We have found many good tools for reducing image size. Often 
times these tools are specific to particular image formats and work much better in certain circumstances than others. To “smush” really means to try many different image reduction algorithms and figure out which one gives the best result. These are the tools which we frequently used on crushing, ie Imagemagick , pngcrush, jpegtran, gifsicle and finally Smush.it™ online application. Smush.it uses optimization techniques specific to image format to remove unnecessary bytes from image files. It is a “lossless” tool, which means it optimizes the images without changing their look or visual quality. Smush.it is included with YSlow and is no longer available as a separate download. Download YSlow now to get Smush.it and start saving bytes on image files.
Smush.it can process JPG, GIF, and PNG images that are up to one megabyte in size. Converting GIF files to PNG files often produces substantial performance improvements. Here you can Smush your image files online.
