Research Of Ink Layer Thickness Detection Of Print Quality Detection System Based On Dot Image

With the increasing speed of the press and the improvement of printing technology, the demands of printing quality detection and control are also rising. Subjective visual method of printing quality detection has developed into a full image online detection. The subject is based on existing research, mainly on the dot image ink layer thickness detection.The subject needs to print CMYK various ink film thickness color lumps by IGT. Calculating the ink film thickness and measuring the Lab values of the color lump. Then find the Lab values range of CMYK and the relationship between ink film thickness and Lab values through Matlab. Digital images are obtained from scanning the print. From the microscopic point of view, the print is composed of the color elements of different colors. And the pixel is smaller than the dot. The color of each pixel may be classified as a certain color elements. The digital image has monochrome pixels based on the dot color rendering principle. After the print is scanned by CCD, the digital image is zoned according to ink zone. Then identify the monochrome pixel by Lab values range and calculate ink film thickness by the formula of the relationship between ink film thickness and Lab values.Ink film thickness calculation result with the density calculated as compared with the actual measurement result, the average error is about 0.07. The ink film thickness using multiple linear regression method is compared with the actual measurements, with an average error of about 0.08.The calculation result with the use of multiple linear regression is similar to the traditional method by using density. However, calculating ink film thickness by using density method must measure the control bar. Overall quality of the printed matter is not reflected by measuring control bar. Using multiple linear regression method calculating ink film thickness can not reflect the whole image quality and can form a complete detection system with defect detection, dot area rate detection module. Write the ink film thickness detection procedure by using Microsoft Visual C++and place this module in the whole image quality detection system.Calculating ink film thickness by using multiple linear regression method is feasible within a certain range. Now intelligent detection is accomplished by shooting print.It can get the color values of picture, cannot obtain density values directly. To calculate ink layer thickness by density, we still need to change the color values into the density values. Therefore, using multiple linear regression method to calculate the ink layer thickness is more feasible. The calculation is similar to the actual measurement result. It has some guiding significance for the actual production.