Optical and Photoelectric Analog of the Eye

A photoelectric analog of the visual system is constructed in conformance with anatomical data. The analog has the form of a color television camera chain feeding electrical signals to a “computer” (the brain). Evaluation of characteristics is limited to elements preceding the computer, and particularly to the “luminance channel” of the color system.The primary photoelectric transfer characteristics n¯1=f(Er) of the receptors (rods and cones) are computed as a function of retinal illumination (Er) from threshold signal-to-noise ratios in the effective image area of point sources, disks, and other test objects. The effective image area, which is the convolution of the object area with the sampling area of the visual system, is determined from its Fourier spectrum. The constants of the transfer functions are established from the optical constants of the eye, its storage-time function, and the maximum transfer ratio of statistical units of the rod and cone systems. There is little room for variation of constants, if they are to remain in agreement with observed values.