commit fa3c56a7d0e10e778af6bee3c2dfdd16a6687915
author Sally Qi <sallyqi@google.com> Mon Apr 04 15:46:33 2022 -0700
committer Sally Qi <sallyqi@google.com> Tue Apr 05 15:48:09 2022 -0700
tree 601893f1d3d11e39452e2685a5fde59130abe1ad
parent 6451714a234f10fe5c206319ad3cd62d00389a20

Skia HLG should scale to [0, 1] instead of [0, 12]

Bug: 224841108
Test: test HLG video on Instagram
Change-Id: Ib87d42eb23cdef48967f64ff9609aef5af34a719

libs/renderengine/skia/ColorSpaces.cpp

diff --git a/libs/renderengine/skia/ColorSpaces.cpp b/libs/renderengine/skia/ColorSpaces.cpp
index f367a84..37ff5df 100644
--- a/libs/renderengine/skia/ColorSpaces.cpp
+++ b/libs/renderengine/skia/ColorSpaces.cpp
@@ -65,7 +65,15 @@
         case HAL_DATASPACE_TRANSFER_SMPTE_170M:
             return SkColorSpace::MakeRGB(SkNamedTransferFn::kRec2020, gamut);
         case HAL_DATASPACE_TRANSFER_HLG:
-            return SkColorSpace::MakeRGB(SkNamedTransferFn::kHLG, gamut);
+            // return HLG transfer but scale by 1/12
+            skcms_TransferFunction hlgFn;
+            if (skcms_TransferFunction_makeScaledHLGish(&hlgFn, 1.f / 12.f, 2.f, 2.f,
+                                                        1.f / 0.17883277f, 0.28466892f,
+                                                        0.55991073f)) {
+                return SkColorSpace::MakeRGB(hlgFn, gamut);
+            } else {
+                return SkColorSpace::MakeRGB(SkNamedTransferFn::kSRGB, gamut);
+            }
         case HAL_DATASPACE_TRANSFER_UNSPECIFIED:
         default:
             return SkColorSpace::MakeRGB(SkNamedTransferFn::kSRGB, gamut);