SIPS - Easy Image Conversion

SIPS
Add Icon(Mostly Useless)


Resize to Largest Plane - Very Useful - Supports Wildcards:


Convert PDF to JPG

Other Command-Line Conversion Options

Imagemagick
Convert - convert image A to image B

Mogrify
Alter existing images in place
To resize a folder full of .jpgs, use the following examples (adjust -sample and -quality values to your liking):