Changes the color of images to the indexed color space.
The indexed color space uses no more than 256 colors, and is as such particularly suited for use in Web applications. Images are typically converted to indexed color mode in order to decrease their file sizes. When an image is converted to indexed color, a color lookup table is created, in which the colors that were used in the image are stored and indexed. Using an indexed color table lets you reduce the file size of an image while maintaining the visual quality that you need.