The Measurement and Specification of Nonlinear Amplitude Response Characteristics in Television

With the advent of color television the need for extreme linearity of over-all systems has become apparent. The general problem of the measurement and specification of nonlinear characteristics in television is considered. A function, called the gradient gain of a system, is presented. At a point in the picture for which the gradient gain is positive there is an enhancement (expansion) of the tone rendition. Similarly there is a reduction (compression) in tone rendition when the gradient gain is negative. The gradient gain is a function of the characteristics of the camera tube, picture tube, and purely electronic devices. These characteristics have been defined and methods of measurements suggested in a way which follows most simply from the physical and physiological factors involved. The characteristics of electronic amplifiers are defined so that the extension to color television is readily achieved. The terms "Differential Gain" and "Differential Phase," which have been adopted by the IRE, are defined so that they are applicable to electronic devices, such as amplifiers, used for either monochrome or color television.