Cleaner, Sharper GIF, JPEG, And PNG Images
http://www.sitepoint.com/article/sharper-gif-jpeg-png-images

Rutter, Thomas
SitePoint
2003

Abstract:

While they're not absolutely necessary for Website functionality, images help improve the appearance of a site. With a few gcood quality, highly optimised images, you can give your site the edge it needs to leave a lasting impression. The problem is that many Webmasters, both novice and experienced, don't feel confident when it comes to creating clean looking graphics and optimising them for the Web.