1. visible light
Light is radiant energy that propagates in the form of electromagnetic waves. The wavelength range of electromagnetic wave radiation is very wide, and only this part of the radiation with a wavelength of 380-760 nm can cause light vision, called visible light. Light with a wavelength shorter than 380 nm is ultraviolet light, x-ray, and gamma rays; light longer than 760 nm is infrared light, radio waves, etc., which cannot produce light vision for the human eye, that is, it is invisible. Therefore, light is an objective energy and is closely related to people's subjective feelings.
2. Classification of colors
Colors can be divided into two categories: achromatic and color. Achromatic refers to white, light gray, gray to dark gray, to black, called white and black series. Pure white is an ideal fully light-reflecting object with a reflectivity of 1; pure black is an ideal non-reflective object with a reflectivity of zero. Therefore, the achromatic white-black series represents the change in the reflectance of the object. We know that the light reflectivity is proportional to the brightness, and the white walls and ceilings in the room can get higher brightness. Color refers to various colors other than the white and black series. Color has three characteristics: hue, lightness, and saturation, called the three elements of color.
The hue is the color that is presented. That is, the names of various colors, such as red, green, and blue. It is related to the wavelength of light. Brightness (brightness) is the brightness of the color. The brightness of different tones varies, even if the same color is different depending on the nature of the surface of the object and the intensity of the light, there will be a difference in lightness and darkness. If it is also yellow, it can be light yellow, medium yellow, deep yellow, etc.
Saturation (chroma) indicates the shade (shade) of the color, which can also be said to be the purity of the color and the degree of vividness. The higher the saturation, the darker the color appears (dense), and the various monochromatic lights in visible light are the most saturated colors. The more white light is incorporated into the spectral color, the less saturated it is. For example, red light is more saturated than pink light because white light is incorporated into the pink light. In general, in the same hue, when the brightness changes, the saturation also changes, but the increase or decrease in brightness decreases, and the saturation (purity) is maximized only when the brightness is moderate. However, in the feeling of giving people, it is always felt that the colors that are always bright and bright look brighter.
Three primary colors and color matching methods
Red, green, and blue are called the three primary colors. These three colors are mixed in different proportions to produce a variety of colors. There are two basic methods for color mixing: additive color mixing and subtractive color mixing.
The so-called additive color mixing is when the different colors of light are mixed, they add together the parts occupied in the spectrum to produce a new mixed color method. Indicates the color relationship of light additive color mixing. When the three primary colors of red, green and blue are mixed in equal amounts, they are available:
Red light + green light = yellow light green light + blue light = blue light
Green light + red light = magenta red light + green light + blue light = white light
If you do not mix the three primary colors, you can get a variety of intermediate colors, such as:
Red light + green light less = orange light
Red light + less blue light = pink light
Subtractive mixing is the method of producing a synthetic color effect by selectively absorbing a corresponding portion of the incident light from the incident light when mixed in different colors. If any two kinds of color light are added, if white light is generated, the two color lights are called complement light (complementary color). For example, yellow and blue complement each other, and green and red complement each other, and magenta and green complement each other. Therefore, yellow, cyan, and magenta are respectively called blue reduction, red reduction, and green reduction, that is, the three complementary colors are obtained by subtracting a corresponding primary color from white light. Therefore, yellow, cyan, and magenta can be called the primary colors of the subtractive method.
When the primary colors of yellow, magenta, and cyan are overlapped, black will be produced. In the process of subtractive color method, the density changes of the three subtracted primary colors respectively control the absorption ratios of red, green and blue, thereby obtaining various mixed colors, which can achieve the same effect mixed with the additive color method.
4. Color and vision
Color will give people a sense of warmth, distance, size and lightness, and often make people associate with each other to form different psychological effects. These are the visual habits that people have formed for a long time.
Colors can usually be divided into cool, warm and neutral (intermediate). The coldness and warmth of color are divided according to the visual response and psychological association caused by various colors. Red reminds people of the heat of the fire, which creates a warmth, called warm color. Blue makes people think of cold water, giving people a cold feeling, so it is called cool color. Purple, green is not cold, not warm, neutral. Different colors can affect the size of the object's appearance. If you put together objects of the same size and different colors, you will have a light white object in the visual sense. Dark black objects are small. In general, white objects look the most, black objects look the smallest, yellow objects are larger, followed by green, red, and blue.
People's visual habits of color will also produce a sense of distance. Objects of different colors give different visual perceptions at the same distance. Warm colors give people the feeling of moving forward, and the cool colors look like they are moving backwards. And the sense of distance that color gives people is also affected by the background hue. For example, when white is the background, the blue looks closer; when the background is black, the red looks the closest, followed by orange, yellow, green, blue, and purple. Using this feature can help us create an illusion of a sense of color and distance.
The light and heavy feeling of color is also a long-term visual habit. It is generally believed that white is the lightest and black is the heaviest. Among the three primary colors, the green is the lightest, the blue is the heaviest, and the red is the center. There are two colors of primary colors mixed in equal color, which are light in color and heavy in weight. The sense of weight of the color is not only manifested by brightness and purity, but also by the size of the area occupied by the color in the picture. Large areas appear to be heavier and attract more attention than small areas.
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