Based on prepare_icons.sh from https://github.com/coronalabs-samples/CoronaCannon
- Install ImageMagick (https://www.imagemagick.org/script/download.php)
- Put original large version of icons in same folder as this script.
- Original iOS icon file should be named IOSIcon.png (preferably at least 2048x2048).
- Original Android icon file should be named AndroidIcon.png (preferably at least 512x512).
- run the script from the command line: $ bash makeIcons.sh