2005.03.22 17:20 "[Tiff] tif_jpeg.c and 12bit JPEG Files", by Frank Warmerdam

2005.03.22 22:28 "Re: [Tiff] tif_jpeg.c and 12bit JPEG Files", by Frank Warmerdam

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.

Performance seemed slower than expected, but then again my test image is 125MB, tiled, and multi-frame encoded (7680x13824 largest frame) so that might explain the slowness.

Did you include a writer-path in your updates?

I did no updates to the JPEGEncode() function so I would not expect it to work properly for 12bit images.

Best regards,

I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent