Revert "Check that the gain map metadata is valid on decoding. (AOMed…

…iaCodec#2453)"

I had forgotten to merge it and merged it after a couple of weeks
thinking it would be fine because github was green but it broke.

This reverts commit 5b6fe91.

src/read.c

@@ -2028,11 +2028,6 @@ static avifResult avifParseToneMappedImageBox(avifGainMap * gainMap, const uint8
     if (writerVersion <= supportedMetadataVersion) {
         AVIF_CHECKERR(avifROStreamRemainingBytes(&s) == 0, AVIF_RESULT_INVALID_TONE_MAPPED_IMAGE);
     }
-
-    if (avifGainMapValidateMetadata(gainMap, diag) != AVIF_RESULT_OK) {
-        return AVIF_RESULT_INVALID_TONE_MAPPED_IMAGE;
-    }
-
     return AVIF_RESULT_OK;
 }
 #endif // AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP

tests/data/README.md

@@ -654,18 +654,6 @@ Source : same as seine_sdr_gainmap_srgb.avif before commit 10b7232
 An image with a `tmap` item (i.e. a gain map) but no 'tmap' brand in the `ftyp` box.
 The gain map should be ignored by the decoder since the `tmap` brand is missing.
 
-### File [seine_sdr_gainmap_gammazero.avif](seine_sdr_gainmap_gammazero.avif)
-
-![](seine_sdr_gainmap_gammazero.avif)
-
-License: [same as libavif](https://github.com/AOMediaCodec/libavif/blob/main/LICENSE)
-
-Source : same as seine_sdr_gainmap_srgb.avif generated with a modified avifenc that
-writes 0 instead of the gain map gamma numerator.
-
-An image with a gain map where the gain map gamma value is zero (invalid).
-
-
 ### File [seine_sdr_gainmap_big_srgb.avif](seine_sdr_gainmap_big_srgb.avif)
 
 ![](seine_sdr_gainmap_big_srgb.avif)

tests/gtest/avifgainmaptest.cc

@@ -928,21 +928,6 @@ TEST(GainMapTest, DecodeInvalidFtyp) {
   ASSERT_EQ(decoded->gainMap, nullptr);
 }
 
-TEST(GainMapTest, DecodeInvalidGamma) {
-  const std::string path =
-      std::string(data_path) + "seine_sdr_gainmap_gammazero.avif";
-  ImagePtr decoded(avifImageCreateEmpty());
-  ASSERT_NE(decoded, nullptr);
-  DecoderPtr decoder(avifDecoderCreate());
-  ASSERT_NE(decoder, nullptr);
-  decoder->enableDecodingGainMap = true;
-  decoder->enableParsingGainMapMetadata = true;
-  // Fails to decode: the gain map is ignored because the gain map gamma is zero
-  // (invalid).
-  ASSERT_EQ(avifDecoderReadFile(decoder.get(), decoded.get(), path.c_str()),
-            AVIF_RESULT_INVALID_TONE_MAPPED_IMAGE);
-}
-
 #define EXPECT_FRACTION_NEAR(numerator, denominator, expected)     \
   EXPECT_NEAR(std::abs((double)numerator / denominator), expected, \
               expected * 0.001);