pnmtopng and pngtopnm add PNG conversion capabilities to Jef Poskanzer's PBMPLUS suite (last released in 1991, aside from a significantly updated beta that was released in late 1999), more commonly known by the name of its unofficial Internet releases, NetPBM (last released 1 March 1994 before being adopted by a new maintainer in September 1999; see the SourceForge NetPBM site for details). This is arguably the most complete PNG-supporting application in existence, but it is command-line based and generally geared toward Unix users and CGI-script programmers.

Note that there are at least two or three variants floating around, including one in the newer NetPBM distributions. Willem van Schaik attempts to catalog all of them here.

Current version: 2.39
Authors: Alexander Lehmann, Willem van Schaik, Greg Roelofs
License: Open Source
Platforms: primarily Unix (though OS/2 and NT ports of NetPBM exist)
README: local web site
Binaries: Linux/x86/glibc   (site 2)   [version 2.39]
SGI Irix 6.3   (site 2)   [version 2.37.3]
Amiga   [version 1.0]
Source code:
Supporting libraries: libpng
PBMPLUS (update coming?) or NetPBM (old or new)
Related software: pnmtopng, "pamquant" with alpha-channel support - very crude hack to support a piped alpha channel; allows a full 32-bit RGBA PNG to be quantized to an 8-bit RGBA-palette (PLTE + tRNS) PNG. (Note: these are out of date and will be replaced by a more logical and comprehensive modification to PBMPLUS at some point.)

wpng - limited-functionality demo program that converts binary PPM files to RGB PNGs (i.e., similar to pnmtopng); differences include on-the-fly conversion to non-interlaced PNGs (small memory footprint) and interactive entry of text annotations; compiles under Unix and 32-bit Windows.

[primary site hosted by] Last modified 12 November 2005.

Copyright © 2000-2005 Greg Roelofs.