Kries zone theory

The zone theory is a historical theory of the perception of colors in the human eye. It was erected by Johannes von Kries at the end of the 19th century. With his work, he combined the three-component theory with the opposite color theory .

For the current state of knowledge, see color perception .

thesis

Painters had known for a long time that all colors in painting can be mixed from three basic colors. This three-dimensionality was recorded by the French blonde and formulated as a hypothesis by Thomas Young . Around 1850, the physicist Hermann von Helmholtz worked out the theoretical basis for this. Today it is used as an additive color mixture in the RGB color space . The cause lies in the three cones of color vision. These have their sensitivities for blue (S cone), green (M cone) and red (L cone).

Antithesis

On the basis of his observation of the effect of colors, the physiologist Ewald Hering established his color theory 25 years later. In his four-color theory, he assumed that color vision is based on three independent processes. Since no color is reddish and greenish at the same time, or yellow and blue at the same time, he assumed complementary perceptions in which the color perception consists of a red-green, a yellow-blue and a black-white sequence. This opposite color theory is used in the Lab color space .

Conclusion

In order to defuse this conflict of three or four basic colors , Kries divided the process of seeing colors into a peripheral and a central zone. The peripheral zone of the photoreceptor cells picks up three signals. These signals are formed into two opposing pairs of basic colors in a process in the central zone, i.e. in the nervous system.

Mathematical basis

The theoretical underpinning was created by Robert Luther in preparation for the CIE norm valence system . The Luther transformation named after him explains the conversion. On the one hand, he took the trichromatic cone excitation and its sensitivity curves as a basis and converted them into "assimilation" - "dissimilation" values according to the following equations.

Let L, M, S be the excitation strengths of the color stimulus and the excitation components of the cones , the color valence results as: ${\ displaystyle \ varphi _ {\ lambda}}$ ${\ displaystyle {\ vec {S}} {\ text {,}} {\ vec {M}} {\ text {and}} {\ vec {L}}}$

{\ displaystyle {\ vec {F}} = S \ cdot {\ vec {S}} + M \ cdot {\ vec {M}} + L \ cdot {\ vec {L}}}

.

The spectral values of the color stimulus can be measured ${\ displaystyle {\ bar {l}} (\ lambda) {\ text {,}} {\ bar {m}} (\ lambda) {\ text {and}} {\ bar {s}} (\ lambda) }$

{\ displaystyle L = k \ int _ {380 \, \ mathrm {nm}} ^ {780 \, \ mathrm {nm}} \ varphi _ {\ lambda} {\ bar {l}} (\ lambda) \, \ mathrm {d} \ lambda \,}

{\ displaystyle M = k \ int _ {380 \, \ mathrm {nm}} ^ {780 \, \ mathrm {nm}} \ varphi _ {\ lambda} {\ bar {m}} (\ lambda) \, \ mathrm {d} \ lambda \,}

{\ displaystyle S = k \ int _ {380 \, \ mathrm {nm}} ^ {780 \, \ mathrm {nm}} \ varphi _ {\ lambda} {\ bar {s}} (\ lambda) \, \ mathrm {d} \ lambda \,}

The color stimulus is effective in its spectral distribution between 380 nm and 780 nm. Therefore, for the calculation, the value of excitation strengths is introduced at the point, but practically in the bandwidth around the wavelength . ${\ displaystyle \ lambda}$

The following system of equations then applies to the red-green process. Luther's moments can be determined as the difference between the spectral values of the excitation strengths.

Red Green:

{\ displaystyle {\ bar {m}} _ {rg} (\ lambda) = {\ bar {m}} (\ lambda) - {\ bar {l}} (\ lambda)}

Blue yellow:

{\ displaystyle {\ bar {m}} _ {by} (\ lambda) = {\ bar {l}} (\ lambda) - {\ bar {s}} (\ lambda)}

Light-dark:

{\ displaystyle {\ bar {w}} (\ lambda) = V (\ lambda)}

It should be noted: is the brightness sensitivity. ${\ displaystyle V (\ lambda)}$

A formula approach that can be found in the color spaces of color television. The same formalism applies to the YCbCr color model or the YPbPr color model .

Individual evidence

^ Hermann von Helmholtz: Handbook of physiological optics . Voss, Hamburg-Leipzig 1896. 2nd edition
↑ Ewald Hering: Basic features of the doctrine of the sense of light . In: Handbook of Ophthalmology . I. Engelmann, Leipzig 1905.
↑ Johann von Kries: Theoretical studies on the retuning of the visual organ . In: Festschrift . University of Freiburg 1902. pp. 144–158
↑ Manfred Richter: Introduction to colorimetry . Walter deGruyter, Berlin 1981, p. 81

literature

Manfred Richter: Introduction to colorimetry . Walter deGruyter, Berlin 1981

[1] Hermann von Helmholtz: Handbook of physiological optics . Voss, Hamburg-Leipzig 1896. 2nd edition

[2] Ewald Hering: Basic features of the doctrine of the sense of light . In: Handbook of Ophthalmology . I. Engelmann, Leipzig 1905.

[3] Johann von Kries: Theoretical studies on the retuning of the visual organ . In: Festschrift . University of Freiburg 1902. pp. 144–158

[4] Manfred Richter: Introduction to colorimetry . Walter deGruyter, Berlin 1981, p. 81