About Gamma Correction
Gamma correction compensates for the fact that video display devices (such as
televisions) inherently convert image signals to light intensity in a nonlinear fashion,
usually with an assumed gamma value of 2.5. The ITU-R BT.709 specification
recommends an in-camera gamma correction of 1/2.2 (or 0.45). When the camera
gamma correction is multiplied by the CRT gamma (2.5/2.2), the result is an overall
display gamma of 1.14, which has slightly more contrast than a display gamma of 1.0.
A display gamma of 1.1–1.2 is desired for television viewing in dim viewing conditions.
In summary, a gamma of 2.5 is inherent in CRT displays. Gamma correction is
automatically applied in a video camera so that the video is displayed on a CRT with a
bit of contrast, and this value is usually 1/2.2.
Chapter 29
Rendering and Video Processing Settings
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IV