Exact cause of libpng: decompression error

From: Rich Rattanni
>On rare occasion, the program crashes with the message
>"libpng: decompression error".  I was
wondering what were
>all the conditions that could generate this message?  

I believe it can only happen if the stream of bytes sent,
by libpng, to the zlib decompression code is incorrect -
corrupted or incomplete.

>Could it be the file is corrupt?

Yes

> Or could it be an actual error internal the
>libpng or z decompression? 

Conceivably but unlikely.  More likely the code which
delivers
the byte stream to libpng (which in turn passes it to zlib)
messes
up the bytes.

If you can capture the byte stream to a file then the
original
data can be tested with pngcheck.  Try to do this at the
point
where the bytes are passed to libpng.  I would be surprised
if
the error cannot be reproduced this way.

John Bowler <jbowleracm.org>


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