Abstract

This brief paper is presented as an illustration of the possible use of the Fourier transform as an aid in evaluating the performance of digital image scanners. A discussion is presented on the interpretation of Fourier energy along the horizontal and vertical frequency axes, and it is suggested that such perfectly aligned energy is most often man-induced (purposefully or unknowingly). Windowing, scanner jitter, and aperture effects are described; specific examples are presented illustrating all these points for a laser scanner system on some scanned imagery. In addition to the main theme of scanner evaluation, a peripheral example of the use of a priori knowledge for image enhancement is presented. A nonlinear space domain transformation (amplifier) is described, based on a priori knowledge, as a tool for noise reduction in the above-mentioned imagery examples.

© 1974 Optical Society of America

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