(2018-02-04, 18:28)fritsch Wrote: Kodi's visuals on X11 are 8 bit only. So whatever you think you get out to the TV is something you are imaginating. Kodi renders in OpenGL which means it needs to do a transformation to sRGB while keeping all the clibber BT601/709/2020 and additional undoing certain non linear transformations.
How did you actually output 10 bit on your linux machine? Can you tell us?
Edit: With even the transformation wrong (until some days ago) I think the LUT you used just gave you some "contrast effect" but should be far away from the real values that you would get.
Thx for pointing out the 8 Bit issue. I wasn't aware of it and I will look into that. My X11-log indeed tells me 24 Bits, so that would translate to 8 bits for each channel, correct? Funny thing is, my Projector tells me 12 Bits, so I trusted that. I will ask Florian Höch, the writer of displaycal about that. He seems to know a lot about the inner workings of all things color in Linux. He was the one to tell me, the LUT creation from Rec.2020 to DCI-P3 was done the right way and the result is what I would have expected. A very much better picture.
Anyway, what I am seeing are the correct colors and due to less bits probably little to no HDR-Effect. The colors are correct, because the LUT is based upon a measurement, so displaycal expects a certain color and manipulates the LUT to output as close as possible to that. Displaycal tells me I get ninetysomething percent of the DCI-P3 color range.
To my understanding a colorspace is not dependent on bitdepth but to the correct color coordinates, so that should work fine with 8 bits as well. It might be that the resolution of these coordinates suffers from 8 bits but the corners of the triangle should be up to spec.
Gamma should also be correct, because again it is measured and corrected to match the expected curve.
Well, this Rec.2020+HDR stuff all rather new to me so there is a ton of stuff to look into and learn.. Isn't that the fun part?
