Hi Mattias, On 14 December 2016 at 00:20, Mattias Andrée <[email protected]> wrote: > There should also be a protocol for identifying whether a VDC have > CLUT that can be edited, and whether the compositor supports cooperative > gamma. The size and the depth of the CLUT should should also be > retrievable. Since cooperative gamma is supported, the size and depth of > the CLUT can exceed the controller’s CLUT for better results when output > filters are chained together.
'The size and depth' and 'the CLUT' are no longer applicable. Colour management units, incorporating two LUTs and a matrix (coarsely, degamma-transform-regamma) are becoming rather common now. These units can be present per-plane as well as per-output/pipe. Sometimes you have to make tradeoffs. For instance, on recent Intel hardware, you can have the matrix with 10-bit LUTs on either side with 512 entries each, or you can have the matrix with only _one_ 10-bit LUT (either pre- or post-matrix) which can now contain 1024 entries. The weighting for interpolation between entries can be programmable, and the last entry in the post-matrix LUT is used to deal with overshoot, as the matrix can produce values in the range of [-3.0,3.0]. Tegra is pretty similar, except that its indexing into the LUT is very much non-uniform; the tradeoff for simplicity is that it's a fixed 8-bit -> 12-bit LUT pre-matrix, and the reverse post-matrix; wider colour modes are not supported. NVIDIA's desktop hardware is a black box to me, but their technical marketing material (if nothing else) very strongly suggests that they have something very similar. AMD hardware (CIK, at least) has roughly the same similar functionality, except it's not supported with the open driver. The point is that I'm extremely wary of copying X11 by way of encoding this into an API; it's a truly dizzying space to even enumerate, let alone abstract. Cheers, Daniel _______________________________________________ wayland-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/wayland-devel
