An image, of course, is any visual representation. Still images, such as photographs and drawings, capture a single, visual moment in time; while moving and video images, such as television and movies, are able to capture entire periods of time.

A digital image is simply an image that can be represented in a computer's numeric, or digital, language. A digital image is composed of millions of tiny dots called pixels. If you look closely at a computer monitor, you can probably see these tiny dots at the edges of curved images, such as letters, for example. These pixels can be displayed as any one of several million colors, and when all of the pixels are placed in the right order, they form an image.

The proper ordering and coloring of these pixels is often stored in a file on a computer. Image file types--such as GIF, JPG, BMP, EPS and others--simply use a slightly different technique for describing the proper order and color of the pixels that comprise a given image. Videos--which are a series of still images--are stored in formats that can support information for a soundtrack that goes with the video.

Image files are saved using different formats. For still images alone there are nearly 100 different file formats. Each format offers its own compression technique and image quality for a variety of practical applications. Here are the most common file formats for still images and a brief description of their common use.

To enable the sharing of such a photo, one solution is to compress the photographic data (data that represents the photo), meaning rearranging the data and reducing the number of colors in the photo so that the data takes up less space. This technique is used by the Graphics Interchange Format (GIF) file format.

Although the GIF image appears less detailed than the original raw photo--a result of the compression and reduction in color-- the GIF image takes up only 68,000 bytes of storage. This size is a reasonable size for sharing the photo. To enable file sharing of a more detailed image, the developers of the JPEG format came up with a more sophisticated way of compressing data. They realized that the human eye cannot distinguish every possible shade of color or every detail; thus, they developed a technique that reduces a photo's colors and complexity without the appearance of having done so. In other words, the only data eliminated in the JPEG technique is data that your eye would not process. The image below shows an example. As you can see, this photo is much more lifelike than the GIF version, and it takes up less storage space. Digital images play a very important role in designing websites, choosing right format enables users to view your website fast. Learn more about digital images and creating websites.

Article written by David Manson.