What is gamma correction?
In a video system, linear-light intensity is transformed to a nonlinear video signal by gamma correction, which is universally done at the camera. The Rec. 709 transfer function [2] takes linear-light intensity (here R) to a nonlinear component (here R’), for example, voltage in a video system: The linear segment near black minimizes the effect of sensor noise in practical cameras and scanners. Here is a graph of the Rec. 709 transfer function, for a signal range from zero to unity: An idealized monitor inverts the transform: Real monitors are not as exact as this equation suggests, and have no linear segment, but the precise definition is necessary for accurate intermediate processing in the linear-light domain. In a colour system, an identical transfer function is applied to each of the three tristimulus (linear-light) RGB components. See Frequently Asked Questions about Colour. By the way, the nonlinearity of a CRT is a function of the electrostatics of the cathode and the grid of a
In a video system, linear-light intensity is transformed to a nonlinear video signal by gamma correction, which is universally done at the camera. The Rec. 709 transfer function [2] takes linear-light intensity (here R) to a nonlinear component (here R’), for example, voltage in a video system: The linear segment near black minimizes the effect of sensor noise in practical cameras and scanners. Here is a graph of the Rec. 709 transfer function, for a signal range from zero to unity: An idealized monitor inverts the transform: Real monitors are not as exact as this equation suggests, and have no linear segment, but the precise definition is necessary for accurate intermediate processing in the linear-light domain. In a colour system, an identical transfer function is applied to each of the three tristimulus (linear-light) RGB components. See Frequently Asked Questions about Colour. Incidentally, the nonlinearity of a CRT is a function of the electrostatics of the cathode and the grid of
