Method and apparatus for checking print products, a computer program and a computer program product
First Claim
1. A method for checking print products of the same kind which are transported by a conveying device, comprising:
- recording test images in a teach-in phase at a plurality of points on the print product using a digital camera;
defining an evaluation region within each test image, which evaluation region is smaller than, or equal to, a size of the test image;
analyzing characteristic information of each evaluation region;
selecting the test image, in which the evaluation region with a most distinctive characteristic information is located, as a reference image; and
checking subsequent print products of the same kind by recording at least one check image at a position corresponding to the reference image and by image-data comparison of at least one subregion of the check image with the evaluation region of the reference image;
wherein, for ascertaining the reference image, the evaluation region is divided into a plurality of subregions, which are evaluated in terms of their characteristic information;
wherein, for checking subsequent print products, a comparison of characteristic information of the subregions of the evaluation region of the reference image with corresponding subregions of the check image is carried out; and
wherein the comparison is carried out for a number of subregions by correlation methods and for a number of subregions by comparing gray-scale mean values.
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Accused Products
Abstract
The invention relates to a method and a device for checking print products of the same kind, more particularly printed sheets of paper of the same kind, which are transported by a conveying device. For this purpose, during a teach-in phase, test images are recorded at a plurality of points on the print product by means of a digital camera. The test images recorded, or parts thereof, are analyzed with respect to their characteristic information, and the test image having the most distinct characteristic information is selected as the reference image. For the purpose of checking print products of the same kind, the subsequent print products of the same kind are checked by recording at least one image at a position corresponding to the reference image and by comparing it with the image data of the reference image. Such checking is carried out by means of a device comprising a digital camera for recording test images of the print product, an illuminating device for illuminating the print product, an input for supplying a position signal, and a control and evaluation unit for controlling the digital camera and the illuminating device and for analyzing image data produced by the digital camera. The invention further relates to a computer program and to a computer program product.
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Citations
18 Claims
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1. A method for checking print products of the same kind which are transported by a conveying device, comprising:
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recording test images in a teach-in phase at a plurality of points on the print product using a digital camera; defining an evaluation region within each test image, which evaluation region is smaller than, or equal to, a size of the test image; analyzing characteristic information of each evaluation region; selecting the test image, in which the evaluation region with a most distinctive characteristic information is located, as a reference image; and checking subsequent print products of the same kind by recording at least one check image at a position corresponding to the reference image and by image-data comparison of at least one subregion of the check image with the evaluation region of the reference image; wherein, for ascertaining the reference image, the evaluation region is divided into a plurality of subregions, which are evaluated in terms of their characteristic information; wherein, for checking subsequent print products, a comparison of characteristic information of the subregions of the evaluation region of the reference image with corresponding subregions of the check image is carried out; and wherein the comparison is carried out for a number of subregions by correlation methods and for a number of subregions by comparing gray-scale mean values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 18)
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14. A device for checking similar print products of the same kind, comprising:
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a digital camera for recording test images of a print product; an illuminating unit for illuminating the print product; an input for the supply of a position signal; a control and evaluation unit for controlling the digital camera and the illuminating unit and for analyzing image data produced by the digital camera; wherein the control and evaluation unit, the illuminating unit, and the digital camera, carry out a teach-in phase in which test images are recorded at a plurality of points on the print product using the digital camera; wherein the control and evaluation unit is further configured for; analyzing characteristic information in evaluation regions of the recorded test images; selecting a test image, comprising the evaluation region having the most distinctive characteristic information, as a reference image; and checking subsequent print products of the same kind by recording checking images at positions corresponding to the reference image and by comparing evaluation regions of the recorded check images with the image data of the evaluation region of the reference image; wherein a comparison of characteristic information of subregions of the evaluation region of the reference image with corresponding subregions of the check image is carried out, and the comparison is carried out for a number of subregions by correlation methods and for a number of subregions by comparing gray-scale mean values. - View Dependent Claims (15, 16, 17)
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Specification