A Windows 95/98/NT/2000/XP command prompt driven program for optimizing and watermarking multiple JPEGs, GIFs, and PNGs on a disk or file server. JPEG Disk Optimizer is designed to optimize multiple JPEGs, GIFs, and PNGs in a directory and, optionally, in sub directories. JPEG Disk Optimizer is a command prompt program and so can be easily driven from other programs or scripting languages. JPEG Disk Optimizer includes MagiCompressionTM 2 to reduce the size of JPEGs by up to 50% more than standard JPEGs. This can dramatically cut the cost of disk storage, bandwidth usage, server load as well as speeding up web pages.