AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

2008.08.27 19:32 "[Tiff] TIFFReadScanline doesn't work at all for subsampled YCbCr JPEG data", by Tom Lane

I'd be interested in getting comments on http://bugzilla.maptools.org/show_bug.cgi?id=1936

Although TIFFReadScanline is documented not to work for fetching subsampled data as such, it ought to work for data that's been converted back to RGB, as tiff2ps requests libtiff to do. The problem basically is that too many decisions are made before the

        TIFFSetField(tif, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB);

call and never revisited. The check-ycbcr-subsampling kluge is definitely making things worse, but it fails even without that.

Years ago I might've been able to fix this myself, but I no longer grok libtiff well enough; can anyone help?

                        regards, tom lane