Single-Exposure HDR Technique Based on Tunable Balance Between Local and Global Adaptation

Abstract

This brief describes a high-dynamic-range technique that compresses wide ranges of illuminations into the available signal range with a single exposure. An online analysis of the image histogram provides the sensor with the necessary feedback to dynamically accommodate changing illumination conditions. This adaptation is accomplished by properly weighing the influence of local and global illuminations on each pixel response. The main advantages of this technique with respect to similar approaches previously reported are as follows: 1) standard active-pixel-sensor circuitry can be used to render the pixel values and 2) the resulting compressed image representation is ready either for readout or for early vision processing at the very focal plane without requiring any additional peripheral circuit block. Experimental results from a prototype smart image sensor achieving a dynamic range of 102 dB are presented.