Gammasäätö

Gammasäätö, often translated as gamma correction or gamma control, is a crucial concept in image processing and display technology. It refers to the nonlinear relationship between the numerical value of a pixel and its actual luminance or brightness. This relationship is described by a power-law function, where the output intensity is proportional to the input intensity raised to the power of gamma.

The primary purpose of gammasäätö is to compensate for the nonlinear response of display devices, such as CRT monitors, and to ensure that images appear as intended across different devices. Early displays, particularly cathode ray tubes (CRTs), naturally exhibited a nonlinear brightness output. Gamma correction was implemented to counteract this inherent characteristic, ensuring that images displayed on these devices matched the brightness perceived by the human eye.

Human vision itself has a nonlinear response to light intensity; we are more sensitive to changes in darker tones than in brighter ones. Gammasäätö helps to align the digital representation of an image with this perceptual characteristic, ensuring that shadow detail is preserved and that the overall image appears natural.

In digital imaging, gamma correction is applied both during image capture and during display. Cameras and image sensors often apply a gamma curve to the captured data, and display devices also apply their own gamma curves. The typical gamma value used is around 2.2, which is considered a good compromise for matching human perception and common display characteristics. Modern systems often handle gamma correction more implicitly, but understanding the underlying principle is essential for appreciating how images are rendered accurately on various screens.