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TIFF and LibTiff Mail List Archive

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2008.02.13 22:45 "[Tiff] 12 bit jpeg", by Joel Wilson
2008.02.13 23:50 "Re: [Tiff] 12 bit jpeg", by Frank Warmerdam

2008.02.13 22:45 "[Tiff] 12 bit jpeg", by Joel Wilson

I am trying to implement 12 bit jpeg and have run into some issues. I am using the mk1-branch version of libjpeg. I made some minor changes to tif_jpeg.c and jcofig.h to get it to build with visual studio 9. When I try to compress a 12 bit image I receive this error.

            JPEGLib: Missing Huffman code table entry

I found a post that suggested to change line 1345 of tif_jpeg.c from

if (sp->jpegtablesmode & JPEGTABLESMODE_HUFF )

to

            if( (sp->jpegtablesmode & JPEGTABLESMODE_HUFF &&
sp->tif->tif_dir.td_bitspersample == 8 ))

This did allow the compression to run, but the resulting image shows up as all green with some detail in the background. I am trying to match Intergraph's 12 bit jpeg compressed imagery. It appears that the problem is that my jpeg table is a third the size of when I run it with the Intergraph software. Does anyone have any suggestions?

Joel