CN114972179A - A paper defect localization method, system and device - Google Patents

Abstract

The invention discloses a method, system and device for locating paper defects. The method includes: acquiring a paper image; acquiring a template image; making a difference between the paper image and the template image to obtain corresponding difference pixels; determining the paper image according to the difference pixels Whether there is a paper defect in the paper image; when it is determined that there is a paper defect in the paper image, determine the paper defect area in the paper image; convert the coordinates of the center point of the paper defect area to the world coordinate system to obtain the corresponding world coordinate point; according to the world coordinate Point to mark on the paper. The invention solves paper waste caused by inaccurate positioning of paper defects and workers do not know the general direction of paper defects, saves production cost, and improves production efficiency at the same time.

Description

A paper defect localization method, system and device

technical field

The invention relates to the technical field of paper defect detection, in particular to a method, system and device for locating paper defects.

Background technique

In recent years, with the continuous progress and development of China's manufacturing industry, my country's paper industry is transforming towards modernization. The speed of paper machines and the width of paper have been significantly improved. High-speed and wide-width high-efficiency production has been It has become the main development direction of papermaking technology, and changes in intelligence and automation have gradually emerged in the detection of paper defects. In the production process, the CCD camera will collect pictures, use the image processing method to detect the paper defects, and then use the laser marking machine to mark the fixed area (not necessarily the defect position) of the paper with paper defects. In the process of rewinding, the paper with paper defects is reprocessed by finding the marking points by human eyes.

During this process, the following will occur:

1. The fixed position of the marking machine above the paper. When the paper defect appears in the area other than the corresponding position of the marking machine on the paper, the marking machine will mark the area that does not contain the paper defect, so that the original normal paper cannot be used. , causing serious waste for paper with larger paper width.

2. For paper machines with larger paper width, it is easy to cause workers to not know which side of the paper machine to go to when recycling paper containing paper defects, which affects the occurrence of paper defects during rewinding. Recycling efficiency reduces production efficiency.

SUMMARY OF THE INVENTION

The embodiments of the present invention provide a method, system and device for locating paper defects, which are used to solve the problems of serious waste of paper and impact on production efficiency in the prior art when marking the fixed position of paper.

On the one hand, an embodiment of the present invention provides a method for locating paper defects, including:

get the paper image;

get template image;

Difference between the paper image and the template image to obtain the corresponding difference pixels;

Determine whether there is a paper defect in the paper image according to the difference pixels;

When it is determined that there is a paper defect in the paper image, determine the paper defect area in the paper image;

Convert the coordinates of the center point of the paper defect area to the world coordinate system to obtain the corresponding world coordinate point;

Mark the paper according to the world coordinate point.

On the other hand, an embodiment of the present invention provides a paper defect locating system, including:

camera to acquire paper images and template images,

The industrial computer is used to make the difference between the paper image and the template image to obtain the corresponding difference pixels; according to the difference pixels to determine whether there is a paper defect in the paper image, when it is determined that there is a paper defect in the paper image, determine the paper in the paper image. disease area; convert the coordinates of the center point of the paper disease area to the world coordinate system to obtain the corresponding world coordinate point;

Marker for marking on paper according to world coordinate points.

On the other hand, an embodiment of the present invention provides a paper defect positioning device, comprising a conveying belt and the above-mentioned paper defect positioning system, wherein the conveying belt is used for conveying paper.

A paper defect locating method, system and device in the present invention have the following advantages:

1. It solves the waste of paper caused by inaccurate positioning of paper defects and saves production costs.

2. Solve the problem that the workers do not know the general direction of the paper disease due to the inaccurate positioning of the paper disease, and improve the production efficiency.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a flowchart of a method for locating paper defects according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a calibration board used for camera internal parameter calibration according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

FIG. 1 is a flowchart of a method for locating paper defects according to an embodiment of the present invention. An embodiment of the present invention provides a method for locating paper defects, including:

S100. Acquire a paper image.

Exemplarily, before S100, the method further includes: performing parameter calibration on the camera to obtain a corresponding camera calibration file.

In the embodiment of the present invention, the parameter calibration of the camera includes internal parameter calibration and external parameter calibration. A calibration plate is required for internal parameter calibration. As shown in Figure 2, internal parameter calibration can reduce the radial and tangential distortion of the camera due to process errors, resulting in barrel or pincushion distortion of the acquired image. The method of Zhang Zhengyou's calibration is used in the internal parameter calibration of the present invention. After traversing 9 calibration board images of different poses with the Find_Calib_Object() function, the calibration board images are analyzed by the Get_Calib_Data() function to generate the FinalCamPar.dat file, that is, the camera internal parameter calibration file to achieve the camera's internal parameter calibration.

After completing the internal parameter calibration, perform the external parameter calibration. External parameter calibration can realize the function of converting the coordinate points in the image coordinate system to the camera coordinate system, and then to the world coordinate system, so that the coordinates transmitted to the marking machine each time are the real coordinates, that is, the world coordinates. Since the marking of the marking machine only involves the abscissa, that is, a one-dimensional straight line, only the world coordinate point and the image coordinate point of the positions of any three points on the same straight line can be used, and the coordinate points of these three positions are filled in In the table, the Vector_To_Pose() function is used for coordinate transformation, and finally the world coordinates in the world coordinate system are obtained, and the FinalPose.dat file is generated, that is, the camera external parameter calibration file, and the camera external parameter calibration is completed. , the greater the distance between the three points, the higher the accuracy of the final calibration. The above-mentioned camera internal parameter calibration file and camera external parameter calibration file are collectively referred to as a camera calibration file.

S110. Obtain a template image.

Exemplarily, S110 specifically includes: acquiring an image of the paper-free paper; saving the image of the paper-free paper as a template image.

S120, make a difference between the paper image and the template image to obtain corresponding difference pixels.

Exemplarily, the acquired paper image and the template image are stored in the memory in real time, and the difference() function is used to make a difference between the real-time acquired paper image and the template image to obtain corresponding difference pixels.

S130. Determine whether there is a paper defect in the paper image according to the difference pixels.

Exemplarily, S130 specifically includes: when the average value of the difference pixels is equal to zero, determining that there is no paper defect in the paper image; when the average value of the difference pixels is greater than zero, determining that there is a paper defect in the paper image.

S140. When it is determined that there is a paper defect in the paper image, determine a paper defect area in the paper image.

Exemplarily, S140 specifically includes: using an automatic threshold segmentation method to segment the paper image to determine the paper defect area.

In the embodiment of the present invention, after determining the paper defect area in the paper image in S140, the method further includes: performing morphological processing on the paper defect area by using a closed operation to obtain the processed paper defect area. Due to the variety of paper defects, it is necessary to use the closed operation to morphologically process the paper defect area, so as to fill in the small holes of the paper defect, bridge the small cracks of the paper defect, and keep the overall position and shape unchanged.

S150: Convert the coordinates of the center point of the paper defect area to a world coordinate system to obtain a corresponding world coordinate point.

Exemplarily, after the paper defect area is determined, the center point of the area is also determined, and then the camera calibration file is read, and the coordinates of the center point of the paper defect area are converted into the world coordinate system to obtain the world coordinate point.

In the embodiment of the present invention, for the morphologically processed paper defect area, determine the center point of the processed paper defect area, then read the camera calibration file, and use the Image_Points_To_World_Plane() function to convert the processed paper defect area. The coordinates of the center point of the area are converted to the world coordinate system to obtain the world coordinate point.

S160, marking on the paper according to the world coordinate point.

Exemplarily, after the world coordinate point is determined, the TCP (Transmission Control Protocol, Transmission Control Protocol) communication mode is used to send the world coordinate point to the marking machine, and after the marking machine moves laterally to the position corresponding to the world coordinate point, The paper is marked by laser marking to achieve precise positioning of paper defects.

The embodiment of the present invention also provides a paper defect locating system, including:

camera to acquire paper images and template images,

The industrial computer is used to make the difference between the paper image and the template image to obtain the corresponding difference pixels; according to the difference pixels to determine whether there is a paper defect in the paper image, when it is determined that there is a paper defect in the paper image, determine the paper in the paper image. disease area; convert the coordinates of the center point of the paper disease area to the world coordinate system to obtain the corresponding world coordinate point;

Marker for marking on paper according to world coordinate points.

Exemplarily, the system may further include a light source and a display, the light source being used to provide illumination to the paper to improve the quality of the image captured by the camera. The display is used to display the user interaction interface, which is convenient for the operator to check the status and other information of each device in the system.

An embodiment of the present invention further provides a paper defect positioning device, comprising a conveyor belt and the above-mentioned paper defect positioning system, wherein the conveyor belt is used for conveying paper.

Although preferred embodiments of the present invention have been described, additional changes and modifications to these embodiments may occur to those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be construed to include the preferred embodiment and all changes and modifications that fall within the scope of the present invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (9)

1. A paper defect positioning method is characterized by comprising the following steps:

acquiring a paper image;

acquiring a template image;

making a difference between the paper image and the template image to obtain corresponding difference value pixels;

determining whether paper defects exist in the paper image according to the difference value pixels;

when determining that paper defects exist in the paper image, determining a paper defect area in the paper image;

converting the coordinate of the central point of the paper defect area into a world coordinate system to obtain a corresponding world coordinate point;

and marking on the paper according to the world coordinate point.

2. A paper defect locating method according to claim 1, further comprising, before acquiring the paper image:

calibrating parameters of the camera to obtain a corresponding camera calibration file;

converting the coordinates of the central point into a world coordinate system to obtain corresponding world coordinate points, wherein the converting includes:

and converting the coordinates of the central point into a world coordinate system by using the camera calibration file to obtain the world coordinate point.

3. A paper defect positioning method according to claim 2, wherein said calibrating the camera parameters to obtain the corresponding camera calibration file comprises:

traversing the calibration plate image;

analyzing the calibration plate image to obtain a camera internal reference calibration file;

and carrying out external reference calibration on the camera to obtain an external reference calibration file of the camera, and completing the parameter calibration of the camera.

4. The paper defect positioning method according to claim 1, wherein the acquiring of the template image comprises:

acquiring a paper image without paper defects;

and saving the paper disease-free paper image as the template image.

5. The method for locating paper defects according to claim 1, wherein the determining whether paper defects exist in the paper image according to the difference pixels comprises:

when the average value of the difference pixels is equal to zero, determining that no paper defects exist in the paper image;

and when the average value of the difference value pixels is larger than zero, determining that paper defects exist in the paper image.

6. The method as claimed in claim 1, wherein when determining that the paper defect exists in the paper image, determining the paper defect area in the paper image comprises:

and segmenting the paper image by adopting a threshold segmentation method to determine the paper defect area.

7. The method of claim 1, after determining the paper defect area in the paper image, further comprising:

performing morphological processing on the paper defect area by using closed operation to obtain a processed paper defect area;

the converting the coordinate of the central point of the paper defect area into a world coordinate system to obtain a corresponding world coordinate point comprises:

determining the central point of the processed paper defect area;

and converting the coordinates of the central point of the processed paper defect area into a world coordinate system to obtain the world coordinate point.

8. A system for applying the paper defect positioning method of any one of claims 1-7, comprising:

a camera for acquiring a sheet image and a template image,

the industrial personal computer is used for subtracting the paper image from the template image to obtain corresponding difference value pixels; determining whether paper defects exist in the paper image according to the difference pixels, and determining a paper defect area in the paper image when the paper defects exist in the paper image; converting the coordinate of the central point of the paper defect area into a world coordinate system to obtain a corresponding world coordinate point;

and the marking machine is used for marking on the paper according to the world coordinate point.

9. A paper defect locating device comprising a conveyor belt for conveying paper and a paper defect locating system as claimed in claim 8.

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