | VFX vs. Narrative Grading |
| Shadow Lift Wheel Response | Aggressive; lifts pure black floor linearly | Gentle; mimics traditional telecine shadow roll-off | Traditional Colorist Workflow |
| 18% Middle Gray Value | 0.413 (41.3% IRE) | 0.413 (41.3% IRE) | Universal Gray Anchor |
| Color Primaries | ACES AP1 (Working Gamut) | ACES AP1 (Working Gamut) | Optimized for Grading Operators |
| Archival Suitability | Grading workspace only | Grading workspace only | ACES 2065-1 (AP0) for Master Storage |
For 95% of digital narrative colorists, ACEScct is strongly recommended over ACEScc. The added toe prevents the Lift wheel from feeling overly sensitive, enabling smoother shadow density adjustments without unseating black levels.
Always select ACEScct instead of ACEScc when grading with three-way color wheels. The toe below -4.5 stops ensures shadow Lift adjustments mimic optical film printer lights without lifting baseline zero blacks.
3. Color Space Primaries: AP0 vs. AP1
ACES defines two distinct sets of RGB primaries:
- ACES AP0 (SMPTE ST 2065-1): A ultra-wide gamut encompassing the entire visible human chromaticity spectrum (CIE 1931 xy). Used strictly for master archival, file exchange, and visual effects interchange.
- ACES AP1 (ACEScg / ACEScc / ACEScct): A slightly restricted gamut aligned closer to modern cinema lasers and LED phosphors. Designed to prevent negative color values during grading math and computational 3D LUT filtering.
4. Output Device Transforms (ODTs): Simultaneous SDR & HDR Deliverables
One of the chief architectural triumphs of ACES is the Output Device Transform (ODT). Once a project is graded in ACEScct, mastering for Rec.709 100-nit SDR, DCI-P3 theatrical projection, and Rec.2020 1000-nit HDR (Dolby Vision) requires simply toggling the ODT node. The mathematical tone mapping handles the highlight expansion automatically.
5. Production Setup in DaVinci Resolve ACES 1.3
To configure ACES 1.3 in DaVinci Resolve Project Settings:
- Under Color Science, select ACEScc or ACEScct (version 1.3).
- Set ACES Working Space to ACEScct.
- Set ACES Output Device Transform to your calibrated mastering display (e.g. Rec.709 for standard web and television).
- In the Media Pool, right-click clips to assign appropriate camera IDTs (e.g. Sony S-Log3/S-Gamut3.Cine, ARRI LogC4, Canon C-Log3).
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