pngcrush

pngcrush [options] input [output]

pngcrush optimizes PNG files by testing multiple compression strategies and selecting the smallest result. The optimization is completely lossless - the image data is preserved exactly while reducing file size through better compression parameters.The -brute option tries all filter and compression combinations for maximum reduction at the cost of processing time. The -rem option strips metadata chunks like text comments, timestamps, and color profiles to further reduce size.

INPUT

Input PNG file.

Output PNG file.

Overwrite the input file in place.

Write output files to the specified directory.

Remove a specified ancillary chunk. Use alla to remove all text chunks, or allb to remove all non-critical chunks.

Try all 148 filter/compression combinations for maximum reduction.

Reduce color depth and bit depth where possible without data loss.

Set zlib compression level (0 = no compression, 9 = maximum).

No output file; test compression without writing (useful for benchmarks).

Fix otherwise fatal conditions such as bad CRCs.

All optimization is lossless; image data is preserved exactly. The -brute option can be very slow on large images as it tests all 148 compression strategies. The -ow flag creates a temporary file and replaces the original, so sufficient disk space is needed. Does not support animated PNGs (APNG).

pngcrush was created by Glenn Randers-Pehrson and has been one of the oldest and most widely used PNG optimization tools, first released in 1998.

optipng(1), pngcheck(1), pngquant(1), zopflipng(1), convert(1)