Images are a powerful, efficient means for communicating information, spurring advances in technologies underlying image capture, transfer, storage and display. This text asks the fundamental question: what is image quality? The answer requires that we think of images not as signals, but as carriers of visual information, and the visuo-cognitive processing of images as information processing. This processing is an essential stage in human interaction with the environment; the perceived adequacy of an image is based on comparisons to our memory standards of what is natural and correct. With...