Look into pngquant as an alternative to optipng

[fsundermeyer]

Seems to do a much better job than optipng: http://download.opensuse.org/repositories/home:/drankinatty/

Also see the discussion "pngquant - PNG compressor" on the openSUSE list https://lists.opensuse.org/opensuse/2019-05/

[StefanBruens]

pngquant is definitely not a a drop-in replacement. It quantizes the (typically) 24-bit image into an image with at most 256 colors. In other words, it is a lossy compression.

pngcrush on the other hand is lossless, and typically achieves slighly better results than optipng. It applies the same tricks as optipng, but just does better.

Another lossless option is zopflipng, which on top of the optimization strategies of optipng/pngcrush optimizes the huffman tables.

[dunlavy]

Great intel!