My list of image processing commands
[Edit]This is ever growing list of commands that help me with image processing. I hope you will find it useful.
Lossless PNG compression
find . -name \*.png | parallel --bar optipng -o9 -zm1-9 {}
Cap image size to 1080
mogrify -resize x1080\> *.jpg
Turn white transparent
convert test.png -transparent white transparent.png
Turn white transparent + soft edges
convert input.png -fuzz 2% -transparent white output.png