ThumbsUp is a simple, drag & drop based utility to create thumbnails or icons for a bunch of pictures or movies and supports all image & movie formats of Mac OS X and QuickTime (including PDF documents).
Thumbnails are either scaled by percentage or limited to a maximal size and created as JPEG, TIFF, PNG, BMP or GIF files. In addition, it's possible to specify antialiasing, sharpening and compression to optimize the results. Finally, use ThumbsUp to convert PDF screenshots easily to other image formats using drag-and-drop and scaling to 100 percent.