tree 303f0defa401832a661d3449781e44fec057a832
parent a58dfb3b43532dbda18030f7cf24d79d2e49e634
author Christopher Cameron <ccameron@chromium.org> 1756328225 +0200
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> 1756388680 -0700

skcms_Transform: Add HLG OOTF

The full transform for HLG applies an opt-optical transfer function, and
reaches a peak value of 1000/203. This was avoided in the past due to
complexity.

Add this step. Unlike the formulation in SkColorSpace, perform this step
in the XYZD50 linear space, and fuse it with the scaling. This greatly
simplifies the pipeline (and SkColorSpace will probably be changed to
match this).

Add tests (using test pixel values from a WPT test) to verify the
transformation between sRGB, Rec2100PQ, and Rec2100HLG all perform
appropriately.

Bug: skia:420956739
Change-Id: Iafd6f19317b8c210bbac51c8ea2cdedaac7c4a78
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/1046556
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Christopher Cameron <ccameron@google.com>
Commit-Queue: Christopher Cameron <ccameron@google.com>