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JPG sub sampling setting

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see issue 1502
This commit is contained in:
Oliver Duis
2012-07-21 08:38:46 +02:00
parent a335c22d85
commit 98615e7f65
14 changed files with 74 additions and 14 deletions
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17
rtengine/imageio.cc
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@@ -610,7 +610,8 @@ int ImageIO::savePNG (Glib::ustring fname, int compression, volatile int bps) {
}
int ImageIO::saveJPEG (Glib::ustring fname, int quality) {
// Quality 0..100, subsampling: 1=low quality, 2=medium, 3=high
int ImageIO::saveJPEG (Glib::ustring fname, int quality, int subSamp) {
jpeg_compress_struct cinfo;
jpeg_error_mgr jerr;
@@ -650,6 +651,20 @@ int ImageIO::saveJPEG (Glib::ustring fname, int quality) {
if (quality>=0 && quality<=100)
jpeg_set_quality (&cinfo, quality, true);
cinfo.comp_info[1].h_samp_factor=cinfo.comp_info[1].v_samp_factor = 1;
cinfo.comp_info[2].h_samp_factor=cinfo.comp_info[2].v_samp_factor = 1;
if (subSamp==1) {
// Best compression, default of the JPEG library: 2x2, 1x1, 1x1 (4:1:1)
cinfo.comp_info[0].h_samp_factor=cinfo.comp_info[0].v_samp_factor = 2;
} else if (subSamp==2) {
// Widely used normal ratio 2x1, 1x1, 1x1 (4:2:2)
cinfo.comp_info[0].h_samp_factor = 2; cinfo.comp_info[0].v_samp_factor = 1;
} else if (subSamp==3) {
// Best quality 1x1 1x1 1x1 (4:4:4)
cinfo.comp_info[0].h_samp_factor=cinfo.comp_info[0].v_samp_factor = 1;
}
jpeg_start_compress(&cinfo, TRUE);
// buffer for exif and iptc markers