Demo programs rpng, rpng2, and wpng come with O'Reilly's 'PNG: The Definitive Guide.'
The first tool, rpng, is a simple file viewer with a nice bonus: the ability to set a background color when displaying transparent PNGs.
The second program, rpng2, is a progressive PNG viewer that's similar to a web browser. Although it doesn't contain any network code, it can generate a background image when displaying transparent PNGs.
The third tool, wpng, is a NetPBM to PNG format converter. It's less comprehensive than pnmtopng in many ways, but it does have some useful features. For example, it supports interactive entry of PNG text annotations, and it generates noninterlaced PNGs on-the-fly instead of buffering the entire image first, like pnmtopng.
You can use the viewers on either X or Win32, and there's a simple front-end for both. The converter is a command-line application that compiles on several different platforms, including Unix and Windows.
To run these programs, you'll need to have libpng and zlib installed on your computer. The latest release includes a fix for handling truncated or partly unreadable image files, as well as an improved usage screen that makes error messages easier to spot.
Version 20080316: N/A