The coordination of colors is the subject of studying practical colors. It mainly pursues the harmony and beauty of color.
Pure color science is called color engineering, including color expression method, color measurement method, color planning and design, color adjustment, color management and so on. Packaging chromatics is the concrete application of color engineering in packaging color design and color reproduction, and it is the organic unity of natural color, social color and artistic color. Starting from the packaging color, packaging chromatics systematically reflects the phenomena and laws of color formation and expression, color design and reproduction. It is an organic combination of color composition, colorimetry and printing colorimetry, and an organic combination of perceptual knowledge and rational analysis of packaging color.
Chapter V Color Description Theory
Section 1 Color Stereo
First, the psychological attributes of color
(A), psychological color
The color observed in daily life is greatly influenced by psychological factors, that is, psychological color perception is formed. In colorimetry, the name of color is tristimulus value (x, y, z); (R，G，B)； Tone, brightness, purity, dominant wavelength, etc. However, in the production, it is customary to use pink, golden yellow, green, sky blue, bright or not, shades, fresh and not fresh. These popular expressions are not as accurate as colorimetry, and their names are not uniform. According to their similarity, these names can be roughly divided into three groups. Summarize hue, color light and color expression into a group; Brightness, lightness, depth, lightness and darkness, the hierarchical performance is summarized as a group; Saturation, freshness, purity, chromaticity, color correctness and so on are summarized as a group. Such grouping is just a feeling, there is no strict definition, and their meanings are not exactly the same. For example, hue is not equal to color light, lightness is not equal to brightness, and saturation is not equal to purity, freshness and depth. But when judging color, they are also three variables, which can roughly correspond to the three variables in colorimetry. The dominant wavelength corresponds to the hue. It is often said that red has a certain wavelength range, and red is only an area on the chromaticity diagram. People will never call 500nm monochromatic light red. Brightness in colorimetry corresponds to lightness, brightness, subjective lightness, lightness, lightness, hierarchy and so on. In the same background, the color with low brightness is always darker than the color with high brightness. Purity in colorimetry corresponds to saturation, freshness, chromaticity, purity and so on.
Although the name of psychological color vision corresponds to several physical quantities in colorimetry, this correspondence is not a simple proportional relationship, nor is it a one-to-one correspondence. There are many different characteristics between them. For example, purity in colorimetry can be divided into stimulus purity and chromaticity purity. It is considered that the purity of white light is zero, and the purity of all monochromatic light (whether stimulus purity or chromaticity purity) is 1. Chromaticity purity is defined as the proportion of monochromatic light contained in colored light, indicating the proximity of a color to neutral color or white light. When psychological color vision distinguishes colored light from neutral color, it thinks that the purity of each monochromatic light is not the same. For the same monochromatic light, there is little difference among yellow, green and white light, but there is significant difference among red, blue and white light. So psychologically, although yellow light is monochromatic, its purity is lower than blue light. These psychological differences between color and white light are usually called saturation to distinguish them from chromaticity purity. Psychological light can be divided into two kinds, one is connected with the object and the other is not connected with the object. For example, when observing the surface of an object through a small hole, the observer can't see the object and can't judge the brightness by touching the object, but it is also different from the brightness in colorimetry. In order to separate the brightness of the object surface from the brightness in colorimetry, it is called lightness.
In terms of color mixing, psychological color and chromaticity color are also different. When you see orange, you will think it is a mixture of red and yellow, and when you see purple, you will think it is a mixture of blue and red. But when you see yellow light, you don't think yellow light can be a mixture of red light and green light. In psychological color vision, all colors "look" cannot be mixed with other colors. Generally speaking, there is orange with yellow in red, blue-green in green and grass green in green, but there is no blue in yellow or green in red.
Therefore, psychologically, colors are divided into red, yellow, green and blue, which are called four primary colors. Usually red, green, yellow and blue are called psychological complementary colors. No one can imagine that white is a mixture of these four primary colors, while black cannot be mixed with other colors. Therefore, red, yellow, green and blue, plus white and black, become the six basic feelings of psychological color perception. Although physically black is the situation that human eyes are not exposed to light, psychologically many people think that exposure to light is just a feeling, and black is indeed a feeling. For example, looking at a black object is different from closing your eyes. Ostwald (German) and others put black and white in an important position when making color labels, and Herring's theory of black-and-white opposition of red, green, yellow and blue shows that these six colors have physiological and psychological basis.
Another difference between psychological color and colorimetry is that colorimetry studies the color light itself, and does not involve the study of the changes in the environment, the position of the observer in space and the observation angle. For example, the background of colored light in CIE system is dark and colorless, and the experiment proves that different backgrounds do not change the matching value. However, this is not the case in psychological color perception. When the background changes, many psychological effects such as color resolution, hue, saturation and lightness will change.
In colorimetry, the size of visual field affects matching, and the role of macula in small visual field (such as reducing the sensitivity to blue light) affects matching. In large visual field, rod cells will play a certain role because some visual fields are beyond the scope of macula. In our daily life, we see not only colors, but colors and objects, not just colored light, but colored light mixed with many other lights, which further complicates the problem.