Effective display of computer-generated biomedical images draws on computer graphics and image processing, display technology and human factors, visual psychophysics and perception, cognitive psychology, and the new field of scientific data visualization. In converting from raw, acquired data to a visual display, developers need to know the limitations of the data and of the display technology. To obtain reliable inferences about the clinical or physiological state of the patient requires that the computer display be matched to the visual information-processing competence and limitations of human observers. The issues that should be considered by both developers and users of computer-based display technologies to enhance clinical performance in observation and diagnosis are surveyed with reference to electrical activity brain maps.