Right Click Image Converter 2.2.4
Convert between image formats from the Windows shell. Supports JPEG, BMP, PNG, GIF, WBMP, ICON, TGA, and several other file formats. Also has ability to rotate and resize images. Right click on a file or a group of files in Windows, and select Convert to.
As simple as that. You can use the utility to compress large files, create icons, convert images to Wireless BMPs, convert batch files and use the program through the command line.