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be more cautious enabling tiff ycbcr

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we were turning on ycbcr for all jpeg tiffs and relying on the jpeg
compressor to only use it when possible ... now just turn on ycbcr for
8-bit RGB images
This commit is contained in:
John Cupitt 2012-08-07 12:17:25 +01:00
parent 4cb63cf1ba
commit a9c7a36670
2 changed files with 29 additions and 16 deletions
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1
ChangeLog
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@ -4,6 +4,7 @@
overlap now matches the openslide writer
- wrap VipsInterpolate for C++
- so affinei and affinei_all appear in Python
- be more cautious enabling YCbCr mode in tiff write
20/7/12 started 7.30.0
- support "rs" mode in vips7

44
libvips/foreign/vips2tiff.c
View File

@ -131,6 +131,8 @@
* 2/6/12
* - copy jpeg pyramid in gather in RGB mode ... tiff4 doesn't do ycbcr
* mode
* 7/8/12
* - be more cautious enabling YCbCr mode
*/
/*
@ -458,15 +460,9 @@ write_tiff_header( TiffWrite *tw, TIFF *tif, int width, int height )
TIFFSetField( tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT );
TIFFSetField( tif, TIFFTAG_COMPRESSION, tw->compression );
if( tw->compression == COMPRESSION_JPEG ) {
if( tw->compression == COMPRESSION_JPEG )
TIFFSetField( tif, TIFFTAG_JPEGQUALITY, tw->jpqual );
/* Enable rgb->ycbcr conversion in the jpeg write. See also
* the photometric selection below.
*/
TIFFSetField( tif, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB );
}
if( tw->predictor != VIPS_FOREIGN_TIFF_PREDICTOR_NONE )
TIFFSetField( tif, TIFFTAG_PREDICTOR, tw->predictor );
@ -515,6 +511,9 @@ write_tiff_header( TiffWrite *tw, TIFF *tif, int width, int height )
case 3:
case 4:
/* could be: RGB, RGBA, CMYK, LAB, LABA, generic
* multi-band image.
*/
if( tw->im->Type == VIPS_INTERPRETATION_LAB ||
tw->im->Type == VIPS_INTERPRETATION_LABS )
photometric = PHOTOMETRIC_CIELAB;
@ -524,12 +523,16 @@ write_tiff_header( TiffWrite *tw, TIFF *tif, int width, int height )
TIFFTAG_INKSET, INKSET_CMYK );
}
else if( tw->compression == COMPRESSION_JPEG &&
tw->im->Bands == 3 )
tw->im->Bands == 3 &&
tw->im->BandFmt == VIPS_FORMAT_UCHAR ) {
/* This signals to libjpeg that it can do
* YCbCr chrominance subsampling from RGB, not
* that we will supply the image as YCbCr.
*/
photometric = PHOTOMETRIC_YCBCR;
TIFFSetField( tif, TIFFTAG_JPEGCOLORMODE,
JPEGCOLORMODE_RGB );
}
else
photometric = PHOTOMETRIC_RGB;
@ -538,9 +541,12 @@ write_tiff_header( TiffWrite *tw, TIFF *tif, int width, int height )
v[0] = EXTRASAMPLE_ASSOCALPHA;
TIFFSetField( tif, TIFFTAG_EXTRASAMPLES, 1, v );
}
break;
case 5:
/* Only CMYKA
*/
if( tw->im->Type == VIPS_INTERPRETATION_CMYK ) {
photometric = PHOTOMETRIC_SEPARATED;
TIFFSetField( tif,
@ -1358,16 +1364,22 @@ tiff_copy( TiffWrite *tw, TIFF *out, TIFF *in )
if( tw->compression == COMPRESSION_JPEG ) {
TIFFSetField( out, TIFFTAG_JPEGQUALITY, tw->jpqual );
/* Enable rgb->ycbcr conversion in the jpeg write. See also
* the photometric selection below.
/* Only for three-band, 8-bit images.
*/
TIFFSetField( out, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB );
if( tw->im->Bands == 3 &&
tw->im->BandFmt == VIPS_FORMAT_UCHAR ) {
/* Enable rgb->ycbcr conversion in the jpeg write.
*/
TIFFSetField( out,
TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB );
/* And we want ycbcr expanded to rgb on read. Otherwise
* TIFFTileSize() will give us the size of a chrominance
* subsampled tile.
*/
TIFFSetField( in, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB );
/* And we want ycbcr expanded to rgb on read. Otherwise
* TIFFTileSize() will give us the size of a chrominance
* subsampled tile.
*/
TIFFSetField( in,
TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB );
}
}
/* We can't copy profiles :( Set again from TiffWrite.