[Image-SIG] PIL 1.0b1 bug confirmation wanted

Andrew M. Kuchling akuchlin@mems-exchange.org
Thu, 17 Jun 1999 18:34:12 -0400 (EDT)

PIL 1.0b1 seems to have problems generating PNG files; I can replicate
it, but want to verify that other people see the bug too.  Here's how
to reproduce it:

1) Go to http://www.mems-exchange.org/software/microscope/PIL/ and
download gif2png.py and output.gif into the same directory.  (The
output.png file in that directory is an example of a corrupt PNG

2) Run gif2png.py, which reads output.gif and writes it out as

When attempting to view output.png, xv reports 'libpng error: bad
adaptive filter type'.  The error happens whether I run PIL on Solaris
or Linux; it does not happen with PIL 0.3b2 on Linux, but I haven't
verified that on Solaris.  I wrote a little Python program to parse
the PNG apart into chunks, because I initially suspected my patch for
adding comments to PNG files.  However, the PNG seems to be legal; the
problem is in the masses of compressed data making up the image.  

I'm willing to expend some effort tracking this down, but want to be
sure that other people can reproduce the bug first, in case it depends
on the version of libpng, zlib, or some other factor.

A.M. Kuchling			http://starship.python.net/crew/amk/
I want to be young and wild, and then I want to be middle-aged and rich, and
then I want to be old and annoy people by pretending that I'm deaf.
    -- _Blackadder III_: "Nob and Nobility"