Color technology foundation and theory(one)
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First, recognize color
How color is formed has been noticed since ancient times. Since the 1930s, color science with color as a research object has become an emerging application technology, which has attracted the attention of the scientific and industrial circles. In the surrounding environment of our lives, color is almost omnipresent around you, and color has a very close relationship with everyone, in terms of food, clothing, housing, travel, education, music, etc.; and color for everyone's emotions , emotions, and personality also have in-depth influence. So what is color? How is color produced? How do you form a color after the object is stimulated by light? What are the basic requirements for color formation? The average person must be quite vague about such problems. The reason is that people have poor knowledge of color, and the field of color technology includes scientific knowledge of mathematics, physics, chemistry, physiology and psychology. Therefore, in order to establish the correct color technology for readers, The concept will be explained in the following articles, introducing concepts and knowledge about color technology.
The feeling of color is a complicated and complicated process. According to the scientific explanation and definition, the main factor of color formation is that after the light source is irradiated onto the object, the transmitted (or reversed) light stimulates the naked eye to produce color. Feeling, so the formation of color is not only related to the stimulation of light, but also to the visual organs of the naked eye. For the above explanation and definition of the description, we can clearly understand the basic elements of color formation: 1. light source (source), 2. object (object; attenuator), 3. viewer (viewer; observer), for color The basic elements of formation. Since color is a phenomenon caused by the light stimulation of the naked eye, light plays a key role in the formation of color.
But what is it? Light is an electromagnetic wave, because light has the characteristics of reflection, interference, polarization and other waves, and the light absorption phenomenon of light and object, it is a kind of light quantum with energy, so light has both undulation and quantum physics. characteristic. The physical properties of light are determined by the wave and energy of light—the wavelength of light determines the color of light; the energy of light determines the intensity of light. Since the range of electromagnetic waves is quite large, it includes cosmic rays, ultraviolet rays, visible rays, infrared rays, microwaves, etc., but electromagnetic waves that can actually produce color perception on the visual system of the human eye are visible light waves having a wavelength range of about 380 nm to 780 nm. In this visible spectrum, electromagnetic waves of different wavelengths produce different color sensations.
The general light source is a complex color light composed of monochromatic light of different wavelengths. The so-called "monochromatic light" means that the white light or the sunlight is separated by the Mitsubishi mirror to separate the spectral color light - red, orange, yellow, green. Seven colors, such as blue, enamel, and purple, because this decomposed color light will not be decomposed into other colors even if it passes through the Mitsubishi mirror again, so the color light that cannot be decomposed is called monochromatic light; The light mixed by "monochromatic light" is called "multi-color light". The light emitted by sunlight in nature and artificially produced fluorescent lamps is a complex light.
After a preliminary understanding of the nature of light, we will further explore the effects and effects of light produced by light on objects. Objects in nature can be divided into two categories:
1. Luminous body - refers to an object that can radiate light to the surrounding space, also known as a light source.
2. Non-luminous body - refers to all substances other than the illuminant in nature.
The non-illuminator can only show color when it is illuminated by the ground source, so there is no light, and the color of the object is not seen, and there is no color feeling. Different objects have different molecular and atomic structures. Therefore, when incident light is incident on an object, when the incident light of a certain wavelength matches the characteristics of the object itself, the object absorbs the incident light of the wavelength, and the remaining The color light is reflected to reveal the color of the object, so the reason for the color of the surface of the object is the result of the selective absorption and reflection of the object. The color of the object that people see is the color light that is reflected or transmitted after the action of light and matter. In addition, the object absorbs the incident light of the wavelength corresponding to the characteristics of the object itself, which causes the electron energy level of the object to jump to the orbit of the high energy level. This phenomenon is called light absorption; and because the electron energy level is jumped to the high energy level. The track is less stable, so the electrons then return to the original stable orbit and release the absorbed light radiation in the form of heat, or partially in the form of light radiation.
Therefore, what color the object presents is related to the selective absorption of the monochromatic light of each wavelength in the visible light, and the selective absorption of the monochromatic light of each wavelength in the visible light depends on the physical properties and chemical structure of the object itself. Light is the only reason why the human eye perceives color; the color of an object is the property of the object itself for light stimulation. Finally, we can get the following conclusion: "The material of nature itself can be said to be colorless, because the object itself produces selective absorption of light waves for different wavelengths of light in the light source, and then determines the color of the object itself. It is colorless, it is the light source that gives the natural world a colorful color; the light source is the first element of color display, and the change of the light source has an absolute influence on the appearance of color."
Second, the human eye visual color system
The color is mainly generated because the human eye receives reflection or transmission from the surface or inside of the object to the light source. Therefore, the color is covered by three factors: light, object characteristics and human visual mechanism. In the previous article, the light source was irradiated. The role of the object has been explained, and in this paper, the reason why the light reflected or transmitted by the object enters the human visual system and how the color is perceived is explained.
The eye is the window of the soul, playing the role of evaluation, viewing and judgment. However, how does the eye accept the reflection (transmission) or the light emitted by the external object, so that people feel the color? First of all, we need to understand that the electromagnetic waves that can actually produce color perception on the human visual system are visible waves with wavelengths ranging from about 380 nm to 780 nm. However, in this visible spectrum, electromagnetic waves of different wavelengths can produce different colors. Feeling, and the natural colors of hundreds of millions of colors, then how does the human eye's visual system recognize the color stimuli generated by the reflected or transmitted light of objects? The main reason lies in the photoreceptor cells in the visual system of the human eye? The results of the action of rod cells and cone cells are described below for the visual characteristics of the visual photoreceptor cells:
Rod cell
Rod-shaped cells only work under dark conditions, and their brightness is below 0.01 nits. It is a high-sensitivity, low-resolution cell that can only recognize changes in light and dark, and has no sensory effect on color. It is said that rod-shaped cells have only a black-and-white sensation of light. Its sensitivity range is from 400 to 600 nm.
2. Cone cells
Because the cone-shaped cells do not work under weak light, it is a low-sensitivity cell suitable for daytime vision; but when the light is brighter than a few nits, the cone cells can distinguish Color and object details are low-sensitivity, high-resolution cells. Cone cells contain three different types of sensitized cells, which are red-lights that sense long wavelengths - (cone cells, medium-wavelength green light - (cone cells and short-wavelength blue light - ( Cone-like cells, so cone-shaped cells can distinguish colors. The sensitivity range is from 400 to 700 nm. The maximum sensitivity of the three different types of sensitized cells to the spectral wavelength is in the range of blue shades in the visible spectrum. 420nm, green color light - 530nm and yellow-green light - 560nm, the number of three different types of sensitive cells on the retina is about ρ: γ: β = 40: 20:1.
Therefore, through the above explanation, we can understand that the main reason for human eye perception of color is due to the overlapping spectra of three different types of chromophoric cells on the retina, so that each wavelength in the visible spectrum has The only absorption rate, through the absorption ratio of these three cones, the visual system of the human eye can distinguish the color of the object. In addition, since the human eye has three different kinds of cone-shaped cells, the theory of color vision has developed the "Three-cimponent or Trichromatic theory" which has been dominant in color science for many years. The "Three Colors of Visual Colors" will be explained in the next color technology article.
Third, the visual color of the three primary colors
Theory of Color Vision is based on the color recognition mechanism of the human visual system. The purpose of this is to explain or assist researchers to understand and master the visual and color production. Phenomenon and relationship. After years of research, the theory of color vision can be summarized into the following three theories:
1. Three-component or Trichromatic Theory
2. Optolent color theory (Opponent-colors Theory)
3. Stage Theory of Color Vision
The theory of "three primary colors of visual color" is the earliest proposed theory, and it has always been dominant in color science; then the "opposite color theory" was proposed. This theory is another one besides the three primary colors theory of visual color. Important doctrines are also valued by the color science community; although these two color visual theories can explain most of the visual color phenomena, there are also "stage visual color theory" proposed in recent years, and accepted by everyone, In this way, the doctrine is a comprehensive concept of the "three primary colors theory of visual color" and the "optical color theory", which are combined and complemented. As for the details of these three color vision theories, they will be explained in the color technology monographs. In this paper, we will first discuss the "three primary colors theory of visual color".
In 1802, Tomas Young of the United Kingdom discovered that a mixture of red, green and blue colors could produce various colors, so the theory of color three primary colors was published and proposed. In 1861, Maxwell produced a mixture of three primary colors. The first color photo; this theory reached the end of the 19th century? In 1892, Helmholtz of Germany verified and elaborated its doctrine, so the theory of visual color trichromatic colors was also called "Young-helmholtz color three primary color theory".
The doctrine suggests that the three visual cells on the human retina are named from three different neural cells in the cortex, and the stimulation of each cell causes a primary color sensation? The feelings of red, green and blue are respectively. This argument has detailed information in the previous article, and the reader should have some impressions. When the light reflected (or transmitted) from the illuminating object enters the human visual system, it will simultaneously cause the stimulation of three different cells, and the wavelength characteristics of the light make the ratio of the strength of the total stimulation of the three cells different. Produce a variety of different colors. This theory was proposed by Tomas Young of the United Kingdom. When a certain color sensation occurs, one of the three cells will have the strongest stimulation, but the other two cells will also produce some stimulation, which means that all three cells will be stimulated, so for each A color will have a white light component, that is, a lightness feeling. The feeling of brightness is the sum of the brightness perceptions provided by each of the three cells. Later, German helmholtz supplemented Tomas Young's theory, arguing that different parts of the spectrum can cause different proportions of different cells with different intensity ratios. The color seen in mixed color light is the stimulation result of three different cells, and this argument is put forward. For the eyes, you can see the monochromatic light other than the red, green and blue colors to get a more reasonable explanation. All in all, any color seen by the eye is the result of a total stimulus after light stimulating the three visual cells.
The biggest advantage of Young-Helmholtz color three-primary color theory is that it can fully explain the mixing phenomenon of various colors and solve the problem of color reproduction. For example, the color reproduction of color film and color TV is developed based on this theoretical basis; The hypothesis of the three photoreceptor cells has also been proved in the experimental results, laying the basic concept of spectral tristimulus values. This theory can be said to be the root of the development of modern "colorimetry". However, the shortcoming of this color vision theory is that it cannot satisfactorily explain the phenomenon of color blindness (Color Blindness). In terms of Color Blindness, Helmholtz believes that color blindness is caused by the lack of one (monochrome blind) or some two, or even three (full color blind) cone cells, so according to its theory, red blind, green Color blindness and blue blindness can exist alone, but in fact all red blind people are also green blinds at the same time, which means that red blind people generally cannot distinguish between red and green, called red-green blindness; and according to its theory It is inferred that the red-green blind should not have a yellow feeling - because red-green blindness is lacking red and green cone cells, and the yellow color feel is induced by red and green cone cells, but in fact red-green The blind person has the same yellow feeling; in addition, according to its theory, the three photoreceptors will have a neutral color at the same time - white or gray feeling, the color blind person lacks at least one of the cone cells, should there be no neutral color? White or gray feels, but even people with full color blindness have the same brightness or white feel. Therefore, as far as the "three primary colors theory of visual color" is concerned, there are contradictions and phenomena that cannot be explained. Therefore, there is another school of color vision theory - Hering's "opposite color theory". As for the "opposite color theory" will be left to the next issue of the article to discuss and explain.