Re: [PATCH] fix jbig in tiff container

On Mon, 22 Dec 2014, Yuriy Kaminskiy wrote:

> libtiff jbig (en|de)coder supports only TIFFReadEncodedStrip (and encoder only
> supports single whole-image strip); gm tries to use either ScanlineMethod, or
> StripMethod depending on strip size in decoder, and always use ScanlineMethod in
> encoder. Decoder fails with larger samples, encoder always fails. Force
> StripMethod in tiff decoder for JBIG codec.
>
> Unsolved: encoder side.
>
> Samples for testing can be obtained by converting bi-level tiff to jbig by
> tiffcp -r -1 -c jbig in-ccitt-g4.tiff out-jbig.tiff

I had forgotten about this problem.

While the GraphicsMagick TIFF writer obviously needs a strip-writer 
(which is much more than a small patch), it seems that the problems 
are deeper since 'tiffcp' has the same problem:

% tiffcp -r -1 -c jbig golfer-150-bilevel.tiff golfer-150-bilevel-jbig.tiff
golfer-150-bilevel-jbig.tiff: ISO JBIG scanline encoding is not implemented.
golfer-150-bilevel-jbig.tiff: Error, can't write scanline 0.

I commited a possible fix for the reader issue (not able to properly 
test) via Mercurial changeset c62696363b2f.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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