A mathematically defined standard display function is proposed for black-and-white hard and soft-copy image displays based on perceptual linearization. Since perceptual linearization is related to threshold contrast of targets with specific parameters, perceptually linearized display functions are calculated for a variety of target descriptors to illustrate the range of linearization by the proposed standard. Rogers and Carel's formula and the two-dimensional models of visual system sensitivity of Barten and Daly are used to calculate such display functions. The proposed standard provides perceptual linearization for the peak contrast sensitivity near 4 c/deg. The standard is adaptable to black-and-white display systems independent of maximum luminance and luminance range. Perceptual linearization is maintained largely independent of object size, external noise, observer performance variations, low supra-threshold contrast, target orientation, and ambient light. The standard facilitates similarity between the soft and hard-copy of an image independent of luminance. When using the standard function for displaying images, a minimum number of bits for the D/A converter is required that provides uniform digitization resolution over the entire display range. The standard display function, however, is not a visualization standard for images of specific applications.