2005.03.22 17:20 "[Tiff] tif_jpeg.c and 12bit JPEG Files", by Frank
Warmerdam
Thread
2005.03.22 22:41 "Re: [Tiff] tif_jpeg.c and 12bit JPEG Files", by Bob Friesenhahn
I just verified your updates against IJG JPEG 6b (not the Mk1 version) built at 12 bits and am happy to report that it almost works! I say *almost* since the image appears as if the red and green samples have been interchanged. Trees and grass in the image are shown as red.
Hmm, odd. I tried with a 12bit jpeg encoded TIFF file with the IJG 6b code build in 12bit mode, and the colors displayed fine. I wonder if this is a platform endianness issue. Are you working on a big endian system? Can you provide your file? Unfortunately I cannot provide my test data as it is under NDA, and I can't generate data since the write paths are not working.
Unfortunately, I obtained my file under similar terms. The person who provided me with the file has likely never seen what it is supposed to look like either.
I am doing my testing on a big-endian machine. It is quite possible that there is an endianness issue. It took me a while to get to this point so I am not readily prepared to test on a little-endian machine.
As a point of reference, the pixel read rate was 1.2m pixels/second on my machine.
Bob
======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/