Re: Strange effects when just changing sizes (gmh: message 2 of 20)

On Sun, 17 May 2015, [email protected] wrote:
>
>> Since I am not able to reproduce the problem, I am suspecting a build
>> problem.
>
> I'll try to build from sources to verify. How could I create a simple file
> similar to my source.tif? If it's a bug in the debian package I'd like to write
> a proper bugreport...

In order to write a proper bug report, you should decompose your 
complex command into the most minimum command which causes the 
problem.  See if

    gm convert source.tif -crop 640x480+0+0 nsource.tif

results in a smaller input file which also exibits the problem.

Since you are changing the compression from ZIP to LZW, check that

    gm convert source.tif -compress LZW result.tif

is not already enough to exibit the problem.  If so, then try 
'-compress zip' and if that works, then LZW is related to the problem.

Take your complex command and remove elements (compression request, 
-geometry request, -gravity request, -resize request, etc.) and see 
when (and if) the problem goes away.

Regardless, Debian is very conservative and they continue testing old 
versions as if they improve with time like fine wine.  There is only 
one known regression in 1.3.21 vs 1.3.20 (related to reading BMP 
format), and 1.3.21 is more secure against intentionally corrupted 
files.

I did run your command under 'valgrind' and it did not reveal any 
memory issues.

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

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