Colorimetry Data for Oculus HMDs¶
Published by Matthew Cutone on 14/03/2021
The version 23.0 release of the Oculus PC SDK exposes a color management API which has been made accessible through PsychXR. The purpose of the API seems to ensure that content authored to one display appears “correct” on others if color gamuts vary between them (due to different display technologies in use). Going forward, this is a feature that users of PsychXR should be aware of and consider using, since perceived colors may vary greatly across displays if not accounted for.
However, the use of this API is not the focus of this article. The new API documentation provides lots of colorimetry information about various HMDs in the Oculus product lineup. Such data may be of interest to researchers and users, so I present them here for reference.
Chromaticity Coordinates¶
The device manufacturer lists the nominal chromaticity coordinates (CIE 1931 xy) of RGB primaries and white points for their displays [1]. The values are represented in the following table:
| HMD Model | Red (xy) | Green (xy) | Blue (xy) | White Point (xy) |
|---|---|---|---|---|
| Rift CV1 | (0.666, 0.334) | (0.238, 0.714) | (0.139, 0.053) | (0.298, 0.318) |
| Rift S | (0.640, 0.330) | (0.292, 0.586) | (0.156, 0.058) | (0.156, 0.058) |
| Quest | (0.661, 0.338) | (0.228, 0.718) | (0.142, 0.042) | (0.298, 0.318) |
Below is a CIE 1931 xy chromaticity diagram showing the color models of each HMD based on the provided data. The ITU-R BT.709 color model [2] is also shown for comparison.
We see that the Quest and Rift CV1 have a considerably larger color gamut than the Rift S. This difference seems to have necessitated the addition of the color management API, as image content authored to the CV1 and Quest platforms will appear less saturated when presented on the Rift S unless colors are remapped.