Neal said:
Me, I bought a computer which contained, free of any obvious extra
charge, a simple graphics program which creates gifs but not pngs. If
the average user can locate a free png creator, there's a greater
likelihood it will catch on.
the Gimp is a free image manipulation package with features on par with
Paint Shop Pro. it is available on Windows and most flavors of Unix.
libpng is a free, open-source implementation of the PNG format. any
program that incorporates that library (which i think is under the LGPL)
has the capability of reading and writing PNG images.
PHP, the popular server-side language can be linked against libGD, which
uses libpng. it also links to ImageMagick, which also supports PNG
images. both libraries can be used to generate PNG images on the fly.
Macromedia's Fireworks (part of their very popular web development
studio and available independently) uses PNG as its native file format
and supports the export of web PNG images. (its native file format uses
extensions to PNG that do not change decoded images, but are much larger
to store the additional image editing data that the software needs to
keep track of, such as histories, snapshots, etc.)
PNG itslef is a royalty-free, patent-free, open standard that anyone is
perfectly free to develop software for. there is a lot of free and
non-free software that i'm not aware of. open-source, proprietary,
whatever. Photoshop has supported PNG images for quite some time.
Internet Explorer's decoder is the only implementation i know of that
doesn't support PNG alpha channels in its latest release. all other
decoders and encoders i've seen and used support the PNG file format in
its entirety.