"It reduces the size of the PNG IDAT datastream by
trying various compression levels of PNG filter methods. It also
can be used to remove unwanted ancillary chunks, or to add certain
chunks including gAMA, tRNS, iCCP, and textual chunks and it can
fix incorrect gamma info written by Photoshop 5.0 as well as the
erroneous iCCP chunk written by Photoshop 5.5.
"pngcrush is a command line tool and can run on Linux, UNIX and