FastStone Photo Resizer - Convert and Rename images in batch mode Support JPEG, BMP, GIF, PNG, TIFF and JPEG2000
Color Hunter - Color Hunter is a place to find and make color palettes created from images.
ImageMagick - ImageMagick is a software suite to create, edit, and compose bitmap images.
OpenCV - OpenCV is the world's biggest computer vision library
GraphicsMagick - GraphicsMagick is the swiss army knife of image processing.
Cloudimage - Cloudimage.io is the easiest way to resize, store, and deliver your images to your customers through a rocket fast CDN.