ImgCmp

ImgCmp is a tool that helps you manage large collections of images including wallpapers, scans, and photos. ImgCmp detects similar (not equal) images, thus allowing to eliminate redundant copies of the same image in multiple resolutions or formats. Support for BMP, GIF, and JPG image formats. Automatic assignment of ratings to similar images so that you can save only the better ones. Maintenance of a database of processed files so that once you want to update your image collection you won't need to rescan it.