PNG

Download pngquant:

brew install pngquant 

Syntax:

pngquant <filename> --ext <extension>

Example:

pngquant myimage.png --ext -optimised.png

This will create a myimage-optimised.png file in the current directory.

If you leave out the --ext option, it’ll output use -or8.png or -fs8.png

Sources/further reading

• Tools for image optimization