Reducing the Number of Colors in an Image

One of the most effective ways to reduce the size of, and therefore the download time for, an image is to reduce the number of colors used in the image. This can drastically reduce the visual quality of some photographic images, but it works great for most banners, buttons, and other icons.

You’ll be glad to know that there is a special file format for images with a limited number of colors; it’s called the Graphics Interchange Format (GIF). When you save an image as a GIF, you might be prompted to flatten layers or reduce the number of colors by converting to an indexed image, as those are requirements for GIFs, as shown in Figure 8.9. The dialog box will simply ask you to confirm these changes that the save process will do for you—do not concern yourself with understanding these options at this time, but read your software’s help file regarding layers and indexed colors for a full understanding.