Weißleuchtdichte

Weißleuchtdichte is a term used in optics and display technology to denote the luminance of white light. It describes how bright white light appears from a surface or source when viewed from a specified direction. In practice, it is closely related to the general concept of luminance, but it emphasizes the white component of the light or the white point of a display.

The quantity is expressed in luminance units, typically candela per square meter (cd/m²). In everyday usage the term is often associated with the brightness of white on screens or signage. The human eye’s sensitivity to different wavelengths is accounted for through the photopic luminous efficiency function, so the perceived brightness of a white light depends on its spectral power distribution even if its radiant intensity is fixed.

Measurement of Weißleuchtdichte is performed with a luminance meter or a spectroradiometer, under specified viewing geometry and ambient conditions. In displays, white luminance is measured when the display is driven to produce white (all color channels combined) and is used together with the white point (color temperature) to characterize image quality and contrast. Calibration procedures aim to achieve a specified Weißleuchtdichte for consistent viewing across devices and environments.

Applications of Weißleuchtdichte include display calibration for televisions, monitors, and mobile devices, architectural and automotive lighting, and signage. It serves as a practical metric for visibility, legibility, and perceived brightness in white content, complementing color accuracy and contrast measurements.