If your working color space does not match the color space of your deliverables, the colors must be transformed for output. When you are manually setting up a custom chain of transforms to accomplish this, there are several transforms that can be used, depending on your working space and the desired output.
If your images are scene-linear, you can convert them to ACES 2065-1 if necessary using one of the transforms in the primaries/ directory. After that:
- If you are targeting video or digital cinema, use one of the transforms in the RRT+ODT/ directory.
- If you are targeting a film recorder, use one of the ACES_to_ADX transforms in the film/ADX/ directory.
If your images are in a log space and you are not outputting to film, first apply one of the transforms in the film/ directory to convert them to scene-linear and then continue as above.
Managing Gamut for Digital Cinema
Digital Cinema Distribution Masters (DCDMs) require images in the DCI/SMPTE X'Y'Z' color space. The RRT+ODT/ACES_to_DCI transforms produce images in this color space (with variations for different creative white points).
However, this color space is much larger than that of any real projector. A typical cinema projector has a gamut closer to that of the DCI/SMPTE reference projector (P3 primaries).
Therefore, it is sometimes desirable to limit the gamut of colors placed in the X'Y'Z' color space to that of a more representative projector. This has two advantages:
- The gamut mapping is performed by the output transform (which preserves hue) rather than by the projector (which typically clips).
- Assuming that the content was graded and approved on a projector with a typical P3 gamut, limiting the colors to that gamut assures there will be no unpleasant surprises if the content is later viewed on a device with a wider gamut.
To achieve this:
- Select the RRT+ODT for the device whose gamut you want to limit to, for example, RRT+ODT/ACES_to_P3-D60.
- Then add transforms to convert to DCI/SMPTE X'Y'Z', for example, display/projector/P3-D60_to_CIE-XYZ followed by display/DCDM/CIE-XYZ_to_DCI-D60.