The colour sensation

The colour sensation is the ability of the eye to distinguish the 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 range of different colours. Certain color is felt at predominance of radiation with wavelength. Long-wave radiation causes the sensation of red, orange, medium - yellow and green, short - blue, blue and purple. In the spectrum of the seven basic colors: red, orange, yellow, green, blue, Indigo and violet. There are also many intermediate shades (Fig. 1). White, gray and black colors is called achromatic(devoid of color).test for color blindness

The colour sensation. Fig. 1. The color wheel. Fig. 2. Test for color blindness - table "nine" from a set of polychromatic tables. Person with normal colour sensation read the digit "9", and with color blindness (violation of sensitivity to red color) - the figure "6".

The perception of color is connected with the function of cone cells of the retina (see Vision). From the theories explaining colour vision, the most widely three-component theory. According to this theory assumes that in the eye, there are three tsvetovospriatia system, active to varying degrees under the action of the red, green, and blue.
Normal colour sensation is called normal trichromatic, and people with normal color vision is normal trichromats.
Disorder color vision are congenital and acquired.
Acquired disorders color vision observed with various diseases of the retina and optic nerve, especially their atrophy; sensitivity decreases to all three of the primary colors: red, green, and blue.
Congenital disorder was called previously color-blind (on behalf of the English scientist Dalton, who described the colour vision).
Color blindness (the inability to distinguish colors) is full and partial. When complete color blindness all colors are represented grey and only differ in brightness. Complete color blindness is rare, there are also other changes eyes: photophobia (see), Central scotoma (see), low visual acuity (see).
Partial color blindness is perceived as one of three main color sensations. Color blindness, predominantly in red color called Protanopia, the green - deuteranopia, blue - Tritan. When partial color blindness all possible color shades are composed of only two colors. Most often blindness happens to red and green.
The study of color sense make with the help special polychromatic tables E. B. Rabkin (Fig. 2) or the special device - anomaloscope (see).
The forecast. In the treatment of diseases, caused the violation of color sense, you can restore the color sense; congenital disorders of color sense incurable.

The colour sensation (colour vision - the ability to discern the color of visible objects.
Light is a 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 thousand meters (printing. Fig. 3). Wavelength radiation is measured in millimicron (MMK) or in nanometers (1 nm=1·10-9 m). Visible to the human eye part of the spectrum consists of the radiation wavelength of approximately 380 to 760 nm.
In the spectrum there are seven colors, which are conventionally called main.
Observed in nature colors are divided into chromatic and achromatic. To chromatic colors, distinguished in the spectrum, include red, orange, yellow, yellow-green, blue, Indigo and violet. To achromatic - white, gray and black colors, each of which can have different reflectivity. Chromatic colors possess three properties: hue-defined wavelength (l nm), saturation, or purity of the color (R,%), and brightness (nits).
In addition to spectral, there are purple, missing in the spectrum, which are characterized by a wavelength corresponding additional colors, denoted by a dash ('). Additional called two colors, mixing of forming a white color. For example, to red (l 650 nm) additional color is blue (l 495 nm). Range of basic colors present in the form of spatial three-dimensional model, called "color body", which shows the variation of colors by hue, saturation, and brightness.
Measurement of flowers is carried out using a colorimeter and spectrophotometers and atlases colors. In the USSR the spread of American Atlas colors Mansilla and domestic satin flowers E. C. Rabkin.
The primary process of perception of light and color is associated with a cone - day and colour vision and with sticks devices twilight and night vision, and the completion of the formation of a color image with the visual centers in the occipital region of the cerebral cortex (see Vision). If the body of view of a person falling at the same time stimuli all wavelengths, in it there is a feeling of white color. If the beam of light is predominant group stimuli of a certain wavelength, there is a sensation of chromatic colors corresponding to the dominant wavelength.
The perception of color is influenced by simultaneous and consecutive contrasts. Simultaneous contrast change in svetorasseyaniya occurs in connection with a simultaneous action, in addition to the main, and other irritants in series and in connection with the previous irritation to the eyes of a different color. Unlike the color, there is a light contrast (contrast).

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

In the process of observation color occurs color fatigue and the phenomenon of adaptation (see Adaptation of the eye), which is a process of adaptive character. With long-term observation colors there is also a temporary increase of thresholds of svetorasseyaniya, which explained earlier exhaustion of the retina. Such temporary reduction of svetorasseyaniya - color astenopia" Engelking, or "color disparate" Rabkina - Engelking interpreted as the latent pathology color vision. Upon further study of this phenomenon was referred to the category of physiological. Color disparate characterizes the degree of stability chromatic vision and is an indicator of cortical dynamics. The curves in Fig. 1 illustrate several features of the radiation spectrum and their perception of the human eye.
The most common three-component theory of color vision. According to this theory, the presence in the body of view of the three colour devices that are excited to varying degrees under the action of stimuli different wavelengths, resulting in the feeling of all visible colors [Koenig, Giderici (A. Konig, S. Dieterici), 1892]. Further development of the three-component theory of color vision got in the works of p. P. Lazarev (1916)relating to its ionic theory of excitation. At various times were proposed and other theories: the theory of opposite colors [Goering (E. Hering), 1872], modulatory-dominatory hypothesis [Granite (R.Granit),1947], quantum theory [Saxby (A. Shaxby), 1947], the theory of duality of view [Schultze (M Schultze), 1866], developed M. Voinov (1874), Marino (N. Parinaud, 1881) and Chris (J. Kries, 1894), and other

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

Normal colour sensation is called normal trichromatic, and persons with the same color vision is normal trichromats. Disorder color vision may be congenital and acquired. Congenital disorder first described by Dalton and formerly known as color blindness, seen among men on average 8%, and among women - 0.5%. Under these disorders become less sensitive to red and green colors, and when acquired, emerging diseases visually-nervous system and Central nervous system, - to all primary colors. In some cases decreasing sensitivity applies to both colours, but mostly it is marked in red, then these forms are called Protanopia (Fig. 2 and printing. Fig. 1 and 2) and protanomaliey; in other cases, reduced sensitivity refers mainly to green. These forms are called deuteranopia and deuteranomaly. Total absence of color vision - color blindness, or monochromate.

visible spectrum of electromagnetic radiation
Fig. 1. A reproduction of the painting by Giorgione, reproduced by the artist with normal colour sensation. Fig. 2. The same picture is reproduced by the artist-protanopes. Fig. 3. Visible spectrum of electromagnetic radiation.

For the study, the color of view, there are two main groups of methods - pigment and spectral. To pigment include research methods with the help of colored wool skeins [Holmgren (F. Holmgren), 1878], pseudoisochromatic tables Stellinga (1878), non-ferrous tables Ishihara (1916), polychromatic tables E. C. Rabkin (1936), and also devices with optical filters [lantern, Edric-green (1920), anomaloscope detkinoy (1936), modified, N. Routeenum (1950)]and other
For spectral instruments include: the office of the Girshberg (1878), BNI (1910), anomaloscope Nagel (1907), spectrohelioscope E. B. Rabkin (1939, 1956). Design spectral anomaloscope provides the ability to use a color Rayleigh equation (1881), which is that, when mixed in a certain proportion two monochromatic colors - red (l 671 nm) and green (?, 535 nm) - it turns out effective color similar to the yellow (l 589 nm). Offered color equation from other, less tiring colors of the spectrum, which includes red (To 640 nm) mixed with green (l 521 nm), effective color equal yellow-green (l 570 nm; E. B. Rabkin, 1960).
The exposure of these equations and equations on spectrohelioscope ASR you can define all the main forms of congenital and acquired disorders.
Differential diagnosis of disorders colour vision is of great value for scientific research, clinics and medical assessment by color vision with professional and military selection.
Alarm red and green used in various professions, including transport and military Affairs, cannot be replaced by other color signal blue, and yellow, and the discernment of form items, as the colors are recognized from a longer distance than the shape and color according visibility range in the first place is red, then green, and on the smallest distance is visible blue and yellow.
Use in military Affairs color alarm requires normal color vision.
The reduction of color sense is not an obstacle for military service. But for some professions - civilian and military - is required in normal colour sensation. In aviation encountered the greatest difficulties in the recognition of non-ferrous signals. Feature is the perception of color signals from great distances, visible from the perspective of less than 0.5 minutes (point signals), with great speed, and during the flight and another under the action of some other factors (noise of the motor, hypoxemia, and so on).
The perception of color in aviation is necessary when selecting the site in case of a forced landing, the soil which can be defined by color, etc. In military Affairs is required, in addition, to distinguish objects, disguised as the color of the surrounding area, as well as objects with different brightness and color contrasts.