 describing the level of color saturation. Frequency interleaving is the name of this technique. A digital image is a grid that contains a two-dimensional array of values representing intensity or color. To achieve this format, an analog image must first be converted to the 2-D space, using pixels to convey its resolution. If the image is black and white, the values used might be 0 and 1. Eight bits might be used for a gray-scale image. True color requires at least eight bits each for R, G, and B; it also requires three frames of information, one for each color component. Coding and Compression Multiple video-encoding schemes correlate to multiple divergent applications. Still video applications demand different requirements than do moving video applications. Digital video can be stored on a typical CD-ROM or on a powerful video server, and delivered in broadcast (one-way transmission) format. However, digital video is not always stored; video communication is an interactive real-time digital video application. COMPRESSION: KEEPING ONLY THE CRITICAL BITS Compression, the art and the science of compacting a signal for transmission, is far more sophisticated today than it was ten years ago. Nevertheless, despite today's fast networks, a mismatch persists between the bandwidth needed to transport digitized video, and the bandwidth available to carry it. Different approaches to encoding a video signal produce different results, but virtually all techniques result uncompressed bandwidth requirements of 25 Mbps or more. Networks that offer this capacity are rare and expensive. Compression would be superfluous were bandwidth available in limitless quantities and at extremely low cost. Economy mandates compression. If the additional cost to compress is lower than the price of necessary additional bandwidth to carry an uncompressed signal, customers will compress. In the early 1980s, both costs were very high and, consequently, video communication was not very popular. As time went by, video codecs became more powerful. B