Re: [Libjpeg-devel-6x] Compressing 12bit JPEG with high quality triggers Bogus Huffman table definition

[Frank W. <war...@po...>]

Frank Warmerdam wrote:
> Folks,
> 
> I thought I had pretty much slain the 12bit jpeg dragon until my client
> actually tried compressing with high quality values.  At this point I
> start getting "Bogus Huffman table definition" which appears to reflect
> some sort of table size overflow.
> 
> I am wondering if anyone else is using libjpeg to compress 12bit jpeg
> data and could suggest ways of resolving this problem?
> 
> The file in question is:
> 
>   http://download.osgeo.org/gdal/data/pnm/mandril_12bit.pnm
> 
> Try compressing it like:
> 
>   cjpeg -quality 90 -outfile out.jpg mandril_12bit.pnm
> 
> after building libjpeg and cjpeg in 12bit mode of course.  If appropriate
> I can seek client funding for meaningful assistance.

Folks,

It turns out the problem was only occuring when I was adapting the optimized
huffman table, not with normal optimized huffman tables.  I found a bug in
the way I was adapting them, which I have corrected and I have updated
the 12bit default table accordingly in jcparam.c.  The issue now seems to be
resolved.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, war...@po...
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and watch the world go round - Rush    | Geospatial Programmer for Rent