Retina-like image acquisition system with wide-range light adaptation

Abstract

The principles of organization of biological visual systems provide a valuable inspiration to the design and construction of image acquisition systems. The adaptive sensitivity mechanism of human-like retina enables the acquisition of extremely wide range of light intensity (1013:1), much wider than that of conventional semiconductor photoreceptors (103:1), while preserving image details and dynamically adapting to the image contents. In order to better design intelligent visual data acquisition and processing systems, a three- layer visual neural model would be proposed to exploit the attractive capability of human retina. Due to the limited range of photoreceptor, each photoreceptor in the first layer could improve its range by shifting the operating characteristics and adjusting the threshold along the intensity axis. The concept of light adaptation of photoreceptor is based on a combination of the photopigment bleaching and regeneration kinetics and the feedback neural inhibition mechanism. The horizontal cells which are located just below the photoreceptors form the second layer, which performs the spatially weighted averages of photoreceptor outputs and determines the settings of the light-adaptation parameters of neural inhibition mechanism. The third layer, which includes a number of bipolar cells, is used to perform the lateral inhibition that could do contrast and edge enhancement. This approach allows for perception of visible scene that is independent of changes in the overall level of illumination. A model of combination of light adaptation and lateral inhibition would be employed in designing the smart image acquisition systems and conducted to be verified in our HDTV Lab.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.