Inspection apparatus, image forming apparatus, storage medium, inspection method, and computer program product

Abstract

Provided is an inspection device, an image forming device, a storage medium, an inspection method, and a computer program product, which can suppress a decrease in inspection accuracy of defects, as compared with a case in which, when a correct image and an object image are collated per block, a block of the object image is moved so as to simply align with the correct image and collation is performed. An inspection device includes a processor that performs the following processing: acquires image information of a correct image and an object image of an inspection target, respectively; divides images of the correct image and the object image into blocks using the acquired image information and performs alignment per block; collates the correct image and the object image per block to detect defects, using a region including an amount of movement of the alignment as a block.

Description

Technical Field

[0001] This invention relates to an inspection apparatus, an image forming apparatus, a storage medium, an inspection method, and a computer program product. Background Technology

[0002] Patent Document 1 discloses an image inspection apparatus that performs inspection by comparing an image to be inspected (as a read image) with an original master image. The read image is obtained by reading an image output from an image forming apparatus on paper. Specifically, it includes an inspection comparison unit that divides the entire image into a plurality of blocks, performs a first alignment in a plurality of regions around the image periphery, calculates the positional offset of each block of the image to be inspected based on the result, and performs alignment while slightly offsetting the blocks of the image to be inspected and the blocks of the master image from each other, and then compares and verifies the results. Furthermore, the inspection comparison unit performs a second alignment by selecting predetermined blocks in the image and recalculating the positional offset of the selected blocks, and corrects the positional offset of each block of the image to be inspected based on the result.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-186562

[0004] When checking the correct image against the object image of the object to be inspected block by block, if the blocks of the object image are moved to align with the correct image and then checked, the inspection accuracy of defects may sometimes decrease due to the presence of images in the remaining blocks. Therefore, the object of the present invention is to provide an inspection apparatus, image forming apparatus, storage medium, and inspection method that can suppress the decrease in the inspection accuracy of defects compared to the case where, when checking the correct image against the object image block by block, the blocks of the object image are moved to simply align with the correct image and then checked. Summary of the Invention

[0005] To achieve the above objective, the inspection device according to the first method includes a processor that performs the following processing: acquiring image information of a correct image and an object image of the object to be inspected; using the acquired image information to divide the correct image and the object image into blocks and aligning them according to each block; taking the region containing the amount of movement for alignment as a block; and checking the correct image and the object image according to each block to detect defects.

[0006] Furthermore, according to the inspection apparatus of the first method, in the inspection apparatus of the second method, the processor performs overall image alignment before aligning each block.

[0007] Furthermore, in the inspection apparatus according to the first or second method, the processor performs the following processing in the inspection apparatus according to the third method: detecting defects by further extracting the edge information of the correct image and the object image respectively, and verifying the extracted edge information of the correct image and the object image respectively.

[0008] Furthermore, in the inspection apparatus according to the third method, in the inspection apparatus according to the fourth method, the processor performs the following processing: using the edge information to change the threshold for detecting defects, thereby detecting defects.

[0009] Furthermore, according to the inspection device involved in the fourth method, in the inspection device involved in the fifth method, the processor also uses the object information of the correct image to change the threshold.

[0010] Furthermore, in the inspection apparatus according to any of the third to fifth methods, in the inspection apparatus according to the sixth method, the processor performs the following processes in parallel: dividing the images of the correct image and the object image into blocks, aligning each block, and setting the area containing the alignment movement as a block and extracting the edge information.

[0011] Furthermore, in the inspection apparatus according to any one of the third to sixth methods, in the inspection apparatus according to the seventh method, the processor uses the object information of the correct image to change the extraction threshold when extracting the edge information, thereby extracting the edge information.

[0012] Furthermore, according to the inspection apparatus of the seventh method, in the inspection apparatus of the eighth method, the processor is changed to the extraction threshold of a value predetermined for each type of object.

[0013] Furthermore, the image forming apparatus according to the ninth method includes: an inspection device according to any one of the first to eighth methods; an image forming unit that forms an image on a recording medium using image information of the pre-generated correct image; and a reading unit that reads the image information of the recording medium on which the image has been formed by the image forming unit to generate the object image.

[0014] Furthermore, the storage medium involved in the 10th method stores an inspection program for causing a computer to perform the following processing: acquiring image information of a correct image and an object image of the object to be inspected, using the acquired image information to divide the images of the correct image and the object image into blocks and aligning them according to each block, taking the region containing the amount of movement for alignment as a block, and checking the correct image and the object image according to each block to detect defects.

[0015] Furthermore, the inspection method involved in the 11th method includes the following steps: acquiring image information of the correct image and the object image of the object to be inspected; using the acquired image information to segment the correct image and the object image into blocks and aligning them according to each block; and taking the region containing the alignment displacement as a block, and checking the correct image and the object image according to each block to detect defects.

[0016] Invention Effects

[0017] According to the first method, an inspection device can be provided that, compared with the case where, when checking the correct image and the object image block by block, the blocks of the object image are moved so that they are simply aligned with the correct image for verification, the decrease in the inspection accuracy of defects can be suppressed.

[0018] According to the second method, the amount of alignment per block can be reduced compared to the case where alignment is performed only for each block.

[0019] According to the third method, the processing load for detecting defects can be reduced compared to simply checking the correct image against the object image.

[0020] According to the fourth method, compared with the case where the detection thresholds for defects in the edge portion and other portions are the same, it is possible to reduce the false detection of defects in the edge portion.

[0021] According to method 5, the detection accuracy of defects can be improved compared to using only edge information to change the threshold.

[0022] According to the sixth method, compared with the process of sequentially dividing the correct image and the object image into blocks, aligning each block, and setting the area containing the alignment movement as a block and the process of extracting edge information, the processing time can be shortened.

[0023] According to method 7, edge information corresponding to the object in the correct image can be extracted.

[0024] According to method 8, the threshold for extracting edge information can be changed to be suitable for the type of object.

[0025] According to the ninth method, an image forming apparatus can be provided that, compared to the case where, when checking the correct image and the object image block by block, the blocks of the object image are moved so that they are simply aligned with the correct image for checking, the decrease in the accuracy of defect inspection can be suppressed.

[0026] According to the 10th method, a storage medium can be provided that, compared to the case where, when checking the correct image and the object image by each block, the blocks of the object image are moved so that they are simply aligned with the correct image for checking, the decrease in the accuracy of defect inspection can be suppressed.

[0027] According to the 11th method, an inspection method can be provided that, compared with the case where, when checking the correct image and the object image block by block, the blocks of the object image are moved to simply align with the correct image for verification, thus suppressing the decrease in the accuracy of defect inspection. Attached Figure Description

[0028] The embodiments of the present invention will be described in detail with reference to the following figures.

[0029] Figure 1 This is a diagram showing the schematic structure of the inspection device according to this embodiment;

[0030] Figure 2 This is a functional block diagram showing the functional structure of the inspection device according to the first embodiment;

[0031] Figure 3 This is a diagram illustrating an example of missing dust detection in existing techniques that simply perform block segmentation to verify the correct image and the object image;

[0032] Figure 4 This is a diagram illustrating an example in the inspection apparatus according to the first embodiment where residual areas are eliminated by setting a region of three pixels containing the amount of alignment movement as a block.

[0033] Figure 5 This is a diagram illustrating an example of a block that is reset to contain the amount of movement of the object image in both directions when it is offset in two directions;

[0034] Figure 6 This is a flowchart illustrating an example of the processing flow performed by the inspection apparatus according to the first embodiment;

[0035] Figure 7 This is a functional block diagram showing the functional structure of the inspection device according to the second embodiment;

[0036] Figure 8 This is an example of how, when a block of an object image is offset by -3 pixels relative to the correct image, a region of 3 pixels from the right end of the block will remain. If there are edge images such as the frame ends of the edge image in this remaining region, the frame ends of the image will disappear.

[0037] Figure 9 This is a flowchart illustrating an example of the processing flow performed by the display device according to the second embodiment;

[0038] Figure 10 This is a functional block diagram showing the functional structure of a modified example of the inspection device according to the second embodiment;

[0039] Figure 11 This is a block diagram illustrating an example of the structure of an image forming apparatus that includes the inspection device according to this embodiment, and is equipped with a printing device and a reading device.

[0040] Symbol Explanation

[0041] 10-Inspection device, 10A-CPU, 12-Correct image acquisition unit, 14-Object image acquisition unit, 16-Block segmentation unit, 18-Alignment unit, 20-Block setting unit, 21-Edge extraction unit, 22-Block verification unit. Detailed Implementation

[0042] Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a diagram showing the schematic structure of the inspection device involved in this embodiment.

[0043] The inspection apparatus 10 according to this embodiment performs a process of detecting image defects by comparing a correct image with an image of the object to be inspected. Furthermore, in the following description, the image of the object to be inspected will be referred to as the object image.

[0044] As an example of image defects in this embodiment, there are defects such as missing images of the object image relative to the correct image, image addition caused by dust, and image distortion. Furthermore, in this embodiment, as an example, an inspection device 10 will be described. This inspection device 10 checks the digital image information (e.g., information obtained by transforming / generating a PDL (page description language) file into a raster image) that will form the basis of image formation, treating it as the correct image, and checks the object image being inspected as image information obtained by forming an image based on the image information of the correct image and reading it from a recording medium such as paper. In addition, among defects in the object image, the defect of having an image that is not present in the correct image but is present in the object image is called addition, and the defect of having an image that is present in the correct image but not in the object image is called missing.

[0045] The inspection device 10 includes, as an example, a CPU (Central Processing Unit) 10A, a ROM (Read Only Memory) 10B, a RAM (Random Access Memory) 10C, a memory 10D, an operation unit 10E, a display unit 10F, and a communication line I / F (interface) unit 10G. The CPU 10A controls the overall operation of the inspection device 10. The ROM 10B pre-stores various control programs and parameters. The RAM 10C serves as a working area when the CPU 10A executes various programs. The memory 10D stores various data or application programs. The operation unit 10E is used to input various information. The display unit 10F is used to display various information. The communication line I / F unit 10G can be connected to external devices to transmit and receive various data. All the components of the inspection device 10 are electrically connected to each other via a system bus 10H. In addition, in the inspection device 10 according to this embodiment, the memory 10D is used as the storage unit, but it is not limited to this, and other non-volatile storage units such as hard disks or flash memory can also be used.

[0046] Based on the above structure, the inspection device 10 according to this embodiment performs access to the ROM 10B, RAM 10C and memory 10D via the CPU 10A, acquires various data via the operation unit 10E, and displays various information on the display unit 10F. Furthermore, the inspection device 10 performs control over the transmission and reception of various data via the communication line I / F unit 10G via the CPU 10A.

[0047] (First Embodiment)

[0048] Here, the functional structure implemented by the CPU 10A of the inspection device 10 according to the first embodiment executing the program stored in the ROM 10B will be described. Figure 2 This is a functional block diagram showing the functional structure of the inspection device 10 according to the first embodiment.

[0049] like Figure 2 As shown, the inspection device 10 has the functions of a correct image acquisition unit 12, an object image acquisition unit 14, a block segmentation unit 16, an alignment unit 18, a block setting unit 20, and a block verification unit 22.

[0050] The correct image acquisition unit 12 acquires a correct image that serves as a reference relative to the object image. In this embodiment, the correct image acquisition unit acquires image information from a pre-generated correct image.

[0051] The object image acquisition unit 14 acquires an object image that is the object to be inspected. Object image acquisition refers to obtaining image information of the object image by reading image information from a recording medium such as paper that forms the image based on image information of a pre-generated correct image. Furthermore, in the following description, image information representing a correct image will sometimes be simply referred to as "correct image," and image information representing an object image will sometimes be simply referred to as "object image."

[0052] The block segmentation unit 16 performs the process of segmenting the correct image and the object image into blocks of a predetermined size.

[0053] The alignment unit 18 aligns the correct image with the object image according to each block divided by the block segmentation unit 16.

[0054] The block setting unit 20 resets the area containing the alignment movement amount as a block based on the alignment result of the alignment unit 18.

[0055] The block core matching unit 22 performs a process to detect defects by matching the correct image and the object image according to each block core set by the block setting unit 20.

[0056] However, as with existing technologies, when simply segmenting the correct image and the object image into blocks for verification, the object image is shifted by an offset to be compared with the correct image. Therefore, if dust or other contaminants are present in the remaining blocks, dust detection may be missed. For example, regarding... Figure 3 The correct image and object image shown in the first paragraph are as follows: Figure 3 As shown in paragraphs 2 and 3, when a block of the object image is offset by -3 pixels relative to the correct image (along... Figure 3 When it is 3 pixels to the left, if from Figure 3 The left side is checked by aligning each block sequentially, then as follows: Figure 3 As shown in the third paragraph, a region of 3 pixels from the rightmost block will remain. If there is dust or other image content in this remaining region, then... Figure 3 As shown in paragraphs 4 and 5, defects will be missed.

[0057] Therefore, in this embodiment, the block setting unit 20 eliminates residual areas by setting a region of three pixels containing the alignment displacement as a block based on the alignment results of each block of the alignment unit 18. For example, as Figure 4 As shown in the second paragraph, when Figure 4 The correct image and object image shown in the first paragraph are similar to those described above. When the block of the object image is offset 3 pixels to the left relative to the correct image, as shown... Figure 4 As shown in paragraphs 3 and 4, the block setting unit 20 resets the blocks, which contain blocks equivalent to a movement of 3 pixels, to verify the correct image against the object image. Thus, as... Figure 4As shown in paragraph 5, the residual area is eliminated, and the correct image is compared with the object image in the block on the right with defects such as dust, thereby detecting the defects in the image.

[0058] Furthermore, alignment is not limited to one direction; it can also be performed in two directions on a plane. Therefore, as... Figure 5 As shown in the second paragraph, when Figure 5 The correct image and object image shown in paragraph 1, except for Figure 5 When the offset is not only in the left and right directions but also in the up and down directions, such as Figure 5 As shown in paragraphs 3 and 4, the block setting unit 20 resets the block to include the amount of movement of the object image in the vertical direction, thus, similarly to the above, as Figure 5 As shown in paragraph 5, the residual area is eliminated to prevent defects from being missed.

[0059] Next, the specific processing performed by the inspection device 10 according to this embodiment, configured as described above, will be explained. Figure 6 This is a flowchart illustrating an example of the processing flow performed by the inspection apparatus 10 according to this embodiment. Additionally, Figure 6 The process begins, for example, through the operation of the operation unit 10E, when the instruction to start the inspection is given.

[0060] In step S100, CPU 10A acquires the correct image and proceeds to step S102. That is, the correct image acquisition unit 12 acquires the image information of the pre-generated correct image.

[0061] In step S102, CPU 10A acquires the object image and proceeds to step S104. That is, the object image acquisition unit 14 acquires image information representing the object image obtained by reading image information from a recording medium such as paper, which forms the image based on a pre-generated correct image. Furthermore, the order of steps S100 and S102 can be reversed.

[0062] In step S104, CPU 10A performs block segmentation on the correct image and the object image and transfers the process to step S106. That is, the block segmentation unit 16 performs the process of segmenting the correct image and the object image into blocks of a predetermined size.

[0063] In step S106, CPU 10A performs block alignment of the correct image and the object image and proceeds to step S108. That is, the alignment unit 18 performs alignment of the correct image and the object image according to each block divided by the block segmentation unit 16.

[0064] In step S108, CPU 10A sets the region containing the movement amount of the block generated by the alignment as a block and proceeds to step S110. That is, the block setting unit 20 resets the region containing the movement amount of the alignment as a block according to the alignment result of the alignment unit 18.

[0065] In step S110, CPU10A focuses on a corresponding block of the correct image and the object image and proceeds to step S112.

[0066] In step S112, the CPU 10A checks the blocks of the correct image against the blocks of the object image and proceeds to step S114. That is, the block checking unit 22 performs a process of checking the correct image against the object image according to each block checking set by the block setting unit 20 to detect defects.

[0067] In step S114, CPU10A determines whether the verification of all blocks of the correct image and the object image has been completed. If the determination is negative, it returns to step S110 and repeats the above process for the next block. If the determination is positive, it proceeds to step S116.

[0068] In step S116, the CPU10A outputs the detection result of the defect and ends the series of processes of the inspection device 10.

[0069] (Second Implementation)

[0070] Next, the functional structure implemented by the CPU 10A of the inspection device 10 according to the second embodiment executing the program stored in the ROM 10B will be described. Figure 7 This is a functional block diagram illustrating the functional structure of the inspection device 10 according to the second embodiment. Furthermore, the general structure of the inspection device according to the second embodiment is similar to... Figure 1 The above implementation method is the same, therefore detailed description is omitted. Furthermore, for [the following]... Figure 2 The same structure is labeled with the same symbols, and detailed descriptions are omitted.

[0071] like Figure 7 As shown, compared to the first embodiment, the inspection device 10 according to this embodiment has the function of the edge extraction unit 21.

[0072] The edge extraction unit 21 generates edge information by extracting the edges of the correct image and the object image based on their respective image information. Furthermore, when extracting the edges of the correct image and the object image, the extraction threshold can be changed using object information. For example, the extraction threshold can be changed to a value predetermined for each type of object. Specifically, when the object information is text or graphics, the edge extraction threshold is set to a higher threshold than that for images, and when it is an image, it is set to a lower threshold than that for text or graphics. Thus, edge extraction corresponding to the characteristics of the object is performed.

[0073] In this embodiment, the block verification unit 22 performs a process to detect defects by verifying the image with extracted edges against the correct image and the object image.

[0074] Furthermore, edge extraction based on edge extraction unit 21 can be performed before each block is aligned by alignment unit 18, or before the blocks are reset by block setting unit 20.

[0075] Furthermore, when the edge-extracted image in the block verification unit 22 is compared with the correct image and the object image, edge information can be used to change the threshold for detecting defects. For example, the threshold can be changed according to the degree of the edge. Alternatively, different thresholds can be used to detect defects based on the presence or absence of edges. Moreover, the threshold for detecting defects can also be changed using object information. For example, a pre-determined threshold can be set for each type of object, such as text, graphics, and images. Specifically, compared to images, text and graphics are more prone to false detections of defects at their edges; therefore, the threshold can be increased compared to images to make defects less likely to be detected.

[0076] In edge extraction as described in this embodiment, as in the prior art, when the correct image and the object image are simply compared by block segmentation, the position offset of the object image is shifted to compare it with the correct image. Therefore, if the edges of the edge image's frame exist in the remaining blocks, the edges of the edge image's frame will disappear. For example, as... Figure 8 As shown, when a block of the object image is offset by -3 pixels relative to the correct image (along...) Figure 8 When it is 3 pixels to the left, if from Figure 8 The left side is aligned and checked block by block. A region of 3 pixels from the rightmost block will remain. If there are edge images such as the frame ends in this remaining region, the frame ends will disappear.

[0077] Therefore, similar to the first embodiment, the block setting unit 20 eliminates residual areas and prevents the image from disappearing by setting a region of 3 pixels containing the alignment displacement as a block according to the alignment results of each block of the alignment unit 18 and checking it.

[0078] Next, the specific processing performed by the inspection device 10 according to this embodiment, configured as described above, will be explained. Figure 9 This is a flowchart illustrating an example of the processing flow performed by the display device 10 according to this embodiment. Additionally, Figure 9 The processing begins, for example, through the operation of the operation unit 10E, when an instruction to begin inspection is given. Furthermore, for... Figure 6 The same processing is described using the same symbols.

[0079] In step S100, CPU 10A acquires the correct image and proceeds to step S102. That is, the correct image acquisition unit 12 acquires the image information of the pre-generated correct image.

[0080] In step S102, CPU 10A acquires the object image and proceeds to step S104. That is, the object image acquisition unit 14 acquires image information representing the object image obtained by reading image information from a recording medium such as paper, which forms the image based on a pre-generated correct image. Furthermore, the order of steps S100 and S102 can be reversed.

[0081] In step S104, CPU 10A performs block segmentation on the correct image and the object image and transfers the process to step S106. That is, the block segmentation unit 16 performs the process of segmenting the correct image and the object image into blocks of a predetermined size.

[0082] In step S106, CPU 10A performs block alignment of the correct image and the object image and proceeds to step S108. That is, the alignment unit 18 performs alignment of the correct image and the object image according to each block divided by the block segmentation unit 16.

[0083] In step S108, CPU 10A sets the region containing the movement amount of the block generated by the alignment as a block and proceeds to step S109. That is, the block setting unit 20 resets the region containing the movement amount of the alignment as a block according to the alignment result of the alignment unit 18.

[0084] In step S109, CPU10A performs edge extraction processing on both the correct image and the object image and then proceeds to step S110.

[0085] In step S110, CPU10A focuses on a corresponding block of the correct image and the object image and proceeds to step S112.

[0086] In step S112, the CPU 10A checks the blocks of the correct image against the blocks of the object image and proceeds to step S114. That is, the block checking unit 22 performs a process of checking the correct image against the object image according to each block set by the block setting unit 20 to detect defects. In this embodiment, image defects are detected by checking the blocks of the correct image with extracted edges against the blocks of the object image with extracted edges.

[0087] In step S114, CPU10A determines whether the verification of all blocks of the correct image and the object image has been completed. If the determination is negative, it returns to step S110 and repeats the above process for the next block. If the determination is positive, it proceeds to step S116.

[0088] In step S116, the CPU10A outputs the detection result of the defect and ends the series of processes of the inspection device 10.

[0089] Furthermore, in the second embodiment, when the CPU has a plurality of processor cores, such as Figure 10 As shown, the edge extraction processing based on the edge extraction unit 21 can be configured to be performed in parallel with the processing of the alignment unit 18 and the block setting unit 20. Furthermore, Figure 10 This is a functional block diagram showing the functional structure of a modified example of the inspection device 10 according to the second embodiment. Figure 10 In China, for the sake of Figure 2 The same structure is labeled with the same symbols.

[0090] like Figure 10 As shown, by performing edge extraction processing based on edge extraction unit 21 and processing based on alignment unit 18 and block setting unit 20 in parallel, the processing time can be shortened.

[0091] Furthermore, the inspection device 10 according to the above embodiments can be configured to be included in an image forming apparatus that has the functions of a printing device and a reading device. Alternatively, it can be configured to include the inspection device 10 in an image forming apparatus that has the functions of a printing device or a reading device.

[0092] Here, the structure of the image forming apparatus 50, which includes the inspection device 10, and which has the functions of a printing device and a reading device, will be described. Figure 11 This is a block diagram illustrating an example of the structure of an image forming apparatus 50 that includes the inspection device 10 according to this embodiment, and is equipped with a printing device and a reading device.

[0093] like Figure 11 As shown, the image forming apparatus 50 includes a display operation unit 52, a control unit 54, an image generation unit 56, a forming unit 58, and an ejection unit 60.

[0094] The display operation unit 52 includes a display unit such as a liquid crystal display and an operation unit for making various settings related to image formation. For example, various settings such as image formation conditions or the type of recording medium used to form the image are made by operating the display operation unit 52.

[0095] The control unit 54 encompasses all parts of the image forming apparatus 50 and controls each part of the image forming apparatus 50 according to the settings configured in the display operation unit 52. The control unit 54 may be, for example, a microcomputer equipped with a CPU, ROM, RAM, and input / output units. A program for controlling the operations of image forming is pre-stored in the ROM, and the operation of each part of the image forming apparatus 50 is controlled by expanding this program into RAM and executing it through the CPU.

[0096] The image generation unit 56 generates image information representing the original image by reading the original image. Alternatively, it generates image information of the original image to be formed by acquiring image information sent from an external computer. Then, the inspection device 10 acquires the image information generated by the image generation unit 56 as the correct image.

[0097] The forming unit 58 includes a paper feeding unit 62, a transport unit 64, an image processing unit 66, an image forming unit 68, a fixing unit 70, and an image reading unit 72 as a reading unit.

[0098] The paper supply unit 62 holds recording paper, which serves as the recording medium, and supplies the recording paper to the transport unit 64. For example, the paper supply unit 62 holds recording paper wound into a roll, pulls it out, and supplies it to the transport unit. Alternatively, the paper supply unit 62 has multiple receiving sections for holding paper of different sizes or types, pulls paper out from the main section, and supplies it to the transport unit. In this case, the paper set by the display operation unit 52, etc., is supplied from each receiving section to the transport unit 64. Furthermore, when image information is acquired from the outside, paper of the type specified externally is supplied from each receiving section to the transport unit 64.

[0099] The transport unit 64 transports the recording paper or sheet supplied from the paper supply unit 62 to the position where an image is formed on the recording paper or sheet, and then transports the recording paper or sheet with the image formed to the discharge unit 60.

[0100] The image processing unit 66 receives image information generated by the image generation unit 56 or received from the outside by the image generation unit 56, performs image processing for processing by the image forming unit 68, and outputs the processed image information to the image forming unit 68.

[0101] The image forming unit 68 receives image information from the image processing unit 66 and forms an image represented by the image information onto recording paper or paper. For example, the image forming unit 68 may transfer the image onto the recording paper or paper using an electrophotographic method, or it may form an image by spraying ink onto the recording paper or paper using an inkjet method or the like.

[0102] The fixing unit 70 performs a process for fixing an image onto the recording paper. As a fixing process, the image is fixed onto the recording paper or sheet paper by applying pressure and heating at least one of these processes.

[0103] The image reading unit 72 reads the recording paper or sheet on which the image is formed to acquire image information for various corrections (e.g., position offset correction, color correction, etc.). Furthermore, the inspection device 10 acquires the image information obtained by the image reading unit 72.

[0104] Furthermore, the discharge section 60 rolls up the recording paper with the image formed and stores it. Alternatively, it discharges the paper with the image formed.

[0105] Furthermore, in the above embodiment, an example of aligning the correct image with the object image for each block divided by the block segmentation unit 16 was described, but it is not limited to this. For example, the alignment of each block can be performed after aligning the correct image with the object image as a whole by performing an affine transformation or the like.

[0106] Furthermore, in the above embodiment, as an example, the case where the digital image information that will form the basis of the image is used as the correct image and the image of the object to be inspected is used as the image information obtained by forming an image based on the correct image and reading the image from a recording medium such as paper is described. The following inspection device is predetermined but can also be applied to the following inspection device, which performs AA (analog-analog) inspection by using the image information obtained by reading the correct image of a predetermined reference as the correct image instead of the correct digital image.

[0107] In the above embodiments, processor refers to processor in a broad sense, including general-purpose processors (e.g., CPU: Central Processing Unit, etc.) or dedicated processors (e.g., GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic devices, etc.).

[0108] Furthermore, the operations of the processors in the above embodiments can be performed by a single processor or by a plurality of processors located in physically separate positions working together. Also, the order of the processors' operations is not limited to the order described in the above embodiments and can be appropriately modified.

[0109] Furthermore, the processing performed by the inspection device 10 according to the above embodiments can be software-based, hardware-based, or a combination of both. Moreover, the processing performed by each part of the inspection device 10 can be stored as a program in a storage medium and circulated.

[0110] Furthermore, the present invention is not limited to the above description, and various modifications can be made without departing from its spirit.

[0111] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

Claims

1. An inspection device comprising a processor, the processor performing the following processing: Obtain image information for both the correct image and the object image being inspected. Using the acquired image information, the images of the correct image and the object image are each segmented into blocks, and each block is aligned in at least one of the left-right or up-down directions. The region containing the object image is defined as the amount of pixels offset relative to the correct image in at least one of the left-right and up-down directions, i.e., the amount of alignment shift, and defects are detected by checking the correct image against the object image on a block-by-block basis.

2. The inspection device according to claim 1, wherein, The processor performs overall image alignment before aligning each block.

3. The inspection device according to claim 1, wherein, The processor performs the following processing: it detects defects by extracting the edge information of the correct image and the object image respectively, and verifying the extracted edge information of the correct image and the object image respectively.

4. The inspection device according to claim 3, wherein, The processor performs the following processing: using the edge information to change the threshold used for defect detection, thereby detecting defects.

5. The inspection device according to claim 4, wherein, The processor also uses object information from the correct image to change the threshold.

6. The inspection device according to any one of claims 3 to 5, wherein, The processor performs the following processing in parallel: dividing the images of the correct image and the object image into blocks, aligning each block, and setting the region containing the alignment movement as the block processing; And the processing of extracting the edge information.

7. The inspection device according to any one of claims 3 to 5, wherein, The processor uses the object information of the correct image to change the extraction threshold when extracting the edge information, thereby extracting the edge information.

8. The inspection device according to claim 7, wherein, The processor is changed to the extraction threshold, which is a pre-determined value for each type of object.

9. An image forming apparatus comprising: The inspection device according to any one of claims 1 to 8; The image forming unit forms an image on a recording medium using image information from the pre-generated correct image; and The reading unit reads image information generated by the recording medium through which the image is formed by the image forming unit to generate the object image.

10. A storage medium storing a checking program for causing a computer to perform the following processes: Obtain image information for both the correct image and the object image being inspected. Using the acquired image information, the images of the correct image and the object image are each segmented into blocks, and each block is aligned in at least one of the left-right or up-down directions. The region containing the object image is defined as the amount of pixels offset relative to the correct image in at least one of the left-right and up-down directions, i.e., the amount of alignment shift, and defects are detected by checking the correct image against the object image on a block-by-block basis.

11. An inspection method comprising the following steps: Obtain image information for both the correct image and the object image of the object being inspected; Using the acquired image information, the images of the correct image and the object image are each segmented into blocks, and each block is aligned in at least one of the left-right and up-down directions; and The region containing the object image is defined as the amount of pixels offset relative to the correct image in at least one of the left-right and up-down directions, i.e., the amount of alignment shift, and defects are detected by checking the correct image against the object image on a block-by-block basis.

12. A computer program product comprising a checking program for causing a computer to perform the following processes: Obtain image information for both the correct image and the object image being inspected. Using the acquired image information, the images of the correct image and the object image are each segmented into blocks, and each block is aligned in at least one of the left-right or up-down directions. The region containing the object image is defined as the amount of pixels offset relative to the correct image in at least one of the left-right and up-down directions, i.e., the amount of alignment shift, and defects are detected by checking the correct image against the object image on a block-by-block basis.

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