On 2021-09-22 04:31, Pekka Paalanen wrote: > On Tue, 21 Sep 2021 14:05:05 -0400 > Harry Wentland <harry.wentland@xxxxxxx> wrote: > >> On 2021-09-21 09:31, Pekka Paalanen wrote: >>> On Mon, 20 Sep 2021 20:14:50 -0400 >>> Harry Wentland <harry.wentland@xxxxxxx> 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/color-management/color.rst > 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&utf8=%E2%9C%93&state=opened > >>> 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 >
