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Machine vision integration - complementary light sources
  1. [ 日期:2017-07-14 查看次数:270 ]

Colors of light and objects
We know that in a dark room without light, or in a dark night, no one can recognize the color of an object; only the light can illuminate the object's color to the human eye.
So the color of the object is produced by the interaction of light and the eye, the result of the brain's recognition of light at different wavelengths that are projected across the retina.
Our daily said in the color of the object refers to the environment in the daily sunlight when the color of the object, called the true nature of the object. In a special environment, the color of an object is called derivative color.
For example: when the sun leaves are green, this is its natural color, while under red light, the green leaves appear black, with ultraviolet radiation, it is fire red, this color is derived after two kinds of color.
An object has only one true color, while the derivative color has several. Therefore, when we say the color of an object, if it does not make a special description, it means the nature of the object.
Human color sense features
Different wavelengths of light illuminate the human retina, giving the brain a different sensation, known as color vision. People depend on their color vision to distinguish objects.
The eyes of the average person can distinguish more than 120 colors, and if the colors complement each other and contrast each other, experienced people can distinguish between 13000 colors.
Why can the human eye distinguish so many colors?
Modern scientific research suggests that there are three kinds of cone shaped color cells in human eyes, each of which is good at receiving light of a color, but can react to different levels of light in visible light.
The three cones are most sensitive to red, green, and blue light. Therefore, people choose these three colors as the primary colors of light. Color television is also a color display process based on the above theory.
When the eyes received the mixing light, the three color vision cells were excited by their own regularity and produced three visual signals. The optic nerve to the brain, but the brain is not interested in every single signal, but put them together to form a comprehensive vision, this is what people feel received mixed light color. According to the characteristics of human vision in red, green and blue three colors are mixed according to the proportion of the myriads of changes will make people feel, different color.
Use color properly to filter the background
White light
Red light source
The red light filters out the red text
Color properties of light
In 1666 the British scientist Newton first revealed the light color properties and color of the secret. He used experiments to show that the sun's light was a mixture of colors and found that the color of light depends on the wavelength of light. The color of light at different wavelengths in the visible range is shown below.
The color of objects: objects that people perceive are related to different disciplines such as color science, optics, chemistry and physiology.
Main colors: red, yellow, blue and green
The color of light at different wavelengths
To facilitate the study of the color properties of light, the visible spectrum is surrounded by a ring and divided into nine regions (see Figure), called the color ring. Digital color ring said corresponding light wavelength, unit (nm), nano color ring two on top of any sector in color, are called complementary.
Complementary colors: also called contrast colors, complementary colors correspond to each other on the color ring (right picture).
If two colors (monochromatic or polychromatic) with proper mixing ratio and can produce white feeling, these two kinds of color is called complementary color; two complementary color intensity can be mixed white.
The complementary colors in the color are complementary to red and cyan, blue and yellow complement each other, and green and magenta complement each other.
For example, the blue wavelength of red light and 492nm 656nm light for mutual complement color; again, magenta and green, yellow and blue colors, or in any of the other two primary colors mixed color light which is complementary to. Color subtraction (such as color pigments, two kinds of color paint on the white paper on the same point), become black. This tied, will cause a strong contrast color, feel more red red, green green. If the color saturation decreases, which can tend to reconcile, called subtractive mixture. The white light reflection object is completely white; can fully absorb light objects (called blackbody blackbody).
The complementary principle of visible light
Visible light wavelength (400nm~700nm)
The color wavelength lambda (nm) represents the wavelength
Red (Red) 780~630700
Orange (Orange) 630~600620
Yellow (Yellow) 600~570580
Green (Green) 570~500550
500~470500 (Cyan)
Blue (Blue) 470~420470
Purple (Violet) 420~380420
If you want to highlight some of the colors more brightly, choose the complementary colors on the color ring, so that the contrast of the image can be significantly improved.
In the figure below, the green background uses a red light source to increase contrast (grayscale images)
For example: Blue (435~480nm) color yellow (580~595nm). Through the study found that the color also has the following characteristic
(L) complementary colors are mixed in a certain proportion to obtain white light. White light, such as blue light and yellow light, is white. Similarly, blue and orange light is obtained by mixing Bai Guang
(2) any color on a color ring can be made up of two monochromatic lights on either side of it, and can even be duplicated from the two monochromatic lights of the secondary neighborhood.
If yellow light and red light are mixed, get orange light. Typically, the red light and green light blend into Huang Guang
(3) if you choose three separate monochromatic colors on the color ring

(4) when the sun light irradiation of an object, a wavelength of light by the object from the object, the display color (reflected light) for the light color. If the sun shining on the object, if the object absorbs a violet light of 400~435nm wavelength, the object appears yellow green.
It should be noted that some people say that the object's color is that the object absorbs other colored light, reflecting the light of this color. This statement is wrong.
Yellow green leaves, for example, absorb only violet light at 400~435nm wavelengths, suggesting that yellow green is a mixture of reflected other colors rather than reflecting yellow green light.
Improving the color rendering of light source
A good color light source can be compared to the true primary color of a true object.
Using natural light source can improve the color rendering
The color of an object depends on its absorption and reflection of light. It is essentially determined by the structure of matter, and different structures of matter absorb different wavelengths of light.
We know that light is made up of photons, and different wavelengths of light are composed of photons of different energies. The relation between lambda lambda and energy E is E=hc/ lambda. In formula, the Planck constant C is the speed of light. When a photon shoots into an object, the photon energy of a certain wavelength is easily absorbed by the material when the vibrational energy of the atom in the material or the energy required for the transition of the electron is equal, and the light of other wavelengths is not easily absorbed.
The choice and absorption of light by matter results in their own colors. The color changes as the same material changes its internal structure.
Such as red Affirmative crystal in mercuric iodide, and heated to 127 DEG C to make the transformation to the orthorhombic is blue. This is mainly due to changes in the structure of the material, the choice of light absorption has also changed. According to this point has been made in color coating material.
In addition, such as solvents, fluorescence and other substances will also affect the color, here is no longer detailed. The wavelength and energy (EV) relationship after conversion can get the lambda =hc/E=[1239.8/E (eV)]nm
Guangdong Yuanxing optics, optical image measurement is committed to the cause, because the focus, so professional; Guangdong Yuanxing, your side of the image measurement expert.


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