luminanssignalet

Luminanssignalet, or luminance signal, is the component of a color image or video that encodes brightness information. It represents the grayscale intensity of the picture at each point and is distinct from chrominance, which carries color information such as hue and saturation. In most video systems, the luminance signal contains the majority of the spatial detail and edge information that determines perceived sharpness.

In analog television, the luminance signal is transmitted as a baseband signal and is combined with chrominance information that is modulated on a color subcarrier. The two components are later separated by a decoder, allowing the display to reconstruct the full color image while preserving luminance detail. In digital video, brightness is represented by the Y' channel in color spaces such as Y'CbCr or Y'UV. The Y' signal is often sampled more densely than the chroma channels (for example 4:2:0 or 4:2:2) to reduce data rate without sacrificing perceived brightness.

Standards such as Rec. 601 for standard-definition and Rec. 709 for high-definition define the transformation from RGB to luma and the appropriate coefficients. In video processing, the luminanssignalet is routinely manipulated for tasks such as contrast adjustment, gamma correction, and edge detection, while chrominance channels handle color information. Overall, the luminanssignalet is central to image fidelity, brightness management, and perceptual quality in both traditional broadcasting and modern digital displays.