Image processing device, image processing method and program

Abstract

To provide processing for highly accurately inspecting an output of a printer even when no clear change occurs in the printer.SOLUTION: An image processing device comprises: reception means configured to receive designation of information on a circular defect and a linear defect from a user; first acquisition means configured to acquire first data of a reference image; second acquisition means configured to acquire second data of a print image obtained by reading a printed material; setting means configured to set a comparison area including a pixel of interest corresponding to the same pixel position in each reference image and print image based on the first data; first calculation means configured to calculate a density difference between a comparison region of the reference image and a comparison region of the print image based on the first data and the second data; second calculation means for subtracting the density difference from a difference between a pixel value of the pixel of interest of the reference image and a pixel value of the pixel of interest of the print image; and processing means configured to inspect the print image based on the information on the circular defect and the linear defect and results of the subtraction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image processing technique for inspecting printed matter for defects. [Background technology]

[0002] Traditionally, in the printing industry, inspection (quality control) is performed after printing to ensure that printed products delivered to clients are free of defects and of acceptable quality. While manual inspection is sometimes performed, this is costly, and so in recent years, automated inspection techniques have been developed. For example, this method involves creating image data of a non-defective printed product (hereinafter referred to as reference image data) in advance. Next, image data of the print to be inspected (hereinafter referred to as print image data) is acquired by scanning, imaging, or other means. These two sets of image data are then compared for inspection. If there is a significant difference between the reference image data, which represents a non-defective product, and the print image data to be inspected that exceeds a predetermined tolerance, it is determined to be a defect.

[0003] The density and color of the output product for the same input data may differ depending on the state of the printing device at the time of output. Patent Document 1 is an inspection technology that takes this case into consideration. Patent Document 1 discloses a technology that regenerates an image to be used for defect inspection of a scanned image when a change in calibration or the like occurs in the printing device, and compares the scanned image with the regenerated image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-178970 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the image used for defect inspection is regenerated only when a clear change occurs in the printing device, such as calibration, etc. As a result, it is not possible to deal with density fluctuations that do not accompany a clear change in the printing device, such as fluctuations in the amount of toner adhesion or fluctuations in the light intensity of the light source used to read the image, and there are cases where it is not possible to inspect the output of the printing device with high accuracy.

[0006] SUMMARY OF THE INVENTION It is an object of the present invention to provide a process for inspecting the output of a printing device with high accuracy even when no obvious changes occur in the printing device. [Means for solving the problem]

[0007] In order to solve the above problems, the image processing device of the present invention includes a receiving means for receiving designation of information regarding circular defects and linear defects from a user, a first obtaining means for obtaining first data of a reference image, a second obtaining means for obtaining second data of a printed image obtained by reading a printed material, a setting means for setting a comparison area including a pixel of interest corresponding to the same pixel position in the reference image and the printed image based on the first data, a first calculating means for calculating a density difference between the comparison area of ​​the reference image and the comparison area of ​​the printed image based on the first data and the second data, and a second calculating means for subtracting the density difference from a difference between a pixel value of the pixel of interest in the reference image and a pixel value of the pixel of interest in the printed image. before The result of subtraction to and processing means for inspecting the printed image based on the inspection result. [Effects of the Invention]

[0008] According to the present invention, even when no obvious change occurs in the printing device, the output of the printing device can be inspected with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] Schematic diagram showing the relationship between a pixel of interest and a comparison region [Figure 2]FIG. 1 is a diagram showing the overall configuration of a printing system including an image processing apparatus. [Figure 3] Schematic diagram showing an example of a UI screen [Figure 4] Block diagram showing the functional configuration of an image processing device [Figure 5] Schematic diagram showing examples of defects to be detected [Figure 6] 1 is a flowchart showing a process executed by an image processing apparatus; [Figure 7] Schematic diagram for explaining processing on a reference image [Figure 8] Schematic diagram showing density fluctuations of a reference image and a printed image [Figure 9] FIG. 10 is a schematic diagram illustrating a process for determining the size of a comparison region; [Figure 10] FIG. 10 is a schematic diagram illustrating a process for correcting the size of a comparison region; [Figure 11] FIG. 10 is a schematic diagram illustrating a process for correcting the size of a comparison region; [Figure 12] Schematic diagram showing an example of an inspection area [Figure 13] FIG. 10 is a schematic diagram illustrating a process for correcting the shape of a comparison region; [Figure 14] FIG. 10 is a schematic diagram illustrating a process for correcting the position of a comparison region; DETAILED DESCRIPTION OF THE INVENTION

[0010] The present embodiment will be described below with reference to the drawings. Note that the following embodiment does not necessarily limit the present invention. Furthermore, not all of the combinations of features described in the present embodiment are necessarily essential to the solution of the present invention.

[0011] [First embodiment] In this embodiment, an inspection is performed taking into account the average pixel values ​​of the reference image and the printed image in the surrounding areas (hereinafter referred to as comparison areas) of the pixel of interest in Fig. 1. Note that the inspection in this embodiment is performed based on the absolute value of the difference between the image representing the target print result (reference image) and the image to be inspected (printed image).

[0012] <Printing system configuration> FIG. 2 is a diagram showing an example of the overall configuration of a printing system that outputs and inspects printed materials, including an image processing device 200. The printing system in this embodiment includes the image processing device 200, a printing server 280, and a printing device 290. The printing server 280 generates a print job for a document to be printed and submits the print job to the printing device 290. The printing device 290 forms an image on a recording medium (printing paper) based on the print job submitted from the printing server 280. The printing device 290 has a paper feed unit 291, and the user loads printing paper in the paper feed unit 291 in advance. When a print job is submitted, the printing device 290 transports the printing paper loaded in the paper feed unit 291 along a transport path 292, forms an image on one or both sides of the paper, and sends it to the image processing device 200.

[0013] The image processing device 200 inspects a printed object to be inspected for defects after printing. The printed object to be inspected, which is obtained by forming an image on printing paper by the printing device 290, is transported along a transport path 292 and inspected by the image processing device 200. The image processing device 200 functions as an inspection processing device. The image processing device 200 has a CPU 201, a RAM 202, and a ROM 203. The image processing device 200 also has a storage device 204, an image reading device 205, a printing interface (I / F) 206, a general-purpose interface (I / F) 207, a user interface (UI) panel 208, and a main bus 209. The image processing device 200 also has a transport path 210 for printed objects connected to the transport path 292 of the printing device 290, an output tray 211 for printed products that have passed inspection, and an output tray 212 for printed products that have been found to have defects and have failed inspection. In the printing system, the storage device 204 , the image reading device 205 , the UI panel 208 , the conveying path 210 , the output tray 211 , and the output tray 212 may be provided outside the image processing device 200 .

[0014] The CPU 201 is a processor that comprehensively controls each unit of the image processing device 200. The RAM 202 functions as the main memory, work area, etc. of the CPU 201. The ROM 203 stores a group of programs executed by the CPU 201. The storage device 204 stores applications executed by the CPU 201, data used for image processing, etc. The image reading device 205 is a scanner that reads one or both sides of a printed material sent from the printing device 290 on the conveying path 210 and acquires the data as image data.

[0015] The print I / F 206 is connected to the printing device 290 and serves as an interface for synchronizing the timing of print processing between the image processing device 200 and the printing device 290 and for communicating each other's operating status. The general-purpose I / F 207 is a serial bus interface such as USB or IEEE 1394, allowing the user to carry data such as logs. The UI panel 208 is a display device such as an LCD display, and functions as a user interface for informing the user of the current status and settings of the image processing device 200, as shown in FIG. 3(a). The UI panel 208 may also include an input device such as a touch panel or buttons, and can accept instructions from the user regarding inspections, etc., as shown in FIG. 3(b). The input device, such as a mouse or keyboard, may be provided separately from the UI panel 208. The main bus 209 is a transmission path connecting each module of the image processing device 200.

[0016] The image processing device 200 carries the printed matter sent from the printing device 290 along a transport path 210, while carrying out an inspection process, which will be described below, based on the image data of the printed matter read by the image reading device 205. If the printed matter passes the inspection, it is transported to a pass output tray 211, and if it fails the inspection, it is transported to a fail output tray 212. This allows only printed matters that have been confirmed to meet the quality standards to be collected in the output tray 211 as printed matters for delivery.

[0017] <Functional configuration of image processing device> 4 shows the functional configuration of the image processing device 200. The image processing device 200 has a reference image data acquisition unit 401, a print image data acquisition unit 402, an image data storage unit 403, an inspection information acquisition unit 404, a comparison area setting unit 405, a fluctuation degree calculation unit 406, and an inspection processing unit 407.

[0018] The reference image data acquisition unit 401 acquires reference image data representing a reference image that serves as a reference for inspection. The reference image data is assumed to be created in advance based on a scanned image obtained by reading a printed material output by the printing device 290. The print image data acquisition unit 402 acquires print image data representing a printed image to be inspected, obtained by the image reading device 205 reading a printed material on the conveying path 210. The image data acquired by the reference image data acquisition unit 401 and the print image data acquisition unit 402 is stored in the image data storage unit 403. The inspection information acquisition unit 404 acquires preset inspection information. The comparison area setting unit 405 sets a comparison area for comparing the reference image and the printed image. The variation degree calculation unit 406 acquires predetermined indices from each of the comparison area of ​​the reference image and the comparison area of ​​the printed image, and calculates the degree of density variation (density difference) by comparing the two indices. Specifically, the fluctuation degree calculation unit 406 calculates the difference between the average pixel value in a comparison area centered on the pixel of interest in the reference image and the average pixel value in a comparison area centered on the pixel of interest in the print image.

[0019] The inspection processing unit 407 inspects the print image represented by the print image data based on the reference image data, the print image data, and the degree of density variation. Details of the inspection processing by the inspection processing unit 407 will be described below. Uniform density variations can occur in the print image due to variations in the amount of toner adhesion or variations in the amount of light from the light source of the image reading device 205. As shown in FIG. 8 , when uniform density variations occur in a certain area of ​​the print image, a defect in the print image is detected due to the uniform density variation when comparing the difference in the pixel value of a target pixel between the print image and the reference image with a threshold value. However, this uniform density variation may be small and have little visual impact, making it undesirable to detect it as a defect. Therefore, in this embodiment, the difference D(x, y) between the print image and the reference image used for inspection is calculated as shown in Equation (1).

[0020]

number

[0021] Here, P(x,y) represents the pixel value of the pixel of interest in the printed image, and R(x,y) represents the pixel value of the pixel of interest in the reference image. mp represents the average pixel value in the comparison region centered on the pixel of interest in the printed image, and mr represents the average pixel value in the comparison region centered on the pixel of interest in the reference image. In equation (1), the difference D(x,y) is calculated by subtracting the difference in the average pixel values ​​in the comparison region (mp-mr) from the difference in the pixel value of the pixel of interest. In other words, the difference in the average pixel values ​​in the comparison region between the printed image and the reference image is used as the degree of average density fluctuation around the pixel of interest, and the difference D(x,y) is calculated so that this average density fluctuation does not affect the inspection. Furthermore, as can be seen from the transformation of equation (1), this can be interpreted as a process of correcting the printed image or reference image by the degree of fluctuation and then calculating the difference in the pixel value of the pixel of interest. It can also be interpreted as a process of subtracting the average pixel value in each comparison region of the printed image and the reference image from the pixel value of the pixel of interest and then calculating the difference in the pixel value of the pixel of interest. In either process, a highly accurate inspection can be performed by calculating the difference between the printed image and the reference image so that the inspection is not affected by density fluctuations.

[0022] <Defects to be detected> FIG. 5 shows examples of defects to be detected. The defect shown in FIG. 5(a) is a circular defect (hereinafter referred to as a circular defect). The defect shown in FIG. 5(b) is a line defect (hereinafter referred to as a line defect). In this embodiment, the diameter 501 of the circular defect and the line width 502 of the line defect are defined as defect sizes and used as inspection setting items. Note that, apart from the defect size, the difference in pixel values ​​between the defect and the background may be defined as defect contrast and used as an inspection setting item.

[0023] <Processing performed by the image processing device> 6 is a flowchart showing the processing executed by the image processing device 200. Hereinafter, each step (process) is represented by adding an S before the reference numeral. In S601, the inspection information acquisition unit 404 acquires preset inspection information. Specifically, the inspection information acquisition unit 404 acquires, as the inspection information, inspection settings preset by the user via the UI panel 208. In this embodiment, the size of the defect to be detected is set.

[0024] In S602, the comparison area setting unit 405 determines the size of the comparison area based on the size of the defect to be detected, acquired as inspection information. Details of the process for determining the size of the comparison area will be described using FIG. 9 . FIG. 9 shows an example of a printed image containing a defect and a reference image. For simplicity, it is assumed that there is no variation in pixel values ​​in the image, and only the pixels in the area corresponding to the defect have different pixel values. Consider a case where the comparison area falls within the defective area, as shown in FIG. 9(a). When calculating the average pixel value of this comparison area, the average pixel value matches the pixel value of interest in both the printed image and the reference image. As a result, the difference D(x, y) becomes 0, and it is determined that there is no defect. Therefore, as shown in FIG. 9(b), the size of the comparison area must be set larger than the defective area. In this case, a difference occurs between the pixel value of interest and the average pixel value, making it possible to detect the defect shown in FIG. 9 . In this embodiment, the comparison area setting unit 405 determines the size of the comparison area so that it is sufficiently larger than the size of the defect to be detected.

[0025] In S603, the reference image data acquisition unit 401 acquires reference image data representing the reference image. The reference image data is assumed to be stored in advance in the storage device 204. The acquired reference image data is held by the image data holding unit 403. In this embodiment, the reference image is assumed to be an image in which the pixel values ​​(R, G, B) of each pixel are expressed in 8 bits. In S604, the reference image data acquisition unit 401 performs edge extraction processing on the reference image represented by the reference image data acquired in S603, and performs binarization processing on the reference image after edge extraction processing. The reference image data acquisition unit 401 further performs expansion processing on the binarized reference image. The expansion processing is performed in units of areas of the same size as the comparison area determined in S602. Figure 7 shows the processing in S604. If the reference image represented by the reference image data acquired in S603 is the image shown in Figure 7(a), the edge extraction processing and binarization processing will result in the binary image shown in Figure 7(b). By performing expansion processing on the binary image of FIG. 7(b), the image shown in FIG. 7(c) can be obtained.

[0026] After completing the process of S604, the image processing device 200 starts operation of the printing device 290. While the printing device 290 operates and sequentially sends printed materials to the image processing device 200, the image processing device 200 repeats the processes of S605 to S613 for the printed materials that are sent in until the printing device 290 has completed printing the predetermined number of sheets.

[0027] In S606, the print image data acquisition unit 402 acquires print image data obtained by the image reading device 205 reading the printout output by the printing device 290. The acquired print image data is stored in the image data storage unit 403. The print image represented by the print data in this embodiment is an image in which the pixel values ​​(R, G, B) of each pixel are expressed in 8 bits, similar to the reference image.

[0028] The processing of S607 to S611 is repeated while updating the pixel of interest (x, y) until the difference D(x, y) between the print image and the reference image described above is calculated for all pixel positions.

[0029] In S608, the comparison area setting unit 405 corrects the size of the comparison area determined in S602 based on the reference image expanded in S604. The process of correcting the size of the comparison area will be described in detail below. Local misalignment may occur in a printed image due to slight changes in the transport speed during printing or image reading. Figure 10 shows an example of an area near the boundary between the printed and non-printed areas in the printed image and the reference image. Note that there is no density variation in the image shown in Figure 10. As shown in Figure 10(a), if the comparison area includes a printed area, the proportion of the printed area included in the comparison area differs between the printed image and the reference image due to local misalignment. This results in a difference in the average pixel value in the comparison area between the printed image and the reference image, even though there is no difference in the actual average density. This difference in average pixel value affects the difference D(x, y) described above, which may prevent appropriate inspection. Specifically, even though there is no difference in the pixel value of the pixel of interest, the absolute value of the difference D(x, y) due to the difference (mp-mr) of the average pixel values ​​in the comparison area exceeds the threshold, and it is determined that there is a defect. In response to this, in S608, the comparison area setting unit 405 corrects the size of the comparison area so that the comparison area does not include the print area.

[0030] By the processing of S604, discontinuous changes in pixel values ​​are extracted as edges at the boundary between the printed and non-printed areas. Therefore, the comparison area setting unit 405 refers to the reference image after the expansion processing and determines whether the comparison area includes a printed area (edge). If the comparison area setting unit 405 determines that the comparison area includes an edge, it reduces the size of the comparison area, as shown in FIG. 10(b). This prevents the comparison area from including a printed area. The correction processing of the comparison area in S608 not only prevents a decrease in inspection accuracy due to the difference between printed and non-printed areas, but also prevents a decrease in inspection accuracy due to discontinuous color changes in the comparison area.

[0031] In S609, the variation degree calculation unit 406 calculates the average pixel value in a comparison area centered on the pixel of interest (x, y) for each of the printed image and the reference image. The comparison area in S609 is an area centered on the pixel of interest (x, y) and having the size corrected in S608. In S610, the inspection processing unit 407 calculates the difference D(x, y) between the printed image and the reference image based on the pixel value of the pixel of interest in the printed image, the pixel value of the pixel of interest in the reference image, and the average pixel value in the comparison area. The inspection processing unit 407 calculates the difference D(x, y) according to equation (1) as described above.

[0032] After the processes of S607 to S611 have been performed for pixels at all pixel positions, the process proceeds to S612. In S612, the inspection processing unit 407 determines whether or not there is a defect in the printed image based on the difference D(x, y) calculated by the processes of S607 to S611. The inspection processing unit 407 determines whether or not there is a defect by comparing the absolute value of the difference D(x, y) with a predetermined threshold. The inspection processing unit 407 extracts pixels whose absolute value of the difference D(x, y) is equal to or greater than the threshold, and determines whether the area made up of the extracted pixel group is a circular defect area or a linear defect area. The determination of whether the area made up of the extracted pixel group is a circular defect area or a linear defect area is performed using known pattern matching.

[0033] As described above, while the printing device 290 sequentially sends printed materials to the image processing device 200, the image processing device 200 repeats the processes of S605 to S613 until a predetermined number of printed products are produced. This makes it possible to separate acceptable products, in which no defects were detected, from unacceptable products, in which defects were detected. By adopting the acceptable products as the final products, a predetermined number of products with a certain level of quality can be obtained.

[0034] <Effects of the first embodiment> As described above, the image processing device in this embodiment acquires information regarding settings for inspecting an image. Acquires data of a reference image that represents a target print result. Acquires data of the print image to be inspected. Based on the information regarding settings and the reference image data, sets a comparison area that includes a pixel of interest that corresponds to the same pixel position in the reference image and the print image. Based on the reference image data and the print image data, calculates the density difference between the comparison area of ​​the reference image and the comparison area of ​​the print image. Inspects the print image based on the reference image data, print image data, and density difference. This allows the comparison area for comparing the reference image and print image to be appropriately set, enabling highly accurate inspection of the output from the printing device.

[0035] <Modification> In this embodiment, the size of the defect to be detected is set as an inspection setting, but the contrast of the defect to be detected may also be set. It is preferable to calculate a more accurate difference when the contrast of the defect to be detected is small. Therefore, it is desirable to set a larger comparison region to reduce the influence of noise when calculating the average pixel value in the comparison region. Therefore, in S602, the comparison region setting unit 405 sets the size of the comparison region to be larger as the contrast of the defect to be detected acquired as the inspection information becomes smaller. FIG. 11(a) is a diagram showing the size of the comparison region when the defect contrast is large, and FIG. 11(b) is a diagram showing the size of the comparison region when the defect contrast is small.

[0036] The purpose of inspecting printed materials is to ensure that the quality of the printed material is satisfactory. However, overly strict inspection standards, prioritizing quality, can lead to an increase in rejected products and a decline in productivity. To address this issue, it is possible to vary the size and contrast of defects to be detected for each region of the printed image, thereby setting different inspection standards for each region. For example, consider the case of inspecting the printed image shown in FIG. 12(a). In this case, it is desirable to detect even small defects in the facial region of a person, but to lower the inspection standards for regions other than the facial region. To address this issue, the comparison region setting unit 405 may set the facial region and the non-facial region as separate inspection regions, as shown in FIG. 12(b), and set the size and contrast of defects to be detected for each inspection region. In this case, the comparison region setting unit 405 determines the size of the comparison region for each inspection region in S602, and then determines which inspection region the target pixel belongs to before S608, and obtains the size of the comparison region according to the inspection region to which it belongs. This process enables both the quality of the printed material and productivity to be achieved.

[0037] In this embodiment, the reference image data acquisition unit 401 acquires reference image data stored in advance in the storage device 204, but may generate the reference image data before the inspection process. For example, instead of acquiring the reference image data stored in the storage device 204 in S603, the printing device 290 may be operated to acquire any number of sheets of print image data, and the reference image data may be generated based on the acquired print image data.

[0038] In this embodiment, the average pixel value in the comparison region is calculated as the degree of variation in average density, but the median value of the pixel values ​​in the comparison region may be calculated instead of the average pixel value.

[0039] In this embodiment, the size of the comparison region is corrected using an edge image obtained by performing edge extraction processing on the reference image, but features other than edges may also be used. For example, the variance (variation) of pixel values ​​in the comparison region is calculated, and if the variance is equal to or greater than a predetermined threshold, processing is performed to reduce the size of the comparison region. This processing may be repeated until the variance of pixel values ​​in the comparison region becomes less than the predetermined threshold, thereby correcting the size of the comparison region.

[0040] In this embodiment, the size of the comparison region is reduced to prevent the comparison region from including a printed area, but the shape of the comparison region may be changed instead of changing the size. For example, as shown in Figures 13(a), 13(b), 13(c), and 13(d), the shape of the comparison region may be selected from multiple predetermined shapes based on an edge image corresponding to the reference image so as not to include an edge area. Alternatively, both the size and shape of the comparison region may be changed so as not to include an edge area.

[0041] In this embodiment, the size of the comparison region is reduced to prevent the comparison region from including the printed region, but the position of the comparison region may be shifted instead of changing the size. By moving the comparison region shown in Figure 14(a) to the comparison region shown in Figure 14(b) based on the position of the edge in the edge image, it is possible to prevent the comparison region from including the printed region.

[0042] In this embodiment, the difference D(x, y) is calculated by subtracting the degree of fluctuation in the average density in the comparison region from the difference in pixel value of the pixel of interest, but if the degree of fluctuation is greater than a predetermined threshold, the subtraction may be omitted. This allows the degree of fluctuation to be detected as a defect when it is visually significant.

[0043] In this embodiment, the difference in the average pixel value in the comparison region is subtracted from the difference in pixel value of the pixel of interest so that the degree of variation in average density in the comparison region does not affect the inspection, but instead of subtraction processing, the threshold value used in the inspection processing in S612 may be corrected. For example, the difference D(x, y) may be the difference in pixel value of the pixel of interest, and the inspection processing unit 407 in S612 may add the difference in average pixel value in the comparison region to a predetermined threshold value, thereby setting the threshold value to a value greater than the difference in average pixel values.

[0044] In this embodiment, the inspection processing unit 407 calculates the difference D(x, y) in S610. However, S610 may be divided into multiple steps. For example, as shown in Equation (2), the difference in pixel value of the target pixel may first be calculated, and then the difference in average pixel value in the comparison area may be subtracted from the difference in pixel value of the target pixel. Alternatively, as shown in Equation (3), the difference in average pixel value in the comparison area may first be subtracted from the pixel value of the target pixel of the printed image, and then the pixel value of the target pixel of the reference image may be subtracted from the result of the subtraction. Alternatively, as shown in Equation (4), the difference in average pixel value in the comparison area may first be subtracted from the pixel value of the target pixel of the reference image, and then the pixel value of the target pixel of the printed image may be subtracted from the result of the subtraction. Alternatively, as shown in Equation (5), the average pixel value in the comparison area may first be subtracted from the pixel value of the target pixel in each of the printed image and the reference image, and then the difference in pixel value of the target pixel may be calculated after the subtraction process.

[0045]

number

[0046]

number

[0047]

number

[0048]

number

[0049] The image reading device 205 in this embodiment is a scanner that reads an image, but may also be an imaging device that generates image data by capturing an image.

[0050] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. [Explanation of symbols]

[0051] 200 Image processing device 401 Reference image data acquisition unit 402 Print image data acquisition unit 404 Inspection Information Acquisition Unit 405 Comparison area setting section 406 Fluctuation degree calculation unit 407 Inspection Processing Unit

Claims

1. a receiving means for receiving designation of information regarding circular defects and linear defects from a user; a first acquisition means for acquiring first data of a reference image; a second acquisition means for acquiring second data of a print image obtained by reading the print; a setting means for setting a comparison region including a pixel of interest corresponding to the same pixel position in each of the reference image and the print image based on the first data; a first calculation means for calculating a density difference between the comparison area of ​​the reference image and the comparison area of ​​the printed image based on the first data and the second data; a second calculation means for subtracting the density difference from the difference between the pixel value of the pixel of interest in the reference image and the pixel value of the pixel of interest in the print image; processing means for inspecting the printed image based on the result of the subtraction; 1. An image processing device comprising:

2. 2. The image processing apparatus according to claim 1, wherein the receiving unit acquires the information about the circular defects and the linear defects based on a user's specification in a user interface for specifying information about the circular defects and the linear defects.

3. 2. The image processing apparatus according to claim 1, wherein the information about the circular defect and the linear defect is the size of the circular defect and the linear defect.

4. 2. The image processing apparatus according to claim 1, wherein the information about the circular defect and the linear defect is a contrast between the circular defect and the linear defect and a background.

5. 2. The image processing apparatus according to claim 1, wherein the setting means sets the comparison area based on characteristics of a peripheral area including the pixel of interest in the reference image.

6. 2. The image processing apparatus according to claim 1, wherein said setting means sets the size of said comparison region.

7. 2. The image processing apparatus according to claim 1, wherein the first calculation means calculates, as the density difference, a difference between an average pixel value in the comparison area of ​​the reference image and an average pixel value in the comparison area of ​​the printed image.

8. A program for causing a computer to function as each of the means of the image processing apparatus according to any one of claims 1 to 7.

9. Accepting designation of information regarding circular defects and linear defects from a user; obtaining first data of a reference image; acquiring second data of the print image obtained by reading the print; setting a comparison area including a pixel of interest corresponding to the same pixel position in each of the reference image and the print image based on the first data; calculating a density difference between the comparison area of ​​the reference image and the comparison area of ​​the printed image based on the first data and the second data; subtracting the density difference from the difference between the pixel value of the pixel of interest in the reference image and the pixel value of the pixel of interest in the print image; inspecting the printed image based on the result of the subtraction; An image processing method comprising:

Images