ACES, the Academy Color Encoding System, is an open color management framework developed under the Academy of Motion Picture Arts and Sciences that converts footage from any camera into a common, scene-referred color space, allows grading and visual effects in that space, and produces outputs for any display through standardized transforms. In color grading for film and video, ACES provides a shared, device-independent pipeline in place of camera-specific LUTs and ad hoc conversions.
ACES is standardized in the SMPTE ST 2065 family and is supported by major grading, compositing and rendering applications. Its main promise is consistency: footage from different cameras, CG renders and archival material can be combined and delivered to SDR, HDR and cinema formats from one master.
How the ACES pipeline works
ACES organizes color into three stages. An input transform converts each camera’s log or RAW encoding into the ACES working space. Creative work happens in that space. An output transform then renders the image for a specific display, such as Rec. 709, P3 cinema projection or PQ-based HDR.
Because ACES data is scene-referred, values represent light in the scene rather than display brightness. Highlights are not clipped at a fixed white, and the system can describe a range of more than 25 stops. The display limitations are handled only at the final output stage, which keeps the master future-proof for new display technologies.
| Component | Function | Earlier or common name |
|---|---|---|
| Input transform | Converts camera encoding into ACES | IDT |
| Look modification transform | Applies a defined creative look | LMT |
| Output transform | Renders ACES for a target display | RRT combined with ODT |
| ACES Metadata File | Records the transforms used for a clip | AMF |
| Reference gamut compression | Brings extreme out-of-gamut camera colors into range | RGC |
ACES 2.0 introduced redesigned output transforms intended to give smoother highlight roll-off, better hue preservation in saturated colors and more consistent looks between SDR and HDR. Projects begun in earlier versions such as ACES 1.3 should keep a consistent version through delivery.
ACES color spaces and encodings
ACES defines several encodings for different tasks, built on two sets of primaries. AP0 encloses the entire visible spectrum and is used for archiving, while AP1 is slightly smaller, closer to Rec. 2020, and practical for rendering and grading.
| Encoding | Primaries | Transfer | Main use |
|---|---|---|---|
| ACES2065-1 | AP0 | Linear | Archiving and interchange between facilities |
| ACEScg | AP1 | Linear | CG rendering and compositing |
| ACEScc | AP1 | Pure logarithmic | Color grading |
| ACEScct | AP1 | Logarithmic with a toe | Color grading with a film-like shadow response |
| ACESproxy | AP1 | Logarithmic, integer | On-set monitoring over SDI |
Most colorists prefer ACEScct because its toe makes lift and offset controls behave like familiar log grading. Visual effects artists work in ACEScg, where linear values make light addition and blending physically correct.
ACES compared with other color management approaches
ACES is one of several ways to manage color in post-production. Its distinguishing feature is that it is open, standardized and vendor-neutral, while many alternatives are tied to a manufacturer or a single application.
| Workflow | Working space | Strength | Limitation |
|---|---|---|---|
| ACES | Standardized scene-referred spaces | Interchange across vendors and facilities | Fixed output look unless modified |
| Display-referred Rec. 709 | Display gamma and gamut | Simple and familiar | Poor for HDR and mixed sources |
| Camera LUT workflow | Camera log space | Matches manufacturer intent | Hard to mix cameras consistently |
| Application-managed wide gamut | Vendor-defined working space | Flexible tone mapping controls | Less portable between facilities |
ACES does not replace creative decisions or the need for LUTs entirely. A show LUT can still be expressed as an LMT, and a monitoring LUT on set can be derived from the same ACES transforms used later in grading.
Setting up and using ACES in a project
Adopting ACES starts with agreeing on versions and transforms across the production. The editorial, grading and visual effects teams must use the same ACES version, input transforms and output transforms, otherwise the same file will look different in each department.
| Decision | Typical choice | Reason |
|---|---|---|
| Grading working space | ACEScct | Natural behavior of grading controls |
| VFX exchange format | OpenEXR in ACES2065-1 or ACEScg | Linear data with full range |
| Archive master | ACES2065-1 OpenEXR | Standard long-term interchange |
| SDR output | Rec. 709 output transform | Broadcast and web delivery |
| HDR output | PQ output transform at 1000 nits | Common HDR mastering level |
Color decisions travel between departments as CDL values and AMF files, which record exactly which transforms were applied. This documentation is what makes ACES valuable on large productions with multiple vendors.
Limitations and common mistakes
ACES solves interchange problems but introduces its own pitfalls, especially for teams new to scene-referred workflows.
- Applying the wrong input transform, such as a different camera log curve, causes immediate color and contrast errors.
- Mixing ACES versions between departments produces subtle but visible differences in highlights and saturation.
- Double transforms, for example a camera LUT applied before the ACES input transform, distort the image.
- Grading in ACEScg makes lift and gamma controls feel unnatural compared with ACEScct.
- Expecting a neutral look: the output transform has its own contrast and highlight rendering that colorists must learn.
For small single-camera projects delivered only in SDR, ACES may add complexity without clear benefit. Its value grows with the number of cameras, vendors and delivery formats involved.
Stripped to the essentials
Every camera records color in its own way, and every screen shows color differently. ACES is a shared system that translates all footage into one common color language, lets people work on it there and then translates it correctly for each type of screen.
It works like an international airport with one common language for every traveler. People arrive from different countries, communicate in the same language inside and leave for different destinations. Nobody gets lost in translation along the way.
Where it is applied
An independent feature film is shot on two different cinema cameras plus a small action camera, and it includes about 150 visual effects shots. Without a shared system, each camera would need its own LUT and the effects vendor would receive files in inconsistent spaces. The production chooses an ACES workflow with ACEScct for grading and ACEScg for visual effects.
Each camera’s footage enters ACES through its matching input transform, so the shots already match closely before grading. The visual effects vendor returns OpenEXR files in ACES2065-1 that drop into the timeline without conversion errors. At the end, the colorist creates a cinema P3 master, an HDR PQ version and a Rec. 709 version from the same grade, with minimal trim passes for each.