Simplistically gamma is the attenuation or gain of a voltage level; increasing or decreasing the level from what it was. What makes gamma complex is that for video imaging its function is to create a non-linear response thereby enhancing mid-tones, highlights or dark areas. It is a process that is encoded by the video camera when the image is captured and decoded by the display device. When the camera gamma and display gamma match then a linear response is produced for the viewer. In this scenario gamma does not affect video signals and therefore the video signal itself does have a linear response. If you view the video signal response of a stair step grayscale pattern you will see that each step is equal in level going from peak black to peak white yet a display will take this linear response and make it non linear by increasing the difference in video levels at the top and bottom while decreasing the video levels in the middle, the exact opposite of the encoded gamma created by the video camera. With our old analog displays the CRT itself naturally decoded the gamma response of the camera. As technology progressed additional gamma correction was applied via circuitry for better performance or to even change the gamma response to a different value.
Digital displays add a distinctive twist to gamma because they don
Gamma
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