VISUAL ASSESSMENT OF VARIABLE-RESOLUTION IMAGERY

A technique is described for producing variable-resolution images whos e spatial detail decreases as a function of distance from their center s. These images can be matched in some sense to the normal spatial inh omogeneities of the human visual system, as well as to various abnorma lities in spatial discrimination. A set of images was generated with a series of linear distortion functions whose low-pass characteristics differed at both the center and the periphery of the image as well as across the image. A forced-choice procedure was used to determine whic h test images were indistinguishable from unprocessed versions of them selves. Certain of the threshold distortion functions are compared wit h eccentricity scaling functions that have been used by others to char acterize various aspects of peripheral vision. Finally, the concept of locally band-limited spaces is discussed, and an efficient sampling t echnique based on the concept is described. This technique can be used to generate an image that, under certain conditions, is visually equi valent to an otherwise identical image containing significantly more i nformation.