§5 The main characteristics of color. color theory. The main characteristics of the color The color is rich and important

1. What is color?
2. Physics of color
3. Primary colors
4. Warm and cold colors

What is color?

Color is waves of a certain kind of electromagnetic energy, which, after being perceived by the human eye and brain, are converted into color sensations (see color physics).

Color is not available to all animals on Earth. Birds and primates have full color vision, the rest at best distinguish some shades, mainly red.

The appearance of color vision is associated with the way of nutrition. It is believed that in primates it appeared in the process of searching for edible leaves and ripe fruits. In further evolution, color began to help a person determine danger, remember the area, distinguish plants, and determine impending weather by the color of the clouds.

Color as a carrier of information began to play a huge role in a person's life.

Color as a symbol. Information about objects or phenomena painted in a certain color was combined into an image that made a symbol out of color. This symbol changes its meaning from the situation, but is always understandable (it may not be realized, but accepted by the subconscious).
Example: red in the "heart" is a symbol of love. A red traffic light is a danger warning.

With the help of color images, you can convey more information to the reader. This linguistic understanding of color.
Example: I put on black,
There is no hope in my heart
I got sick of the white light.

color calls Aesthetic pleasure or displeasure.
Example: Aesthetics is expressed in art, although it consists not only of color, but also of form and plot. You, not knowing why, will say that it is beautiful, but it cannot be called art.

Color affects our nervous system, makes the heart beat faster or slower, affects metabolism, etc.
For example: in a room painted blue it seems cooler than it really is. Because, blue slows down our heartbeat, immerses us in peace.

With each century, color carries more and more information for us, and now there is such a thing as “the color of culture”, color in political movements and societies.

Physics of color

As such, color does not exist in nature. Color is a product of the mental processing of information that comes through the eye in the form of a light wave.

A person can distinguish up to 100,000 shades: waves from 400 to 700 millimicrons. Outside the distinguishable spectra are infrared (with a wavelength of more than 700 nm) and ultraviolet (with a wavelength of less than 400 nm).

In 1676, I. Newton conducted an experiment on splitting a light beam using a prism. As a result, he received 7 clearly distinguishable colors of the spectrum.

These colors are often reduced to 3 primary colors (see Primary Colors)

Waves have not only length, but also frequency. These quantities are interrelated, so you can set a specific wave either by the length or the frequency of oscillations.

Having obtained a continuous spectrum, Newton passed it through a converging lens and obtained White color. Thereby proving:

1 White color consists of all colors.
2 For color waves, the principle of addition applies
3 Lack of light leads to a lack of color.
4 Black is the complete absence of color.

During the experiments, it was found that the objects themselves have no color. Illuminated by light, they reflect some of the light waves and absorb some, depending on their physical properties. Reflected light waves will be the color of the object.
(For example, if a blue mug is shined with light passed through a red filter, then we will see that the mug is black, because the blue waves are blocked by the red filter, and the mug can only reflect blue waves)

It turns out that the value of paint in its physical properties, but if you decide to mix blue, yellow and red (because the rest of the colors can be obtained from a combination of primary colors (see primary colors)), then you will not get white (as if you mixed waves), but indefinitely dark color, since in this case the principle of subtraction applies.

The principle of subtraction says: any mixing leads to reflection of a shorter wavelength.
If you mix yellow and red, you get orange, the wavelength of which is less than the wavelength of red. When red, yellow and blue are mixed, an indefinitely dark color is obtained - a reflection tending to the minimum perceived wave.

This property explains the whiteness of the white color. White color is a reflection of all color waves, the application of any substance leads to a decrease in reflection, and the color becomes not pure white.

Black is the opposite. To stand out on it, you need to increase the wavelength and the number of reflections, and mixing leads to a decrease in the wavelength.

Primary colors

Primary colors are the colors with which you can get all the others.

It's RED YELLOW BLUE

If you mix red, blue and yellow color waves together, you get white.

If you mix red, yellow and blue paints, you get a dark indefinite color (see color physics).

These colors are different in lightness, in which the brightness is at its peak. If you convert them to black and white, you will clearly see the contrast.

It is difficult to imagine a bright dark - yellow like a bright light red. Due to the brightness in different ranges of lightness, a huge range of intermediate bright colors is created.

RED+YELLOW=ORANGE
YELLOW+BLUE=GREEN
BLUE+RED=PURPLE

Hue, brightness, saturation, lightness

Hue is the main characteristic by which colors are named.

For example, red or yellow. There is an extensive palette of colors, which is based on 3 colors (blue, yellow and red), which, in turn, are an abbreviation of the 7 primary colors of the rainbow (because by mixing the primary colors you can get the missing 4)

Tones are obtained by mixing in different proportions of primary colors.

Tones and shades are synonyms.

Halftones is a slight, but perceptible change in color.

Brightness is a characteristic of perception. It is determined by our speed of highlighting one color against the background of others.

"Pure" colors are considered bright, without the admixture of white or black. For each tone, the maximum brightness is observed at different lightness: tone / lightness.

This statement is true if we consider a line of shades of the same color.

If, however, to highlight the brightest shade among other tones, then the color that differs in lightness from the rest as much as possible will be brighter.

Saturation (intensity) - is the degree of expression of a certain tone. The concept operates in the redistribution of one tone, where the degree of saturation is measured by the degree of difference from gray: saturation / lightness

This concept is also related to brightness, since the most saturated tone in its line will be the brightest.

On the lightness scale, you can see that the more saturation, the lighter the tone.

Lightness is the degree to which a color differs from white and black. If the difference between the determined color and black is greater than between it and white, then the color is light. Otherwise, dark. If the difference between black and white is equal, then the color is medium in lightness.

For a more convenient determination of the lightness of a color, without being distracted by the tone, you can convert the colors to black and white:

Lightness important property colors. The definition of dark and light is a very ancient mechanism, it is observed in the simplest unicellular animals, to distinguish between light and dark. It was the evolution of this ability that led to color vision, but until now the eye is more likely to cling to the contrast of light and dark than to any other.

Warm and cold colors

Warm and cold colors are associated with attributes of the seasons. Cold shades are called shades inherent in winter, and warm shades are called summer.

This is the "indefinite" that lies on the surface at the first encounter with the concept. It is true, but the real principle of separation lies much deeper.

The division into cold and warm goes along the wavelength. The shorter the wave, the colder the color, the longer the wave, the warmer the color.

Green is a border color: shades of green can be cold and warm, but at the same time they retain their middle position in their properties.

The green spectrum is the most comfortable for the eye. We distinguish the greatest number of shades in this color.

Why such a division: into cold and warm? After all, waves have no temperature.

At first, the division was intuitive, because the action of the short-wavelength spectra is soothing. The feeling of lethargy resembles the state of a person in winter. Long-wavelength spectra, on the contrary, contributed to the activity, which is similar to the state in summer. (see psychology of color)

Understandable with primary colors. But there are many complex shades that are also referred to as cold or warm.

Effect of lightness on color temperature.

To begin with, let's define: are black and white colors cold or warm?

White color is the presence of all colors at the same time, which means that it is the most balanced and neutral in temperature. According to its properties, green tends to it. (we can distinguish a huge number of white shades)

Black is the absence of colors. The shorter the wave, the colder the color. Black has reached its apogee - its wavelength is 0, but due to the absence of waves, it can also be classified as neutral.

For example, let's take red, which is definitely warm, and consider its light and dark shades.

The warmest will be a “pure wave”, rich, bright red color (which is in the middle).

How do you get more dark shade red?

Red is mixed with black - it takes over some of its properties. More precisely, in this case, neutral mixes with warm and cools it. The higher the degree of "dilution" of red with black, the closer the temperature of burgundy to black.

How do you get a lighter shade of red (pink)?

White with its neutrality dilutes warm red. Due to this, red loses "amount" of heat, depending on the mixing ratio.

Colors diluted with black or white will never move from the category of warm to cold: they will only approach neutral properties.

Temperature neutral colors

Neutral in temperature can be called colors that have a cold and warm hue in the same lightness. For example: tone / lightness

Color contrasts

With the ratio of two opposites, according to some quality, the properties of each of the group are multiplied. So, for example, a long stripe seems even longer next to a short one.

With the help of 7 contrasts, one or another quality can be emphasized in a color.

There are 7 contrasts:

1 built on the difference between colors. It is a combination of colors close to certain spectra.

This contrast affects the subconscious. If we consider color as a source of information about the world around us, then such a combination will carry an informational message. (and in some cases cause epilepsy).

The most expressive example is the combination of white and black.

Perfect for achieving the effect of certainty.

As mentioned in the article about color lightness: the difference between light and dark is easier to see than to correlate shades. Due to this contrast, you can achieve volume and realism of the image.

Based on the difference between "inhibiting" and exciting colors. To create a thermal color contrast, in pure form, the colors are taken the same lightness.

This contrast is good for creating images with different activities: from “ snow queen to a "fighter for justice".

Complementary colors are colors that, when mixed, produce gray. If you mix spectra of complementary colors, you get white.

In Itten's circle, these colors are opposite each other.

This is the most balanced contrast, since together the complementary colors reach the “golden mean” (white), but the problem is that they can neither create movement nor achieve the goal. Therefore, these combinations are rarely used in everyday life, as they create the impression of passions, and it is difficult to stay in this state for a long time.

But in painting, this tool is very appropriate.

- it does not exist outside of our perception. This contrast, more than others, confirms the striving of our consciousness towards the golden mean.

Simultaneous contrast is the creation of the illusion of an additional color on an adjacent shade.

This is most evident in the combination of black or gray with aromatic (other than black and white) colors.

If you focus on each gray rectangle in turn, waiting for the eye to get tired, then the gray will change its hue to an additional one in relation to the background.

On orange, gray will take on a bluish tint,

On red - greenish,

Purple has a yellowish tint.

This contrast is more harmful than helpful. To cancel it, you should add a shade of the main one to the changeable color. More precisely, if yellowness is added to a gray color and it is defined against an orange background, then the simultaneous contrast will be reduced to zero.

The concept of saturation can be found .

I will add that darkened, lightened, complex, not bright colors can also belong to unsaturated colors.

Net contrast in saturation is based on the difference between bright and non-bright. bright colors one lightness.

This contrast gives the impression that bright colors are pushed forward against a background that is not bright. With the help of contrast in saturation, you can emphasize the detail of the wardrobe, place accents.

Based on the quantitative difference between colors. In this contrast, balance or dynamics can be achieved.

It has been noted that in order to achieve harmony, there should be less light than dark.

The lighter the spot on a dark background, the less space it takes up for balance.

With colors equal in lightness, the space occupied by spots is equal.

Color psychology, color meaning

Color combinations

color harmony

The harmony of colors lies in their consistency and strict combination. When choosing harmonious combinations, it is easier to use watercolor paints, and having certain skills in selecting tones on paints, it will not be difficult to cope with threads.

The harmony of colors obeys certain laws, and in order to better understand them, it is necessary to study the formation of colors. To do this, use the color wheel, which is a closed band of the spectrum.

At the ends of the diameters dividing the circle into 4 equal parts, there are 4 main pure colors - red, yellow, green, blue. Speaking of "pure color", they mean that it does not contain shades of other colors adjacent to it in the spectrum (for example, red, in which neither yellow nor blue shades are noticed).

Further, on the circle between the pure colors, intermediate or transitional colors are placed, which are obtained by mixing adjacent pure colors in pairs in various proportions (for example, by mixing green with yellow, several shades of green are obtained). In each spectrum, 2 or 4 intermediate colors can be arranged.

By mixing each color separately with white and black paint, light and dark tones of the same color are obtained, for example, blue, cyan, dark blue, etc. Light tones are arranged with inside color circle, and dark - from the outside. Having filled the color wheel, you can notice that warm colors (red, yellow, orange) are located in one half of the circle, and cold colors (blue, cyan, violet) are in the other half.

Green color can be warm if it has an admixture of yellow, or cold - with an admixture of blue. Red can also be warm with a yellowish tint and cold with a blue tint. The harmonious combination of colors lies in the balance of warm and cold tones, as well as in the consistency of different colors and shades with each other. Most in a simple way determining harmonious color combinations is to find these colors on color wheel.

There are 4 groups of color combinations.

monochrome- colors that have the same name, but different lightness, that is, transitional tones of the same color from dark to light (obtained by adding black or white paint to one color in different quantities). These colors are the most harmoniously combined with each other and are easy to select.

The harmony of several tones of the same color (preferably 3-4) looks more interesting, richer than a single color composition, such as white, light blue, blue and dark blue or brown, light brown, beige, white.

Monochrome combinations are often used in the embroidery of clothes (for example, on a blue background they embroider with threads of dark blue, light blue and white), decorative napkins (for example, on a harsh canvas they embroider with threads of brown, light brown, beige), as well as in artistic embroidery of leaves and flower petals to convey light and shade.

related colors are located in one quarter of the color wheel and have one common main color (for example, yellow, yellow-red, yellowish-red). There are 4 groups of related colors: yellow-red, red-blue, blue-green and green-yellow.

Transitional shades of the same color are well coordinated with each other and harmoniously combined, as they have a common main color in their composition. Harmonious combinations of related colors are calm, soft, especially if the colors are weakly saturated and close in lightness (red, purple, violet).

Related-contrasting colors located in two adjacent quarters of the color wheel at the ends of the chords (that is, lines parallel to the diameters) and have one common color and two other color components, for example, yellow with a red tint (yolk) and blue with a red tint (violet). These colors are coordinated (combined) with each other by a common (red) tint and are harmoniously combined. There are 4 groups of related-contrasting colors: yellow-red and yellow-green; blue-red and blue-green; red-yellow and red-blue; green-yellow and green-blue.

Related-contrasting colors are harmoniously combined if they are balanced by an equal amount of the common color present in them (that is, reds and greens are equally yellowish or bluish). These color combinations look more dramatic than related ones.

Contrasting colors. Diametrically opposite colors and shades on the color wheel are the most contrasting and inconsistent with each other.

The more colors differ from each other in hue, lightness and saturation, the less they harmonize with each other. When these colors come into contact, a variegation unpleasant for the eye occurs. But there is a way to match contrasting colors. To do this, intermediate colors are added to the main contrasting colors, which harmoniously connect them.

Color saturation- a color parameter that characterizes the degree of purity of a color tone. The closer a color is to monochromatic, the more saturated it is.

In color theory saturation- this is the intensity of a certain tone, that is, the degree of visual difference between a chromatic color and an achromatic (gray) color of equal lightness. A saturated color can be called juicy, deep, less saturated - muted, close to gray. A fully desaturated color will be a shade of gray. Saturation is one of three coordinates in HSL and HSV color spaces. Saturation (chroma) in the CIE 1976 Lab and Luv color spaces is a non-formalized value used in the CIE LCH representation (lightness (lightness), chroma (chroma, saturation), hue (tone)).

In physical terms, color saturation is determined by the nature of the distribution of radiation in the spectrum of visible light. The most saturated color is formed when there is a peak of radiation at one wavelength, while radiation that is more uniform in spectrum will be perceived as a less saturated color. In a subtractive model of color formation, for example, when mixing paints on paper, a decrease in saturation will be observed when adding white, gray, black paints, as well as when adding paint of an additional color. ()

Purity- this is the degree of approximation of a given color to a pure spectral color, expressed in fractions of a unit.

The colors of the spectrum have the highest purity. Therefore, the purity of all spectral colors is taken as one, despite their different saturation. The most saturated color is blue, the least - yellow. Particularly saturated colors are observed in the spectrum, which does not contain impurities of white or black.

A chromatic composition can be built by varying the saturation of one color of constant lightness. This is achieved by adding to the selected color the required amount of gray equal in lightness to it. As a result, the variants of the selected color form a pure saturation series, in which the saturation naturally changes, the lightness remains unchanged, and the color tone becomes achromatic. ()

When black is added to a pure color, its lightness changes:

Another example of how the saturation of blue changes when gray is added to it:

Changing the saturation and lightness of shades of orange and blue:

As you can see in the picture, when adding medium gray and black to warm colors, reducing the saturation results in brownish shades of color, cool colors become grayish. In this picture, the change in pure color is based on two parameters: saturation and lightness. Lightness decreases with the addition of black, saturation - gray.

Least saturated and most light colors- pastel:

There are several quality characteristics color saturation:
- live (vivid) saturation;
- strong (strong) saturation;
- deep (deep) saturation.
Desaturated colors are characterized as dull (dull), weak (weak), or washed out.

An example of changing a color depending on its lightness (value) and saturation (chroma), using the example of red from Munsell's color book:

And this is how a green color looks like with the same lightness, but with different saturation (percentages of primary colors in the CMYK system are given).

Color saturation (intensity) is the degree of expression of a certain tone. The concept comes next after brightness. Photo.

Saturation (intensity) is the degree of expression of a particular color. It operates in the redistribution of one, where the degree of saturation is determined by the purity of the reflection of a certain spectrum from the surface. The more accurate and complete the reflection is, the more saturated the shade we see. If the surface does not perfectly reflect one wave, but there is an impurity, then such shades are usually paler. They can be greyish, brownish, or with a different tint, they can be characterized as dusty, foggy, complex, soft, etc. Saturated colors can be characterized as bright, catchy, full, expressive, spectacular, etc.

The concept of "saturation" is also associated with. But if brightness is a relative value: white can also be catchy, then saturation is an attribute of chromatic tone. A pure tone, without an admixture of gray, with a moderate presence of white or black, is the standard of this concept.
In contrast to this definition, there will be fading of the hue - the higher the contamination of the paint, the more complex the resulting hue and closer to gray. Paleness, pallor can be defined as the absence of brightness, however, we also understand that it is a light, muted (pastel) tone or with a significant admixture of gray.

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I am a programmer by education, but at work I had to deal with image processing. And then an amazing and unknown world of color spaces opened up for me. I do not think that designers and photographers will learn something new for themselves, but perhaps someone will find this knowledge at least useful, and at best interesting.

The main task of color models is to make it possible to specify colors in a unified way. In fact, color models define certain coordinate systems that allow you to uniquely determine the color.

The most popular today are the following color models: RGB (used mainly in monitors and cameras), CMY (K) (used in printing), HSI (widely used in machine vision and design). There are many other models. For example, CIE XYZ (standard models), YCbCr, etc. The following is given short review these color patterns.

RGB color cube

From Grassmann's law, the idea of ​​an additive (i.e., based on mixing colors from directly emitting objects) model of color reproduction arises. For the first time, such a model was proposed by James Maxwell in 1861, but it received the greatest distribution much later.

In the RGB model (from the English red - red, green - green, blue - cyan) all colors are obtained by mixing three basic (red, green and blue) colors in various proportions. The proportion of each base color in the final can be perceived as a coordinate in the corresponding three-dimensional space, so this model is often called a color cube. On Fig. 1 shows the color cube model.

Most often, the model is built so that the cube is single. The points corresponding to the base colors are located at the cube vertices lying on the axes: red - (1; 0; 0), green - (0; 1; 0), blue - (0; 0; 1). In this case, the secondary colors (obtained by mixing two base ones) are located in other vertices of the cube: blue - (0;1;1), magenta - (1;0;1) and yellow - (1;1;0). Black and white colors are located at the origin (0;0;0) and the point farthest from the origin (1;1;1). Rice. shows only the vertices of the cube.

Color images in the RGB model are built from three separate image channels. In Table. the decomposition of the original image into color channels is shown.

In the RGB model, a certain number of bits are allocated for each color component, for example, if 1 byte is allocated for encoding each component, then using this model, 2 ^ (3 * 8) ≈ 16 million colors can be encoded. In practice, such coding is redundant, because most people are not able to distinguish between so many colors. Often limited to the so-called. mode "High Color" in which 5 bits are allocated for encoding each component. In some applications, a 16-bit mode is used in which 5 bits are allocated for encoding the R and B components, and 6 bits for encoding the G component. This mode, firstly, takes into account the higher sensitivity of a person to green color, and secondly, it allows more efficient use of the features of the computer architecture. The number of bits allocated for encoding one pixel is called the color depth. In Table. examples of encoding the same image with different color depths are given.

Subtractive CMY and CMYK models

The subtractive CMY model (from the English cyan - cyan, magenta - magenta, yellow - yellow) is used to obtain hard copies (printing) of images, and in some way is the antipode of the RGB color cube. If in the RGB model the base colors are the colors of the light sources, then the CMY model is the color absorption model.

For example, paper coated with yellow dye does not reflect blue light; we can say that the yellow dye subtracts blue from the reflected white light. Similarly, cyan dye subtracts red from reflected light, and magenta dye subtracts green. That is why this model is called subtractive. The conversion algorithm from the RGB model to the CMY model is very simple:

This assumes that the RGB colors are in the interval . It is easy to see that in order to obtain black in the CMY model, it is necessary to mix cyan, magenta and yellow in equal proportions. This method has two serious drawbacks: firstly, the black color obtained as a result of mixing will look lighter than “real” black, and secondly, this leads to significant dye costs. Therefore, in practice, the CMY model is extended to the CMYK model, adding black to the three colors.

Color space hue, saturation, intensity (HSI)

The RGB and CMY(K) color models discussed earlier are very simple in terms of hardware implementation, but they have one significant drawback. It is very difficult for a person to operate with colors given in these models, because a person, describing colors, uses not the content of the basic components in the described color, but somewhat different categories.

Most often, people operate with the following concepts: hue, saturation and lightness. At the same time, when talking about the color tone, they usually mean exactly the color. Saturation indicates how much the described color is diluted with white (pink, for example, is a mixture of red and white). The concept of lightness is the most difficult to describe, and with some assumptions, lightness can be understood as the intensity of light.

If we consider the projection of the RGB cube in the direction of the white-black diagonal, we get a hexagon:

All gray colors (lying on the diagonal of the cube) are projected to the central point. In order to be able to encode all the colors available in the RGB model using this model, you need to add a vertical lightness (or intensity) axis (I). The result is a hexagonal cone:

In this case, the tone (H) is set by the angle relative to the red axis, the saturation (S) characterizes the purity of the color (1 means a completely pure color, and 0 corresponds to a shade of gray). It is important to understand that hue and saturation are not defined at zero intensity.

The conversion algorithm from RGB to HSI can be performed using the following formulas:

The HSI color model is very popular among designers and artists because this system provides direct control of hue, saturation and brightness. These same properties make this model very popular in machine vision systems. In Table. shows how the image changes with increasing and decreasing intensity, hue (rotated by ±50°), and saturation.

Model CIE XYZ

For the purpose of unification, an international standard color model was developed. As a result of a series of experiments, the International Commission on Illumination (CIE) determined the addition curves for the primary (red, green and blue) colors. In this system, each visible color corresponds to a certain ratio of primary colors. At the same time, in order for the developed model to reflect all visible to man colors had to enter a negative amount of base colors. To get away from negative CIE values, introduced the so-called. unreal or imaginary primary colors: X (imaginary red), Y (imaginary green), Z (imaginary blue).

When describing color X,Y,Z values are called standard fundamental excitations, and the coordinates obtained on their basis are called standard color coordinates. The standard addition curves X(λ),Y(λ),Z(λ) (see Fig.) describe the sensitivity of the average observer to standard excitations:

In addition to standard color coordinates, the concept of relative color coordinates is often used, which can be calculated using the following formulas:

It is easy to see that x+y+z=1, which means that any pair of values ​​is sufficient to uniquely set relative coordinates, and the corresponding color space can be represented as a two-dimensional graph:

The set of colors defined in this way is called the CIE triangle.
It is easy to see that the CIE triangle describes only the hue, but does not describe the brightness in any way. To describe the brightness, an additional axis is introduced, passing through a point with coordinates (1/3; 1/3) (the so-called white point). The result is a CIE color body (see Fig.):

This solid contains all the colors visible to the average observer. The main disadvantage of this system is that using it, we can only state the coincidence or difference of two colors, but the distance between two points of this color space does not correspond to the visual perception of the color difference.

Model CIELAB

The main goal in the development of CIELAB was to eliminate the non-linearity of the CIE XYZ system from the point of view of human perception. The abbreviation LAB usually refers to the CIE L*a*b* color space, which is currently the international standard.

In the CIE L*a*b system, the L coordinate means lightness (in the range from 0 to 100), and a,b coordinates- indicate a position between green-magenta, and blue-yellow colors. Formulas for converting coordinates from CIE XYZ to CIE L*a*b* are given below:

where (Xn,Yn,Zn) are the coordinates of the white point in CIE XYZ space, and

On Fig. slices of the CIE L*a*b* color body are presented for two lightness values:

Compared to CIE XYZ system Euclidean distance (√((L1-L2)^2+(a1^*-a2^*)^2+(b1^*-b2^*)^2)) in CIE L*a system *b* matches the human perceived color difference much better, however the standard color difference formula is the extremely complex CIEDE2000.

Television color difference color systems

In the YIQ and YUV color systems, color information is represented as a luminance signal (Y) and two color difference signals (IQ and UV, respectively).

The popularity of these color systems is due primarily to the advent of color television. Because Since the Y component essentially contains the original image in grayscale, the signal in the YIQ system could be received and correctly displayed both on old black-and-white TVs and on new color ones.

The second, perhaps more important, advantage of these spaces is the separation of information about the color and brightness of the image. The fact is that the human eye is very sensitive to changes in brightness, and much less sensitive to changes in color. This allows the transmission and storage of chrominance information with reduced depth. It is on this feature of the human eye that the most popular image compression algorithms (including jpeg) are built today. To convert from RGB space to YIQ, you can use the following formulas:

So, briefly for reference: initially light, as electromagnetic radiation with a certain wavelength, is white. But when passing it through a prism, it decomposes into the following components of it visible colors (visible spectrum): To red, O range, and yellow, h green, G blue, With blue, f purple ( To every O hotnik and does h nat G de With goes f azan).

Why did I single out visible"? The structural features of the human eye allow us to distinguish only these colors, leaving ultraviolet and infrared radiation out of our field of vision. The ability of the human eye to perceive color directly depends on the ability of the matter of the world around us to absorb some light waves and reflect others. Why is a red apple red? Because that the surface of an apple, having a certain bio-chemical composition, absorbs all waves of the visible spectrum, with the exception of red, which is reflected from the surface and, entering our eye in the form of electromagnetic radiation of a certain frequency, is perceived by receptors and is recognized by the brain as red. or orange orange the situation is similar, as with all the matter that surrounds us.

The receptors of the human eye are most sensitive to the blue, green and red colors of the visible spectrum. Today there are about 150,000 color tones and shades. At the same time, a person can distinguish about 100 shades by color tone, about 500 shades of gray. Naturally, artists, designers, etc. have a wider range of color perception. All colors located in the visible spectrum are called chromatic.

visible spectrum of chromatic colors

Along with this, it is also obvious that in addition to "color" colors, we also recognize "non-color", "black and white" colors. So here are the shades. gray color in the range "white - black" are called achromatic (colorless) due to the absence of a specific color tone (shade of the visible spectrum) in them. The brightest achromatic color is white, the darkest is black.

achromatic colors

Further, for a correct understanding of the terminology and the competent use of theoretical knowledge in practice, it is necessary to find differences in the concepts of "tone" and "shade". So here it is Color tone- a characteristic of a color that determines its position in the spectrum. Blue color is a tone, red is also a tone. A shade- this is a variety of one color, which differs from it both in brightness, lightness and saturation, and in the presence of an additional color that appears against the background of the main one. Light blue and dark blue are shades of blue in terms of saturation, and bluish-green (turquoise) is due to the presence of an additional green color in blue.

What's happened color brightness? This is a color characteristic that directly depends on the degree of illumination of the object and characterizes the density of the light flux directed towards the observer. Simply put, if, under all other conditions being equal, the same object is successively illuminated by light sources different power, in proportion to the incoming light, the light reflected from the object will also be of different power. As a result, the same red apple in bright light will look bright red, and in the absence of light we will not see it at all. The peculiarity of the brightness of the color is that when it is reduced, any color tends to black.

And one more thing: under the same lighting conditions, the same color can differ in brightness due to the ability to reflect (or absorb) incoming light. Glossy black will be brighter than matte black precisely because gloss reflects incoming light more, while matte black absorbs more.

Lightness, lightness ... As a characteristic of color - it exists. As an accurate definition - probably not. According to one source, lightness- the degree of closeness of color to white. According to other sources - the subjective brightness of an area of ​​the image, related to the subjective brightness of the surface, perceived by a person as white. Third sources refer the concepts of brightness and lightness of color to synonyms, which is not devoid of logic: if the color tends to black (becomes darker) when the brightness decreases, then when the brightness increases, the color will tend to white (becomes lighter).

In practice, this is what happens. During photo or video shooting, underexposed (not enough light) objects in the frame become a black spot, and overexposed (too much light) - white.

A similar situation applies to the terms "saturation" and "intensity" of color, when some sources say that "color saturation is intensity .... etc. etc." In fact it is absolutely different characteristics. Saturation- "depth" of color, expressed in the degree of difference between a chromatic color and a gray color that is identical with it in lightness. As saturation decreases, each chromatic color approaches gray.

Intensity- the predominance of any tone in comparison with others (in the landscape of the autumn forest, the orange tone will be predominant).

Such a "substitution" of concepts occurs, most likely, for one reason: the line between brightness and lightness, saturation and intensity of color is as thin as the concept of color itself is subjective.

From the definitions of the main characteristics of color, the following pattern can be distinguished: the color rendering (and, accordingly, color perception) of chromatic colors is greatly influenced by achromatic colors. They not only help to form shades, but also make the color light or dark, saturated or faded.

How can this knowledge help a photographer or videographer? Well, firstly, no camera or video camera is capable of conveying color in the way a person perceives it. And in order to achieve harmony in the image or bring the image closer to reality during post-processing of photo or video material, it is necessary to skillfully manipulate the brightness, lightness and color saturation so that the result satisfies either you, as an artist, or those around you, as viewers. It is not for nothing that the profession of colorist exists in film production (in photography, this function is usually performed by the photographer himself). A person with knowledge of color, through color correction, brings the filmed and edited material to such a state when color scheme The film simply makes the viewer wonder and admire at the same time. Secondly, in coloristics, all these color features are intertwined quite subtly and in various sequences, allowing not only to expand the possibilities of color reproduction, but also to achieve some individual results. If these tools are used illiterately, it will be difficult to find fans of your work.

And on this positive note, we finally approached the color scheme.

Coloristics, as the science of color, in its laws relies precisely on the spectrum of visible radiation, which, by the works of researchers of the 17th-20th centuries. from a linear representation (illustration above) was transformed into a chromatic circle shape.

What allows us to understand the chromatic circle?

1. There are only 3 primary (basic, primary, pure) colors:

Red

Yellow

Blue

2. Composite colors of the second order (secondary) are also 3:

Green

Orange

Violet

Not only are they located opposite the primary colors in the chromatic circle, but they are also obtained by mixing the primary colors with each other (green = blue + yellow, orange = yellow + red, violet = red + blue).

3. Composite colors of the third order (tertiary) 6:

yellow-orange

red-orange

Red purple

blue purple

blue green

yellow green

Composite colors of the third order are obtained by mixing primary colors with secondary colors of the second order.

It is the location of the color in the twelve-part color wheel that allows you to understand which colors and how can be combined with each other.

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