Over the years, chart printing color management relies on visual observation and experience, and these methods are no longer able to meet the current digital production process. How to make the printing color control more in line with scientific standards is an urgent problem we need to solve now. This paper focuses on the characteristics of the ColorPilot control system and its application in chart color control, and looks forward to its future development in printing color control.
The chart is a special kind of printed matter, which plays an important role in ensuring the safety of navigation. Therefore, the quality control from the compilation to the printing and printing process is particularly important. With the introduction of advanced printing technology and printing equipment in recent years, the quality of chart printing has been greatly improved. However, if the stability of the printing quality is to be ensured, especially under the control of different batches of products and different operators, it is ensured that the quality indicators such as color, level and definition of the chart are consistent, and it is difficult to rely on traditional manual detection and monitoring. Online color control systems are urgently needed, regardless of monitoring reaction speed, quality accuracy, and process volatility.
At present, in the printing process of charts, the quality control is mainly based on the comprehensive evaluation method. It is based on objective evaluation methods, supplemented by subjective evaluation and various factors to obtain a comprehensive evaluation criteria and conclusions. It combines the advantages of subjective evaluation and objective evaluation. While considering the visual effect, the ColorPilot control system is used for accurate measurement and control, and the evaluation is more comprehensive and scientific.
First, the introduction of ColorPilot control system
ColorPilot is a new system installed on the Manroland sheetfed offset press that is used to comprehensively control the density and chromaticity of the ink. This is the fastest color control system available. After only 12 seconds of scanning, you can adjust the color in 2 seconds. It can print the first printed sheet in a very short time. It is more obvious for difficult-to-print jobs. In the production of long orders, batch color difference will not be caused by different captains or the same captain in different environments, and the color difference can be strictly controlled. Small range.
The ColorPilot system avoids interference from human factors and objectively evaluates color control without the operator's experience and external environment such as lighting. In addition to its control over printing color, it can also improve work efficiency and reduce waste of raw materials. Traditional printing operators usually sample at the delivery position, manually evaluate it on the console, and feed the information back to the press for adjustment. This is not done once or twice, and requires an average of at least 7 sampling tests. Formally printed. With the ColorPilot control system, 7 samples can be reduced to 4 times. Although the difference between one print is not large, the amount of raw material data saved over time is still large. According to statistics, in 2008, more than 60% of the printing presses worldwide were equipped with ColorPilot control systems.
Second, the characteristics of ColorPilot control system
Density measurement
Densitometry is a technique suitable for measuring the amount of ink. This density is directly related to the thickness of the ink layer on the sheet: usually in the range of the color ink layer thickness (up to 1/1000 mm), there is an almost linear relationship between the density and the thickness of the ink layer, making the density suitable for the sheet. The thickness of the ink layer is measured and adjusted. The measured value is directly affected by the adjustment of the ink fountain slide, so that the measured value becomes the thickness of the ink layer. As a result of the measurement, the system determines whether a little more or less ink is needed in the measured ink zone, and complex adjustment algorithms ultimately result in precise opening/closing of the ink metering elements that control the ink zones. Within this range, a little more or less ink is printed on the paper to control the amount of ink.
The automated control of the ink keys makes the job of the press operator easier. The operator only needs to take samples at intervals and measure and confirm whether the color of the printed sheets meets the relevant control values. In the formal printing process, the ink measurement work is completed by the control program to statistically evaluate the quality of the production operation throughout the process to ensure stable control of the thickness of the ink film. Once a certain printing effect is achieved, stable print quality can be easily maintained by density control. Its advantage is to adjust the important process parameters, ie the thickness of the ink layer, by density, to bring stability to the printing process, and to maintain the stable printing effect.
The printing of the chart has a very high requirement for the appearance of the color, and there is a large area of ​​the spot color on the printed part. The density value cannot completely determine the accuracy of the ink, for example, the color tone of the color cannot be determined. Since the actual used chart paper is different from the general print, the same amount of ink supply will have different visual effects on the printed sheet. Therefore, it is not enough to rely on the density measurement method to control the color of the chart printing.
2. Chroma measurement
The colorimetric measurement system mimics the visual impression of the human eye and is a measurement and evaluation system that enables an objective assessment of the printed sheet. The printing industry has used colorimetric methods to evaluate print quality for several years. This method is often used in the digital production process in conjunction with standardization and color management of all process steps. Through the colorimetric measurement analysis, the final color effect can be determined more, especially in the application of spot color printing. Therefore, colorimetric measurements are particularly important in chart printing.
In the ColorPilot control system, the color measurement results are visually displayed as a color difference record of the figure and the number (ΔE-record), so that the tolerance range (allowing the color difference) and the excess tolerance range can be immediately seen. The press can select a zoom display with a single ink control element for each ink zone. The color difference between the nominal and actual values ​​is displayed in numbers, graphics, and a square control block to visually check the authenticity of the color.
The "Statistical Recording" function of the ColorPilot system makes statistics from all recorded measurements of a job and creates a histogram based on ΔE. In the “Statistics†function, the minimum, large and medium chromatic aberrations are calculated from all measurements for each ink fountain slide zone (one gauge block per slide) and displayed in numbers and graphs. The “Rectangle†function also calculates the smallest, larger, and medium chromatic aberrations from all of the inkjet skateboard areas for each measured sheet, and displays them graphically and numerically, with graphical and digital records printed as reports.
3. Chroma measurement complementary density measurement
Chart printing is done using spot color printing. In order to objectively evaluate the printed sheet, one needs a colorimetric method that mimics the visual impression of the eye. If only the density value is used, it is impossible to accurately recognize whether the color tone of an ink is accurate.
Chroma measurement Complementary density measurement is the ideal solution. It has high-precision measurement and control based on ink density. It can measure the color block by independent sensing technology under the same measuring head, and has the chromaticity measurement value and density. An important feature that combines control processes. Therefore, the ColorPilot system closely combines the density measurement, colorimetric measurement and ink supply control of the printed sheet, and simultaneously determines the chromaticity value from each small measurement block of the printed measuring strip of only 3 mm × 4 mm, realizing online on-line detection and control. The control of printing quality is controlled by closed-loop quality, real-time reaction of detection and control is realized, printing efficiency is greatly improved, printing loss is reduced, printing process is smoother, and printing quality is more stable.
Third, the development prospects
In recent years, the color management of China's printing industry has developed rapidly, and the ColorPilot control system has been rapidly promoted and applied in China. Needless to say, better products and better services are the direction of our development. As an important part of color management technology, ColorPilot control system has a broad development ground in China with the development of printing industry and modern management and the increase of product quality requirements.
Over the years, chart printing color management relies on visual observation and experience, and these methods are no longer able to meet the current digital production process. How to make the printing color control more in line with scientific standards is an urgent problem we need to solve now. This paper focuses on the characteristics of the ColorPilot control system and its application in chart color control, and looks forward to its future development in printing color control.
The chart is a special kind of printed matter, which plays an important role in ensuring the safety of navigation. Therefore, the quality control from the compilation to the printing and printing process is particularly important. With the introduction of advanced printing technology and printing equipment in recent years, the quality of chart printing has been greatly improved. However, if the stability of the printing quality is to be ensured, especially under the control of different batches of products and different operators, it is ensured that the quality indicators such as color, level and definition of the chart are consistent, and it is difficult to rely on traditional manual detection and monitoring. Online color control systems are urgently needed, regardless of monitoring reaction speed, quality accuracy, and process volatility.
At present, in the printing process of charts, the quality control is mainly based on the comprehensive evaluation method. It is based on objective evaluation methods, supplemented by subjective evaluation and various factors to obtain a comprehensive evaluation criteria and conclusions. It combines the advantages of subjective evaluation and objective evaluation. While considering the visual effect, the ColorPilot control system is used for accurate measurement and control, and the evaluation is more comprehensive and scientific.
First, the introduction of ColorPilot control system
ColorPilot is a new system installed on the Manroland sheetfed offset press that is used to comprehensively control the density and chromaticity of the ink. This is the fastest color control system available. After only 12 seconds of scanning, you can adjust the color in 2 seconds. It can print the first printed sheet in a very short time. It is more obvious for difficult-to-print jobs. In the production of long orders, batch color difference will not be caused by different captains or the same captain in different environments, and the color difference can be strictly controlled. Small range.
The ColorPilot system avoids interference from human factors and objectively evaluates color control without the operator's experience and external environment such as lighting. In addition to its control over printing color, it can also improve work efficiency and reduce waste of raw materials. Traditional printing operators usually sample at the delivery position, manually evaluate it on the console, and feed the information back to the press for adjustment. This is not done once or twice, and requires an average of at least 7 sampling tests. Formally printed. With the ColorPilot control system, 7 samples can be reduced to 4 times. Although the difference between one print is not large, the amount of raw material data saved over time is still large. According to statistics, in 2008, more than 60% of the printing presses worldwide were equipped with ColorPilot control systems.
Second, the characteristics of ColorPilot control system
Density measurement
Densitometry is a technique suitable for measuring the amount of ink. This density is directly related to the thickness of the ink layer on the sheet: usually in the range of the color ink layer thickness (up to 1/1000 mm), there is an almost linear relationship between the density and the thickness of the ink layer, making the density suitable for the sheet. The thickness of the ink layer is measured and adjusted. The measured value is directly affected by the adjustment of the ink fountain slide, so that the measured value becomes the thickness of the ink layer. As a result of the measurement, the system determines whether a little more or less ink is needed in the measured ink zone, and complex adjustment algorithms ultimately result in precise opening/closing of the ink metering elements that control the ink zones. Within this range, a little more or less ink is printed on the paper to control the amount of ink.
The automated control of the ink keys makes the job of the press operator easier. The operator only needs to take samples at intervals and measure and confirm whether the color of the printed sheets meets the relevant control values. In the formal printing process, the ink measurement work is completed by the control program to statistically evaluate the quality of the production operation throughout the process to ensure stable control of the thickness of the ink film. Once a certain printing effect is achieved, stable print quality can be easily maintained by density control. Its advantage is to adjust the important process parameters, ie the thickness of the ink layer, by density, to bring stability to the printing process, and to maintain the stable printing effect.
The printing of the chart has a very high requirement for the appearance of the color, and there is a large area of ​​the spot color on the printed part. The density value cannot completely determine the accuracy of the ink, for example, the color tone of the color cannot be determined. Since the actual used chart paper is different from the general print, the same amount of ink supply will have different visual effects on the printed sheet. Therefore, it is not enough to rely on the density measurement method to control the color of the chart printing.
2. Chroma measurement
The colorimetric measurement system mimics the visual impression of the human eye and is a measurement and evaluation system that enables an objective assessment of the printed sheet. The printing industry has used colorimetric methods to evaluate print quality for several years. This method is often used in the digital production process in conjunction with standardization and color management of all process steps. Through the colorimetric measurement analysis, the final color effect can be determined more, especially in the application of spot color printing. Therefore, colorimetric measurements are particularly important in chart printing.
In the ColorPilot control system, the color measurement results are visually displayed as a color difference record of the figure and the number (ΔE-record), so that the tolerance range (allowing the color difference) and the excess tolerance range can be immediately seen. The press can select a zoom display with a single ink control element for each ink zone. The color difference between the nominal and actual values ​​is displayed in numbers, graphics, and a square control block to visually check the authenticity of the color.
The "Statistical Recording" function of the ColorPilot system makes statistics from all recorded measurements of a job and creates a histogram based on ΔE. In the “Statistics†function, the minimum, large and medium chromatic aberrations are calculated from all measurements for each ink fountain slide zone (one gauge block per slide) and displayed in numbers and graphs. The “Rectangle†function also calculates the smallest, larger, and medium chromatic aberrations from all of the inkjet skateboard areas for each measured sheet, and displays them graphically and numerically, with graphical and digital records printed as reports.
3. Chroma measurement complementary density measurement
Chart printing is done using spot color printing. In order to objectively evaluate the printed sheet, one needs a colorimetric method that mimics the visual impression of the eye. If only the density value is used, it is impossible to accurately recognize whether the color tone of an ink is accurate.
Chroma measurement Complementary density measurement is the ideal solution. It has high-precision measurement and control based on ink density. It can measure the color block by independent sensing technology under the same measuring head, and has the chromaticity measurement value and density. An important feature that combines control processes. Therefore, the ColorPilot system closely combines the density measurement, colorimetric measurement and ink supply control of the printed sheet, and simultaneously determines the chromaticity value from each small measurement block of the printed measuring strip of only 3 mm × 4 mm, realizing online on-line detection and control. The control of printing quality is controlled by closed-loop quality, real-time reaction of detection and control is realized, printing efficiency is greatly improved, printing loss is reduced, printing process is smoother, and printing quality is more stable.
Third, the development prospects
In recent years, the color management of China's printing industry has developed rapidly, and the ColorPilot control system has been rapidly promoted and applied in China. Needless to say, better products and better services are the direction of our development. As an important part of color management technology, ColorPilot control system has a broad development ground in China with the development of printing industry and modern management and the increase of product quality requirements.
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