[Magick-bugs] Problem converting 16-color images to png8

[Ryan Schmidt]

Hi! I've noticed a problem when converting 16-color images (PNG or  
GIF) to 8-bit PNG. Apologies if this has been reported before; I  
couldn't find it in the mailing list archives. The problem is that  
the resulting image is squished to half the desired width. The right  
half of the resulting image is filled with garbage. The problem does  
not occur when converting 32- or 256-color images to 8-bit PNG, or  
when converting any image to 24-bit PNG.

$ convert test16.png png8:converted16.png
$ convert test32.png png8:converted32.png
$ convert test256.png png8:converted256.png

I wasn't sure if I could post images to this list so I've put them  
here instead:

http://www.ryandesign.com/tmp/imagemagick/test16.png
http://www.ryandesign.com/tmp/imagemagick/test32.png
http://www.ryandesign.com/tmp/imagemagick/test256.png
http://www.ryandesign.com/tmp/imagemagick/converted16.png
http://www.ryandesign.com/tmp/imagemagick/converted32.png
http://www.ryandesign.com/tmp/imagemagick/converted256.png

"converted16.png" demonstrates the problem.

$ convert --version
Version: ImageMagick 6.2.9 10/16/06 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2006 ImageMagick Studio LLC

This is ImageMagick 6.2.9-8 installed through MacPorts on a PowerBook  
G4 with Mac OS X 10.4.8.