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jpegrutils: interpret Apple gain-map headroom as linear #491

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jpegrutils: interpret Apple gain-map headroom as linear #491

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2 changes: 1 addition & 1 deletion lib/src/jpegrutils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -258,7 +258,7 @@ class XMPXmlHandler : public XmlHandler {
stringstream ss(maxContentBoostStr);
float val;
if (ss >> val) {
*max_content_boost = exp2(val);
*max_content_boost = isApple ? val : exp2(val);
return true;
} else {
return false;
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29 changes: 28 additions & 1 deletion tests/jpegr_test.cpp
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Expand Up @@ -1712,6 +1712,33 @@ TEST(JpegRTest, writeXmpThenRead) {
EXPECT_TRUE(metadata_read.use_base_cg);
}

TEST(JpegRTest, readAppleHeadroomXmpAsLinearBoost) {
const std::string nameSpace = "http://ns.adobe.com/xap/1.0/\0";
const size_t nameSpaceLength = nameSpace.size() + 1;
const std::string xmp =
"<x:xmpmeta xmlns:x=\"adobe:ns:meta/\"><rdf:RDF "
"xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"><rdf:Description "
"xmlns:HDRGainMap=\"http://ns.apple.com/HDRGainMap/1.0/\">"
"<HDRGainMap:HDRGainMapVersion>131072</HDRGainMap:HDRGainMapVersion>"
"<HDRGainMap:HDRGainMapHeadroom>4.0</HDRGainMap:HDRGainMapHeadroom>"
"</rdf:Description></rdf:RDF></x:xmpmeta>";

std::vector<uint8_t> xmpData;
xmpData.reserve(nameSpaceLength + xmp.size());
xmpData.insert(xmpData.end(), reinterpret_cast<const uint8_t*>(nameSpace.c_str()),
reinterpret_cast<const uint8_t*>(nameSpace.c_str()) + nameSpaceLength);
xmpData.insert(xmpData.end(), reinterpret_cast<const uint8_t*>(xmp.c_str()),
reinterpret_cast<const uint8_t*>(xmp.c_str()) + xmp.size());

uhdr_gainmap_metadata_ext_t metadata;
ASSERT_EQ(getMetadataFromXMP(xmpData.data(), xmpData.size(), /*exif_data=*/nullptr,
/*exif_size=*/0, &metadata)
.error_code,
UHDR_CODEC_OK);
EXPECT_FLOAT_EQ(metadata.max_content_boost[0], 4.0f);
EXPECT_FLOAT_EQ(metadata.hdr_capacity_max, 4.0f);
}

TEST(JpegRTest, decodeApple) {
JpegR decoder;
uhdr_compressed_image_t uhdrCompressedImg;
Expand Down Expand Up @@ -1743,7 +1770,7 @@ TEST(JpegRTest, decodeApple) {
const uhdr_gainmap_metadata_t* gainmapMetadata = uhdr_dec_get_gainmap_metadata(dec);
ASSERT_NE(gainmapMetadata, nullptr);

const double headroom = fileName == kOldAppleFileName ? 8.0 : 23.1474762;
const double headroom = fileName == kOldAppleFileName ? 8.0 : 4.532783;
for (int c = 0; c < 3; ++c) {
EXPECT_EQ(gainmapMetadata->gamma[c], 1.0f);
EXPECT_EQ(gainmapMetadata->offset_sdr[c], 0.0f);
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