-*- coding: utf-8; -*- oxipng 8.0.0 Joshua Holmer Losslessly improves compression of PNG files USAGE: oxipng.exe [OPTIONS] ... ARGS: ... File(s) to compress (use "-" for stdin) OPTIONS: -o, --opt Optimization level - Default: 2 [possible values: 0, 1, 2, 3, 4, 5, 6, max] -b, --backup Back up modified files -r, --recursive Recurse into subdirectories --dir Write output file(s) to --out Write output file to --stdout Write output to stdout -p, --preserve Preserve file attributes if possible -c, --check Do not run any optimization passes -P, --pretend Do not write any files, only calculate compression gains -s Strip safely-removable metadata objects --strip Strip metadata objects ['safe', 'all', or comma-separated list] --keep Strip all optional metadata except objects in the comma-separated list -a, --alpha Perform additional alpha optimizations -i, --interlace <0/1> PNG interlace type [possible values: 0, 1] -v, --verbose Run in verbose mode -q, --quiet Run in quiet mode -f, --filters PNG delta filters (0-9) - Default: 0,5 --fast Use fast filter evaluation --zc zlib compression level (1-12) - Default: 11 --nb No bit depth reduction --nc No color type reduction --np No palette reduction --ng No grayscale reduction --nx No reductions --nz No IDAT recoding unless necessary --fix Enable error recovery --force Write the output even if it is larger than the input -Z, --zopfli Use the slower but better compressing Zopfli algorithm --timeout Maximum amount of time, in seconds, to spend on optimizations -t, --threads Set number of threads to use - default 1.5x CPU cores -h, --help Print help information -V, --version Print version information Optimization levels: -o 0 => --zc 5 --fast (1 trial, determined heuristically) -o 1 => --zc 10 --fast (1 trial, determined heuristically) -o 2 => --zc 11 -f 0,1,6,7 --fast (1 trial, determined by fast evaluation) -o 3 => --zc 11 -f 0,7,8,9 (4 trials) -o 4 => --zc 12 -f 0,7,8,9 (4 trials; same as `-o 3` for zopfli) -o 5 => --zc 12 -f 0,1,2,5,6,7,8,9 (8 trials) -o 6 => --zc 12 -f 0-9 (10 trials) -o max => (stable alias for the max compression) Manually specifying a compression option (zc, f, etc.) will override the optimization preset, regardless of the order you write the arguments. PNG delta filters: 0 => None 1 => Sub 2 => Up 3 => Average 4 => Paeth Heuristic filter selection strategies: 5 => MinSum Minimum sum of absolute differences 6 => Entropy Highest Shannon entropy 7 => Bigrams Lowest count of distinct bigrams 8 => BigEnt Highest Shannon entropy of bigrams 9 => Brute Smallest compressed size (slow)