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be more cautious enabling tiff ycbcr 

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.