Image optimization is an SEO factor. Google has stated in their Webmaster Guidelines that websites should be optimized to load quickly:
Monitor your site's performance and optimize load times. Google's goal is to give users with the most relevant results and a great user experience. Fast sites increase user satisfaction and improve the overall quality of the web (especially for those users with slow Internet connections), and we hope that as webmasters improve their sites, the overall speed of the web will improve.
Shrink-O-Matic is a free (donation) tool that can help with image optimization. This is a very handy tool for resizing images in bulk. As part of this process it strips out unnecessary information resulting in 'lighter' file sizes. The images aren't as light as possible, but generally much improved. The ease of use of this tool makes it ideal for bulk image optimizing. Add resizing, renaming, and watermarking to the mix and you have a winner.
Shrink-O-Matic as an Adobe Air application so it should work on all platforms, as long as you have Air installed. If you find it useful I encourage you to make a donation to support author Quentin Thiaucourt's work.
My Image Optimization Workflow
(Sorry, this is not a beginner's guide)
- use Google's PageSpeed extension for the Firefox plugin Firebug (another great tool for SEO and web development)
- review the list of images indicated requiring compression
- use the 'save as' option to overwrite my local versions of images that have wide use through the website
- use Shrink-O-Matic if there are many single use images requiring compression
Other Image Optimization Options
For images that are used repeatedly throughout a website I recommend using Google's PageSpeed Tools for a more complete image compression.