Imagemagick and pngquant

http://www.fmwconcepts.com/imagemagick/overlapcrop/index.php

http://www.rubblewebs.co.uk/imagemagick/batch.php

http://www.imagemagick.org/discourse-server/viewtopic.php?t=16144

Combine 2 folders of images
https://www.imagemagick.org/discourse-server/viewtopic.php?t=29699