On 2021-09-22 04:31, Pekka Paalanen wrote:
On Tue, 21 Sep 2021 14:05:05 -0400 Harry Wentland harry.wentland@amd.com wrote:
On 2021-09-21 09:31, Pekka Paalanen wrote:
On Mon, 20 Sep 2021 20:14:50 -0400 Harry Wentland harry.wentland@amd.com wrote:
...
Did anybody start any CM doc patches in Weston or Wayland yet?
There is the https://gitlab.freedesktop.org/swick/wayland-protocols/-/blob/color/unstable... we started a long time ago, and have not really touched it for a while. Since we last touched it, at least my understanding has developed somewhat.
It is linked from the overview in https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/14 and if you want to propose changes, the way to do it is file a MR in https://gitlab.freedesktop.org/swick/wayland-protocols/-/merge_requests against the 'color' branch. Patches very much welcome, that doc does not need to limit itself to Wayland. :-)
Right, I've read all that a while back.
It might be a good place to consolidate most of the Linux CM/HDR discussion, since gitlab is good with allowing discussions, we can track changes, and it's more formatting and diagram friendly than text-only email.
We also have issues tracked at https://gitlab.freedesktop.org/swick/wayland-protocols/-/issues?scope=all&am...
Pre-curve for instance could be a combination of decoding to linear light and a shaper for the 3D LUT coming next. That's why we don't call them gamma or EOTF, that would be too limiting.
(Using a shaper may help to keep the 3D LUT size reasonable - I suppose very much like those multi-segmented LUTs.)
AFAIU a 3D LUTs will need a shaper as they don't have enough precision. But that's going deeper into color theory than I understand. Vitaly would know better all the details around 3D LUT usage.
There is a very practical problem: the sheer number of elements in a 3D LUT grows to the power of three. So you can't have very many taps per channel without storage requirements blowing up. Each element needs to be a 3-channel value, too. And then 8 bits is not enough.
And those storage requirements would have a direct impact on silicon real estate and therefore the price and power usage of the HW.
Harry
I'm really happy that Vitaly is working with us on Weston and Wayland. :-) He's a huge help, and I feel like I'm currently the one slowing things down by being backlogged in reviews.
Thanks, pq