Two digital test patterns are used to evaluate computer video display systems. One pattern consists of linear and logarithmic gray-scale wedges, blocks of constant brightness, and horizontal and vertical bar patterns. The other is a cross-hatch bar pattern. These patterns are used to assess display systems' gray scale, resolution, and spatial linearity. Microdensitometry measurements were performed to determine brightness uniformity, spatial resolution, and to relate optical density to exposure. These test patterns, used qualitatively, are useful in the routine adjustment and quality control of digital systems. The precise quantitative characterization of a display system is important in research applications involving image processing.