Save your image bandwidth using Smush.it
Smushit.com is a free web service offering image optimization service. You can select images stored on your computer or an URL and optimize it(smush it).
Optimize images on your blog using SEO Friendly Images
One very important and often missed SEO management tactic is optimizing the images on your website. SEO Friendly Images is a simple but very effective plugin which automatically optimizes all your website images with proper ALT and TITLE attributes.