Density measurement has always been the most commonly used measurement method in the printing industry, but densitometers cannot provide psychophysical quantities that are related to human eye sensitivity, so their analytical measurement capabilities are limited, coupled with density measurements that cannot be in some form and CIE's The color system is correlated (CIE's color system is a recognized color representation language). Therefore, color measurement plays an increasingly important role in the detection and evaluation of printed materials. In colorimetry, there are several important factors that must be taken care of, otherwise the measured data will not correctly reflect the quality of the printed matter. The following uses X-Rite 528 as an example to explain the factors that affect the measurement results of colorimetry.
1 Whiteboard correction
Each instrument comes with a standard whiteboard that must be calibrated before each use of the instrument.
2 measuring light source
The light source is a very important factor influencing the color reproduction. The colors of the same color object are different from each other under different light sources. For example, a blue dress under the sunlight looks black under the red light; a yellow object is red under the red light, green under the green light, and black under the blue light. Therefore, the choice of light source in color measurement should be paid attention to. The light sources that can be selected in X-Rite 528 are A, C, D50, D55, D65, D75, F2, F7, F11, and F12. The F-series light source is a light source for measuring fluorescent products. The color temperature of A light source is 2856K. The color of the light source is yellow, and it is rarely used now. The color temperature of the C light source is 6744K. It represents the sunlight of the northern sky, and the D65 light source represents the average daylight.
A light source and other light source measurement results are very different, D series of light because of its color temperature in the 5000K ~ 7500K, close to white, so its display is good, in the printing industry, the observation of the original type of transmission samples recommended D50 light source It is recommended to use the D65 light source when observing reflective samples such as prints. Therefore, the measured data must indicate what light source was measured.
3 measured field of view
The ability of the human eye to observe the details of an object is related to the size of the field of view during observation. Similarly, the resolution of the human eye to color is also affected by the size of the field of view. Experiments show that the ability of the human eye to discriminate differences when viewing colors with a small field of view (<4°) is low, and when the viewing field of view is increased from 2° to 10°, the accuracy of color matching and the ability to discriminate color differences increase. However, when the field of view is further increased, the accuracy of color matching is not improved. The X-Rite 528 supports both 2° and 10° fields of view. In the 2° and 10° fields of view, the same color presents different colors. Therefore, in the color measurement, the field of view selected for measurement must also be marked.
4 color space
X-Rite 528 has 6 color spaces to choose from, namely XYZ, Yxy, L*a*b*, L*C*H*, L*U*V*, Yu*v*. In fact, both XYZ and Yxy are different representations of the CIE 1931 XYZ standard colorimetric system in color theory, but X-Rite uses them as two color spaces. The choice of color space is actually the choice of the expression of the measurement results.
5 Measurement of color difference
Chromatic aberration is an important parameter indicator for quality inspection and evaluation of printed matter. The size of color difference directly affects the quality of the product and its grade. Commonly used in the printing industry is the color difference formula ΔE*ab based on the CIE 1976 LAB uniform color space. With the deepening of research, it has gradually been found that the color difference formula also has a problem. That is, its data expression cannot match the visual perception of the human eye. Therefore, experts in color science have successively introduced the CMC (1:c) color difference formula and the CIE94 color difference formula. As well as the latest CIEDE2000 color difference formula, the CMC (1:c) color difference formula is listed as an international and national standard in the textile industry. X-Rite 528 integrates CIE 1976 LAB color difference formula, CMC (1:c) color difference formula and CIE94 color difference formula, and is freely selectable in color difference measurement. Table 1 shows the results of the two pairs of colors measured using the above three color difference formulae, respectively.
The results of measurement using different color difference formulas are quite different. The color difference of the qualified products in accordance with GB7705-87 on-site colorimetric inspection standards is less than 6.0. For the color pair 1 in Table 1, the requirements for qualified products are not met, but Measured by the CMC and CIE94 color difference formulas, the color difference is significantly less than 6.0. Therefore, the selected color difference formula must also be specified in the measured color difference data. We know that CMC (1:c) has two parameters 1 and c, which can only be 1 = 1 and c = 1 under the reference conditions specified by the CIE, 1 = 2 in the textile industry, and c = 1 that is CMC ( 2:1) Formula, CIE94 has 3 parameters, ie KL, Kc, KH. Similarly, under the standard reference conditions, KL=KC=KH=1, otherwise, it will not work. We did not tell it in the X-Rite 528 instrument. What is the setting of each parameter when using these formulas for color difference measurement?
6 Conclusion
Chromaticity measurement is a very important measurement method in the printing industry. In the process of measurement, attention must be paid to the choice of light source, color difference, color space, etc., and be noted in the measurement results, otherwise it may meet the customer's parameter index requirements. Inconsistently, the products that should have been qualified are turned into unqualified products, and it is also not conducive to the implementation of data-based and standardized production processes.
What`s Umbrella:
The umbrella making material usually includes a malleable fabric as skeleton materials and tangled lines and other available. When used in the hand will lift, although the umbrella main purpose in the first invented, is used to block the sun, but now most often regarded as rain rain tools. Other functions include an umbrella as a decoration, crutches or even a weapon, one of Hongkong's time-honored umbrella umbrella is beam Suji weapons. Auto parts processing transfer fast.
Who Invented Umbrella:
The legend of Luban's wife is a cunning workman cloud. Jade crumbs also describes, she is the inventor of the umbrella, the umbrella is she gave her husband go to build houses with somebody else. "Umbrella" word appears early, she probably created can stay close. Who invented the umbrella umbrella? On this issue has been in Chinese. Public opinions are divergent. 1000 BC, the umbrella was invented by Luban's wife, the umbrella is called "mobile homes". In the UK, in eighteenth Century began to use an umbrella. The umbrella once supplies specifically for women that love the attitude of women. An umbrella up, said left hand open love loyal through thick and thin; the umbrella, said: "I have no spare time. Now slowly shaking the umbrella, said no confidence or trust umbrella; an umbrella on the right shoulder, said don't want to see you again. By nineteenth Century the men began to use the umbrella umbrella. The picture of the rain As the British umbrella rain, umbrella is an indispensable part of British life, become a traditional symbol of the British way of life, to become the London businessmen and officials necessary, a symbol of British - Bull takes an umbrella on the hand. In literary works, is an indispensable thing in the movie. The British established umbrella Museum on 1969. There are a variety of purposes. Sometimes the umbrella umbrella as a weapon.
Social Function:
In the UK, in eighteenth Century began to use an umbrella. The pathonas umbrella used supplies specifically for women, said the umbrella pictures umbrella pictures women's attitude to love. Stand up umbrella, said to love to be loyal through thick and thin left hand open umbrella; said, "I didn't have free time now. The umbrella slowly shaking, said the lack of confidence; an umbrella on the right shoulder, said don't want to see you again.
Because the umbrella derived meaning in sociology, in ancient Chinese, umbrella is the emperor, a symbol of power in this high officials and noble lords, "Zuo Zhuan" > preparation books "< a > and a costume will have a clear record, and hierarchical. The umbrella material, color, size like the head position, body the court, is the distinction between the official size, a symbol of identity hierarchy. Such as the Han Dynasty: Food millet two thousand stone more than three public Jiuqing, black umbrella, three more than officials with a green umbrella, and the Song Dynasty emperor with red and yellow two colors are cyan. Liao Shu so the ancient emperor or official tour when a car seat or a canopy, a" shadow people ". So this umbrella is also called" umbrella "," Luo umbrella "," people "umbrella", written language is also called the "canopy".
What VESTA brings to you?
Conceived in the cradle of umbrella culture in China Umbrella City,Shangyu Songxia from 1990s, Ningbo VESTA Leisure Co.,ltd has developed from a small workshop which lived on umbrella cloth cutting and sewing into an enterprise that provides high quality outdoor leisure parts.Relying on several production bases and processing factories in Shangyu area,VESTA meets its customer`s requirements via complete solutions in the professional integration of design, manufacturing, sales and after-sale service of outdoor leisure parts.
Umbrella
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