Retinal model with adaptive contrast sensitivity and resolution

A computer-simulated retina (called IRIS) is described which has useful features for computer vision.: IRIS discriminates small differences in reflected light when these differences occur in a restricted domain of space and time, and maintains sensitivity to these differences for a wide range of lighting environments. As prevailing light levels decrease and photon noise becomes significant, IRIS reduces its spatiotemporal resolution to provide greater redundancy. Electrically, IRIS could be implemented by 2-D lattice of photosensors attached to a passively conducting grid. Inthe present study, the model is implemented in FORTRAN. Similarities to the human retina are noted; the photosensor design is based on a photoreceptor model, and each conducting grid may be realized by tight-junction coupling of receptors and by horizontal-cell interconnections (effectively forming a syncytium).