Research On The Linear Map Printing Quality Auto Detection Algorithms

Paper linear map plays an important role in the national economy construction, society building and military construction. With the rapid development of the present science and technology, the print technology of linear map is changed deeply. The digitization and standardization is accomplished from prepress and press. But the key of the linear map printing, print quality detection just stays in the same level as twenty years ago. And this is not matched to the modern developing trend of the print industry. Based on deep research on the normal printing product quality auto detection technology and considering characteristics of the linear map printing quality control, this paper makes deep study in the technology scheme and key algorithms for the linear map printing quality auto detection. The main contents of this paper are as following.1. The classification method of the linear map printing defects is put forward.The linear map printing quality auto detection technology is based on the digital image processing technology. With the analysis of the characteristics of the linear map image contents,The classification method of the linear map printing defects is put forward. The linear map printing defects can be classified in four species: the dot defects with small area but high gray value, the line defects with small width, location offset defects and surface defects with large area.2. The model of the linear map printing quality detection is established and the structure of its hardware system is analyzed.With the full study of the research fruit of the normal presswork printing quality auto detection, and considering the linear map printing characteristics, the technology scheme of the linear map printing quality auto detection is established. The linear map printing quality auto detection technology also depends on the structure of its hardware system. Based on the research on the normal industry defects detection hardware system, the hardware which is suitable to the linear map printing quality auto detection is supposed to get.3. The key algorithms which are suitable to linear map printing quality auto detection are deeply studied.With the experiment analysis of the part averages method, weighted averages method and median filter image intensifier algorithm, the weighted averages method is chosen for linear map image preprocessing algorithm.Based on the analysis and compare of the normally use standard template image making algorithms, the statistic dynamic threshold algorithm is selected as the linear map standard template image making algorithm. Considering that every linear map has an obvious outline, the linear map image registration algorithm based on the edge detection is put forward. After the experiment of normal edge detection algorithms, the Roberts operator is selected for the outline detection of the linear map. The registration between the linear map image waiting for detection and the standard template image is finished with the help of the outline.With the deep study on the NTM algorithm, it is found than this algorithm can not detect the register angle error. With the help of edge detection algorithm, the angle of register angle error can be detected. And this method is used to linear map register detection together with the NTM algorithm. And the validity of this method is proved in experiment.The linear map color copy quality detection algorithm is put forward, which is based on the fact that the color difference between the good paper map image and the disposed paper map image is mostly expressed by the pixel gray value difference. With the extraction of color copy area of the linear map image, which is waiting for detecting, the average gray value is computed for each color separation image. And then the average gray value is compared to the threshold value, which can judge the color copy quality. And the signal strip in the linear map is chosen in the experiment, which proves the validity of this algorithm.Based on the deep analysis and compare of image difference algorithm, delaminating detection algorithm and the algorithm based on the dynamic threshold and the cross delaminating detection, the image difference together with Blob analysis algorithm is chosen as the linear map printing defects detecting algorithm. And the validity of this method is proved in experiment.