Scan-display of high-resolution images using the Apple II

Two programs are presented for the scan-display of high-resolution images using the Apple II+ and Apple IIe. The first program permits the user to move a rectangular aperture about the video screen to reveal different portions of a stationary image. The second program scrolls an image vertically within a horizontal window, giving rise to the impression of an object moving behind a stationary slit. These programs should be useful in the study of anorthoscopic perception, motion perception, perceptual integration of successively displayed information and other topics in visual perception.