METHOD AND DEVICE FOR DETECTING PERIODICAL CONTINUOUS DEFECT OF PRINTED MATTER

摘要

PURPOSE: To provide method and device for detecting the periodical continuous defects of a printed matter, obtaining a test image of high degree of resolution and capable of processing the image quickly by an image processing unit having a small capacity of memory and capable of detecting defects on a frame surely, by a method wherein a frame, constituted of the printing of the same patterns formed continuously on a sheet type printed matter, is divided while the divided small areas are employed as test areas. ;CONSTITUTION: A frame 1 of length L and width W, which is obtained by printing the same patterns on a sheet 4, is divided equally by n×m and images in the test areas 2 having a small area of W/m×L/n are photographed sequentially one by one by a camera 5 and are inputted into an image processing unit 6 through a changeover switch 7 as test images. The test processing unit 6 compares the test images with reference images, corresponding to the test images, to obtain a differential image, then, the differential image is processed by a filter to obtain a discrimination image and detect defects 8, 9 and the like printed on the frame 1.;COPYRIGHT: (C)1996,JPO