   A picture is worth a thousand words—a frequently used
sentence to introduce the need for digital image processing. And
indeed, a wide variety of aspects in our life is influenced by
digital images in the meantime. For instance, in the World Wide
Web not only still pictures but also small video sequences are
used to enhance the design of web pages. However, the usage of
digital images has a major drawback. An enormous amount of data
has to be transmitted and stored each time an image or video is
requested.  For example, a single uncompressed frame of a high
definition television (HDTV) screen (resolution of 1280x720
pixels, 24 bits per pixel) requires more than 2MB memory. When
assuming a display rate of 60 frames per second (HDTV), one
second of a video movie already requires more than 165MB,
summing up to a total of 2,000 compact discs for a movie of 120
minutes! Clearly, downloading such an uncompressed video stream
is impossible, even though fast Internet connections like
asymmetric digital subscriber l