gammakäyriä

Gamma curves, or gammakäyriä in Finnish, refer to the graphical representation of the relationship between exposure and the resulting density or luminosity in an image. This relationship is fundamental in understanding how different tones are captured and reproduced, particularly in photography and digital imaging.

The gamma curve is typically plotted with the input signal (exposure or light intensity) on the horizontal axis and the output signal (density or perceived brightness) on the vertical axis. In a perfectly linear system, a doubling of input light would result in a doubling of output density, resulting in a straight diagonal line. However, most imaging systems, including human vision, are not linear.

The term "gamma" itself comes from the gamma correction applied to these curves. Gamma correction is a non-linear operation used to encode and decode luminance or intensity values. A gamma value greater than 1 tends to brighten darker areas more than lighter areas, while a gamma value less than 1 has the opposite effect. This adjustment is crucial for compensating for the non-linear response of display devices and for matching the perceived brightness of images to human vision. Different gamma values can drastically alter the mood and contrast of an image, making it a powerful tool in image editing and calibration.