Image inspection device, image inspection method, and program

Abstract

The present invention provides an image inspection device, an image inspection method, and a program capable of detecting large stains such as colorant spills. [Solution] An image inspection device (image reading device 40) is provided with a control unit (reading control unit 41) that detects whether or not there is an abnormality in a read image generated when a recording medium on which an image has been formed is read by a reading unit 42 based on a reference image. The control unit detects color blotting in the read image. Specifically, the control unit reduces the resolution of the reference image and the read image, and detects color blotting based on the reduced-resolution reference image and the read image.

Description

Technical Field

[0001] The present invention relates to an image inspection apparatus, an image inspection method, and a program.

Background Art

[0002] Conventionally, an image inspection apparatus capable of detecting dirt on paper has been known. A general image inspection apparatus detects dirt on paper by comparing a previously registered reference image with an inspection image formed on the paper. When the reference image is an image read from an image formed on paper, dirt on the paper can be detected by performing threshold processing on the difference image between the reference image and the inspection image. On the other hand, when the reference image is RIP data (RIP image), since the color (whiteness) of the paper on which the inspection image is printed is not accurately known, threshold processing cannot be performed on a simple difference image between the reference image and the inspection image. This is because when taking the difference between the RIP image and the inspection image, since the paper color is unknown, the difference value of the dirt portion appearing in the difference image may become large. In this case, even if the difference value exceeds a certain threshold value by simple threshold processing, it cannot be determined as dirt. Therefore, dirt on paper cannot be accurately detected.

[0003] Therefore, Patent Document 1 discloses a configuration for detecting dirt by performing edge detection of dirt using an edge detection filter on a difference image. According to the configuration described in Patent Document 1, dirt can be detected without using the difference value between the RIP image and the inspection image.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the configuration described in Patent Document 1 can only detect stains of a size and shape that react to the edge detection filter. Therefore, stains that are large in size and have a gradient-like edge, such as toner droplets, are difficult to detect due to edge detection issues.

[0006] The present invention aims to provide an image inspection device, an image inspection method, and a program capable of detecting large stains such as colorant drips. [Means for solving the problem]

[0007] The invention described in claim 1 was made to achieve the above objective, In an image inspection device, An image inspection apparatus comprising a control unit that detects whether or not there are abnormalities in a read image generated by reading a recording medium on which an image has been formed based on a reference image, The control unit is characterized by detecting colorant dripping in the read image.

[0008] The invention described in claim 2 is an image inspection apparatus described in claim 1, The control unit is characterized by detecting dirt in the read image during the first inspection and detecting colorant dripping during the second inspection, which is different from the first inspection.

[0009] The invention described in claim 3 is an image inspection apparatus as described in claim 1, The control unit is characterized by reducing the resolution of the reference image and the read image, and detecting the colorant dripping based on the reduced resolution of the reference image and the read image.

[0010] The invention described in claim 4 is an image inspection apparatus described in claim 3, The control unit is characterized by detecting the colorant dripping based on the brightness value in the difference between the low-resolution reference image and the read image.

[0011] The invention described in claim 5 is an image inspection apparatus described in claim 4, The control unit is characterized by detecting the colorant dripping based on the brightness value of the white area of ​​the paper in the difference between the low-resolution reference image and the read image.

[0012] The invention described in claim 6 is an image inspection apparatus as described in claim 3, The control unit is characterized by detecting edges in the difference between the low-resolution reference image and the read image, and detecting the colorant dripping based on the edge detection result.

[0013] The invention described in claim 7 is an image inspection apparatus as described in claim 6, The control unit is characterized by detecting edges in the halftone region of the difference between the low-resolution reference image and the read image, and detecting the colorant dripping based on the edge detection result.

[0014] The invention described in claim 8 is an image inspection apparatus as described in claim 1, The control unit further detects edges in the difference between the reference image and the read image, and detects dirt in the read image based on the edge detection results.

[0015] The invention described in claim 9 is an image inspection apparatus as described in claim 8, The control unit is characterized by detecting the edge using a filter for detecting the edge.

[0016] The invention described in claim 10 is an image inspection apparatus described in claim 1, The aforementioned colorant drips are characterized by stains that have a gradient-like appearance at the edges.

[0017] The invention described in claim 11 is an image inspection apparatus described in claim 1, The coloring material in the coloring material dripping includes either toner or ink.

[0018] The invention according to claim 12 is the image inspection apparatus according to claim 1, wherein the coloring material dripping includes those on the content included in the read image.

[0019] The invention according to claim 13 is the image inspection apparatus according to claim 1, wherein the reference image is a RIP image.

[0020] The invention according to claim 14 is an image inspection method of an image inspection apparatus, including a control step of detecting the presence or absence of an abnormality in a read image generated by reading a recording medium on which an image is formed by a reading unit based on a reference image, wherein the control step is characterized by detecting coloring material dripping in the read image.

[0021] The invention according to claim 15 is a computer of an image inspection apparatus, functioning as a control unit that detects the presence or absence of an abnormality in a read image generated by reading a recording medium on which an image is formed by a reading unit based on a reference image, wherein the control unit is a program characterized by detecting coloring material dripping in the read image.

Effect of the Invention

[0022] According to the present invention, large stains such as coloring material dripping can be detected.

Brief Description of the Drawings

[0023] [Figure 1] It is a diagram showing a schematic configuration of an image inspection system according to the present embodiment. [Figure 2] It is a functional block diagram showing a control structure of an image inspection system according to the present embodiment. [Figure 3] This flowchart shows an example of an anomaly detection control system for detecting colorant dripping. [Figure 4] This figure shows an example of how reference images and inspection images appear when reduced in resolution. [Figure 5] This figure shows an example of brightness values ​​in low-resolution RIP images and examination images. [Figure 6] This figure shows the difference between the brightness values ​​in the RIP image and the brightness values ​​in the examination image. [Figure 7] This figure shows an example of a difference image. [Figure 8] This flowchart shows a modified example of an anomaly detection control that detects colorant dripping. [Figure 9] This figure shows an example of a difference image in which edges have been detected. [Figure 10] This flowchart shows an example of an anomaly detection control system that detects minute contamination. [Modes for carrying out the invention]

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0025] As shown in Figures 1 and 2, the image inspection system 1 according to this embodiment includes a print controller 10, a paper feeder 20, an image forming apparatus 30, an image reading apparatus (image inspection apparatus) 40, and a paper output apparatus 50. The image inspection system 1 is connected to an external device 2 such as a PC via the NIC 13 of the print controller 10, enabling mutual transmission and reception of information.

[0026] The print controller 10 manages and controls image data when the image forming apparatus 30 is used as a network printer. Image data is input to the image forming apparatus 30 from an external device 2 connected to the LAN. The print controller 10 receives the image data to be printed from the external device 2 and transmits it to the image forming apparatus 30.

[0027] The print controller 10 comprises a control unit 11, an image processing unit 12, and a NIC 13. The control unit 11 includes a CPU, ROM, RAM, etc., and comprehensively controls the operation of each part of the print controller 10. The control unit 11 outputs image data input from the external device 2 via the NIC 13 to the image forming apparatus 30. The image processing unit 12 performs rasterization (RIP) processing on the image data input from the external device 2 to generate CMYK color image data (RIP image data). NIC13 is a communication interface that receives image data to be printed from external device 2 via LAN.

[0028] The paper feeder 20 comprises a plurality of paper feed trays 21 and a paper feeding mechanism (not shown), and feeds paper (recording medium) P stored in the paper feed trays 21 to the image forming apparatus 30. The paper feeding mechanism consists of, for example, a paper feed roller, a separation roller, a paper feed / separation rubber, a feed roller, etc. Each paper feed tray 21 stores paper P according to its type (paper type, basis weight, paper size, etc.). The paper feeder 20 transports the paper P one sheet at a time from the top of each paper feed tray 21 to the image forming apparatus 30.

[0029] The image forming apparatus 30 is a multifunction device that forms an image on paper based on image data read from a document and image data received from an external device 2 via LAN. The image forming apparatus 30 comprises a control unit 31, a storage unit 32, a reading unit 33, a scanner image processing unit 34, a printer image processing unit 35, and an image forming unit 36.

[0030] The control unit 31 includes a CPU, RAM, ROM, etc. First, the CPU reads various processing programs stored in the ROM and loads them into the RAM. Next, the CPU, in cooperation with the various programs loaded into the RAM, comprehensively controls the operation of each part of the image forming apparatus 30.

[0031] The memory unit 32 stores programs that can be read by the control unit 31, files used when executing programs, and the like. The memory unit 32 is, for example, a large-capacity memory such as a hard disk.

[0032] The reading unit 33 consists of an automatic document feeder, a scanner, etc., and reads the surface of a document set on the document glass to generate bitmap image data. The image data generated by the reading unit 33 is color-converted from each pixel having three color pixel values ​​of R (red), G (green), and B (blue) to image data having four color pixel values ​​of C, M, Y, and K.

[0033] The scanner image processing unit 34 processes the analog image data input from the reading unit 33 and then generates digital image data. These processes include analog processing, A / D conversion, and shading. The generated image data is output to the printer image processing unit 35.

[0034] The printer image processing unit 35 generates print image data based on image data input from the scanner image processing unit 34 or the image processing unit 12 of the print controller 10. The print image data is image data for image formation. The print image data generated by the printer image processing unit 35 is output to the image forming unit 36.

[0035] The image forming unit 36 ​​performs electrophotographic image forming processing. The image forming unit 36 ​​forms an image consisting of four colors, C, M, Y, and K, on ​​the paper according to the pixel values ​​of the four colors of each pixel in the printed image data.

[0036] The image forming unit 36 ​​includes a paper feeding unit 361, a transport unit 362, four writing units 363, an intermediate transfer belt 364, a transfer unit 365, and a fixing unit 366.

[0037] The paper feeding unit 361 comprises a plurality of paper trays and a paper feeding means (not shown). The paper feeding means consists of, for example, a paper feed roller, a separation roller, a paper feed / separation rubber, a feed roller, etc. Each paper tray stores paper according to its type (paper type, basis weight, paper size, etc.). The paper feeding unit 361 transports the paper one sheet at a time from the top of each paper tray to the transport unit 362.

[0038] The transport unit 362 transports the paper transported from the paper feeding unit 361 to the secondary transfer position of the image forming unit 36 ​​via the paper transport path to the transfer unit 365.

[0039] The four writing units 363 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 364 and form images of C, M, Y, and K colors. Each writing unit 363 has the same configuration except for the color of the image it forms. Each writing unit 363 comprises an exposure unit 363a, a photosensitive drum 363b, a developing unit 363c, a charging unit 363d, a cleaning unit 363e, and a primary transfer roller 363f.

[0040] During image formation, each writing unit 363 first charges the photoreceptor drum 363b with the charging unit 363d. Next, each writing unit 363 scans the photoreceptor drum 363b with a light beam emitted by the exposure unit 363a based on the image data, forming an electrostatic latent image. Next, each writing unit 363 develops the toner by supplying it with the developing unit 363c. This forms an image (a monochrome toner image) on the photoreceptor drum 363b. Next, each writing unit 363 sequentially transfers the images formed on the photoreceptor drum 363b onto the intermediate transfer belt 364 using its respective primary transfer roller 363f. As a result, an image consisting of each color (color toner image) is formed on the intermediate transfer belt 364. Next, each writing unit 363 uses its cleaning unit 363e to remove any remaining toner from the photoreceptor drum 363b.

[0041] Next, the image forming unit 36 ​​feeds paper from the paper feed device 20 or paper feed unit 361 in time with the image on the rotating intermediate transfer belt 364 reaching the position of the transfer unit 365. Next, the image forming unit 36 ​​transfers the image (color toner image) from the intermediate transfer belt 364 onto the paper using the transfer unit 365. Next, the image forming unit 36 ​​transports the paper to the fixing unit 366 for fixing. Fixing is a process in which the fixing unit 366 heats and pressurizes the paper to fix the image onto the paper. When forming an image on both sides of the paper, the image forming unit 36 ​​transports the paper to the inversion path R1 to invert the paper surface, and then transports the paper back to the position of the transfer unit 365.

[0042] The image reading device 40 is positioned downstream of the image forming apparatus 30. The image reading device 40 comprises a reading control unit (control unit) 41, a reading unit 42, and a page memory 43.

[0043] The reading control unit 41 processes the analog image data input from the reading unit 42 and then generates RGB digital image data. These processes include, for example, analog processing, A / D conversion, shading correction, color conversion, and scaling. The generated image data is output to the page memory 43.

[0044] Furthermore, the reading control unit 41 detects whether or not there are any abnormalities in the read image (inspection image) generated when the paper on which the image is formed is read by the reading unit 42, based on the reference image. This makes it possible to detect dirt or printing errors.

[0045] The reading unit 42 scans both sides of the paper on which the image has been formed by the image forming unit 36 ​​and optically reads the images on both sides of the paper. The reading unit 42 comprises a back-side image reading unit 42a and a front-side image reading unit 42b.

[0046] The reverse side image reading unit 42a is located below the transport path R40 and reads the image formed on the reverse side of the paper. The front side image reading unit 42b is located above the transport path R40 and reads the image formed on the front side of the paper. The front side image reading unit 42b is located downstream of the reverse side image reading unit 42a in the paper transport direction. The reverse side image reading unit 42a and the front side image reading unit 42b are located at different positions with a distance between them in the paper transport direction. This allows both sides of the paper to be read in a single pass. The reading results (analog image data) read by the reverse side image reading unit 42a and the front side image reading unit 42b are output to the reading control unit 41.

[0047] The page memory 43 is configured, for example, with DRAM and stores image data generated by the read control unit 41.

[0048] The paper output device 50 is located downstream of the image reading device 40 and outputs the paper from which the image has been read by the image reading device 40 to the paper output tray 51.

[0049] Next, the control of the image inspection system 1 according to this embodiment will be explained with reference to the flowcharts in Figures 3, 8, and 10.

[0050] Figure 3 is a flowchart illustrating an example of an anomaly detection control for detecting colorant spills (stains that are large in size and have a gradient-like edge). The colorant in colorant spills includes either toner or ink. The control in Figure 3 is a second inspection of the present invention for detecting colorant spills in a read image. The second inspection differs from the first inspection of the present invention (see Figure 10), which detects minute stains in a read image.

[0051] First, the reading control unit 41 of the image reading device 40 acquires a reference image and an inspection image (step S101). In this embodiment, the reference image is a RIP image. The RIP image is a printable image after RIP processing. The reference image is stored, for example, in the storage unit 32 of the image forming apparatus 30. The inspection image is a read image generated when the paper (printed material) on which the image has been formed is read by the reading unit 42.

[0052] Next, the reading control unit 41 reduces the resolution of the reference image and inspection image acquired in step S101 (step S102). This increases the area occupied by each pixel, making it easier to detect large stains such as colorant spills. It also simplifies and speeds up the processing. Figure 4 shows an example of a reference image and an examination image with reduced resolution. In Figure 4, code G1 represents an example of a reference image. Code G2 represents an example of an examination image. Code G11 represents an example of a reduced-resolution reference image. Code G21 represents an example of a reduced-resolution examination image.

[0053] Next, the reading control unit 41 generates a difference image between the reference image, which was reduced in resolution in step S102, and the inspection image (step S103). The difference image is generated by calculating the difference in the pixel value (luminance value) of each pixel. In order to eliminate the influence of the paper color of the inspection image, the reading control unit 41 generates the difference image such that the difference value of the white areas of the paper is 0.

[0054] Figure 5 shows an example of brightness values ​​in a low-resolution RIP image and an inspection image. In Figure 5, the symbol L1 is an example of a brightness value in a low-resolution RIP image. In Figure 5, the symbol L2 is an example of a brightness value in a low-resolution inspection image. The area protruding downwards in the brightness value L2 of the inspection image (symbol D1) indicates that there is dirt in the inspection image.

[0055] Figure 6 shows the difference (luminance difference) between the luminance value L1 in the RIP image and the luminance value L2 in the inspection image. In the example shown in Figure 6, it can be seen that the difference value is 0 in the areas of the white paper that are free of dirt, after eliminating the influence of the paper color in the inspection image.

[0056] Figure 7 shows an example of a difference image. In the example shown in Figure 7, it can be seen that the area E1 with dirt is darker than the other areas.

[0057] Next, the reading control unit 41 performs thresholding on the white areas of the difference image generated in step S103 (step S104). Thresholding is a binarization process using a predetermined threshold. The reading control unit 41 extracts pixels from the white areas of the difference image whose pixel value (luminance value) exceeds a predetermined threshold.

[0058] Next, the reading control unit 41 performs noise processing on the difference image after threshold processing (step S105). This removes dirt that is only a few dots in size as noise, thereby suppressing false detection of dirt.

[0059] Next, the reading control unit 41 detects that there is smudges (colorant spills) in the pixels extracted by threshold processing (step S106). This allows the reading control unit 41 to detect colorant spills in the read image.

[0060] As described above, the reading control unit 41 reduces the resolution of the reference image and the read image, and detects color blob based on the reduced resolution reference image and the read image. Specifically, the reading control unit 41 detects color blob based on the luminance value in the difference (difference image) between the reduced resolution reference image and the read image. More specifically, the reading control unit 41 detects color blob based on the luminance value of the white area of ​​the paper in the difference between the reduced resolution reference image and the read image.

[0061] In the white areas of the paper, the luminance values ​​in the RIP image and the luminance values ​​in the inspection image can be matched (the luminance difference can be set to 0), so thresholding can be performed. On the other hand, in the halftone areas, the paper color (whiteness of the paper) of the inspection image has an effect, so the luminance values ​​in the RIP image and the luminance values ​​in the inspection image cannot be matched. Therefore, the control (thresholding) shown in Figure 3 cannot be directly applied to the halftone areas.

[0062] Figure 8 is a flowchart showing a modified example of an anomaly detection control for detecting colorant dripping. The control shown in Figure 8 detects colorant dripping within the halftone area.

[0063] The processes in steps S201 and S202 are the same as those in steps S101 and S102 in Figure 3, so their explanation is omitted.

[0064] Next, the reading control unit 41 generates a difference image between the reference image and the inspection image (step S203). The difference image is generated by calculating the difference in pixel values ​​(luminance values) of each pixel. In order to eliminate the influence of the paper color of the inspection image, the reading control unit 41 generates the difference image such that the difference value of the white areas of the paper is 0.

[0065] Next, the reading control unit 41 performs edge detection processing (step S204) on the halftone region of the difference image generated in step S203. An edge is a location in the difference image where the variation in pixel value (luminance value) is large compared to adjacent pixels. Specifically, the reading control unit 41 applies an edge detection filter to the difference image. This process makes it possible to highlight locations (edges) in the difference image where the variation in value is large between pixels. For example, a Sobel filter or a Robinson filter can be used as an edge detection filter. Figure 9 shows an example of a difference image in which an edge was detected. In Figure 9, code E2 represents an example of a detected edge region.

[0066] Next, the reading control unit 41 masks the image edge regions of the difference image that have undergone edge detection processing in step S204 (step S205). Specifically, the reading control unit 41 extracts edge information of image regions from the RIP image in advance and excludes those image edge regions from inspection. Because the grayscale fluctuations are large in the edge parts of an image, the difference can become large due to positional shifts, which can cause false detections. The process in step S205 can exclude image edge regions from inspection, thereby suppressing false detections.

[0067] Next, the reading control unit 41 performs thresholding on the difference image that has undergone edge detection processing in step S204 (step S206).

[0068] Next, the reading control unit 41 detects that there is smudges (color pigment spills) in the pixels extracted by threshold processing (step S207). As a result, the reading control unit 41 can detect color pigment spills in the read image even in the halftone region.

[0069] As described above, the reading control unit 41 detects edges in the difference between the low-resolution reference image and the read image, and detects color blotting based on the edge detection results. Specifically, the reading control unit 41 detects edges in the halftone region of the difference between the low-resolution reference image and the read image, and detects color blotting based on the edge detection results.

[0070] Figure 10 is a flowchart showing an example of an anomaly detection control system that detects minute contamination.

[0071] First, the reading control unit 41 acquires the reference image and the inspection image (step S301).

[0072] Next, the reading control unit 41 generates a difference image between the reference image and the inspection image (step S302). The difference image is generated by calculating the difference in pixel values ​​(luminance values) of each pixel.

[0073] Next, the reading control unit 41 performs edge detection processing (edge ​​detection processing) on ​​the difference image generated in step S302 (step S303). Specifically, the reading control unit 41 applies an edge detection filter to the difference image. The edge detection filter is a filter for detecting edges.

[0074] Next, the reading control unit 41 masks the image edge regions of the difference image (step S304).

[0075] Next, the reading control unit 41 performs threshold processing on the difference image (step S305).

[0076] Next, the reading control unit 41 detects that there is dirt (minute dirt) in the pixels extracted by thresholding (step S306). This allows the reading control unit 41 to detect minute dirt in the read image.

[0077] As described above, the reading control unit 41 further detects edges in the difference between the reference image and the read image, and detects (minor) stains in the read image based on the edge detection results.

[0078] As described above, the image inspection apparatus (image reading apparatus 40) according to this embodiment includes a control unit (reading control unit 41) that detects whether or not there is an abnormality in the read image generated when a recording medium on which an image has been formed is read by the reading unit 42 based on a reference image. The control unit detects colorant dripping in the read image. Therefore, the image inspection device according to this embodiment can detect large stains such as colorant drips. Thus, stains on the recording medium can be detected more reliably.

[0079] Furthermore, the control unit detects dirt in the read image during the first inspection and detects colorant spills during the second inspection, which is different from the first inspection. Therefore, it can detect not only large stains such as colorant drips, but also minute stains. Thus, it can more reliably detect stains on the recording medium.

[0080] Furthermore, the control unit reduces the resolution of the reference image and the read image, and detects colorant dripping based on the reduced-resolution reference image and the read image. Therefore, it is possible to detect large stains such as colorant drips. Thus, stains on the recording medium can be detected more reliably.

[0081] Furthermore, the control unit detects colorant smudging based on the luminance values ​​in the difference between the low-resolution reference image and the read image. In particular, the control unit detects colorant smudging based on the luminance values ​​of the white areas of the paper in the difference between the low-resolution reference image and the read image. Therefore, large stains such as colorant drips can be detected concisely. Thus, stains on the recording medium can be detected more reliably and concisely.

[0082] Furthermore, the control unit detects edges in the difference between the low-resolution reference image and the read image, and detects color blotting based on the edge detection results. In particular, the control unit detects edges in the halftone region of the difference between the low-resolution reference image and the read image, and detects color blotting based on the edge detection results. Therefore, it is possible to detect colorant drips within the halftone area. Thus, dirt on the recording medium can be detected more reliably.

[0083] Furthermore, the control unit detects edges in the difference between the reference image and the read image, and detects dirt in the read image based on the edge detection results. At this time, the control unit detects edges using a filter for edge detection. Therefore, it is possible to detect even minute stains in the read image. Thus, stains on the recording medium can be detected more reliably.

[0084] Furthermore, color blotting is a type of stain where the edges have a gradient-like appearance. The color blotting includes either toner or ink. Therefore, it can detect stains (toner and ink splatters) that are difficult to detect by edge detection. Thus, it can more reliably detect stains on the recording medium.

[0085] Furthermore, the reference image is a RIP image. Therefore, even if the exact color (whiteness) of the paper on which the inspection image is printed is unknown, it is possible to detect color smudges. Thus, it is possible to detect dirt on the recording medium more reliably.

[0086] Although the present invention has been specifically described above based on embodiments, the present invention is not limited to the above embodiments and can be modified without departing from its spirit.

[0087] For example, the colorant spills detected in the second inspection may include those on the content contained in the read image. In this case, even color smudges on the content can be detected. Therefore, dirt on the recording medium can be detected more reliably.

[0088] Furthermore, although the above embodiment illustrates a configuration in which the image reading device 40, as an image inspection device of the present invention, includes a reading unit 42, the invention is not limited to this configuration. For example, the device including the reading unit 42 may be configured as a separate unit, and the image inspection device may be configured to specialize in inspecting the read images read by the reading unit 42 of the separate unit.

[0089] Furthermore, although the above embodiment illustrates and describes a configuration in which an electrophotographic method is applied as the image forming unit 36, it is not limited to this. For example, other printing methods such as an inkjet method or a thermal sublimation method may be applied instead of the electrophotographic method.

[0090] Furthermore, each aspect described in this application can also be understood as a method, program, etc. Regarding the categories of methods and programs, the term "part" as used in the apparatus category should be appropriately replaced with terms such as "process," "step," or "means." Also, the order of processes and steps is not limited to those directly specified in this application; the order can be changed, or some processes can be combined or executed in parts at any given time.

[0091] Furthermore, the detailed configuration and operation of each device constituting the image inspection system can also be modified as appropriate without departing from the spirit of the present invention. [Explanation of Symbols]

[0092] 1. Image inspection system 10 Print Controllers 11 Control Unit 12 Image Processing Unit 13 NIC 20 Paper feeder 21 Paper feed tray 30 Image forming apparatus 31 Control Unit 32 Storage section 33 Reading Unit 34 Scanner Image Processing Unit 35 Printer Image Processing Unit 36 Image forming unit 361 Paper feed section 362 Conveying Unit 363 Writing Unit 363a Exposure section 363b Photoconductor Drum 363c developing section 363d Charged part 363e Cleaning Department 363f Primary Transfer Roller 364 Intermediate Transfer Belt 365 Transfer section 366 Fixing section 40. Image reading device (image inspection device) 41. Reading Control Unit (Control Unit) 42 Reading section 42a Rear image reading unit 42b Surface image reading unit 43-page memory 50 Paper ejection device 51 Paper output tray 2 External device P Paper (recording medium)

Claims

1. An image inspection apparatus comprising a control unit that detects whether or not there are abnormalities in a read image generated by reading a recording medium on which an image has been formed based on a reference image, The control unit is characterized by detecting colorant dripping in the read image.

2. The image inspection apparatus according to claim 1, characterized in that the control unit detects dirt in the read image in a first inspection and detects colorant dripping in a second inspection different from the first inspection.

3. The image inspection apparatus according to claim 1, characterized in that the control unit reduces the resolution of the reference image and the read image, and detects the colorant dripping based on the reduced resolution of the reference image and the read image.

4. The image inspection apparatus according to claim 3, characterized in that the control unit detects the colorant dripping based on the brightness value in the difference between the low-resolution reference image and the read image.

5. The image inspection apparatus according to claim 4, characterized in that the control unit detects the colorant dripping based on the brightness value of the white area of ​​the paper in the difference between the low-resolution reference image and the read image.

6. The image inspection apparatus according to claim 3, characterized in that the control unit detects edges in the difference between the low-resolution reference image and the read image, and detects the colorant dripping based on the edge detection result.

7. The image inspection apparatus according to claim 6, characterized in that the control unit detects edges in the halftone region of the difference between the low-resolution reference image and the read image, and detects the colorant dripping based on the edge detection result.

8. The image inspection apparatus according to claim 1, further characterized in that the control unit detects edges in the difference between the reference image and the read image, and detects dirt in the read image based on the edge detection result.

9. The image inspection apparatus according to claim 8, characterized in that the control unit detects the edge using a filter for detecting the edge.

10. The image inspection apparatus according to claim 1, characterized in that the aforementioned colorant dripping is a stain with a gradient-like appearance at the edges.

11. The image inspection apparatus according to claim 1, characterized in that the colorant in the aforementioned colorant dripping includes either toner or ink.

12. The image inspection apparatus according to claim 1, characterized in that the aforementioned colorant dripping includes those on the content included in the read image.

13. The image inspection apparatus according to claim 1, characterized in that the reference image is a RIP image.

14. An image inspection method for an image inspection device, The process includes a control step that detects whether or not there are any abnormalities in the read image generated when a recording medium on which an image has been formed is read by a reading unit based on a reference image. The control step is characterized by detecting colorant dripping in the read image.

15. The computer of the image inspection device, Based on a reference image, the recording medium on which the image is formed is read by the reading unit, and the control unit functions to detect whether or not there are any abnormalities in the generated read image. The control unit is a program characterized by detecting colorant dripping in the read image.

Images