Image Files on the Web

Know your medium. Before you start loading up your site with image files, it helps to know a little bit about the many graphical species roaming around out there and which ones make sense for you to use.

4.1.1. Image File Formats 101

Graphic files today come in all shapes, sizes, and types. Some high-quality graphic file formats, like TIF (Tapped Image Format) and BMP (Windows bitmap), provide terrific detail and color, which is a big reason why these formats are popular with people who want to print their images. But, as in real life, quality costs. The bandwidth and disk space these files require can slow the speed at which your Web pages load.

Most Web browsers are limited and can display only two image types: GIF (Graphic Interchange Format) and JPEG (Joint Photographic Experts Group). These two formats take image information and compress it, while retaining the most important details so that the image remains recognizable. FrontPage also supports a new technology called PNG (Portable Network Graphics). PNG is an improvement on the GIF format, but isn't recognized by all browsers, especially older ones. As you add images to your pages, you'll probably want to use the two more standard file types, GIF and JPEG. GIF files are best for displaying images that have flat areas of color and simple lines, like a cartoon or company logo. JPEGs are good for images that contain subtle color variations, like photographs.

The bottom line: go with a GIF or a JPEG and be careful not to use too many images on one page since they'll affect your page's download time.