This article will explain the application of color science in printing from the aspects of production of printing chromatogram, measurement of printing hue, and deployment of spot color ink.
1Using Colorimetry to Produce Print Chromatographs Through Color Analysis, Color Transfer, and Color Combinations
The three primary color inks are mixed in different proportions to obtain inter- or polychromatic colors of different hues.
Two kinds of primary color inks are mixed in equal amounts to obtain inter-color; in different proportions, inter-colors of different colors can be obtained.
The more types of color hue used in the color match, the worse the brightness is. When black ink is added to any hue ink, the lightness value is decreased; when white ink is added, the lightness is increased.
Pay attention to the effect of the used paper, overprinting sequence, lighting source color on the ink, and changes in color before and after drying of the print.
You can use complementary colors to correct the color cast, but only when the ink brightness value is high.
Try to use different types of original ink as much as possible to reduce the complementary color effect.
Pay attention to the effect of ink viscosity on hue.
Before a more complex spot color ink is dispensed, a small amount of trial mix can be used to determine the ratio, and then the ink volume can be used to avoid wastage.
3.2 The deployment of dark ink only with the three primary colors or the original color ink, without any diluting agent for ink deployment, collectively referred to as dark ink deployment. The dark ink is equipped with the following steps:
Determines which primaries are contained in the original color sample and discharges the main color, the auxiliary color sequence, and the approximate proportion of each color ink.
According to the inked area of ​​the printed matter, the coloring power of the ink, the depth of the printing plate, the properties of the paper, the viscosity of the ink, the number of printing, etc., the number of deployments is determined.
According to the deployment ratio, ink is added in descending order. Firstly, the main color with the highest content is weighed, then the auxiliary color with less content is weighed, and then the auxiliary color ink is added into the main color ink several times, and the color is evenly adjusted.
After comparing the ratio and adjusting the ratio of the three primary colors, the printability was adjusted by the printing auxiliaries.
Record the proportions of the components used in each primary color to ensure that the reproducible ink consistency is maintained when the reprint or ink is insufficient.
3.3 The deployment of light-colored ink In the original ink is added white oil, white ink, diluting agent, bright light and other dilute inks dubbed by the spot color ink are called light-colored ink. The deployment of pale-colored inks is dominated by diluting inks, and primary inks are supplemented. According to the requirements of the transparency of the color sample, choose the appropriate diluent. The pale color ink that is generally used for dot printing should use transparent thinner. White ink can be used as a light-colored ink diluting agent for field printing. The deployment process is as follows:
According to the original color sample control chromatography to determine the type of color ink used and the ratio of the diluent agent.
According to the required amount of ink, the diluting agent is first weighed according to the proportion, and then the selected primary color ink is gradually added. If the primary color ink is more than one kind, the first one is added in a large amount and the latter is added in a small amount.
The small color sample was checked against the original sample, and the amount of raw ink was continuously adjusted. After the original color was satisfied, the printability was adjusted by the printing aid.
Record the proportions of raw materials used.
The deployment of light-colored inks to master the degree of ink dilution is a key. If the ink is too dark, the printing ink layer is required to be thinner, which will cause the “flower pattern†or the field color to be not bright. If the ink color is too light, the printing layer needs a thicker ink layer to achieve the color requirement. Caused "sticking" and incomplete drying, sticky back, etc. Process. The correctness of the color change control in each process is directly related to the final quality of the printed matter, so a color standard, ie, a chromatogram, is required to regulate the various hue in the printing process. Printing chromatography uses three primary colors of yellow, magenta, cyan, and black, and mixes and stacks them in different proportions or dots to form a catalogue of various color patterns for people to design, reproduce as they are, and prepare inks. Check it out.
Four-color chromatography uses yellow, magenta, cyan and black four-color inks, which are overlaid with different dot area percentages and arranged in a certain order. It is important for electronic color separation, proofing and printing processes. Reference and guidance. The spot color in printing is a color ink that has already been mixed and has no direct relationship with Y, M, C, and K. Therefore, a set of standard primary color inks are first defined, and various types of mixing ratios are used to produce various colors. Color color samples, each color sample is marked with a scalar that represents the mixing ratio of the primary colors, so that people can use the three primary color inks to blend out the spot colors of various colors. This is spot color chromatography.
At present, Pantone color chromatography is widely used in the United States. However, chromatograms are used to represent colors in the printing chromatograph. Its production is usually affected by many factors such as ink, paper, printing process, and equipment. Therefore, printing units should make their own products according to the raw materials, production processes, and equipment conditions used by the factory. Printing chromatography.
2 Using Colorimetry to Measure Color and Color Differences Color measurements in color printing can be roughly classified into three categories: visual inspection, density measurement, and colorimetry.
During the printing process, the contrast visual measurement method is used to measure the color, mainly by an experienced operator to evaluate the colors of the original document, the signal strips, and the printed sheets with reference to the standard color rate by means of comparative visual inspection. Due to the observer's own physiological and psychological factors, the accuracy of comparative visual inspection is relatively poor. However, because it does not need to be equipped with sophisticated measuring instruments, it is still widely used in the general print reproduction work.
Densitometry is a method of measuring the tone and color values ​​of a color using optical density values. In the color printing process, the density value can well reflect the proportional relationship and superposition performance of the three primary color inks, and the detection equipment is simple, so it is widely used. However, using optical density as a monitoring and measurement method for the printing process, the size of each single-color ink can only be obtained from the control strip, and color error information cannot be directly obtained from the image, so that it is difficult to communicate with the printing customer. Precise control of color reproduction, so density measurement is only an indirect method of color measurement.
Colorimetry is based on the principle of colorimetry, using the color of the important part of the printed image as a monitoring point, to directly measure the tristimulus value of the color and obtain the colorimetric method of the colorimetric information. The method can accurately express the color difference between the standard proof sheet and the tested sample sheet and the required closeness, without additional inspection or control strips. However, it has not been popularized and popularized at present because of the high price of the instrument and the high color theory requirement for the users.
In the work of color printing and copying, we must not only understand the three attributes of color, but also understand the difference between colors in order to compare and distinguish colors. This is the color difference. The unit of color difference is NBS, which is an abbreviation for the National Bureau of Standards. The current universal color measurement standard in the world is the uniform color space of CIE1976Lab. It was proposed by Canadian Wisky at the 18th CIE Conference in 1975. Where L denotes the psychological brightness, a, b denote the mental chromaticity, and the color difference is denoted by ΔE. When a is positive, it means reddish, and when it is negative, it means green; when b is positive, it means that Yellowish, negative when the value is blue; L is positive when the color is light, and vice versa. The color difference ΔE is generally less than 3, and the color difference does not give a great impression, but it is also affected by the deep and light colors and the printing materials.
3 use of color mixing spot color ink ink is the color material of the printed matter, is a mixture of pigment, binder, filler and co-solvent and other components, is a complex colloidal structure. Ink formulation refers to the process of blending one or more inks together and adding certain auxiliary materials to meet the printing and color requirements. Any color printed in Shanghai can be obtained by mixing three different primary colors.
3.1 The rules for ink color deployment should follow the deployment of spot color ink should be carried out under the standard light source D65, if it is during the day, you can do it in a sunny north window.
The three primary color inks are mixed in equal amounts to obtain approximately black color. If you add different proportions of white ink or thinner, you will get gray ink with different tones.
1Using Colorimetry to Produce Print Chromatographs Through Color Analysis, Color Transfer, and Color Combinations
The three primary color inks are mixed in different proportions to obtain inter- or polychromatic colors of different hues.
Two kinds of primary color inks are mixed in equal amounts to obtain inter-color; in different proportions, inter-colors of different colors can be obtained.
The more types of color hue used in the color match, the worse the brightness is. When black ink is added to any hue ink, the lightness value is decreased; when white ink is added, the lightness is increased.
Pay attention to the effect of the used paper, overprinting sequence, lighting source color on the ink, and changes in color before and after drying of the print.
You can use complementary colors to correct the color cast, but only when the ink brightness value is high.
Try to use different types of original ink as much as possible to reduce the complementary color effect.
Pay attention to the effect of ink viscosity on hue.
Before a more complex spot color ink is dispensed, a small amount of trial mix can be used to determine the ratio, and then the ink volume can be used to avoid wastage.
3.2 The deployment of dark ink only with the three primary colors or the original color ink, without any diluting agent for ink deployment, collectively referred to as dark ink deployment. The dark ink is equipped with the following steps:
Determines which primaries are contained in the original color sample and discharges the main color, the auxiliary color sequence, and the approximate proportion of each color ink.
According to the inked area of ​​the printed matter, the coloring power of the ink, the depth of the printing plate, the properties of the paper, the viscosity of the ink, the number of printing, etc., the number of deployments is determined.
According to the deployment ratio, ink is added in descending order. Firstly, the main color with the highest content is weighed, then the auxiliary color with less content is weighed, and then the auxiliary color ink is added into the main color ink several times, and the color is evenly adjusted.
After comparing the ratio and adjusting the ratio of the three primary colors, the printability was adjusted by the printing auxiliaries.
Record the proportions of the components used in each primary color to ensure that the reproducible ink consistency is maintained when the reprint or ink is insufficient.
3.3 The deployment of light-colored ink In the original ink is added white oil, white ink, diluting agent, bright light and other dilute inks dubbed by the spot color ink are called light-colored ink. The deployment of pale-colored inks is dominated by diluting inks, and primary inks are supplemented. According to the requirements of the transparency of the color sample, choose the appropriate diluent. The pale color ink that is generally used for dot printing should use transparent thinner. White ink can be used as a light-colored ink diluting agent for field printing. The deployment process is as follows:
According to the original color sample control chromatography to determine the type of color ink used and the ratio of the diluent agent.
According to the required amount of ink, the diluting agent is first weighed according to the proportion, and then the selected primary color ink is gradually added. If the primary color ink is more than one kind, the first one is added in a large amount and the latter is added in a small amount.
The small color sample was checked against the original sample, and the amount of raw ink was continuously adjusted. After the original color was satisfied, the printability was adjusted by the printing aid.
Record the proportions of raw materials used.
The deployment of light-colored inks to master the degree of ink dilution is a key. If the ink is too dark, the printing ink layer is required to be thinner, which will cause the “flower pattern†or the field color to be not bright. If the ink color is too light, the printing layer needs a thicker ink layer to achieve the color requirement. Caused "sticking" and incomplete drying, sticky back, etc.
Four-color chromatography uses yellow, magenta, cyan and black four-color inks, which are overlaid with different dot area percentages and arranged in a certain order. It is important for electronic color separation, proofing and printing processes. Reference and guidance. The spot color in printing is a color ink that has already been mixed and has no direct relationship with Y, M, C, and K. Therefore, a set of standard primary color inks are first defined, and various types of mixing ratios are used to produce various colors. Color color samples, each color sample is marked with a scalar that represents the mixing ratio of the primary colors, so that people can use the three primary color inks to blend out the spot colors of various colors. This is spot color chromatography.
At present, Pantone color chromatography is widely used in the United States. However, chromatograms are used to represent colors in the printing chromatograph. Its production is usually affected by many factors such as ink, paper, printing process, and equipment. Therefore, printing units should make their own products according to the raw materials, production processes, and equipment conditions used by the factory. Printing chromatography.
2 Using Colorimetry to Measure Color and Color Differences Color measurements in color printing can be roughly classified into three categories: visual inspection, density measurement, and colorimetry.
During the printing process, the contrast visual measurement method is used to measure the color, mainly by an experienced operator to evaluate the colors of the original document, the signal strips, and the printed sheets with reference to the standard color rate by means of comparative visual inspection. Due to the observer's own physiological and psychological factors, the accuracy of comparative visual inspection is relatively poor. However, because it does not need to be equipped with sophisticated measuring instruments, it is still widely used in the general print reproduction work.
Densitometry is a method of measuring the tone and color values ​​of a color using optical density values. In the color printing process, the density value can well reflect the proportional relationship and superposition performance of the three primary color inks, and the detection equipment is simple, so it is widely used. However, using optical density as a monitoring and measurement method for the printing process, the size of each single-color ink can only be obtained from the control strip, and color error information cannot be directly obtained from the image, so that it is difficult to communicate with the printing customer. Precise control of color reproduction, so density measurement is only an indirect method of color measurement.
Colorimetry is based on the principle of colorimetry, using the color of the important part of the printed image as a monitoring point, to directly measure the tristimulus value of the color and obtain the colorimetric method of the colorimetric information. The method can accurately express the color difference between the standard proof sheet and the tested sample sheet and the required closeness, without additional inspection or control strips. However, it has not been popularized and popularized at present because of the high price of the instrument and the high color theory requirement for the users.
In the work of color printing and copying, we must not only understand the three attributes of color, but also understand the difference between colors in order to compare and distinguish colors. This is the color difference. The unit of color difference is NBS, which is an abbreviation for the National Bureau of Standards. The current universal color measurement standard in the world is the uniform color space of CIE1976Lab. It was proposed by Canadian Wisky at the 18th CIE Conference in 1975. Where L denotes the psychological brightness, a, b denote the mental chromaticity, and the color difference is denoted by ΔE. When a is positive, it means reddish, and when it is negative, it means green; when b is positive, it means that Yellowish, negative when the value is blue; L is positive when the color is light, and vice versa. The color difference ΔE is generally less than 3, and the color difference does not give a great impression, but it is also affected by the deep and light colors and the printing materials.
3 use of color mixing spot color ink ink is the color material of the printed matter, is a mixture of pigment, binder, filler and co-solvent and other components, is a complex colloidal structure. Ink formulation refers to the process of blending one or more inks together and adding certain auxiliary materials to meet the printing and color requirements. Any color printed in Shanghai can be obtained by mixing three different primary colors.
3.1 The rules for ink color deployment should follow the deployment of spot color ink should be carried out under the standard light source D65, if it is during the day, you can do it in a sunny north window.
The three primary color inks are mixed in equal amounts to obtain approximately black color. If you add different proportions of white ink or thinner, you will get gray ink with different tones.
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