Color technology foundation and theory (two)
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Fourth, the theory of opposite color
In the previous issue, we made a detailed discussion on the color vision theory of “the three primary colors of visual color”. Next we will continue to study the “opposite color theory”. In 1878, the German physiologist Ewald, according to the study of psychophysics, found that red-green, yellow-blue, black-white always showed the opposite color phenomenon; also said red and green, yellow and Blue, black and white cannot exist in any color sensation at the same time. Therefore, Hering proposed the "opposable color theory" (Opponent Colors Theory or Opponenyt Process Theory), which assumes that there are three kinds of opposite colors in the photoreceptor cells in the visual mechanism. According to the above hypothesis, we can know that Hering theory claims: "The color space belongs to the three-dimensional space, which are three bipolar coordinate axes of red-green, yellow-blue, black-white, and three opposite colors. The combination of reactions produces a variety of color sensations and various color mixing phenomena." Therefore, Hering's "opposite color theory" is also called "four primary color theory", because he believes that the various color perception phenomena are formed by four colors such as red, green, yellow and blue.
The introduction of Hering's theory of "opposite color theory" explains the following facts and phenomena:
1. Complementary afterimage: This phenomenon is because when a certain color thorn stops, the opposite color associated with the color begins to function, thus producing the opposite color of the color - the complementary color.
2. Simultaneous comparison: When the retina is experiencing a stimulating response to a pair of opposite colors, the adjacent part will produce a simultaneous contrast phenomenon.
3. Color blindness: Because color blindness is caused by a pair of human eyes (red-green or yellow-blue) or two pairs of opposite color reaction processes, color blindness often appears in pairs, that is, color blindness usually It is red-green blind or yellow-blue blind, and when the two pairs of opposite color reaction processes cannot be carried out, the phenomenon of full color blindness occurs. This argument explains the theory of "visual color three primary colors" in the previous color vision theory. Color blindness.
Even so, the Hering doctrine has its shortcomings, that is, the phenomenon that all the primary colors of red, green and blue can produce all spectral colors cannot be satisfactorily explained. However, Hering's theory of opposite color is a very important theory in the theory of colorimetry in recent years. The most obvious example is that CIE's Lab, Luv and other color space coordinates are the opposite colors applied by Hering. The red-green, yellow-blue, black-white three coordinates are composed, so Hering's color vision theory is also a very important basic theory for modern colorimetry.
Fifth, stage visual color theory
The theory of stage visual color was first proposed by GEMuller (1930) and Judd (1949). They believe that the visual color trichromatic theory and the opposite color theory have been in the opposite state for Color Vision Theory for a long time. Experimental research has confirmed that the two can be integrated and coordinated, and a more complete explanation and explanation of the phenomenon of human eye color vision. But how does the stage visual color theory integrate the four opposite color metabolic reactions of the "opposite color theory" with the "visual color three primary color theory"? I will discuss it below.
When light is incorporated into the retina of the human eye, the photo pigments in the cone cells selectively absorb radiation of different wavelengths, and each cone can produce brightness alone according to the amount of light stimulation ( Black or white) reacts with color (red, green, blue). In this stage, the Young-Helmholtz visual color three primary color theory and the color-light mixing experiment can be applied to explain the phenomenon of visual color.
Since the cone cells are connected to the optic nerve cells, the nerve impulses triggered by the light stimulation of the cone cells will form a visual color signal. The signal content is analyzed as follows:
(1) Achromatic signal - responsible for the integration of the brightness signal, receiving a photopic achromatic signal formed by three cone cells.
(2) chromatic signal - responsible for the integration of color signals, received by three cone-shaped cells.
The color signals such as red, green and blue are formed; at this stage, the color signal is represented by the following three color difference signals: C1=RG; C2=GB; C3=BR (R, G, B represent three kinds respectively) The signal produced by the cone cells). When the three color difference signals C1, C2, and C3 are transmitted to the nerve center via the nerve fibers, they are generated and integrated into two color signals, which are C1 and C3-C2.
So in this phase, three pairs of opposite-colored nerve impulse responses are formed, the signals of which are as follows:
(1) Brightness signal............The opposite color of black and white
(2) Color signal C1............The opposite color of red and green
(3) Color signal C3-C2............The opposite color of yellow and blue
While the cone-shaped cells receive light stimulation to the nerve center, the resulting three pairs of opposite-colored neural impulse responses coincide with Hering's theory of opposite color.
If we put the above text description in the following figure, we can clearly understand how the visual color theory integrates two visual color theories to produce color vision phenomena.