A while back I wrote a freebie utility that checks a series of images and then crops them all to the smallest enclosing rect.

In my BREW phone game making adventures, I had single-image horizontal sprite strips that were wasting a lot of space and added features to handle finding the smallest enclosing rect and writing out an optimized version of the image.

8 bit support, color key support (can be used instead of alpha) and some examples were also added.

Download SmartCropper V2.50 with source and examples (updated 12/30/2008)