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Fix explicitly srgb-tagged PNGs #448

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Merged
Tom94 merged 2 commits into from
May 27, 2026
+3 −1
Merged

Fix explicitly srgb-tagged PNGs #448

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4f37143
feat(png): write sRGB chunk on save
Tom94 May 27, 2026
fe1fea0
fix(png): broken sRGB chunk detection
Tom94 May 27, 2026
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2 changes: 1 addition & 1 deletion src/imageio/PngImageLoader.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -543,7 +543,7 @@ Task<vector<ImageData>> PngImageLoader::load(istream& iStream, const fs::path&,
resultData.nativeMetadata.chroma = rec709Chroma(); // default to Rec.709 primaries unless cHRM chunk says otherwise

int srgbIntent = 0;
const bool hasChunkSrgb = png_get_sRGB(pngPtr, infoPtr, &srgbIntent) == PNG_INFO_iCCP;
const bool hasChunkSrgb = png_get_sRGB(pngPtr, infoPtr, &srgbIntent) == PNG_INFO_sRGB;

double invGamma64 = 1.0 / 2.2;
const bool hasChunkGama = png_get_gAMA(pngPtr, infoPtr, &invGamma64) == PNG_INFO_gAMA;
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2 changes: 2 additions & 0 deletions src/imageio/PngImageSaver.cpp
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Expand Up @@ -78,6 +78,8 @@ Task<void> PngImageSaver::save(ostream& oStream, const fs::path&, span<const uin
png, info, imageSize.x(), imageSize.y(), 8, colorType, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT
);

png_set_sRGB(png, info, 3 /* absolute colorimetric */);

png_write_info(png, info);

const auto stride = (size_t)imageSize.x() * nChannels;
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