To be published as Chapter 4 in Optical Design for Visual Instrumentation, Panatazis Mouroulis, Editor
The human eye is an elegant electro-optical image processing system with many parallels to modern optical instruments. For example, the eye could be compared to an advanced video camera with wide field of view, auto-focus and auto-exposure optics, a variable-resolution sensor with 3 color channels plus an ultra-sensitive black and white channel, local and global automatic gain control mechanisms which produces uniform sensitivity over a large dynamic range, all packaged in a pair of light-weight spheres mounted in a lubricated gimbal that allows rapid, servo-controlled, coordinated stereoscopic positioning and the tracking of moving objects. At the same time, the eye is a typical biological system with an inherent complexity and variability which cannot easily be represented by a simple equation or model. Nevertheless, there are many features of the eye that are common to virtually all human eyes which makes it feasible and desirable to represent the average eye by a functional, neuro-optical, schematic model.