Pekka Paalanen authored Feb 28, 2024 and Pekka Paalanen committed Mar 07, 2024

Stop special-casing the blend-to-output category, and pass it through
the same mechnisms and optimizations as all other transformations. In
the future, more curve types will be added to weston_color_transform,
meaning that blend-to-output does not always have to be a LUT. It could
become a parametric curve, which is more efficient and more precise to
compute, when VCGT does not exist.

Drop the special crafting of output_inv_eotf_vcgt LUT and replace it
with inv_eotf cms profile. inv_eotf will be combined with vcgt cms
profile as a chain as needed instead.

Blend-to-output transformations do not use a render intent, but we have
to tell cmsCreateMultiprofileTransformTHR() something, so arbitrarily
pick ICC-Absolute render intent for it.

Now all color transformations go through xform_realize_chain(), where
the documentation is improved.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>