gammakäyrämuunnoksissa

Gammakäyrämuunnoksissa, commonly referred to as gamma correction, is a non-linear operation used to encode and decode luminance or tristimulus values in video and image systems. It is named after the exponent gamma (γ) used in the power-law function that defines the transformation.

The purpose of gamma correction is to compensate for the non-linear response of display devices, such as Cathode Ray Tube (CRT) monitors, to electrical signals. CRTs, in particular, tend to produce an output intensity that is proportional to the input voltage raised to the power of gamma, typically around 2.2 to 2.5. Without gamma correction, images would appear too dark or too bright on different display types.

In a typical workflow, image data is first gamma-encoded at the capture or creation stage. This means the intensity values are adjusted to account for the display's gamma. When the image is displayed, a gamma decoding process is applied, which is the inverse of the encoding process, to restore the linear relationship between the input signal and the perceived brightness.

Gamma correction is essential for ensuring that images and videos appear consistently across various devices and viewing conditions. It helps to preserve detail in both the dark and bright areas of an image, leading to a more natural and visually pleasing representation of the original scene. The specific gamma value used can vary depending on the intended display medium and the desired aesthetic.