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Color perception

Color perception is the ability of the eye to distinguish color tones.

The visible part of the spectrum of light radiation has waves of different lengths and is perceived by the eye in the form of a gamut of different colors. A certain color is felt when radiation with a certain wavelength is predominant. Long-wave radiation causes a feeling of red and orange colors, medium wave - yellow and green, short wave - blue, blue and purple. There are seven primary colors in the spectrum: red, orange, yellow, green, blue, blue and violet. There are also many intermediate shades (Fig. 1). White, gray and black colors are called achromatic (devoid of color).

color circletest for color blindness
Color perception. Fig. 1. Color circle. Fig. 2. Test for color blindness - table "nine" from a set of polychromatic tables. Persons with normal color sensation read the number “9”, and with color blindness (violation of sensitivity to red) - the number “6”.

The perception of color is associated with the function of the cone cells of the retina (see Sight). Of the theories that explain color vision, the three-component theory is most prevalent. According to this theory, it is assumed that there are three color-perceiving apparatus in the eye, which are excited in varying degrees by the action of red, green, and blue.

Normal color perception is called normal trichromasia, and people with normal color vision are called normal trichromates.

Disorders of color vision are congenital and acquired.

Acquired color vision disorders are observed in various diseases of the retina and optic nerve, especially their atrophy; sensitivity is reduced to all three main colors: red, green and blue.

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Congenital disorders were previously referred to as color blindness (after the English scientist Dalton, who described the impaired color vision).

Color blindness (the inability to distinguish color) is complete and partial. With full color blindness, all colors appear gray and differ only in brightness. Full color blindness is rare, while other eye changes are also observed: photophobia (see), central scotoma (see), low visual acuity (see).

Partial color blindness is the failure to perceive one of the three primary color sensations. Color blindness, predominantly red, is called protanopia, green - deuteranopia, and blue - tritanopia. With partial color blindness, all possible color shades are composed of only two colors. Most often, blindness is red and green.

The study of color sensations is carried out with the help of special polychromatic tables by E. B. Rabkin (Fig. 2) or by a special device, the anomaloscope (see).

Forecast . In the treatment of diseases that caused a violation of color perception, restoration of color perception is possible; congenital disorders of color perception are incurable.

Color perception (color vision) - the ability to distinguish the color of visible objects.

Light is composite and consists of radiation of different wavelengths, forming part of the spectrum of electromagnetic radiation, whose wavelength ranges from millionths of a millimeter to hundreds and thousands of meters (color. Fig. 3). The radiation wavelength is measured in millimeters (mmk) or in nanometers (1 nm = 1 · 10 -9 m). The visible part of the spectrum of the human eye consists of radiation with a wavelength of approximately 380 to 760 nm.

There are seven colors in the spectrum, which are conventionally called primary colors.

The colors observed in nature are divided into chromatic and achromatic. The chromatic colors distinguished in the spectrum include red, orange, yellow, yellow-green, blue, blue and violet. To achromatic - white, gray and black colors, each of which may have a different reflectance. Chromatic colors have three qualities: color tone, determined by the wavelength (λ nm), saturation, or purity of color (P%), and brightness (V nit).

In addition to spectral, there are purple colors that are not in the spectrum, which are characterized by the wavelengths of the corresponding additional colors, denoted by the dash () sign. Two colors are called complementary, forming a white color when mixed. For example, to red (λ 650 nm) the complementary color is blue (λ 495 nm). The gamut of primary colors is represented as a spatial three-dimensional model, referred to as a “color body”, in which variations of colors in terms of color tone, saturation and brightness are displayed.

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Color measurement is carried out using colorimeters and spectrophotometers, as well as color atlases. In the USSR, the American Atlas of the colors of Mensell and the domestic atlas of the colors of E. V. Rabkina became widespread.

The primary process of perception of color and light is associated with cones — day and color vision devices and with rods — devices of twilight and night vision, and the completion of the formation of a color image is associated with visual centers in the occipital region of the cerebral cortex (see Vision). If at the same time irritants of all wavelengths fall on an organ of a person, a white color appears in it. If a group of stimuli of a certain wavelength prevails in a beam of light, then a sensation of chromatic color corresponding to the dominant wavelength arises.

The perception of color is influenced by simultaneous and sequential contrasts. With simultaneous contrast, a change in color distinction arises in connection with the simultaneous action, in addition to the main one, and other stimuli, while consistently in connection with the previous irritation of the eye with a different color. In contrast to the color, there is a light contrast (contrast in brightness).




Fig. 1. Schematic curves:
1 - brightness in the spectrum;
2 - visibility in the spectrum;
3 - adysaropia (temporary reduction in color discrimination);
4 - functional stability in the spectrum;
5 - electrical activity;
6 - saturation in the spectrum;
7 - color fatigue in the spectrum.

In the process of observing color, color fatigue and the phenomenon of adaptation arise (see Adaptation of the Eye), which relates to processes of an adaptive nature. With long-term observation of color, there is also a temporary increase in color discrimination thresholds, which was previously explained by retinal fatigue. Engelking interpreted such a temporary decrease in color distinction - “color asthenopia” according to Engelking, or “color adysaropia” according to Rabkin — as a hidden pathology of color vision. Upon further study, this phenomenon was classified as physiological. Color adisaropia characterizes the degree of stability of chromatic vision and is an indicator of cortical dynamics. Curves in fig. 1 illustrates a number of features of the spectrum of radiation and their perception by the human eye.

The most common three-component theory of color vision. According to this theory, the presence of three color-sensing apparatuses in the organ is allowed, which are excited to varying degrees by the action of stimuli of different wavelengths, resulting in the sensation of all visible colors [Koenig and Dieterici (1892). The three-component theory of color vision was further developed in the works of P. P. Lazarev (1916) related to his ionic theory of excitation. At different times, other theories were proposed: the theory of opposite colors [E. Hering, 1872], the modulator-dominator hypothesis [R. G. Granit, 1947], quantum theory [A. Shaxby], 1947 , the theory of duality of vision [Schultze (M. Schultze), 1866], developed by M. Voinov (1874), Parino (N. Parinaud, 1881) and Chris (J. Kries, 1894) and others.

classification of color vision disorders
Fig. 2. Classification of disorders of color vision of Chris and Nagel with the addition of Rabkin.

Normal color perception is referred to as normal trichromasia, and persons with such color vision are normal trichromates. Disorders of color vision can be congenital and acquired. Congenital disorders, first described by Dalton and previously called color blindness, are observed in men in an average of 8% of cases, and among women in 0.5%. In these disorders, the sensitivity to red and green colors decreases, and in case of acquired disorders arising from diseases of the visual-nervous apparatus and the central nervous system - to all primary colors. At the same time, in some cases, a decrease in sensitivity applies to both colors, but to a greater degree is marked in red, then such forms are called protanopia (Fig. 2 and colors. Fig. 1 and 2) and protanomalia; in other cases, the decrease in sensitivity relates mainly to green. Such forms are called deuteranopia and deuteranomalia. The complete absence of color vision is color blindness, or monochromasia.


visible spectrum of electromagnetic radiation
Fig. 1. Reproduction of the painting by Giorgione, reproduced by the artist with a normal color perception. Fig. 2. The same picture, reproduced by the artist protanopom. Fig. 3. The visible spectrum of electromagnetic radiation.

For the study of color vision, there are two main groups of methods - pigment and spectral. Pigment methods include research using hanks of colored wool [Holmgren (F. Holmgren), 1878], Stilling pseudo-isochromatic tables (1878), Ishihara color tables (1916), E. V. Rabkina's polychromatic tables, and devices with light filters [Edridge-Green lamp (1920), Demkina anomaloscope (1936), modified by G. N. Rautian (1950)], and others.

The spectral instruments include: the Girshberg apparatus (1878) and Ebni (1910), the Nagel anomaloscope (1907), the spectroanomoscope by E. B. Rabkina (1939, 1956). The design of the spectral anomaloscopes makes it possible to use the Rayleigh color equation (1881), which consists in mixing two monochromatic colors - red (λ 671 nm) and green (λ, 535 nm) - in a certain proportion - a resultant color similar to yellow ( λ 589 nm). A color equation from other, less tiring colors of the spectrum, which includes red (K 640 nm) mixed with green (λ 521 nm), is proposed, the resulting color is yellow-green (λ 570 nm; E. B. Rabkin, 1960).

By exposing these equations, as well as other equations, to the ASR spectroanomoscope, you can determine all the main forms of congenital and acquired disorders.

Differential diagnosis of color vision disorders is of great importance for scientific research, clinics and medical expertise in color vision in professional and military selection.

Alarms in red and green, used in various professions, including transport and military, cannot be replaced by other color signals — blue and yellow, as well as by distinguishing the shape of objects, since colors are recognized from a distance , and of the colors in terms of visibility in the first place is red, then green and at the shortest distance blue and yellow are visible.

The use of color alarm in military requires normal color vision.

Lowering color perception is not an obstacle to military service. But for some professions - civil and military - requires a normal color perception. In aviation, there are the greatest difficulties in recognizing color signals. A special feature is the perception of color signals from large distances, visible from an angle of view of less than 0.5 minutes. (point signals), with great speed, and during the flight also under the action of some other factors (motor noise, hypoxemia, etc.).

The perception of color in aviation is necessary when choosing a site in the event of a forced landing, the ground of which can be determined by color, etc. In military science, it is also necessary to distinguish between objects disguised as the color of the surrounding area, as well as objects with different brightness and color contrasts.