Abstract

Because the spatial response of optical apertures can never be negative, the associated spatial frequency response decreases gradually with frequency, generally without a finite cut-off (except for lens diffraction). These responses tend to blur small spatial detail and insufficiently bandlimit the radiance field prior to sampling by sensor-array mechanisms.^1,2 Some of these limitations of optical apertures can be overcome with image-plane processing, as suggested by Fig. 1. In this paper we assess the spatial responses that can be shaped by using image-plane signal processing for high-pass filtering, and lens diffraction, lens transmittance shading, and defocus blur for low-pass filtering. The signal processing electronics permit the spatial response of the imaging system to be adjusted either by a human operator, or as it is in human vision, by the intensity of the radiance field. The advantages of image-plane processing over conventional image data acquisition and subsequent digital processing are improved spatial response for edge enhancement, increased dynamic range, and reduced data transmission.

© 1983 Optical Society of America