The presentation of visual information is critical to almost every endeavor in modern technology, from space exploration and military surveillance to diagnostic and therapeutic medicine. The technology of presenting visual information has developed rapidly in recent years; images and data can now be presented in a wide variety of formats and processed to bring out any of an enormous variety of aspects. The challenge is to display the information in such a way that the human observer can use it best. To do so requires understanding how humans process and use information that reaches them through the eye. While the elementary processes are well known, the details are far from clear. This text, comprising a dizen contributions by well-known researchres in the field, examines first what is currently known or understood about human vision and the information processing that it involves; it then considers the implciations for image maniuplation and presentation, particularly for computer processing of data to be presented visually.