The basic principle of color reproduction in the h

The basic principle of color reproduction in silk printing (middle)

the lightness of the color obtained by the addition (mixing) of pigments is reduced, so the mixing of pigments is called subtractive method

the color rendering principle of pigment subtraction can also be expressed by the following formula

y + M = w-b-g = r

y + C = w-b-r = g

c + M = w-r-g = b

y + m + C = w-b-g-r = K (black)

yellow, magenta and cyan are mixed together. Blue light, green light and magenta light are absorbed by yellow, magenta and cyan respectively, so they appear black

it can be seen that black is obtained by mixing yellow material with blue material, black is obtained by mixing magenta material with green material, and black is also obtained by mixing cyan material with red material. When a certain color is mixed with another color for more than 10 years, such as taking root in laboratory black on the 1st, these two colors are complementary to each other. Therefore, yellow and blue are complementary to each other, magenta and green are complementary to each other, and cyan and red are complementary to each other

colorant optimization coal industry chain, the complementary colors appear black after mixing, and the complementary colors of color and light appear white after mixing. The two are exactly the opposite. However, the three primary colors of light are the three primary colors of the complementary colors of colorant, and the complementary colors of the three primary colors of colorant are the three primary colors of light. Therefore, there is an interaction between light and color, which has been cleverly applied to the color decomposition of color originals

(III) achromatic

colors are divided into achromatic and color. Non color refers to black, white and various grays from dark to brightest. They can be arranged into a series, called black and white series. The change from black to white in this series can be represented by a gray band, with pure black at one end and pure white at the other end. The material reflects all visible light, and the reflectance is 100% pure white; The substance absorbs all visible light and is pure black when the reflectivity is equal to 0%. In real life, there are no pure white and pure black substances. Magnesium oxide can only approximate pure white, and black velvet is close to pure black

the non color of black-and-white series can only reflect the change of light reflectivity of substances, and the visual feeling is a bright change

when the reflectivity of the surface of the printed matter to the radiation of all wavelengths of the visible spectrum is more than 80% - 90%, the visual feeling is white. If the reflectivity is less than 4%, it is black. White, black and gray objects have no selectivity for the reflection of various wavelengths of the spectrum, and they are called neutral features

(IV) color

various colors other than black and white series are called colors. Any color is represented by three quantities: hue, brightness and saturation

1. hue

hue is the most basic feature of color. People call colors such as red, yellow, green, etc. according to Dr. Xinyu, the technical director of the R & D center and the chief engineering teacher of Guangzhou Jinfa carbon fiber new material development Co., Ltd. The hue is determined by the colored light reflected from the surface of the object to the optic nerve of the human eye

for monochromatic light, the wavelength of its light can be used to determine. If the color is composed of mixed light, the hue is determined by the proportion of the amount of light at various wavelengths of the mixed light. For example, under sunlight, the surface of the printed matter reflects color light with a wavelength of 500 ~ 550nm, while relatively absorbs color light with other wavelengths. At this time, remove the sample, and the printed matter visually feels green

the hue can be expressed by the shape of the spectral reflectance curve. Curve a indicates that the hue of the object is green, and curve B indicates that the hue of the object is green and blue. (to be continued)