Bezold Bridge Phenomenon

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Dependence of the hue differentiation threshold in nm on the hue range at optimal luminance

The Bezold Bridge phenomenon is understood as the change in color perception depending on the level of adaptation within the range of daytime vision. The phenomenon is named after Wilhelm von Bezold and Ernst Wilhelm von Brücke .

The phenomenon

The color distinction, more precisely the color tone distinction, in the human eye depends on the luminance. At very low luminance, a color stimulus between 380 nm and 480 nm produces a blue-violet, between 480 nm and 570 nm a green and between 570 nm up to the long-wave visibility limit at 760 nm a red color valence. The differentiation becomes better with increasing luminance: At around 0.0015 cd / cm² to 1 cd / cm², 160 spectral color tones and 30 purple tones can be distinguished. The differentiation improves with a further increase in luminance, but decreases again with higher density. In the blending area, only a whitish yellow and a whitish blue-violet are perceptible. Some test subjects can only perceive a bright light. This phenomenon is known as the Bezold-Abney phenomenon . The reason for this dependence is the different light sensitivity of rods ( scotopic or night vision) and the cones of the eye that are also sensitive to color stimuli (photopic or daytime vision).

Number of theoretically possible colors

In order to estimate the number of possible "visible" colors, the saturation and brightness must also be taken into account. The number of perceptible saturation levels for the normal observer in turn depends on the hue, for example specified as "wavelength of the same color", and is highest in the green area. The number is between 4 and 25. A few hundred levels can be specified for the brightness. The number of theoretically possible colors results in a few hundred thousand. However, in real terms around 10,000 to tens of thousands of color nuances that can be distinguished in terms of hue, saturation and brightness are possible, but these also depend on other factors such as ambient light, psychological stress, wakefulness and coloristic exercise.

For Italian mosaic workers, 30,000 distinguishable color nuances are given.

See also

Source and literature

  • Karl Mütze, Leonhard Foitzik, Wolfgang Krug, Günter Schreiber: Brockhaus ABC of Optics . VEB FABrockhaus Verlag, Leipzig 1961.
  • W. von Bezold: The theory of colors with regard to art and applied arts. Braunschweig 1874.
  • W. von Bezold: About the law of color mixing and the physiological basic colors. Annalen der Physiologische Chemie, 1873, 226: 221–247.

Web links