Can a 10-bit monitor connection preserve all tones in 8-bit sRGB gradients on a wide-gamut monitor?
- by hjb981
This question is about color management and the use of a higher color depth, 10 bits per channel (30 bits in total, resulting in 1.07 billion colors, or 1024 shades of gray, sometimes referred to as "deep color") compared to the standard of 8 bits per channel (24 bits in total, 16.7 million colors, 256 shades of gray, sometimes referred to as "true color"). Do not confuse with "32 bit color", which usually refers to standard 8 bit color with an extra channel ("alpha channel") for transparency (used to achieve effects like semi-transparent windows etc).
The following can be assumed to be in place:
1: A wide-gamut monitor that supports 10-bit input. Further, it can be assumed that the monitor has been calibrated to its native gamut and that an ICC color profile has been created.
2: A graphics card that supports 10-bit output (and is connected to the monitor via DisplayPort).
3: Drivers for the graphics card that support 10-bit output.
If applications that support 10-bit output and color profiles would be used, I would expect them to display images that were saved using different color spaces correctly. For example, both an sRGB and an adobeRGB image should be displayed correctly. If an sRGB image was saved using 8 bits per channel (almost always the case), then the 10-bit signal path would ensure that no tonal gradients were lost in the conversion from the sRGB of the image to the native color space of the monitor.
For example:
If the image contains a pixel that is pure red in 8 bits (255,0,0), the corresponding value in 10 bits would be (1023,0,0). However, since the monitor has a larger color space than sRGB, sending the signal (1023,0,0) to the monitor would result in a red that was too saturated. Therefore, according to the ICC color profile, the signal would be transformed into a different value with less red saturation, for example (987,0,0). Since there are still plenty of levels left between 0 and 987, all 256 values (0-255) for red in the sRGB color space of the file could be uniquely mapped to color-corrected 10-bit values in the monitor's native color space.
However, if the conversion was done in 8 bits, (255,0,0) would be translated to (246,0,0), and there would now only be 247 available levels for the red channel instead of 256, degrading the displayed image quality.
My question is: how does this work on Ubuntu? Let's say that I use Firefox (which is color-aware and uses ICC color profiles). Would I get 10-bit processing, thus preserving all levels of an 8-bit picture? What is the situation like for other applications, especially photo applications like Shotwell, Rawtherapee, Darktable, RawStudio, Photivo etc?
Does Ubuntu differ from other operating systems (Linux and others) on this point?
