OptiPNG version 0.7.6 Copyright (C) 2001-2016 Cosmin Truta and the Contributing Authors. This program is open-source software. See LICENSE for more details. Portions of this software are based in part on the work of: Jean-loup Gailly and Mark Adler (zlib) Glenn Randers-Pehrson and the PNG Development Group (libpng) Miyasaka Masaru (BMP support) David Koblas (GIF support) Using libpng version 1.6.32 and zlib version 1.2.11

Synopsis: optipng [options] files ... Files: Image files of type: PNG, BMP, GIF, PNM or TIFF Basic options: -?, -h, -help show this help -o <level> optimization level (0-7) [default: 2] -v run in verbose mode / show copyright and version info General options: -backup, -keep keep a backup of the modified files -clobber overwrite existing files -fix enable error recovery -force enforce writing of a new output file -preserve preserve file attributes if possible -quiet, -silent run in quiet mode -simulate run in simulation mode -out <file> write output file to <file> -dir <directory> write output file(s) to <directory> -log <file> log messages to <file> -- stop option switch parsing Optimization options: -f <filters> PNG delta filters (0-5) [default: 0,5] -i <type> PNG interlace type (0-1) -zc <levels> zlib compression levels (1-9) [default: 9] -zm <levels> zlib memory levels (1-9) [default: 8] -zs <strategies> zlib compression strategies (0-3) [default: 0-3] -zw <size> zlib window size (256,512,1k,2k,4k,8k,16k,32k) -full produce a full report on IDAT (might reduce speed) -nb no bit depth reduction -nc no color type reduction -np no palette reduction -nx no reductions -nz no IDAT recoding Editing options: -snip cut one image out of multi-image or animation files -strip <objects> strip metadata objects (e.g. "all") Optimization levels: -o0 <=> -o1 -nx -nz (0 or 1 trials) -o1 <=> -zc9 -zm8 -zs0 -f0 (1 trial) (or...) -zc9 -zm8 -zs1 -f5 (1 trial) -o2 <=> -zc9 -zm8 -zs0-3 -f0,5 (8 trials) -o3 <=> -zc9 -zm8-9 -zs0-3 -f0,5 (16 trials) -o4 <=> -zc9 -zm8 -zs0-3 -f0-5 (24 trials) -o5 <=> -zc9 -zm8-9 -zs0-3 -f0-5 (48 trials) -o6 <=> -zc1-9 -zm8 -zs0-3 -f0-5 (120 trials) -o7 <=> -zc1-9 -zm8-9 -zs0-3 -f0-5 (240 trials) -o7 -zm1-9 <=> -zc1-9 -zm1-9 -zs0-3 -f0-5 (1080 trials) Notes: The combination for -o1 is chosen heuristically. Exhaustive combinations such as "-o7 -zm1-9" are not generally recommended. Examples: optipng file.png (default speed) optipng -o5 file.png (slow) optipng -o7 file.png (very slow)