Image inspection device, image inspection system, and program

Abstract

To provide an image inspection apparatus, an image inspection system and a program that are less likely to be affected by floating even if a paper sheet on which an image is printed floats.SOLUTION: An image inspection apparatus 30 includes a processor configured to: acquire printing data that is data as a base of an image to be printed; acquire read data that is data obtained by reading the image printed on a paper sheet; correct a blur in the read data caused by floating of the paper sheet occurring in the reading of the image; and inspect the image by comparing the printing data with the corrected read data.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an image inspection device, an image inspection system, and a program. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an image inspection device has been used that compares print data, which is the source of an image to be printed, with read data obtained by reading the printed image, and inspects the printed image.

[0003] Patent Document 1 describes an image inspection device that inspects printed images, including a receiving means for receiving print data, a reading means for reading a print image printed from the received print data, and an image inspection means for comparing the received print data with the read print image to calculate image distortion, generating distortion information including the position on the paper and the magnitude and direction of the distortion based on the calculated image distortion, distorting the received print data based on the distortion information, and comparing the distorted print data with the read print image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2014-117841 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the paper on which the image is printed becomes fuzzy, the read image may become blurred, which may reduce the accuracy of image inspection. An object of the present invention is to provide an image inspection device, an image inspection system, and a program that are less susceptible to the influence of floating, even if floating occurs in paper on which an image is printed. [Means for solving the problem]

[0006] The invention described in claim 1 includes a processor, which acquires print data that is data that is the source of an image to be printed, acquires read data that is data obtained by reading the image printed on paper, corrects blurring caused by paper lift that occurs when reading the image from the read data, compares the print data with the corrected read data, and inspects the image. The correction is performed based on a preset value for each type of paper, assuming that the paper floats in either the transport direction or a direction crossing the transport direction. It is an image inspection device. The invention described in claim 2 is an image inspection device that includes a processor that acquires print data, which is data that is the source of an image to be printed, acquires read data, which is data obtained by reading the image printed on paper, corrects the read data for blurring caused by paper lift that occurs when the image is read, compares the print data with the corrected read data, and inspects the image, and the correction is preset for each type of paper by reading test patterns printed in the center and at both ends of the paper. Claim 3 The invention described in claim 1 is characterized in that the test pattern is printed in the center, both ends of the long sides, and both ends of the short sides of the paper. 2 2. An image inspection device according to claim 1. The invention described in claim 4 is an image inspection device that includes a processor that acquires print data, which is data that is the source of an image to be printed, acquires read data, which is data obtained by reading the image printed on paper, corrects the read data for blurring caused by paper lift that occurs when the image is read, compares the print data with the corrected read data, inspects the image, and changes the strength of the correction between the center and edges of the paper. Claim 5 The invention described in claim 1 is characterized in that the strength of the correction is changed between the center of the paper and either the long side or the short side of the paper, and is not changed at the other end. 4 2. An image inspection device according to claim 1. Claim 6 The invention described in claim 1 further includes a method for determining the strength of the correction in accordance with the spatial frequency of the image. 4 2. An image inspection device according to claim 1. Claim 7 The invention described in claim 1 includes a range in which the strength of the correction decreases as the spatial frequency increases. 6 2. An image inspection device according to claim 1. Claim 8 The invention described in claim 1 is characterized in that the relationship between the spatial frequency and the correction strength is an upwardly convex function. 7 2. An image inspection device according to claim 1. Claim 9The invention described in the item (1) comprises a printing device that prints an image on paper, a reading device that reads the image printed on paper by the printing device, and an inspection device that inspects the image read by the reading device, and the inspection device has a processor, and the processor acquires print data that is data that is the source of the image, acquires read data that is data obtained by reading the image printed on paper, corrects blurring caused by paper lifting that occurs when the image is read from the read data, compares the print data with the corrected read data, and inspects the image. The correction is performed based on a preset value for each type of paper, assuming that the paper floats in either the transport direction or a direction crossing the transport direction. It is an image inspection system. The invention described in claim 10 is an image inspection system comprising a printing device that prints an image on paper, a reading device that reads the image printed on paper by the printing device, and an inspection device that inspects the image read by the reading device, wherein the inspection device has a processor, which acquires printing data that is the original data of the image, acquires read data that is data obtained by reading the image printed on paper, corrects the read data for blurring caused by paper floating when the image is read, compares the printing data with the corrected read data, and inspects the image, wherein the correction is preset for each type of paper by reading test patterns printed in the center and at both ends of the paper. The invention described in claim 11 is an image inspection device comprising a printing device that prints an image on paper, a reading device that reads the image printed on paper by the printing device, and an inspection device that inspects the image read by the reading device, wherein the inspection device has a processor that acquires printing data that is the original data of the image, acquires read data that is data obtained by reading the image printed on paper, corrects the read data for blurring caused by paper floating that occurs when the image is read, compares the printing data with the corrected read data, inspects the image, and changes the strength of the correction between the center and edges of the paper. The invention described in claim 12 allows a computer to realize a function of acquiring print data, which is data that is the source of an image to be printed; a function of acquiring read data, which is data obtained by reading the image printed on paper; a function of correcting blurring caused by paper lifting that occurs when reading the image, for the read data; and a function of comparing the print data with the corrected read data and inspecting the image. The correction is preset for each type of paper, assuming that the paper floats in either the conveying direction or a direction crossing the conveying direction. This is a program for The invention described in claim 13 is a program that enables a computer to realize the following functions: acquire print data, which is data that is the source of an image to be printed; acquire read data, which is data obtained by reading the image printed on paper; correct the read data for blurring caused by paper floating when reading the image; and compare the print data with the corrected read data to inspect the image, and the correction is preset for each type of paper by reading test patterns printed in the center and both ends of the paper. The invention described in claim 14 is a program that enables a computer to implement the following functions: acquire print data, which is the data that forms the basis of an image to be printed; acquire read data, which is data obtained by reading the image printed on paper; correct the read data for blurring caused by paper lift that occurs when reading the image; and compare the print data with the corrected read data to inspect the image, and change the strength of the correction between the center and edges of the paper. [Effects of the Invention]

[0007] According to the invention of claim 1, even if the paper on which an image is printed becomes lifted, the influence of the lifting is reduced. Furthermore, the correction coefficient for correcting blur can be set more easily, and the correction coefficient can be set according to the type of the blur. Claim 2 According to the invention, Even if the paper on which the image is printed is uneven, the image will be less susceptible to the unevenness. Also, it will be easier to set the correction coefficient for correcting blur. A test pattern can be prepared according to the type of float. Claim 3 According to the invention, a test pattern can be prepared according to the shape of the float. Claim 4 According to the invention, Even if the paper on which the image is printed becomes uneven, the effect of the unevenness is reduced. A correction coefficient can be set according to the type of float. Claim 5According to the invention, a correction coefficient can be set according to the form of the float. Claim 6 According to the invention, the strength of the correction can be set according to the susceptibility of the image to the influence of blurring when inspecting the image. Claim 7 According to the invention, it is possible to set a large correction strength for a portion that is easily affected by blurring during image inspection. Claim 8 According to the invention, the strength of blur correction can be set more appropriately. Claim 9 According to the invention, it is possible to provide an image inspection system that is less susceptible to the influence of lifting even when lifting occurs in the paper on which an image is printed. This makes it easier to set the correction coefficient for correcting blurring, and also makes it possible to set the correction coefficient according to the type of blurring. According to the invention of claim 10, It is possible to provide an image inspection system that is less susceptible to the effects of floating, even if floating occurs on the paper on which an image is printed. Also, it becomes easier to set the correction coefficient for correcting blur. A test pattern can be prepared according to the type of float. According to the invention of claim 11, It is possible to provide an image inspection system that is less susceptible to the effects of lifting even when the paper on which an image is printed is lifted. A correction coefficient can be set according to the type of float. According to the invention of claim 12, even if a lift occurs on the paper on which an image is printed, a function that makes it less susceptible to the lift can be realized by a computer. This makes it easier to set the correction coefficient for correcting blurring, and also makes it possible to set the correction coefficient according to the type of floating. According to the invention of claim 13, a function that makes it less susceptible to the effects of floating even when floating occurs on the paper on which an image is printed can be realized by a computer. Also, it becomes easier to set correction coefficients for correcting blur. Also, it is possible to prepare test patterns according to the type of floating. According to the invention of claim 14, even if a lift occurs on the paper on which an image is printed, a function that makes it less susceptible to the lift can be realized by a computer. Also, a correction coefficient can be set according to the type of the lift. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of the configuration of an image inspection system according to an embodiment of the present invention. [Figure 2] FIG. 2 illustrates an example of the hardware configuration of a printing apparatus. [Figure 3] 1(a) and 1(b) are diagrams illustrating a reading device. [Figure 4] FIG. 1 is a diagram showing a processing flow performed in an image inspection system. [Figure 5] FIG. 2 is a block diagram showing a signal processing system in the information processing device. [Figure 6]10(a) to 10(h) are diagrams illustrating floating of paper. [Figure 7] 10(a) to 10(c) are diagrams showing blurring that occurs when a printed sheet is read. [Figure 8] 10(a) to 10(d) are diagrams showing a test paper for detecting which of four modes of lifting occurs. [Figure 9] 10(a) and 10(b) are diagrams showing other forms of the test paper. [Figure 10] 10 is a diagram showing the relationship between the spatial frequency of an image formed on a sheet P and the strength of correction. FIG. [Figure 11] 10 is a flowchart showing a correction process performed by a resolution characteristic correction unit. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0010] <Explanation of the overall image inspection system> FIG. 1 is a diagram showing an example of the configuration of an image inspection system 1 according to this embodiment. As shown in the figure, the image inspection system 1 of this embodiment comprises a printing device 10 that prints an image, a reading device 20 that reads the printed image, an image inspection device 30 that inspects the image, and an information processing device 40 that creates printing data and color data for inspection.

[0011] The printing device 10 is a device that has a printer function for printing an image on paper, which is a recording medium, and outputting it as a printed document.

[0012] FIG. 2 is a diagram showing an example of the hardware configuration of the printing device 10. As shown in FIG. As shown in the figure, the printing device 10 includes a CPU 11, a RAM (Random Access Memory) 12, a ROM (Read Only Memory) 13, a storage 14, an operation panel 15, an image forming unit 16, and a communication I / F 17. These components exchange necessary data via a bus B.

[0013] The CPU 11 loads various programs stored in the ROM 13 or the like into the RAM 12 and executes them to realize various functions, which will be described later. The RAM 12 is a memory used as a working memory for the CPU 11, etc. The ROM 13 is a memory that stores various programs executed by the CPU 11. The storage 14 is a hard disk drive (HDD) or a solid state drive (SSD), and stores image information and the like used by the image forming unit 16.

[0014] The operation panel 15 is, for example, a touch panel that displays various types of information and accepts operation inputs from the user. When the operation panel 15 is a touch panel, it has a display unit such as a liquid crystal panel that displays content (information content) as an image in a predetermined area. It also has a function of detecting the position of a contact object, such as a human finger or a stylus pen, when the contact object touches the liquid crystal panel. In this embodiment, the touch panel is not particularly limited, and various types such as a resistive film type or a capacitive type can be used.

[0015] The image forming unit 16 is an example of a printing mechanism that forms an image on paper. Here, the image forming unit 16 can use an electrophotographic method that forms an image by transferring toner attached to a photosensitive member onto paper, or an inkjet method that forms an image by ejecting ink onto paper.

[0016] The communication I / F 17 transmits and receives various information to and from other devices.

[0017] The reading device 20 reads an image printed on paper by the printing device 10. The reading device 20 is a so-called in-line sensor, and reads an image printed on paper while it is being transported. 3(a) and 3(b) are diagrams illustrating the reading device 20. Here, Fig. 3(a) is a diagram of the reading device 20 viewed from the same direction as Fig. 1. Fig. 3(b) is a diagram of the reading device 20 viewed from the direction IIIb in Fig. 3(a). As shown in the figure, the reading device 20 includes a light source 21, an optical system 22, a CCD (Charge Coupled Device) sensor 23, and a housing 24.

[0018] The light source 21 irradiates light onto the paper P on which an image has been formed. The light source 21 is composed of, for example, a pair of tungsten lamps 21a and 21b. The light source 21 irradiates the image formed on the paper P with light, generating reflected light that contains information about the image.

[0019] The optical system 22 guides light reflected from the image formed on the paper P to the CCD sensor 23. In this embodiment, the optical system 22 is made up of a SELFOC lens array (SLA: registered trademark), which is a lens array. This SELFOC lens array collects mainly diffusely reflected light out of the light reflected from the image, and forms an image on the CCD sensor 23.

[0020] The CCD sensor 23 receives light guided by the optical system 22. The CCD sensor 23 has CCDs 23a arranged in a line as pixels that receive light reflected from the image. In this embodiment, CCDs corresponding to the colors R (Red), G (Green), and B (Blue) are arranged in three lines, allowing the image to be measured in each of the RGB colors. In other words, the CCD 23a is a three-line color CCD. The CCDs 23a are arranged in the main scanning direction for each RGB color. This allows the image to be read in the main scanning direction. In addition, the sub-scanning direction allows reading in accordance with the movement of the paper as it is transported. The light received by the CCD 23a is photoelectrically converted into electric charges, and these electric charges are transferred to the read data generation unit 23b.

[0021] The read data generating unit 23b detects the charges transferred from the CCD 23a and generates a detection signal. This detection signal becomes read data obtained by reading the image formed on the paper. Since the CCD 23a is a color CCD for three colors, R, G, and B, the read data generating unit 23b generates an R signal, a G signal, and a B signal as read data corresponding to each color.

[0022] The housing 24 is a case for housing the light source 21, the optical system 22, and the CCD sensor 23.

[0023] The image inspection device 30 inspects the image read by the reading device 20. The image inspection device 30 acquires print data, which is the data that forms the basis of the image to be printed, from the information processing device 40. The image inspection device 30 also acquires read data from the read data generation unit 23b of the reading device 20. The image inspection device 30 then compares the print data with the read data to inspect the image. This will be described in detail later. The information processing device 40 creates print data, which will also be described in detail later.

[0024] The image inspection device 30 and the information processing device 40 are computer devices. The image inspection device 30 and the information processing device 40 perform their respective processes by running various application software under the control of an OS (Operating System). The image inspection device 30 and the information processing device 40 include a CPU (Central Processing Unit) as a computing means, a main memory as a storage means, and storage such as an HDD or SSD. The CPU executes various programs such as the OS and application software. The main memory is a storage area that stores various programs and data used to execute them, and the storage is a storage area that stores input data for various programs and output data from various programs. The image inspection device 30 and the information processing device 40 also include a communication interface for communicating with the outside. The CPU is an example of a processor.

[0025] FIG. 4 is a diagram showing a processing flow performed by the image inspection system 1. As shown in the figure, in the image inspection system 1, an information processing device 40 creates print data to be printed by the printing device 10. This print data is RIP (Raster Image Processor) data, and is color data based on the colors of color materials such as toner used in the printing device 10. In this embodiment, C (cyan), M (magenta), Y (yellow), and K (black) are used as the colors of the color materials.

[0026] The printing device 10 prints on paper based on the print data. The printed paper is then transported, and the printed image is read by the reading device 20. The read data read by the reading device 20 is then sent to the image inspection device 30 as inspection image data.

[0027] In the image inspection device 30, the data acquisition unit 31 acquires print data, which is the original data for the image to be printed and is created by the information processing device 40. The data acquisition unit 31 also acquires inspection image data as read data, which is data obtained by reading an image printed on paper and sent from the reading device 20. At this time, the data acquisition unit 31 aligns the image based on the print data with the image based on the inspection image data. The resolution characteristic correction unit 32 corrects the resolution characteristics of the inspection image data. In this case, blurring that occurs when the reading device 20 reads the image is corrected. The edge extraction unit 33 then extracts edges and extracts portions of the image. The difference between the print data and the inspection image data is then calculated. The threshold calculation unit 34 calculates a threshold value for determining image defects based on the print data. If the difference between the print data and the inspection image data is equal to or less than the threshold value, it is determined that there is no image defect. If the difference exceeds the threshold value, it is determined that there is an image defect. The threshold comparison unit 35 then compares the difference between the print data and the inspection image data with the threshold value, and the output unit 36 outputs the image defect extraction results. This makes it possible to detect whether or not there are image defects in the image printed by the printing device 10. Note that image defects include, for example, dust on the paper, or dots or streaks that are not actually present in the image. That is, the image inspection device 30 compares the print data with the corrected inspection image data to inspect the image.

[0028] At this time, the inspection image data, which is the read data sent from the reading device 20, is RGB data. Also, the print data sent from the information processing device 40 is converted into RGB data by an RGB conversion unit 49 in FIG. 5, which will be described later. Then, the image inspection device 30 compares the print data with the corrected inspection image data in the same color space, RGB color space, and inspects the image. Note that the inspection image data sent from the reading device 20 is converted from RGB data to L color data in the image inspection device 30. * a * b * In this case, the information processing device 40 may convert the L data into RGB data. * a * b *Furthermore, the image inspection device 30 converts the print data into L * a * b * Then, the image inspection device 30 acquires the data in the same color space, L * a * b * The print data is compared with the corrected inspection image data in color space to inspect the image.

[0029] <Description of Information Processing Device 40> Next, the processing performed by the information processing device 40 will be described in detail. FIG. 5 is a block diagram showing a signal processing system in the information processing device 40. As shown in FIG. The information processing device 40 includes an RGB data acquisition unit 41 that acquires RGB data created to output an image on the printing device 10, a PDL generation unit 42 that receives RGB (Red, Green, Blue) data and converts it into a page description language (PDL), a rasterize unit 43 that creates a raster image from the PDL created by the PDL generation unit 42, a color conversion processing unit 44 that converts RGB data into CMYK data, a color adjustment unit 45 that performs color adjustment on the CMYK data, a raster image adjustment unit 46 that adjusts the raster image converted by the color adjustment unit 45, a halftone processing unit 47 that performs halftone processing, a print data output unit 48 that outputs the print data after signal processing to the printing device 10, and an RGB conversion unit 49 that converts CMYK data into RGB data.

[0030] In this embodiment, first, RGB data is received from an external PC by RGB data acquisition unit 41. This RGB data is image data that a user of the PC wants to print using printing device 10. The RGB data is then sent to the PDL generation unit 42, which converts it into code data written in PDL and outputs it.

[0031] The rasterizing unit 43 converts the code data written in the PDL output from the PDL generating unit 42 into raster data for each pixel, thereby creating a raster image.

[0032] The color conversion processing unit 44 converts the raster data input from the rasterization unit 43 into CMYK data, which is the reproduction color (CMYK, which is the color of the toner, which is the color material) of the printing device 10, and outputs the converted data. This CMYK data consists of C color data, M color data, Y color data, and K color data separated for each color.

[0033] The color adjustment unit 45 functions as a color adjustment means for adjusting the colors of the image formed by the printing device 10. The color adjustment unit 45 adjusts the colors of the CMYK data so that they match the target colors that should originally be output by the printing device 10.

[0034] The raster image adjustment unit 46 performs various adjustments on the CMYK data output from the color adjustment unit 45, such as gamma conversion, resolution processing, and halftone processing, to enable the printing device 10 to obtain better image quality.

[0035] The halftone processing unit 47 performs halftone processing on the print data by dither mask processing using a dither mask having a predetermined threshold array in the main scanning direction and the sub-scanning direction, thereby converting the print data, for example, from multi-valued to binary print data.

[0036] The print data output unit 48 outputs the print data created by the halftone processing unit 47 to the printing device 10. This print data is CMYK data.

[0037] The RGB conversion unit 49 reconverts the CMYK data output from the halftone processing unit 47 into RGB data, and outputs the print data converted into RGB data to the image inspection device 30.

[0038] <Description of the resolution characteristic correction unit 32> Next, a method for correcting blurring that occurs in the read image by the resolution characteristic corrector 32 of the image inspection device 30 will be described in detail. The reason why the image read in this embodiment is blurred is because the paper floats. That is, the optical system 22 of the reading device 20 is designed to be focused on the location on the transport path along which the paper is transported. Therefore, if the paper is positioned outside this transport path, the optical system 22 will not be able to focus, resulting in blur. The main cause of paper being deviated from the transport path is the occurrence of paper float.

[0039] 6(a) to 6(h) are diagrams showing the floating of the paper P. FIG. In this embodiment, there are four main ways in which paper P may become lifted. Figures 6(a) to 6(h) illustrate these four ways in which paper P may become lifted. Note that dotted lines in Figures 6(a) to 6(h) indicate the position of the transport path. Furthermore, arrows in Figures 6(b), (d), (f), and (h) indicate the location and direction in which paper P may become lifted. Of these, Figures 6(a) and 6(b) show cases where the paper P floats in the center in the transport direction (sub-scanning direction). In this case, Figure 6(b) is a view of the paper P viewed from the VIb direction in Figure 6(a). In this case, the two short sides of the paper P are straight and located on the transport path. In contrast, the two long sides of the paper P are convex and float up, located above the transport path. In this case, the area near the center along the long side of the paper P is located at the top.

[0040] 6(c) to 6(d) also show cases where the edge of the paper P is lifted in the transport direction (sub-scanning direction). In this case, FIG. 6(d) is a view of the paper P viewed from the VId direction in FIG. 6(c). In this case, the two short sides of the paper P are lifted and positioned at the top. The two long sides of the paper P are also concave and lifted. The center of the paper P along the short sides is on the transport path.

[0041] Furthermore, Figures 6(e) to (f) show a case where the paper P is lifted in the center in the direction intersecting the transport direction (main scanning direction). In this case, Figure 6(f) is a view of the paper P viewed from the VIf direction in Figure 6(e). In this case, the two long sides of the paper P are straight and located on the transport path. In contrast, the two short sides of the paper P are convex and lifted, and located above the transport path. In this case, the area near the center along the short side direction of the paper P is located at the top.

[0042] Furthermore, Figures 6(g) to (h) also show cases where the edge of the paper P is lifted in the direction intersecting the transport direction (main scanning direction). In this case, Figure 6(h) is a view of the paper P viewed from the VIh direction in Figure 6(g). In this case, the two long sides of the paper P are lifted and positioned at the top. Also, the two short sides of the paper P are concave and lifted. Note that the center of the paper P along the long sides is on the transport path.

[0043] 7(a) to 7(c) are diagrams showing blurring that occurs when a printed sheet P is read. This shows the case where the lifting occurs as shown in Figures 6(c) to (d). In this case, the center of the paper P shown in Figure 7(a) is located on or near the conveying path, and no blurring occurs, as shown in Figure 7(b). On the other hand, as shown in Figure 7(c), the short side of the paper P lifts and blurring occurs.

[0044] In this case, it can also be said that the paper P is warped along the short or long side. When this type of lifting (warping) occurs, blurring occurs when reading a portion located above or below the transport path. Which of the above four modes occurs is determined by the type of paper P. The type of paper P is not particularly limited, and can be classified, for example, by the manufacturer of the paper P, the model number of the paper P, the size of the paper P, the basis weight of the paper P, etc.

[0045] Therefore, in this embodiment, the resolution characteristics correction unit 32 corrects the blur caused by the floating of the paper P that occurs when reading an image in the read data in accordance with these four aspects. The correction of the blur is sharpness. In other words, a correction is performed to emphasize the contours of characters, etc. Which of the four modes will occur depends on the type of paper P. Therefore, it is measured in advance which of the four types of lifting will occur for each type of paper P. As a result, it is already known which mode of lifting will occur for each type of paper P used for printing, and blurring is corrected accordingly. In other words, blurring correction is set in advance for each type of paper P. The correction is set for each type of paper P, assuming that the paper P will lift in either the transport direction (sub-scanning direction) or the direction intersecting the transport direction (main scanning direction).

[0046] 8(a) to 8(c) are diagrams showing a test paper T for detecting which of the four modes in which lifting occurs. In this embodiment, the correction is set for each type of paper P by reading the test patterns Tp printed at the center and both ends of the test paper T. 8(a) shows a case where test patterns Tp are arranged in a total of five locations: one location in the center of the test paper T, two locations on the two short sides, and two locations on the two long sides. That is, the test patterns Tp are printed in the center, both ends of the long sides, and both ends of the short sides of the test paper T. Of these, the test pattern Tp in the one location in the center of the test paper T is called test pattern Tp1, the two test patterns Tp located on the two short sides are called test patterns Tp2 and Tp3, and the two test patterns Tp located on the two long sides are called test patterns Tp4 and Tp5.

[0047] 8(b) and 8(c) are enlarged views of the test pattern Tp. Each of the test patterns Tp1 to Tp5 has the same configuration. Each of the test patterns Tp1 to Tp5 is composed of, for example, a ladder pattern that is striped in the transport direction and in a direction intersecting the transport direction.

[0048] Then, by reading the test paper T on which test patterns Tp1 to Tp5 are printed by the printing device 10 on the paper P shown in Figure 8(a) using the reading device 20, it is possible to detect which of the above four patterns the floating that occurs on the paper P will be. 6(a)-(b), test patterns Tp4 and Tp5 are located on or near the transport path, so no blurring occurs in them. In contrast, test patterns Tp1, Tp2, and Tp3 are located away from the transport path, so blurring occurs in them. 6(c)-(d), test patterns Tp1, Tp2, and Tp3 are positioned on or near the transport path, so no blurring occurs in them. In contrast, test patterns Tp4 and Tp5 are positioned away from the transport path, so blurring occurs in them.

[0049] 6(e) to 6(f), test patterns Tp2 and Tp3 are located on or near the transport path, so no blurring occurs in them. In contrast, test patterns Tp1, Tp4, and Tp5 are located away from the transport path, so blurring occurs in them. 6(g) to 6(h), test patterns Tp1, Tp4, and Tp5 are located on or near the transport path, so no blurring occurs in them. In contrast, test patterns Tp2 and Tp3 are located away from the transport path, so blurring occurs in them.

[0050] Therefore, depending on which test pattern Tp causes blurring, it is possible to detect which of the four modes in which floating occurs. The test paper T is not limited to the one shown in FIG.

[0051] 9(a) and 9(b) are diagrams showing other forms of the test paper T. FIG. Of these, Figure 9(a) shows a case where the test paper T is configured with three test patterns Tp, namely test patterns Tp1, Tp4, and Tp5, in comparison with the test paper T shown in Figure 8. This test paper T is acceptable if the floating of the paper P occurs in the modes shown in Figures 8(a)-(b) and (c)-(d), but does not occur in the modes shown in Figures 8(e)-(f) and (g)-(h). Furthermore, Figure 9(b) shows a case where the test paper T shown in Figure 8 is configured with three test patterns Tp: test patterns Tp1, Tp2, and Tp3. This test paper T may be used if the floating of the paper P occurs in the modes shown in Figures 8(e)-(f) and (g)-(h) but does not occur in the modes shown in Figures 8(a)-(b) and (c)-(d).

[0052] Next, a more specific method for correction by the resolution characteristic corrector 32 will be described. The strength of the correction performed by the resolution characteristic correction unit 32 is changed between the center and the edges of the paper P. More specifically, the strength of the correction is changed between the center and either the edge of the long side or the edge of the short side of the paper P, but is not changed at the other edge. 6(a)-(b), blurring occurs to the same extent at the center of the paper P and at the edges of the short sides, so the strength of correction is left unchanged. And, blurring does not occur at the edges of the long sides of the paper P, so no correction is performed. Furthermore, the strength of correction is calculated by interpolation between the center of the paper P and the edges of the long sides. 6(c) to 6(d), no correction is made at the center of the paper P and the edges of the short sides because no blurring occurs there. In other words, they are assumed to be the same. On the other hand, correction is made at the edges of the long sides of the paper P because blurring occurs there. Furthermore, the strength of correction is found by interpolation between the center of the paper P and the edges of the long sides. 6(e) to 6(f), blurring occurs to the same extent at the center of the paper P and at the end of the long side, so the correction strength is left unchanged. And, blurring does not occur at the end of the short side of the paper P, so no correction is performed. Furthermore, the correction strength is calculated by interpolation between the center of the paper P and the end of the short side. Furthermore, in the cases of Figures 6(g) to (h), no correction is made at the center of the paper P and the edge of the long side because no blurring occurs there. In other words, they are considered to be the same. On the other hand, correction is made at the edge of the short side of the paper P because blurring occurs there. Furthermore, the strength of correction is found by interpolation between the center of the paper P and the edge of the short side.

[0053] Furthermore, the strength of the correction is determined in accordance with the spatial frequency of the image formed on the paper P. 10(a) and 10(b) are diagrams showing the relationship between the spatial frequency of an image formed on paper P and the strength of correction. Here, the horizontal axis represents the spatial frequency of the image, and the vertical axis represents the strength of correction. Of these, FIG. 10(a) shows a case where no blurring occurs in the center of the paper P, but blurring occurs at the end of the long side or the end of the short side of the paper P. As shown in the figure, the relationship between spatial frequency and correction strength is an upwardly convex function with a peak Pk. The correction strength increases in the range of low spatial frequencies and decreases in the range of high spatial frequencies, with the peak Pk as the boundary. In other words, the correction strength includes a range in which it decreases as the spatial frequency increases. In the range of low spatial frequencies, it is less susceptible to blurring. In the range of high spatial frequencies, it is difficult to visually recognize blurring, and even if blurring occurs, it is difficult to visually recognize it. Therefore, the correction strength is increased in the range of spatial frequencies where it is easy to visually recognize and is easily affected by blurring, and the correction strength is decreased as it deviates from this range. In addition, the correction strength is increased at the edges where blurring occurs, as indicated by the straight lines, and decreased at the center where no blurring occurs, as indicated by the dotted lines. In other words, the correction strength is set according to the degree of blurring.

[0054] FIG. 10(b) shows a case where blurring occurs in the center of the paper P, but no blurring occurs at the end of the long side or the end of the short side of the paper P. In Figure 10(b), as in Figure 10(a), the relationship between spatial frequency and correction strength is a function that has a peak Pk and is convex upward. On the other hand, at the edges where no blur occurs, the correction strength is reduced as shown by the straight line, and at the center where blur occurs, the correction strength is increased as shown by the dotted line. In other words, the correction strength is set according to the degree of blur.

[0055] FIG. 11 is a flowchart showing the correction process performed by the resolution characteristic correction unit 32. First, the resolution characteristic correction unit 32 acquires the type of paper (step 101), which can be acquired from the printing conditions and the like. Next, the resolution characteristics correction unit 32 determines the strength of correction for the center and edges of the paper P based on the type of paper (step 102). That is, the resolution characteristics correction unit 32 determines the strength of correction based on the relationship between the type of paper P and the corresponding strength of correction, which has been measured in advance. Then, the resolution characteristic correction unit 32 acquires the inspection image data from the data acquisition unit 31 (step 103). Furthermore, the resolution characteristic corrector 32 corrects blurring of the inspection image data (step 104). Then, the corrected inspection image data is output to the edge extraction unit 33 (step 105).

[0056] According to the embodiment described above, even if a lift occurs in the paper on which an image is printed, the image is less susceptible to the influence of the lift. In other words, if a lift occurs in the paper, blurring occurs in the scanned image. In this embodiment, this blurring is corrected to reduce the degree of blurring. As a result, inspection accuracy is improved. Furthermore, in this embodiment, the locations where blurring will occur are determined in advance depending on the type of paper. The degree of blurring can also be determined. Then, when printing, the blurring is corrected based on the locations and intensity of blurring that have been determined in advance depending on the type of paper. This eliminates the need to inspect and set the locations and intensity of correction each time printing is performed, improving work efficiency.

[0057] <Program Description> The processing performed by the image inspection device 30 in this embodiment described above is realized by the cooperation of software and hardware resources. That is, the CPU in the control computer provided in the information processing device 40 executes a program that realizes each function of the image inspection device 30, thereby realizing each function.

[0058] Therefore, in this embodiment, the processing performed by image inspection device 30 can also be considered as a program that enables a computer to realize the following functions: acquire print data, which is the data that forms the basis of the image to be printed; acquire read data, which is the data obtained by reading the image printed on paper; correct the read data for blurring caused by paper lift that occurs when the image is read; and compare the print data with the corrected read data and inspect the image.

[0059] The program for realizing this embodiment can be provided not only by communication means but also by being stored on a recording medium such as a CD-ROM.

[0060] Although the present embodiment has been described above, the technical scope of the present invention is not limited to the scope of the above embodiment. It is clear from the claims that various modifications and improvements to the above embodiment are also included in the technical scope of the present invention. [Explanation of symbols]

[0061] 1... image inspection system, 10... printing device, 20... reading device, 30... image inspection device, 32... resolution characteristic correction unit, 40... information processing device

Claims

1. a processor; The processor: Acquire print data, which is the data that is the source of the image to be printed, acquiring read data obtained by reading the image printed on paper; correcting blurring caused by paper lifting that occurs when reading the image from the read data; comparing the print data with the corrected read data to inspect the image; The image inspection device is configured in advance to perform the correction for each type of paper, assuming that the paper floats in either the conveying direction or a direction intersecting the conveying direction.

2. A processor is provided, The processor: Acquire print data, which is the data that is the source of the image to be printed, acquiring read data obtained by reading the image printed on paper; correcting blurring caused by paper lifting that occurs when reading the image from the read data; comparing the print data with the corrected read data to inspect the image; The image inspection device performs the correction in advance for each type of paper by reading test patterns printed in the center and both ends of the paper.

3. 3. The image inspection device according to claim 2, wherein the test pattern is printed in the center, at both ends of the long sides, and at both ends of the short sides of the paper.

4. A processor is provided, The processor: Acquire print data, which is the data that is the source of the image to be printed, acquiring read data obtained by reading the image printed on paper; correcting blurring caused by paper lifting that occurs when reading the image from the read data; comparing the print data with the corrected read data to inspect the image; The image inspection device changes the strength of the correction between the center and the edges of the paper.

5. 5. The image inspection device according to claim 4, wherein the strength of the correction is changed between the center of the paper and one of the long side and short side edges, but is not changed at the other edge.

6. 5. The image inspection device according to claim 4, wherein the strength of the correction is further determined in accordance with the spatial frequency of the image.

7. 7. The image inspection device according to claim 6, wherein the strength of the correction includes a range in which the strength of the correction decreases as the spatial frequency increases.

8. 8. The image inspection device according to claim 7, wherein the relationship between the spatial frequency and the correction intensity is an upwardly convex function.

9. a printing device for printing an image on paper; a reading device that reads the image printed on paper by the printing device; an inspection device that inspects the image read by the reading device; Equipped with the inspection device includes a processor; The processor: Acquire print data that is the data that is the source of the image; acquiring read data obtained by reading the image printed on paper; correcting blurring caused by paper lifting that occurs when reading the image from the read data; comparing the print data with the corrected read data to inspect the image; The image inspection system is configured in advance to perform the correction for each type of paper, assuming that the paper floats in either the conveying direction or a direction intersecting the conveying direction.

10. A printing device for printing an image on paper; a reading device that reads the image printed on paper by the printing device; an inspection device that inspects the image read by the reading device; Equipped with the inspection device includes a processor; The processor: Acquire print data that is the data that is the source of the image; acquiring read data obtained by reading the image printed on paper; correcting blurring caused by paper lifting that occurs when reading the image from the read data; comparing the print data with the corrected read data to inspect the image; The image inspection system performs the correction in advance for each type of paper by reading test patterns printed in the center and both edges of the paper.

11. A printing device for printing an image on paper; a reading device that reads the image printed on paper by the printing device; an inspection device that inspects the image read by the reading device; Equipped with the inspection device includes a processor; The processor: Acquire print data that is the data that is the source of the image; acquiring read data obtained by reading the image printed on paper; correcting blurring caused by paper lifting that occurs when reading the image from the read data; comparing the print data with the corrected read data to inspect the image; The image inspection device changes the strength of the correction between the center and the edges of the paper.

12. On the computer, A function to acquire print data, which is the data that will be used to create the image to be printed; a function of acquiring read data obtained by reading the image printed on paper; a function of correcting blurring caused by paper lifting that occurs when reading the image from the read data; a function of comparing the print data with the corrected read data and inspecting the image; Realize this, The correction is a program for setting in advance, for each type of paper, the paper floating in either the conveying direction or a direction intersecting the conveying direction.

13. A computer comprising: A function to acquire print data, which is the data that will be used to create the image to be printed; a function of acquiring read data obtained by reading the image printed on paper; a function of correcting blurring caused by paper lifting that occurs when reading the image from the read data; a function of comparing the print data with the corrected read data and inspecting the image; To achieve this, The correction is a program for setting the correction in advance for each type of paper by reading test patterns printed in the center and both edges of the paper.

14. A computer comprising: A function to acquire print data, which is the data that will be used to create the image to be printed; a function of acquiring read data obtained by reading the image printed on paper; a function of correcting blurring caused by paper lifting that occurs when reading the image from the read data; a function of comparing the print data with the corrected read data and inspecting the image; Realize this, A program for changing the strength of the correction between the center and the edges of the paper.

Images