The basics of lighting technology
I. Visible Light
Light is the form of electromagnetic waves propagated in the form of radiant energy. Electromagnetic wave radiation has a wide range of wavelengths, only wavelengths in the 380 to 760nm of this part of the radiation to cause light vision, known as visible light. Wavelengths shorter than 380nm light is ultraviolet, x-rays, γ-rays; longer than 760nm light is infrared, radio waves, etc., they do not produce light vision to the human eye, that is, invisible. Therefore, light is an objective existence of energy, and has a close relationship with the subjective sense of man.
II. Classification of color
Color can be divided into two categories of non-color and color. Non-color means from white, light gray, gray to dark gray, until black, called the white and black series. Pure white is the ideal completely light-reflecting object, its reflectivity is 1; pure black is the ideal non-reflecting object, its reflectivity is 0. Therefore, the non-color white and black series represents the change of light reflectivity of the object. We know that the light reflectance is proportional to the brightness, and white walls and ceilings indoors can get a higher brightness. Color refers to a variety of colors other than the white and black series. Color has three characteristics: hue, brightness and saturation, called the three elements of color.
Hue is the color that indicates the presentation of the color. It is also the name of a variety of different colors, such as red, green, blue, etc. It is related to the wavelength of light. Brightness (luminance) is the brightness of the color is expressed. Different shades of brightness vary, even if the same shade due to the nature of the surface of the object and the intensity of light will also produce differences in light and dark, shades of light. Such as the same yellow, can have light yellow, yellow, dark yellow, etc..
Saturation (chroma) indicates the depth of color (intensity), which can also be said to be the purity of color, the degree of vividness. The higher the saturation, the deeper (thicker) the color appears, and various monochromatic light in visible light is the most saturated color. When the more white light is mixed into the spectral color, the less saturated. For example, red light is more saturated than pink light, because pink light is mixed with white light. Generally speaking, in the same hue, when the brightness changes, the saturation also changes, but the brightness increases or decreases its saturation are reduced, only when the brightness is moderate saturation (purity) is the maximum. However, the feeling of people always feel that always brightness of the color looks brighter.
III. 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 of color mixing: additive color mixing and subtractive color mixing.
The so-called additive color mixing is when different colors of light mixed, they add together their respective parts of the spectrum, thus producing a new method of mixing colors. Show the color-forming relationship of light additive color mixing. When red, green and blue primary colors of light are mixed in equal amounts, we get
red light + green light = yellow light green light + blue light = cyan light
green light + red light = magenta light red light + green light + blue light = white light
If unequal amounts of the three primary colors of light when mixed, you can get a variety of intermediate colors, for example
More red light + less green light = orange light
more red light + less blue light = pink light
Subtractive color mixing is a mixture of different colors, each of them from the incident light to selectively absorb the corresponding part of their share of the spectrum, and produce a synthetic color effect of the method. Any two colors of light after the addition of white light, the two colors of light will be called complementary light (complementary colors). Such as yellow and blue are complementary to each other, cyan and red are complementary to each other, magenta and green are complementary to each other. Therefore, yellow, cyan, magenta are called minus blue, minus red, minus green, which means that the three complementary colors are made of white light minus a corresponding primary color. Therefore, yellow, cyan, magenta can be called subtractive color method three primary colors.
When three subtractive primary colors, yellow, magenta and cyan, overlap together to produce black. In the process of subtractive color method, the density changes of the three subtractive primary colors control the absorption ratio of red, green and blue respectively, thus yielding a variety of mixed colors, which can achieve the same effect as the additive color mixing.
IV. Color and vision
Color will give people a sense of warm and cold, distance, size and weight, and often make people associate, thus forming a different psychological effect, these are long-established visual habits.
Color can usually be divided into cool, warm and neutral colors (intermediate colors) three categories. The cold and warm colors are divided according to the visual response and psychological association caused by various colors to people. Red makes people think of the heat of fire, thus creating a sense of warmth, and is called a warm color. Blue makes people think of cold water, giving a sense of coldness, so it is called cold color. Purple and green are neutral colors that are not cold or warm. Different colors can affect the size of the appearance of objects. If you put some different colors of the same size objects together, in the visual perception will produce a light white object large. Dark black objects are small. Generally speaking, white objects look the largest, black objects look the smallest, yellow-colored objects larger, followed by green, red, blue.
People's visual habits of color also produce a sense of distance and proximity. Different colors of objects at the same distance give people a different visual perception. Warm colors give people the feeling of moving forward, cold colors will appear to move backward away from the feeling. And color gives people a sense of distance is also affected by the background tone. For example, when white is the background, blue looks closer; when black is the background, red looks closest, followed by orange, yellow, green, blue and purple. The use of this feature can help us create an illusion of color three-dimensional sense of distance effect.
The lightness of color is also a long-established visual habit. It is generally believed that white is the lightest and black is the heaviest. In the three primary colors of light, green is the lightest, blue is the heaviest, red in the middle. There are two primary colors of light mixed in equal amounts to form the color, containing light colors appear light, containing heavy colors appear heavy. The weight of color is not only expressed through brightness and purity, but also influenced by the size of the area occupied by the color in the picture. Large area appears heavier and attracts more attention than the small area of the color.