Web Design in a Nutshell, 3rd Edition

“Optimized” JPEGs

Standard JPEGs use a precalculated, general purpose compression table (called the Huffman table ) for compressing an image. Some tools offer the ability to create an “optimized” compression table that is customized for the particular image. This results in better color fidelity and slightly smaller file sizes. To optimize a JPEG in Photoshop/ImageReady, simply put a check next to “Optimize” in the Save for Web or Optimize palettes.