Sean:
If you enter:
about:plugins
in the URL: bar . . . you will be able to view the 'suffixes' that K-Meleon is supporting . . . with the files in your "plugins" directory.
I have installed Quick-Time . . . that supports "png". For information on downloading/installing Quick-Time (and other plugins) . . . go to . . .
http://kmeleon.sourceforge.net/resources/
Hope this helps . . . let us know.