WebGraphics Optimizer is a useful tool to optimize and compress web images. As a web designer you must always take image sizes into account, so that traffic is not dramatically affected. I have tried this tool myself with one of my sites. Although I keep all my images in JPEG format , I experimented with some of the 5 available copies of the original images, and site speed increased to about one second, without sacrificing image resolutions. Besides, the compression ratio was pretty good, and the transpart areas were recognized successfully when loading an image.
This program also has many other features like adding 3D text to images and a preview function. That is a very good reason why this program must be a part of your web toolset: you can be sure that graphics on your site not only load quickly, but also look pretty good. The software is only a trial, if you want a full version of it, you have to purchase the pro version for a few dollars. I don't know much about it, what the advantages are and any other features not included in this trial, but after playing with it, I think it is worth its price.