Bug 1951423. Use the sRGB transfer characteristics for BT.709, BT.601, and BT.2020. r=gfx-reviewers,aosmond

That is what other apps are doing.

Differential Revision: https://phabricator.services.mozilla.com/D240850

image/Decoder.cpp

@@ -21,6 +21,7 @@ using mozilla::gfx::IntPoint;
 using mozilla::gfx::IntRect;
 using mozilla::gfx::IntSize;
 using mozilla::gfx::SurfaceFormat;
+using namespace mozilla::gfx::CICP;
 
 namespace mozilla {
 namespace image {
@@ -588,5 +589,38 @@ void Decoder::PostError() {
   }
 }
 
+/* static */
+uint8_t Decoder::ChooseTransferCharacteristics(uint8_t aTC) {
+  // Most apps, including Chrome
+  // (https://source.chromium.org/chromium/chromium/src/+/main:ui/gfx/color_space.cc;l=906;drc=2e47178120fb82aced74f8dbccf358aa13073a83),
+  // use the sRGB TC for BT.709 TC. We have a pref to provide that behaviour.
+  // Since BT.2020 uses the same TC we can also optionally use this behaviour
+  // for BT.2020.
+  const bool rec709GammaAsSrgb =
+      StaticPrefs::gfx_color_management_rec709_gamma_as_srgb();
+  const bool rec2020GammaAsRec709 =
+      StaticPrefs::gfx_color_management_rec2020_gamma_as_rec709();
+  switch (aTC) {
+    case TransferCharacteristics::TC_BT709:
+    case TransferCharacteristics::TC_BT601:
+      if (rec709GammaAsSrgb) {
+        return TransferCharacteristics::TC_SRGB;
+      }
+      break;
+    case TransferCharacteristics::TC_BT2020_10BIT:
+    case TransferCharacteristics::TC_BT2020_12BIT:
+      if (rec2020GammaAsRec709) {
+        if (rec709GammaAsSrgb) {
+          return TransferCharacteristics::TC_SRGB;
+        }
+        return TransferCharacteristics::TC_BT709;
+      }
+      break;
+    default:
+      break;
+  }
+  return aTC;
+}
+
 }  // namespace image
 }  // namespace mozilla

image/Decoder.h

@@ -580,6 +580,8 @@ class Decoder {
       RawAccessFrameRef&& aPreviousFrame);
 
  protected:
+  static uint8_t ChooseTransferCharacteristics(uint8_t aTC);
+
   /// Color management profile from the ICCP chunk in the image.
   qcms_profile* mInProfile;
 

image/decoders/nsAVIFDecoder.cpp

@@ -1746,7 +1746,8 @@ nsAVIFDecoder::DecodeResult nsAVIFDecoder::DoDecodeInternal(
       MOZ_ASSERT(tc != CICP::TransferCharacteristics::TC_UNSPECIFIED &&
                  !CICP::IsReserved(tc));
 
-      mInProfile = qcms_profile_create_cicp(cp, tc);
+      mInProfile =
+          qcms_profile_create_cicp(cp, ChooseTransferCharacteristics(tc));
     }
 
     MOZ_LOG(sAVIFLog, LogLevel::Debug,

image/decoders/nsPNGDecoder.cpp

@@ -446,7 +446,8 @@ uint32_t nsPNGDecoder::ReadColorProfile(png_structp png_ptr, png_infop info_ptr,
                    "supported\n"));
         }
 
-        mInProfile = qcms_profile_create_cicp(primaries, tc);
+        mInProfile = qcms_profile_create_cicp(
+            primaries, ChooseTransferCharacteristics(tc));
         if (mInProfile) {
           return qcms_profile_get_rendering_intent(mInProfile);
         }

image/test/reftest/color-management/reftest.list

@@ -5,3 +5,6 @@
 == invalid-whitepoint.png invalid-chrm-ref.png
 # test for bug 488955
 == trc-type.html trc-type-ref.html # Bug 1560617
+# test for bug 1951423, bt709/bt601/bt2020/bt1886
+fuzzy(0-4,0-182740) == 720p-CCWH.png 720p-CCWH_yuv444p_pc-1-13-6.avif
+fuzzy(0-16,0-268977) == 720p-CCWH.png 720p-CCWH_yuv444p_tv-1-1-1.avif