Image-Pngslimmer

is a perl module of functions to reduce the size of PNG computer graphics. It can be found on CPAN [http://search.cpan.org/~acmcmen/Image-Pngslimmer-0.22/lib/Image/Pngslimmer.pm] or at the author's own subversion repository [http://png.transpero.net http://png.transpero.net]

The module offers several basic functions including:

"zlibshink" - which uses perl's zlib implementation to attempt to better compress a PNG's IDAT

"filter" - to apply adaptive filtering to the PNG's IDAT to help improve compression

"discard_noncritical" - to remove non-critical chunks if they exist

"palettize" - to use a colour palette, possibly through colour quantization using the median cut algorithm