Study On Embedded High-speed Gravure Print Image Processing And Analyzing System

During the process of gravure, for reasons of techniques, there are always some defectson the printed matter, such as color difference, inaccurate overprint, defect point, etc. If theseproblems can not be detected in time, there will be a lot of non-qualified products. Generally,stroboscope or still image observation system can be used to test on high speed print imagequality. But these two methods both based on manual visual checking, without image analyzefunction. So here we will base on still image observation system and use digital imagematching technique make to still image observation analysis system instead of manual visualchecking.Still image observation analysis system includes three parts: Image acquisition,preprocessing and image matching analysis modules.Image acquisition: The print images are obtained by CCD camera, connectingphotoelectric encoder to printing board roller, to get synchronized shot signal, which triggersthe camera and strobe light, then the camera transfers these images to the computer throughUSB.Preprocessing: Inevitably, the collected print images mixed with some kinds of noises,which could be reduced by algorithm of neighborhood smoothing filter and median filter, torecover the original images.Cross-correlation algorithm could be used to match real-time image and standard image,forming one-to-one relationship in space. The defects on the real-time image could be foundon binary image, by making use of connected region analysis after subtract operation.The online measure method rate for printing products is higher by adopting digital imageanalysis technology, which could make up for a deficiency in manual visual checking andreduce the defect production.