Most of this book describes image file formats and the types of data compression they employ. However, still images are not the only type of data that can be stored in a file. This chapter describes the other types of graphics data that are becoming popular.
A hot topic in the world of personal computers today is multimedia. Multimedia applications combine text, graphics, audio, and video in much the same way a motion picture film combines sound and motion photography. But, unlike motion pictures, multimedia can be interactive through the use of a keyboard, mouse, joystick, or other input device to control the behavior of the multimedia presentation. The output from a multimedia application can be through conventional speakers or a stereo system, a music or voice synthesizer, or other types of output devices.
A conventional stereo system or television and video tape recorder (VCR) are passive information devices. You can raise and lower the volume of a stereo, change the color of a television picture, or fast-forward a VCR, but this type of control is very limited in capability and is used only intermittently. When you use a passive information device, you normally just sit and watch the picture and listen to the sound.
Anyone who has played a computer or video arcade game has experienced an active information device. The games at your local video arcade, or hooked up to your living room television (and therefore permanently attached to your eight-year-old's hands), require constant input in order to function properly. And, although the sights and sounds of such a game might be staggering, the control and utility a user gains from an active information device is only slightly more than is gained using a passive one.
Personal computers are not only active information devices, but also interactive devices. A computer itself does very little unless a user interacts with it. Computers are, as you would expect, excellent platforms for interactive multimedia applications.
Interactive multimedia provides more than just the stimulus-response reaction of a video game. It also allows a collection of complex data to be manipulated with a much finer control than is possible using non-interactive devices. Sample multimedia applications in existence today include:
Computerized multimedia is still in its infancy. It is currently a tool used for educational and entertainment purposes and is expanding out into the commercial world. There probably isn't a complex computerized control system that wouldn't be easier to learn or to use if it had a standardized, multimedia front end. And one day you might even see multimedia applications with heuristic algorithms that will allow your computer to learn as much from you as you will from your computer.