Download the compressed source code. Open the file, optipng-0.7.4.tar.gz in the Finder. It will create a folder called optipng-0.7.4. Open the Terminal, found under Applications -> Utilities.

How to convert PNG to JPG on Mac. You can save PNG files as JPGs in a number of common Mac apps, but the easiest is to use Preview. 1. Start Finder and then locate the PNG file you want to convert. 2.

A PNG file is a Portable Network Graphics file. Open one with any browser or image program, like Preview (Mac) or Photos ...