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qcam: dng_writer: Generate thumbnail in RGB format

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While the DNG specification supports greyscale ("BlackIsZero") for
thumbnails, RawTherapee seems to have trouble reading them. Generate
thumbnails in RGB instead (but still with greyscale content, to avoid
having to interpolate colour components).

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
This commit is contained in:
Laurent Pinchart
2020-05-02 21:45:56 +03:00
parent 319fc87ef1
commit 2223579dfe
1 changed files with 9 additions and 5 deletions
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14
src/qcam/dng_writer.cpp
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@@ -74,7 +74,10 @@ void thumbScanlineSBGGRxxP(const FormatInfo &info, void *output,
unsigned int skip = info.bitsPerSample * 16 / 8;
for (unsigned int x = 0; x < width; x++) {
*out++ = (in[0] + in[1] + in[stride] + in[stride + 1]) >> 2;
uint8_t value = (in[0] + in[1] + in[stride] + in[stride + 1]) >> 2;
*out++ = value;
*out++ = value;
*out++ = value;
in += skip;
}
}
@@ -175,16 +178,17 @@ int DNGWriter::write(const char *filename, const Camera *camera,
TIFFSetField(tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
/*
* Thumbnail-specific tags. The thumbnail is stored as a greyscale image
* with 1/16 of the raw image resolution.
* Thumbnail-specific tags. The thumbnail is stored as an RGB image
* with 1/16 of the raw image resolution. Greyscale would save space,
* but doesn't seem well supported by RawTherapee.
*/
TIFFSetField(tif, TIFFTAG_SUBFILETYPE, FILETYPE_REDUCEDIMAGE);
TIFFSetField(tif, TIFFTAG_IMAGEWIDTH, config.size.width / 16);
TIFFSetField(tif, TIFFTAG_IMAGELENGTH, config.size.height / 16);
TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, 8);
TIFFSetField(tif, TIFFTAG_COMPRESSION, COMPRESSION_NONE);
TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_MINISBLACK);
TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, 1);
TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_RGB);
TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, 3);
TIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
TIFFSetField(tif, TIFFTAG_SAMPLEFORMAT, SAMPLEFORMAT_UINT);