Pixozip vs pngcrush

Pixozip has no write-up on Specifiction yet; its figures are above.

pngcrush is a free command-line utility for losslessly optimizing PNG files. It tries compression levels and PNG filter methods to reduce the size of a file’s IDAT datastream, and supports batch processing. Its chunk controls can remove unwanted ancillary chunks or add gAMA, tRNS, iCCP, and textual chunks. The supported format is PNG; image resizing and API access are not provided. pngcrush runs from MSDOS, UNIX, or Linux command lines, and the maker links to precompiled Windows binaries for an MSDOS window. Source code is available from SourceForge and the pmt git repository, with libpng and zlib included in the distribution. The maker permits use, modification, and redistribution without a fee; the license is equivalent to, but not identical with, the libpng license. Build choices matter: the maker warns about overflow vulnerabilities when compiling with certain older unpatched libpng versions, and says a build statically linked with the supplied zlib is believed to avoid a particular double-free bug. The SourceForge files page lists pngcrush-1.8.11.tar.xz as the latest version. Free graphical applications that embed pngcrush are also noted by the maker.