Method for image detection of printed products by means of computer

Abstract

A method for image detection of printed products by means of a computer in a machine for processing printing substrates, the printed product is detected and digitized by an image detection system with the aid of an image sensor, the computer performs a comparison, in terms of distorted image areas in the detected image Check the comparison result, calculate the correction factor, perform the correction of the digital reference image, so that the digital print image detected in the official printing is compared with the modified digital reference image by the computer, and when there is a deviation, the printed product with errors is distributed, The computer ascertains the edges in the digital reference image that have too few edges for the calculation of the correction factor, adds the anchor points to the image area, also prints them when printing the printed product and detects the anchor points by at least one sensor, digitizes them and becomes The components of the digitally printed image are detected, and the calculation of local correction factors is performed by the computer with the aid of the anchor points.

Description

technical field [0001] The invention relates to a method for the image detection of printed products in a machine for processing printing materials. [0002] The invention belongs to the technical field of quality control. Background technique [0003] In today's printing industry, especially in larger printing presses, quality control is carried out automatically by means of so-called inline inspection systems (also called image inspection systems). "Inline" in this case means that the image detection system (more precisely the camera of the image detection system) is installed in the printing press. In this case, the camera is usually installed downstream of the last printing unit or, if present, another further processing station (for example a painting unit) and detects the printed products produced by the printing press. The camera can be a single camera or also a camera system with a plurality of cameras. Other image sensors may also be used. However, for simplicit...

AI Technical Summary

Problems solved by technology

Errors caused by image capture (e.g. due to lack of lighting, dirty lenses of cameras or other sources of influence) must not negatively affect the inspection process

[0004] A very specific problem that also negatively affects inspection in this respect is irregularities in the transport of printed substrates inside the printing press

Especially for sheet presses this is very challenging

It is in this case that there is a known problem: in the case of transporting printed sheets, the lower edge of the sheet vibrates during transport through the sheet transport deflectors - i.e. the winding up (to a certain extent A "chatter" occurs at the end of the sheet, so to speak)

[0008] However, this solution has the disadvantage that it only works if the printed image to be printed contains image objects with sufficient corners and edges

Clouds are visible objects and they are also subject to the described nonlinear local distortions and thus lead to false positive errors in image detection

However, clouds do not provide corners or edges where nonlinear local distortions can be located accordingly

Thus, nonlinear local distortions cannot be compensated and further lead to spurious errors in digital image detection

Images