CN112862755B - Device and method for detecting thickness of ink layer of printed matter - Google Patents
Device and method for detecting thickness of ink layer of printed matter Download PDFInfo
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/0002—Inspection of images, e.g. flaw detection
- G06T7/0004—Industrial image inspection
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
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- G06T7/00—Image analysis
- G06T7/10—Segmentation; Edge detection
- G06T7/11—Region-based segmentation
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- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30108—Industrial image inspection
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Abstract
The invention discloses a device and a method for detecting the thickness of an ink layer of a printed matter, wherein the device comprises a printing sheet cutting module, a microscopic image acquisition module and an image processing module.
Description
Technical Field
The invention relates to the technical field of printed matter manufacturing processes and quality detection, in particular to a device and a method for detecting the thickness of an ink layer of a printed matter.
Background
The ink layer thickness of a print refers to the average thickness of the ink layer attached to the surface of the substrate in the direction perpendicular to the substrate. The ink layer thickness is not only one of the key influencing factors of original color reduction reproduction, but also one of the determining factors of the ink consumption. Although the range of the ink layer thickness is not random, the specific printing environment has the corresponding optimal ink layer thickness, so that the full in-situ density and the printing contrast value of the ink color can be maximized; the dot gain value is minimum, and the hierarchical optimal restoration is realized. On the one hand, however, different types of printed matter and printed matter of different printing modes have different requirements on the thickness of the ink layer (for example, the thickness of the ink layer of the high-grade packaging printed matter is more than 7 micrometers and even can reach tens of micrometers); on the other hand, the stability of the printing material conditions such as printing conditions, ink and printing stock can not be ensured, and the printing material conditions are complex and changeable, so that the thickness of the ink layer is uncertain and uneven. Therefore, flexible and accurate measurement of the thickness of the ink layer is critical to control of printing cost, detection and control of color quality of printed matters and improvement of production efficiency.
Currently, there are two commonly used ink layer thickness measurement methods:
One is a weighing method, firstly, the specific gravity ρ of the ink is measured by an ink injector, a balance and the like, then the thickness d of the ink layer is calculated according to the mass m of the ink transferred onto the sheet and the occupied area S of the ink layer of the sheet by the following formula:
Another is densitometry, lambert-Beer law states that absorbance at a wavelength is proportional to the concentration of the colorant contained in the light absorbing material and the thickness of the light absorbing material, expressed as follows:
Wherein D is absorbance, i.e., reflection density; r is spectral reflectance; alpha λ is the absorbance or extinction index, which is related to the molecular structure of the light absorbing material and the wavelength of the irradiated light; d is the thickness of the light absorbing material; c is the concentration of the colorant contained in the light absorbing material. Since the in-field reflection density D gradually increases over a range of increases in the ink layer thickness D and eventually tends to the saturation state D ∞ without significantly increasing. Therefore, by measuring the in-situ reflectance density D of the ink, the thickness of the ink layer of the printed matter or the concentration of the colorant contained in the light absorbing material can be determined, and the expression of the relationship between the in-situ reflectance density and the thickness of the ink layer is deduced as follows:
D＝D∞×(1-e-kd) (3)
Wherein D is the in-situ reflection density of the ink layer; d ∞ is the saturation ink layer in-situ reflection density, e is a constant; k is a constant related to the smoothness of the substrate; d is the ink layer thickness.
Therefore, the two commonly used ink layer thickness measuring methods are required to be manually measured by a certain amount, and are time-consuming and labor-consuming.
In addition, there are some patent documents that provide other methods for ink layer thickness detection. For example, in patent document CN201410299401.1, a method for detecting ink layer thickness based on machine vision is provided, in which first, each ink monochromatic solid color patch is manufactured and its density is measured; secondly, obtaining RGB and HSV descriptions of the solid color block images and the color information of each ink; establishing a relation model between the color information and the density information of each ink color solid color block image again; and finally, the ink layer thickness of the solid color block image of each ink color is calculated according to the established relation model between the color information and the density information and the expression of the relation between the solid reflection density and the ink layer thickness, such as a formula (3). The method only realizes the detection of the ink layer thickness of the four primary colors based on machine vision, and cannot realize the detection of the ink layer thickness of the color stack or spot color.
In another example, in the patent document with the application number CN201510369305.4, a method for measuring the ink layer thickness of a gravure large-sized product is provided, firstly, an ink layer thickness detector is used for acquiring images of the gravure product through a multispectral camera and a light source, and multispectral images are acquired; secondly, obtaining a restored reflection spectrum by utilizing a spectrum reconstruction algorithm; and finally, establishing a mapping relation between the spectrum and the thickness of the ink layer through a relation between the reflection density and the spectrum shown by a Lambert-Beer law, such as formula (2), and a relation between the reflection density and the thickness of the ink layer, such as formula (3), so as to obtain a measured value of the thickness of the ink layer.
It can be seen that the ink layer thickness detection methods mentioned in the prior patent documents are all indirect detection based on a relation model of spectrum or color information and reflection density, and an empirical relation between reflection density and ink layer thickness. Because Lambert-Beer law is deduced under ideal conditions, the influence of complex factors such as actual printing conditions, printing ink and printing stock is not considered, and the influence of some printed matters such as laser paper printed matters on spectrum or color information acquisition is large, the indirect detection method model of the thickness of the ink layer is difficult to realize accurate detection.
In view of the above, the present invention provides a device and a method for detecting the thickness of an ink layer of a printed matter.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a device and a method for detecting the thickness of an ink layer of a printed matter, which aims to avoid the influence of the defect of model accuracy and the instability of spectrum or color information acquisition on the detection result, which are relied on in the detection of the thickness of the ink layer in the prior art, and greatly improve the detection precision and stability.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a print ink layer thickness detection apparatus comprising:
the printing sheet cutting module is used for cutting the printing to be detected Zhang Yangpin on the sample table;
The microscopic image acquisition module is used for acquiring a section image of a cutting surface of the printed sheet sample to be detected;
the image processing module is used for acquiring an ink layer area image of the section image and calculating the ink layer thickness of the printed matter according to the ink layer area image;
the printing sheet cutting module is arranged above the sample table, and the microscopic image acquisition module is positioned on one side of the sample table and connected with the image processing module.
The microscopic image acquisition module comprises:
The microscopic acquisition component is used for acquiring and amplifying a section image of a cutting surface of a sheet sample to be detected;
the image acquisition component is used for acquiring the section image and sending the section image to the image processing module;
The microscopic acquisition assembly is positioned on one side of the sample stage, and the image acquisition assembly is positioned on the imaging side of the microscopic acquisition assembly.
The sheet cutting module includes:
The fixing assembly is used for fixing the to-be-detected printed sheet sample on the sample table at a preset position during cutting;
And the light-emitting panel is arranged on the fixed component and used for enabling the microscopic acquisition component to acquire clear sectional images.
A method of detecting a thickness of a printed matter ink layer according to any one of the preceding claims, comprising:
cutting the to-be-detected seal Zhang Yangpin on the sample stage by a seal cutting module;
Acquiring a section image of a cutting surface of a sheet sample to be detected by a microscopic image acquisition module;
and acquiring an ink layer area image of the section image by an image processing module, and calculating the ink layer thickness of the printed matter according to the ink layer area image.
Before the step of cutting the sheet sample to be tested on the sample stage by the sheet cutting module, the detection method further comprises the following steps:
and fixing the to-be-detected printed sheet sample on the sample table at a preset position through the fixing assembly.
The step of fixing the to-be-measured printed sheet sample on the sample table at a preset position through the fixing assembly further comprises the following steps:
and adjusting the light supplementing light source on the fixing component to make the color of the light source and the color of the ink layer be complementary colors.
The step of collecting the section image of the cutting surface of the sheet sample to be tested by the microscopic image collecting module comprises the following steps:
Acquiring and amplifying a section image of a cutting surface of a sheet sample to be detected by a microscopic acquisition component;
and acquiring the section image by an image acquisition component and sending the section image to an image processing module.
The step of acquiring the ink layer area image of the section image by the image processing module and calculating the ink layer thickness of the printed matter according to the ink layer area image comprises the following steps:
performing edge detection on the section image to acquire and divide an interested region image;
graying treatment is carried out on the region-of-interest image to obtain a gray image;
performing enhancement processing on the gray level image to obtain the edge of the gray level image;
The ink layer thickness of the print is calculated from the edge shape of the greyscale image.
In the step of calculating the ink layer thickness of the printed matter from the edge shape of the grayscale image, the ink layer thickness is obtained by the following formula:
Where d is the ink layer thickness, z is the total number of pixels of the gray scale image, x is the number of pixels in the lateral direction, and a is the lateral width.
Compared with the prior art, the device and the method for detecting the thickness of the ink layer of the printed matter provided by the invention comprise the printing sheet cutting module, the microscopic image acquisition module and the image processing module, the device firstly cuts the printing sheet sample to be detected through the printing sheet cutting module, then acquires the section image of the cutting surface of the printing sheet sample to be detected through the microscopic image acquisition module, finally acquires the ink layer area image of the section image through the image processing module, calculates the thickness of the ink layer according to the ink layer area image, avoids the influence of model precision defects and unstable spectrum or color information acquisition on detection results, greatly improves the detection precision and stability, and can realize the detection of the thickness of each ink layer of overprinting.
Drawings
Fig. 1 is a schematic diagram of a part of a device for detecting the thickness of an ink layer of a printed matter.
Fig. 2 is a block diagram of a device for detecting the thickness of a printing ink layer.
Fig. 3 is a flowchart of a method for detecting the thickness of a printing ink layer.
Detailed Description
In order to make the objects, technical solutions and effects of the present invention clearer and more specific, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It is noted that when an element is referred to as being "mounted," "secured," or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present.
It should be noted that, in the embodiments of the present invention, terms such as left, right, up, and down are merely relative concepts or references to normal use states of the product, and should not be construed as limiting.
The invention provides a device for detecting the thickness of a printing ink layer, referring to fig. 1 and 2, comprising:
the sheet cutting module 1 is used for cutting the sheet sample 200 to be tested on the sample stage 100 by the sheet cutting module 1;
The microscopic image acquisition module 2 is used for acquiring a section image of the cutting surface of the printed sheet sample 200 to be detected by the microscopic image acquisition module 2;
An image processing module 3, configured to obtain an ink layer area image of the cross-sectional image by the image processing module 3, and calculate an ink layer thickness of the printed matter according to the ink layer area image;
The sheet cutting module 1 is arranged above the sample stage 100, and the microscopic image acquisition module 2 is positioned on one side of the sample stage 100 and connected with the image processing module 3. According to the invention, firstly, the sheet sample 200 to be detected is cut through the sheet cutting module 1, then the section image of the cutting surface of the sheet sample 200 to be detected is acquired through the microscopic image acquisition module 2, finally, the ink layer area image of the section image is acquired through the image processing module 3, and the ink layer thickness is calculated according to the ink layer area image, so that the influence of model precision defects and unstable spectrum or color information acquisition on detection results, which are relied on in the ink layer thickness detection in the prior art, is avoided, the detection precision and stability are greatly improved, and the detection of the thickness of each ink layer in overprinting can be realized.
Specifically, the sheet sample 200 to be tested is tiled on the sample stage 100, and a partial area (i.e. an area to be cut) of the sheet sample 200 to be tested properly extends out of the sample stage 100, and the center of gravity of the sheet sample 200 to be tested is positioned on the sample stage 100, so that when the sheet cutting module 1 is cut, the part extending out of the sample stage 100 naturally drops out of the sample stage 100; after cutting of the sheet sample 200 to be tested is completed, selecting a proper magnification by the microscopic image acquisition module 2, acquiring a section image of a cutting surface of the sheet sample 200 to be tested and transmitting the section image to the image processing module 3; after preprocessing and edge detection of the ink layer area image of the cross-sectional image by the image processing module 3, the ink layer thickness is calculated according to the detection data and the formula.
Optionally, the microscopic image acquisition module 2 includes:
a microscopic acquisition component 21 for acquiring and amplifying a sectional image of a cut surface of the sheet sample 200 to be measured;
an image acquisition component 22, configured to acquire the profile image, and send the profile image to the image processing module 3;
The microscopic acquisition assembly 21 is located on one side of the sample stage 100 and the image acquisition assembly 22 is located on the imaging side of the microscopic acquisition assembly 21.
Specifically, the microscopic acquisition component 21 includes a light source system 210 and an optical system (not labeled in the figure), the light source system 210 may be a bulb or other light source meeting illumination intensity, the optical system includes a reflector 2111, a collecting lens group 2112, a half mirror 2113, an objective lens 2114, a prism 2115 and an eyepiece 2116, the light emitted by the light source system 210 irradiates the cutting surface of the sheet sample 200 to be measured with the brightness of the section through the reflector 2111, the collecting lens group 2112, the half mirror 2113 and the objective lens 2114 in sequence, the reflected light of the section passes through the objective lens 2114, the half mirror 2113 and the prism 2115, and the observer can observe the section image through the eyepiece 2116. The image acquisition assembly 22 comprises a CCD camera (not shown in the figure), an image acquisition card (not shown in the figure) and a CRT display (not shown in the figure), wherein the CCD camera, the image acquisition card, the CRT display and a computer are electrically connected, reflected light rays of a section image of a cutting surface of the to-be-detected printed sheet sample 200 penetrate through the half mirror 2113 and the prism 2115, the section image with fixed length and width is captured by the CCD camera after imaging, the CCD camera acquires the section image of the cutting surface of the to-be-detected printed sheet sample 200, and the image data is transferred onto the computer through the image acquisition card, and the computer displays the image data through the CRT display.
Further, the sheet cutting module 1 includes:
The fixing component 11 is used for fixing the to-be-tested printed sheet sample 200 on the sample table 100 at a preset position during cutting, and preventing the to-be-tested printed sheet sample 200 from moving during cutting;
the light-emitting panel is disposed on the fixing component 11, and is used for enabling the microscopic acquisition component 21 to acquire clear sectional images.
Before the sheet cutting module 1 cuts the sheet sample 200 to be tested, the fixing component 11 slightly presses the sample to ensure the position of the sample to be fixed, and the light-emitting panel on the fixing component 11 is adjusted according to the color of the ink layer of the print Zhang Yangpin to be tested, so that the light of the light-emitting panel and the color of the ink layer of the print Zhang Yangpin to be tested are complementary colors as much as possible, the contrast ratio of the two colors is enhanced, and the section image is clearer. The fixing component 11 is used for avoiding that the subsequent image acquisition and image processing are affected by uneven cutting surface caused by the movement of the printed sheet sample 200 to be tested when the printed sheet cutting module 1 is used for cutting; the light-emitting panel is arranged, so that the section image of the cut surface of the sheet sample 200 to be detected, which is acquired by the microscopic image acquisition module 2, is clearer, and meanwhile, the image processing module 3 is convenient for acquiring the ink layer area image of the section image and the section image is easier for an observer to observe.
In an embodiment of the present application, the sheet cutting module 1 selects ion beam cutting, that is, adopts an ion beam profile grinding mode to quickly cut out a profile image of a cutting surface of the sheet sample 200 to be measured and polish, so as to avoid microscopic damage to the profile caused by stress influence generated in a grinding process (such as mechanical cutting grinding, etc.), thereby obtaining high-quality in-situ microscopic morphology information and providing true and reliable sample preparation for subsequent microscopic image acquisition. The ion beam cutting selects a focused ion beam, an ion source of the focused ion beam can be a liquid metal ion source or a gas field emission ion source, the liquid metal ion source can be gallium (with low melting point and good vapor pressure low-level oxidation resistance), and the gas field emission ion source can be inert gas.
For example, when the sheet cutting module 1 adopts a liquid metal ion source, an electric field is applied to the liquid metal ion source in the sheet cutting module 1 to form a fine tip of the liquid metal, and then a negative electric field is applied to pull the metal at the tip to lead out an ion beam; focusing with an electrostatic lens, passing through a series of varying apertures to determine the size of the ion beam; the direction of the ion beam is controlled by the deflection system, the ion beam is secondarily focused to the surface of the printed sheet sample through the electrostatic lens, the printed sheet sample 200 to be tested is subjected to raster scanning cutting, the deflection system controls the scanning path of the ion beam to be a straight line cutting along the edge of the sample stage 100, which is close to one side of the microscopic image acquisition module 2, so that the cut section is vertical to the surface of the ink layer and is flat. In addition, the straight cutting path should be made perpendicular to and at the same level as the reflected light receiving direction of the objective lens 2114 in the microscopic image acquisition module 2. Because the ions in the focused ion beam spot are in Gaussian distribution, if the ion beam bombards a printed sheet sample according to a single pixel point, holes with conical interface outlines are formed, the taper of the section gradually reduces to saturation along with the increase of etching depth, and the section always has 0-4 degrees of taper according to different sample materials. Therefore, to obtain a profile that is perfectly perpendicular to the surface of the sheet to ensure that a true and accurate ink layer thickness is acquired for subsequent microscopic images, the sample stage 100 should be adjusted to have a slightly specific tilt angle to the surface of the sheet and the ion beam so that the ion beam is not perfectly perpendicular to the surface of the sheet to compensate for the deviation between the profile and the ion beam incident angle. In the cutting process, the ion beam and the printed sheet sample are in physical collision, and fragments separated from the samples are immediately pumped away by a vacuum system, so that high-precision cutting is ensured, and the influence of dust on the definition of subsequent microscopic image acquisition is avoided.
The basic working principle of a gas field emission ion source is similar to that of a liquid metal ion source, and ions are generated by ionizing gas atoms or molecules by using a strong electric field, and then an ion beam is formed by using an extraction electrode. The difference is that: the gas field emission ion source does not have a liquid metal reservoir, but instead is an inert gas supply system. The performance of the ion beam emitted by the gas field emission ion source is related to not only voltage and gas pressure, but also the temperature of the gas near the tip, and the ion beam intensity increases sharply with the decrease of the temperature of the gas near the emission tip, so that a low temperature system must be equipped. The ion beam cutting device adopts a liquid metal ion source or a gas field emission ion source, which belongs to the prior art, and the principle and the specific structure of the ion beam cutting device are not repeated.
Furthermore, in the present application, the cross-sectional image actually acquired by the microscopic image acquisition module 2 is often affected by factors such as image acquisition, transmission, processing and external environment, so that the cross-sectional image is interfered by noise, and the cross-sectional image does not have obvious edge characteristics or has blurred edges (i.e. the edge of the transition type is lost and becomes a progressive edge). Therefore, the image processing needs to be performed on the cross-sectional image acquired by the microscopic image acquisition module 2, so that the main purpose is to eliminate irrelevant information in the cross-sectional image, enhance the detectability of relevant information, simplify the data to the maximum extent, and improve the reliability of image feature extraction, matching and identification.
Specifically, the image processing module 3 includes a region-of-interest dividing unit 31 for dividing the region of interest and the irrelevant region, an image graying processing unit 32 for graying the ink layer region image of the cross-sectional image, an image enhancement processing unit 33 for smoothing and sharpening the ink layer region image of the cross-sectional image, and an ink layer thickness calculating unit 34, the region-of-interest dividing unit 31, the image graying processing unit 32, the image enhancement processing unit 33, and the ink layer thickness calculating unit 34 being connected.
Region of interest segmentation unit 31: for a printed matter section image, not all information contained in the whole image needs to be subjected to edge detection, in order to reduce irrelevant interference and reduce the calculation amount of an algorithm, the image is cut, and the process of removing parts which have no practical meaning (such as most areas of a printed matter and the areas of a sample table 100) and remain to be processed is the segmentation of the region of interest. Let the total number of vertical pixels of the image be y and define the variables i and j such that y=i+j is reflected on the image, i.e. the segmentation ratio for the region of interest and the unrelated region is defined as i: j. In connection with the present invention, actually acquired is a cross-sectional image of the cut surface of the sheet sample 200 to be tested, wherein the target area of interest is mainly an ink layer area image of the cross-sectional image.
In order to better divide the region of interest, firstly, selecting a larger number (e.g. 1000) of different printed matter section images as training samples, and assisting in calibrating (i.e. manually calibrating) the region of interest (i.e. ink layer region); then, selecting a certain number of different printed matter section images as test samples for testing; finally, a suitable segmentation ratio of the region of interest and the unrelated region may be determined.
An image graying processing unit 32: because the color information can not reflect the morphological characteristics of the image, is easily interfered by the environment, and has large calculated amount of the multidimensional matrix, in the application process of a plurality of image processing algorithms such as edge detection and the like, the image is required to be subjected to gray processing, so that each pixel point in the pixel point matrix meets the following conditions: r=g=b, i.e., a process of unifying R, G, B three channel components of a sheet cross-sectional image acquired by an optical microscope into one parameter represented by 0 to 255. The common methods for image graying include a weighted average method, a maximum value method, an average value method, a single component method, and the like, and in the embodiment of the present application, the weighted average method is preferred, that is, the R, G, B three channel values are multiplied by different coefficients according to the importance of different channels of the image, and then the average value is taken as the gray value of the pixel point.
The image enhancement processing unit 33: in the process of enhancing the printed sheet profile image, smoothing is firstly performed, and noise and edge information are mainly concentrated in a high frequency band of an image spectrum, so that the edge and contour of the image are easy to blur after the smoothing. Then, image sharpening is performed to make the edges of the image clear. The smoothing process is preferably frequency domain low pass filtering (e.g., guassian filter, etc.), and may also select suitable spatial filtering (e.g., mean or median filtering, etc.). The sharpening process is preferably a high pass filter (e.g., 1 minus a low pass filter template, etc.), and may also select an appropriate first or second order spatial differential. In combination with the cross-sectional image coordinate system of the cut surface of the sheet sample 200 to be tested, a single-direction first-order differential (such as Prewitt operator, sobel operator, etc.) or a proper non-direction first-order differential sharpening can be selected.
The Prewitt operator method calculates the gradient by averaging and then differencing, and the horizontal and vertical templates are respectively:
And (3) obtaining the gradients in the horizontal and vertical directions by using a detection template, and obtaining the detection result of the average difference method by gradient synthesis and edge point judgment. The edge detection result of the Prewitt operator is obvious for the edge detection in the transverse direction and the longitudinal direction of the image coordinate system.
The Sobel operator is established on the basis of the Prewitt operator, and the constraint of setting different weights on surrounding pixel points is increased by combining the Gaussian smoothing thought, so that different influences of adjacent pixel points on a center similar point due to different distances are considered. The Sobel operator is also known as weighted average difference, and the horizontal and vertical gradient templates are respectively:
The former can detect edges in the horizontal direction in the image, and the latter can detect edges in the vertical direction in the image. In practical application, each pixel point takes the maximum value of two template convolutions as the output value of the pixel point, and the operation result is an edge image.
An ink layer thickness calculation unit 34: since the distance between the microscopic image acquisition module 2 and the sample stage 100 is fixed, the lateral dimension (i.e., the number of pixels) of the cross-sectional image of the cut surface of the acquired sheet sample 200 to be measured is fixed, and the lateral dimension a (i.e., the number of pixels x) of the image target area is fixed. The longitudinal dimension of the image target area is different according to the thickness of the ink layer of the cross-section image of different printing sheets. And identifying and counting the total number z of pixels in the ink layer thickness region, and carrying out arithmetic average on the total number z of pixels in the transverse dimension to obtain the number of pixels in the longitudinal dimension of the ink layer thickness region, thus obtaining the ink layer thickness d.
In addition, the device for detecting the thickness of the ink layer of the printed matter further comprises a printing total ink amount calculating module 4, wherein the printing total ink amount calculating formula is as follows:
m＝ρ×d×S×n
ρ is the color ink density, d is the ink layer thickness, S is the print area of the individual print, and n is the order quantity. According to the application, the total ink quantity of printing under a certain order quantity can be obtained through the total ink quantity calculating module 4 of the printed matter, so that on one hand, a merchant can have a certain reference in the ink configuration, waste caused by excessive ink configuration or less influence on printing efficiency caused by the ink configuration is avoided, and on the other hand, the printed matter can reach the maximum ink receiving quantity, and the conditions that the ink cannot be absorbed, the ink cannot be dried normally and the printed matter is adhered together due to the large ink coverage rate are avoided.
Based on the above-mentioned device for detecting the thickness of the ink layer of the printed matter, the invention further provides a corresponding detection method of the device for detecting the thickness of the ink layer of the printed matter, please refer to fig. 1, 2 and 3, comprising:
s100, cutting a to-be-tested printed sheet sample 200 on a sample stage 100 by a printed sheet cutting module 1;
s200, acquiring a section image of a cutting surface of a sheet sample 200 to be tested by a microscopic image acquisition module 2;
s300, acquiring an ink layer area image of the section image by the image processing module 3, and calculating the ink layer thickness of the printed matter according to the ink layer area image.
According to the invention, the sheet sample 200 to be detected on the sample stage 100 is cut through the sheet cutting module 1, after the cutting is completed, the image acquisition module is used for acquiring the section image of the sheet sample 200 to be detected, finally, the image processing module 3 is used for acquiring the ink layer region graph of the section image, and calculating the ink layer area according to the ink layer region image, so that the influence of model precision defects depending on ink layer thickness detection and unstable spectrum or color information acquisition on detection results in the prior art is avoided, the detection precision and stability are greatly improved, and the detection of each ink layer thickness of overprinting can be realized.
In an embodiment of the present invention, before the step S100, the detection method further includes:
the sheet sample 200 to be measured on the sample stage 100 is fixed at a predetermined position by the fixing assembly 11.
The to-be-measured printed sheet sample 200 is located on the sample stage 100, and one end of the to-be-measured printed sheet sample 200 is lightly pressed and fixed through the fixing component 11, the other end of the to-be-measured printed sheet sample 200 extends out of the sample stage 100, after the printed sheet cutting module 1 cuts the to-be-measured printed sheet sample 200, the part extending out of the sample stage 100 naturally drops below the sample stage 100, so that the cutting surface of the to-be-measured printed sheet sample 200 is flush with the side surface of the sample stage 100, and the subsequent microscopic image acquisition module 2 can conveniently acquire the sectional image of the cutting surface of the to-be-measured printed sheet sample 200 and the image processing module 3 can analyze and process the sectional image.
The step of fixing the sheet sample 200 to be tested on the sample stage 100 at a preset position by the fixing assembly 11 further includes:
And adjusting the light supplementing light source on the fixing component 11 to make the light source color and the ink layer color be complementary colors.
After the fixing component 11 lightly presses and fixes the sheet sample 200 to be measured, the light supplementing light source on the fixing component 11 is adjusted, so that the color of the light source and the color of the ink layer become complementary colors, the ink layer is distinguished from the rest of the sheet sample 200 to be measured, the image processing module 3 can obtain the image of the ink layer area more easily and clearly, and the ink layer thickness calculated according to the image of the ink layer area is more accurate. Please refer to the corresponding embodiment of the detection device.
In an embodiment of the present invention, the step S200 includes:
acquiring and amplifying a section image of a cut surface of the sheet sample 200 to be measured by the microscopic acquisition assembly 21;
the sectional images are acquired by the image acquisition component 22 and sent to the image processing module 3.
By adjusting the illumination intensity of the light source system 210 in the micro-acquisition assembly 21 and the angle parameters and the magnification of the optical system, on one hand, the sectional image of the cut surface of the sheet sample 200 to be measured is acquired by the image acquisition assembly 22 after being imaged by the optical system and is sent to the image processing module 3, and on the other hand, an observer can observe the imaged sectional image through the optical system. Please refer to the corresponding embodiment of the detection device.
In an embodiment of the present invention, the step S200:
performing edge detection on the section image to acquire and divide an interested region image;
graying treatment is carried out on the region-of-interest image to obtain a gray image;
performing enhancement processing on the gray level image to obtain the edge of the gray level image;
The ink layer thickness of the print is calculated from the edge shape of the greyscale image.
In the step of calculating the ink layer thickness of the printed matter from the edge shape of the grayscale image, the ink layer thickness is obtained by the following formula:
Where d is the ink layer thickness, z is the total number of pixels of the gray scale image, x is the number of pixels in the lateral direction, and a is the lateral width.
After the step of acquiring the ink layer area image of the cross-sectional image by the image processing module 3 and calculating the ink layer thickness of the printed matter according to the ink layer area image, the detection method further comprises S400, calculating the total ink printing amount according to the ink layer thickness.
The total ink amount printed is obtained by the following formula:
m＝ρ×d×S×n
ρ is the color ink density, d is the ink layer thickness, S is the print area of the individual print, and n is the order quantity.
In summary, the device for detecting the thickness of the ink layer of the printed matter comprises a printing sheet cutting module, a microscopic image acquisition module and an image processing module, wherein the device firstly cuts a printing sheet sample to be detected through the printing sheet cutting module, then acquires a section image of a cutting surface of the printing sheet sample to be detected through the microscopic image acquisition module, finally acquires an ink layer area image of the section image through the image processing module, calculates the thickness of the ink layer according to the ink layer area image, avoids the influence on a detection result caused by model precision defects and unstable spectrum or color information acquisition which are relied on the detection of the ink layer thickness in the prior art, greatly improves the detection precision and stability, and can realize the detection of the thickness of each ink layer of overprinting.
It will be understood that equivalents and modifications will occur to those skilled in the art in light of the present invention and their spirit, and all such modifications and substitutions are intended to be included within the scope of the present invention as defined in the following claims.
Claims (10)
1. A print ink layer thickness detection device, comprising:
the printing sheet cutting module is used for cutting the printing to be detected Zhang Yangpin on the sample table;
The microscopic image acquisition module is used for acquiring a section image of a cutting surface of the printed sheet sample to be detected;
the image processing module is used for acquiring an ink layer area image of the section image and calculating the ink layer thickness of the printed matter according to the ink layer area image;
the printing sheet cutting module is arranged above the sample table, and the microscopic image acquisition module is positioned on one side of the sample table and connected with the image processing module;
The image processing module comprises an interested region segmentation unit for segmenting an interested region and an irrelevant region, an image graying processing unit for carrying out gray processing on an ink layer region image of a section image, an image enhancement unit for carrying out smoothing and sharpening processing on the ink layer region image of the section image and an ink layer thickness calculation unit, wherein the interested region segmentation unit, the image graying processing unit, the image enhancement processing unit and the ink layer thickness calculation unit are connected;
the ink layer thickness calculation unit is used for calculating the ink layer thickness of the printed matter according to the edge shape of the gray level image, and the ink layer thickness is obtained through the following formula:
Where d is the ink layer thickness, z is the total number of pixels of the gray scale image, x is the number of pixels in the lateral direction, and a is the lateral width.
2. The device for detecting the thickness of a printing ink layer according to claim 1, wherein the microscopic image acquisition module comprises:
The microscopic acquisition component is used for acquiring and amplifying a section image of a cutting surface of a sheet sample to be detected;
the image acquisition component is used for acquiring the section image and sending the section image to the image processing module;
The microscopic acquisition assembly is positioned on one side of the sample stage, and the image acquisition assembly is positioned on the imaging side of the microscopic acquisition assembly.
3. The printing ink layer thickness detection apparatus as claimed in claim 2, wherein the sheet cutting module comprises:
The fixing assembly is used for fixing the to-be-detected printed sheet sample on the sample table at a preset position during cutting;
And the light-emitting panel is arranged on the fixed component and used for enabling the microscopic acquisition component to acquire clear sectional images.
4. A method of detecting a thickness of a printed matter ink layer according to claim 1, comprising:
cutting the to-be-detected seal Zhang Yangpin on the sample stage by a seal cutting module;
Acquiring a section image of a cutting surface of a sheet sample to be detected by a microscopic image acquisition module;
and acquiring an ink layer area image of the section image by an image processing module, and calculating the ink layer thickness of the printed matter according to the ink layer area image.
5. The method of claim 4, wherein prior to the step of cutting the sheet sample to be tested on the sample stage by the sheet cutting module, the method further comprises:
and fixing the to-be-detected printed sheet sample on the sample table at a preset position through the fixing assembly.
6. The method according to claim 5, wherein the step of fixing the sheet sample to be tested on the sample stage at a predetermined position by the fixing assembly further comprises:
and adjusting the light supplementing light source on the fixing component to make the color of the light source and the color of the ink layer be complementary colors.
7. The method according to claim 4, wherein the step of acquiring the sectional image of the cut surface of the sheet sample to be measured by the microscopic image acquisition module comprises:
Acquiring and amplifying a section image of a cutting surface of a sheet sample to be detected by a microscopic acquisition component;
and acquiring the section image by an image acquisition component and sending the section image to an image processing module.
8. The method of detecting according to claim 4, wherein the step of acquiring an ink layer area image of the cross-sectional image by the image processing module and calculating the ink layer thickness of the printed matter from the ink layer area image includes:
performing edge detection on the section image to acquire and divide an interested region image;
graying treatment is carried out on the region-of-interest image to obtain a gray image;
performing enhancement processing on the gray level image to obtain the edge of the gray level image;
The ink layer thickness of the print is calculated from the edge shape of the greyscale image.
9. The method according to claim 8, wherein in the step of calculating the ink layer thickness of the printed matter from the edge shape of the gradation image, the ink layer thickness is obtained by the following formula:
Where d is the ink layer thickness, z is the total number of pixels of the gray scale image, x is the number of pixels in the lateral direction, and a is the lateral width.
10. The method according to claim 9, wherein after the step of acquiring an ink layer area image of the cross-sectional image by the image processing module and calculating the ink layer thickness of the printed matter from the ink layer area image, the method further comprises:
and calculating the total printing ink quantity according to the ink layer thickness.
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