WILLIAM K. PRATT, PhD, has worked in imaging technology at the University of Southern California, Vicom Systems, Sun Microsystems, and, more recently, at PixelSoft. He is the author of numerous papers in the fields of communications and signal processing, and is the holder of several patents for image coding and image processing systems. He was one of the primary developers of the Programmer's Imaging Kernel System (PIKS) utilized in this volume.