What is “camera gamma” and its relationship to NTSC/HDTV video?
Gamma is the nonlinear relationship between the light intensity in the scene and the encoded camera responses that is normally described with a power function. The exponent of that power function is called “gamma”. In video, the camera signal is encoded in this nonlinear way to compensate for a similar nonlinear relationship between video signal and display intensity in traditional CRT displays. However the compensation is rarely complete since it is often desired to increase the physical contrast of the video images. Hunt’s text, “The Reproduction of Colour” provides much more background on this topic and Poynton’s FAQ provides many answers on the confusing use of the term “gamma’.
