JP2013009116A - Image processor, image reader, image forming apparatus, image processing method, program and recording medium - Google Patents

Abstract

A streak image that does not exist in a document can be accurately detected.
A streak detection processing unit 129 detects an edge pixel included in a determination region set in read image data of a document, and determines whether the edge pixel is a rising edge pixel or a falling edge pixel. The difference calculation unit 202, the rising / falling edge detection unit 203, and each pixel in the determination region are set as the target pixel, and a block including a plurality of pixels in the main scanning direction and the sub-scanning direction is set around the target pixel. The first condition that is an edge pixel, the second condition that there is one pair of rising edge pixel and falling edge pixel for each line in the main scanning direction in the block, and the edge in all lines in the sub scanning direction in the block A streak pixel determination unit 204 that determines a target pixel as a streak pixel when all the third conditions in which no pixel exists is satisfied.
[Selection] Figure 3

Description

  The present invention relates to an image processing apparatus, an image reading apparatus, an image forming apparatus, an image processing method, a program, and a recording medium that detect a streak image in read image data of a document.

  In a conventional copying machine or facsimile machine, when reading a document image, the document is moved by a sheet-through type automatic document feeder (ADF), and the document image is read by a fixed optical system. An image reading device is provided. In such an image reading apparatus, since the documents placed on the ADF paper feeding unit are automatically and sequentially conveyed onto the contact glass, the user is troublesome to transfer the documents one by one on the contact glass. Can be resolved. Further, since the reading optical system does not reciprocate in the sub-scanning direction, there is an advantage that even when a large number of documents are read, the time until all the documents are read is shortened.

  However, in the image reading apparatus using ADF, if dust or dirt is present on the optical path, there is a problem in that vertical stripes occur in the read image because light applied to the document is blocked. In this case, streaks that do not exist in the original also appear in the printed image.

  In order to solve such a problem, for example, Patent Document 1 discloses a configuration for detecting a streak image in a read image. Specifically, the image reading unit includes a CCD having a peak of response to different colors, and the streak image detecting unit extracts a streak peak pixel for each of the images read by the image reading unit. Further, a pixel determined to be a streak peak pixel by only one CCD is set as a streak image candidate, and a pixel in which a predetermined number or more continues in the sub-scanning line direction is detected as a streak image.

JP 2008-028864 A (published on Feb. 07, 2008) Japanese Patent Application Laid-Open No. 2004-289496 (released on October 14, 2004)

  However, in the technique described in Patent Document 1, pixels that are determined to be streak-peak pixels with only one CCD are used as streak image candidates, and therefore, a plurality of line CCDs out of three line CCDs that have reaction peaks for different colors. In the case of the line CCD, when reaction peaks occur in a plurality of colors, there is a problem that a streak image cannot be detected.

  On the other hand, streaked images are not only caused by dust on the optical path to the CCD, but also when ink, toner, or dirt on the document adheres to the contact glass when the ADF is used. There are also many. When the latter causes a streak image, a reaction peak occurs in each CCD, so that there is a problem that a streak pixel candidate, that is, a streak image cannot be detected.

  Therefore, the present invention does not exist in the original in the read image data of the original due to the presence of dust or dust when using an image reading apparatus (an image reading apparatus using ADF) that reads an image while moving the original, for example. An object of the present invention is to provide an image processing apparatus, an image reading apparatus, an image forming apparatus, an image processing method, a program, and a recording medium that can accurately detect the occurrence of a streak image.

  In order to solve the above-described problem, an image processing apparatus according to the present invention includes an image processing apparatus including a streak detection processing unit that detects read image data including a streak image with respect to read image data read from a document. The streak detection processing unit detects edge pixels included in the determination region set in the read image data read from the document, and the pixel density of the detected edge pixel is the main pixel in reading the document. Pay attention to the edge pixel detection unit that determines whether the rising edge pixel increases in the scanning direction or the falling edge pixel in which the pixel density decreases in the main scanning direction during document reading, and each pixel in the determination area A block including a plurality of pixels in the main scanning direction and the sub-scanning direction around the target pixel is set as the pixel. A first condition that is a wedge pixel, a second condition in which a pair of rising edge pixels and falling edge pixels exist for each line in the main scanning direction in the block, and all of the sub scanning direction in the block A streak pixel determining unit that determines that the target pixel is a streak pixel when all the third conditions in which no edge pixel exists in the line is satisfied is provided.

  The image processing method of the present invention is an image processing method for performing a streak detection process for detecting read image data including a streak image with respect to read image data read from a document, wherein the streak detection process is read from a document. For the determination region set in the read image data, the edge pixel included in the determination region is detected, and the rising edge pixel in which the pixel density of the detected edge pixel becomes higher in the main scanning direction in reading the document. Or an edge pixel detection step for determining whether the pixel density is a falling edge pixel that decreases in the main scanning direction during document reading, and each pixel in the determination area is a pixel of interest, and the pixel of interest is the center of the pixel of interest. A first condition in which a block including a plurality of pixels is set in the scanning direction and the sub-scanning direction, and the target pixel is an edge pixel A second condition in which one set of rising edge pixels and falling edge pixels exists for each line in the main scanning direction in the block, and a third condition in which no edge pixels exist in all lines in the sub scanning direction in the block. And a streak pixel determining step of determining the target pixel as a streak pixel when all the conditions are satisfied.

  According to the above configuration, the streak detection processing unit (in the streak detection processing step) detects read image data including a streak image from the read image data read from the document. In this case, the edge pixel detection unit (in the edge pixel detection step) detects the edge pixel included in the determination area for the determination area set in the read image data read from the document, and detects the detected edge pixel. Is determined whether it is a rising edge pixel whose pixel density increases in the main scanning direction or a falling edge pixel whose pixel density decreases in the main scanning direction. The streak pixel determination unit (in the streak pixel determination step) sets each pixel in the determination region as a target pixel, sets a block including a plurality of pixels in the main scanning direction and the sub-scanning direction around the target pixel, and sets the target pixel Are the first condition, the second condition that there is one set of rising edge pixels and falling edge pixels for each line in the main scanning direction in the block, and all the sub scanning directions in the block The pixel of interest is determined to be a streak pixel when all the third conditions in which no edge pixel exists in the line are satisfied.

  As described above, the streak pixel determination unit (in the streak pixel determination step) determines the target pixel as a streak pixel when all of the first to third conditions are satisfied, so that the streak pixel is determined with high accuracy. be able to. That is, when all of the first to third conditions are satisfied, there is one edge combination having a density difference in the main scanning direction, and there is no edge having a density difference in the sub-scanning direction. Thus, it can be determined that one vertical stripe exists in the sub-scanning direction. Therefore, for example, due to the presence of dust or dust when using an image reading apparatus (an image reading apparatus using ADF) that reads an image while moving the original, a streak image that does not exist in the original is generated in the read image data of the original. Can be detected with high accuracy. In this case, it is not necessary to perform a special operation for detecting the streak image, and the streak image can be detected with high accuracy from the normal read image data.

  In the image processing apparatus, the streak detection processing unit includes: a determination region extraction unit that sets a region on the reading front end side or reading rear end side of the read image data as the determination region; and the edge pixel detection unit. An edge pixel number counting unit that counts the number of edge pixels included in the determination region, and a plain region determination threshold that sets the number of edge pixels for determining whether or not the determination region is a plain region; The number of edge pixels counted by the edge pixel number counting unit is compared to determine whether the determination region is a plain region or not, and the determination region is determined to be a plain region by the plain region determination unit. It may be configured to include a streak presence / absence determining unit that determines whether or not a streak image is included in the determination region when it is determined.

  According to the above configuration, the determination area extraction unit sets an area on the reading front end side or the reading rear end side of the read image data as the determination area. The edge pixel number counting unit counts the number of edge pixels included in the determination region detected by the edge pixel detection unit. The plain region determination unit compares the plain region determination threshold value that sets the number of edge pixels for determining whether or not the determination region is a plain region with the number of edge pixels counted by the edge pixel number counter, and the determination region is It is determined whether it is a plain area. The streak presence / absence determination unit determines whether or not a streak image is included in the determination region when the determination region is determined to be a plain region by the plain region determination unit.

  As described above, the determination area for determining whether or not a streak image is included in the read image data is usually on the reading front end side or the reading rear end side of the original in the read image data where the original image is not drawn. The area is set. Further, when the determination area is determined to be a plain area, it is determined whether or not a streak image is included in the determination area. Therefore, the presence / absence of the streak image is determined only in the optimum region where erroneous determination is unlikely to occur. Thereby, the detection accuracy of the streak image in the read image data can be improved.

  In the image processing apparatus, the streak detection processing unit includes a streak pixel number counting unit that counts the number of pixels determined to be streak pixels by the streak pixel determination unit, and the streak presence determination unit includes the determination region The streak presence / absence determination threshold in which the number of streak pixels for determining that a streak image is included is compared with the number of streak pixels counted by the streak pixel number counting unit, and the streak image is found in the determination region. It is good also as a structure which determines whether it is contained.

  According to the above configuration, the streak presence / absence determination unit sets a streak presence / absence determination threshold in which the number of streak pixels for determining that a streak image is included in the determination region, and the streak count counted by the streak pixel number counting unit. The number of pixels is compared to determine whether a streak image is included in the determination area. As a result, the presence / absence of a streak image in the determination area of the read image data can be detected with high accuracy.

  For example, when a vertical streak composed of three pixels in the sub-scanning direction exists in the determination region, two streak pixels are normally detected for each vertical streak in the main scanning direction, that is, two rising pixels and one falling pixel. On the other hand, among the vertical stripes composed of three pixels, the central vertical stripe pixel may not be determined as an edge pixel due to the density difference between the adjacent vertical stripe pixels. Accordingly, the streak presence / absence determination threshold value is determined by taking into account that there are at least two streaked pixels in the main scanning direction, that is, a rising pixel and a falling pixel, and the number of pixels in the sub-scanning direction (number of lines in the main scanning direction) in the determination region. The value is doubled. The streak presence / absence determination threshold value is compared with the streak pixel number counted by the streak pixel number counting unit, and when the streak pixel number is larger than the streak presence / absence determination threshold value, it is determined that a streak image exists in the determination region.

  As described above, the streak presence / absence determination threshold value is the minimum of the number of streak pixels expected to be generated in one line in the main scanning direction of the determination region, compared to the number of pixels in the sub scanning direction (number of lines in the main scanning direction) It is preferable to set the value multiplied by the value.

  The image processing apparatus includes a streak generation warning device that issues a streak generation warning for notifying that a streak image has occurred in the read image data, and the streak presence / absence determination unit to detect a streak image for a plurality of continuous read image data. When it is determined that a streak generation warning device is included, a control unit that causes the streak generation warning device to perform a streak generation warning may be provided.

  According to the above configuration, the control unit issues a streak generation warning by the streak generation warning device when the streak presence / absence determination unit determines that a plurality of continuous read image data includes a streak image. Make it.

  As a result, the operator of the image processing apparatus can know from the streak generation warning that a streak image has occurred in the read image data of the document, and the dust causing the generation of the streak image at the document reading position. And dust can be removed. In addition, it is possible to avoid an unnecessary streak occurrence warning, for example, when the streak presence / absence determination unit makes an erroneous determination or when a streak image is detected only once and then the streak image is eliminated.

  In the image processing apparatus, the control unit counts the continuous number of streaked document data that is read image data determined by the streak presence / absence determining unit to include a streak image, and the continuous number is a streak. When the occurrence warning threshold value is exceeded, the stripe occurrence warning device causes the occurrence of a stripe occurrence warning, streak generation document data is generated in the first job including processing of a plurality of read image data, and When the continuous number of document data is equal to or less than the streak occurrence warning threshold, the continuous number of streaked document data in the first job is held, and the first job in the second job including processing of a plurality of read image data The streak generation warning device may be configured to issue a streak generation warning device when the number of continuous line generation document data from the job exceeds the streak generation warning threshold.

  According to the above configuration, when streak-generated document data is generated in the first job including processing of a plurality of read image data, and the continuous number of streak-generated document data is equal to or less than the streak generation warning threshold, The continuous number of streaked document data in one job is held. In the second job including processing of a plurality of read image data, a streak generation warning device performs a streak generation warning device when the continuous number of streak generation original data from the first job exceeds a streak generation warning threshold. Make it.

  Therefore, when a streak image is generated in the read image data of the document, a streak generation warning can be promptly performed.

  An image reading apparatus according to the present invention includes any one of the above-described image processing apparatuses, and reads an image of a document while acquiring the read image data while conveying the document to a reading position.

  In an image reading apparatus that reads an image of an original while conveying the original to a reading position and acquires read image data, a streak image is likely to be generated in the read image data due to dust or dirt on an optical path for reading the original. When such an image reading apparatus includes any one of the image processing apparatuses described above, it is possible to provide an image reading apparatus that can accurately detect a streak image in the read image data.

  The above-described image reading apparatus reads the front and back surfaces of a document when reading an image of a single-sided document having an image formed only on the front surface. It is good also as a structure which detects a streak image.

  According to the above configuration, when reading an image of a single-sided document having an image formed only on the front surface, the image reading device reads the front and back surfaces of the document, and the image processing device reads the back surface of the document. A streak image is detected for image data.

  As a result, even when reading an image of a single-sided original, a streak image can be detected from the read image data on the back side, and it is possible to grasp whether or not a streak image is generated in the image reading apparatus. it can.

  An image forming apparatus according to the present invention includes the above-described image reading apparatus and prints an image based on the read image data processed by the image processing apparatus.

  Therefore, a streak image is detected for the read image data, and a situation in which an image including a streak image is printed can be prevented.

  As described above, according to the configuration of the present invention, for example, read image data of a document due to the presence of dust or dust when using an image reading device (an image reading device using ADF) that reads an image while moving the document. The generation of streak images that do not exist in the original can be detected with high accuracy. In this case, it is not necessary to perform a special operation for detecting the streak image, and the streak image can be detected with high accuracy from the normal read image data.

1 is a block diagram illustrating an outline of a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a structure of an image input apparatus as an image reading apparatus provided with an automatic document feeder shown in FIG. 1. It is a block diagram which shows the structure of the stripe detection process part shown in FIG. It is a flowchart which shows the stripe detection operation | movement in the stripe detection process part shown in FIG. 3 is a flowchart showing an operation for giving a warning when streaked document data is detected in the image forming apparatus shown in FIG. 1. 2 is a block diagram illustrating an example of a hardware configuration in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing a state in which one vertical streak exists in the sub-scanning direction in a determination region of read image data extracted by a determination region extraction unit illustrated in FIG. 3.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing an outline of the configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus includes an image input device 111, an image processing device 112, an image output device 113, an image display device 114, a transmission / reception unit / storage unit 115, a control unit 116, and an operation unit 117.

  The image processing device 112 processes image data acquired from the image input device 111 or the transmission / reception unit / storage unit 115 and outputs the processed image data to the image output device 113 or the image display device 114.

  The image input device 111 has a function as a scanner, and optically reads an image formed on a document and generates image data. For this purpose, the image input device 111 includes a CCD (Charge Coupled Device) line sensor (not shown), and converts the light reflected from the original to R, G, B (R: red, G: green, B: blue). Convert to color-separated electrical signals. Details of the image input device 111 will be described later.

  The image output device 113 has a function as a printer, and prints image data processed by the image processing device 112 on a medium such as paper. Accordingly, the image output device 113 is a printing device that reproduces an image, such as an electrophotographic printer or an inkjet printer.

  The image display device 114 displays the contents of the processing (operation) performed in the image forming device, the image of the image data processed by the image processing device 112, or the image of the intermediate image data when the image processing device 112 processes. Or display. Therefore, the image display device 114 is a device that displays an image such as a liquid crystal display installed on an operation panel of a copying machine or a multifunction machine.

  The transmission / reception unit / storage unit 115 transmits / receives image data and control signals input to or output from the image processing apparatus 112 via the network. The transmission / reception unit / storage unit 115 stores image data processed by the image processing apparatus 112. The image data stored in the transmission / reception unit / storage unit 115 is image data input from the image input device 111 and image data transmitted / received by the transmission / reception unit / storage unit 115. Further, the transmission / reception unit / storage unit 115 may have a function as a work memory when the control unit 116 executes control processing.

  The control unit 116 performs settings for various types of image processing executed by the image processing apparatus 112 and controls each unit included in the image processing apparatus 112. The control unit 116 also controls the image input device 111 and the image output device 113 to generate an image to be displayed by the image display device 114. Further, the control unit 116 controls the transmission / reception unit / storage unit 115 to perform transmission / reception of image data, and further causes the recording / reception unit / storage unit 115 to store and read image data from / to a recording device such as an HDD. . The operation unit 117 is an input unit through which an operator inputs setting information for a job performed in the image forming apparatus. The operation unit 117 includes a display unit including a liquid crystal display, a button for setting, and the like.

  The image processing apparatus 112 includes an analog / digital conversion unit (hereinafter referred to as “A / D conversion unit”) 121, a shading correction unit 122, an input processing unit 123, an area separation processing unit 124, a color correction unit 125, a black generation / The undercolor removal unit 126, the spatial filter unit 127, the halftone generation unit 128, the streak detection processing unit 129, and the display control unit 130 are included.

  The A / D converter 121 converts a color image signal (RGB analog signal) input from a CCD line sensor included in the image input device 111 into a digital signal. The shading correction unit 122 removes various distortions generated in the illumination system, the imaging system, and the imaging system of the image input device 111, which are included in the digital signal.

  The input processing unit 123 performs γ correction on the RGB digital signal processed by the shading correction unit 122. In the following description, an image using RGB digital signals is referred to as an RGB image.

  The display control unit 130 generates a screen to be displayed on the image display device 114 and controls the display operation of the image display device 114. Information displayed by the display control unit 130 is the status of processing executed by the image processing apparatus 112 and setting information for the processing. In addition, when a streak or the like is detected by the streak detection processing unit 129, information for prompting the operator to pay attention is also displayed.

  The color correction unit 125 performs color space conversion of the RGB image into a CMY (C: cyan, M: magenta, Y: yellow) image, and further performs processing for improving color reproducibility.

  The region separation processing unit 124 determines whether each pixel of the RGB image belongs to one of a plurality of types of regions such as black characters, color characters, halftone dots, and photographic paper photographs (continuous tone regions). To do. In addition, the region separation processing unit 124 outputs the determination result to the black generation / undercolor removal unit 126, the spatial filter unit 127, and the halftone generation unit 128 as region separation data representing the type of region to which each pixel belongs. In each unit to which the region separation data is input, processing corresponding to the type of region is executed.

  The black generation / under color removal unit 126 converts a CMY image that can be expressed with three colors of toner into a CMYK (K: black) image expressed with four colors of toner. The spatial filter unit 127 performs enhancement processing and smoothing processing on the CMYK image. The halftone generation unit 128 performs gradation reproduction processing to print out the CMYK image.

  FIG. 2 is a longitudinal sectional view showing a structure of an image input apparatus 111 as a scanner provided with an automatic document feeder (ADF). As shown in FIG. 2, the image input device 111 includes a lower housing 1, an upper housing 2, and a paper discharge tray 3. In the image input device 111, a document is read in a stationary reading mode in which an original is stopped and an image is read, a traveling reading mode in which an image is read while the original is being conveyed, and a double-sided reading mode in which an image on both sides of the original is read while being conveyed. The image can be read.

  The selection of the reading mode is performed by the operation unit 117, for example, and the selected reading mode is transmitted as a reading mode signal. When the copy button is pressed while a document is set on the document set tray 22 (a document is detected by the document set detection sensor), the document image is set to be read in the traveling reading mode. Yes. When reading in the double-sided reading mode, the double-sided reading mode is set from the operation unit 117.

  In the image input device 111, when a document is placed on the first contact glass 11 serving as a document table, the document is detected by a document size sensor (for example, a photo sensor) disposed in the lower housing 1 or in the vicinity of the first contact glass 11. When the size is detected and the copy button is pressed, the original is read in the static reading mode.

  The image input device 111 reads the document image by the first reading unit 10 in the lower housing 1 in the stationary reading mode, and performs the reading by the second reading unit 23 in the upper housing 2 in the traveling reading mode. It has become. In the double-sided reading mode, both the first reading unit 10 and the second reading unit 23 are used at the same time.

  As shown in FIG. 2, the lower housing 1 includes a first reading unit 10 and a first contact glass 11, and the first reading unit 10 includes a first scanning unit 12, a second scanning unit 13, and an imaging lens 14. A CCD (Charge Coupled Device) 15 and a second contact glass 16.

  The first contact glass 11 is a document table on which a document to be read in the stationary reading mode is placed. The first scanning unit 12 exposes the document while moving from the left to the right along the first contact glass 11 at a constant speed V. For this purpose, the first scanning unit 12 includes a light source (exposure lamp) 50 and a first reflecting mirror 51 that guides the reflected light of the document to the second scanning unit 13.

  The second scanning unit 13 follows the first scanning unit 12 and moves at a speed of V / 2, and the second reflection that guides the light from the first reflection mirror 51 to the imaging lens 14 and the CCD 15. A mirror 52 and a third reflecting mirror 53 are provided.

  The imaging lens 14 images the reflected light from the third reflection mirror 53 on the CCD 15. The CCD 15 converts the light from the imaging lens 14 into an analog electric signal. This electric signal is converted into digital image data by the image processing device 112.

  The first reading unit 10 reads a document image placed on the first contact glass 11 and reads a document image conveyed by a member of the upper housing 2.

  When the first scanning unit 12 reads a document on the first contact glass 11, it is detected by a document size detection means (not shown) from the position Pos1 to the position Pos2 shown in FIG. It moves by a predetermined distance according to the document size. On the other hand, when reading the conveyed document, it stops at the position Pos3. Further, during standby that is not in use, the vehicle is stopped at a home position that is a position of Pos0 (not shown) between the positions of Pos1 and Pos3.

  A document reference plate (not shown) is provided at the front end side position of the first contact glass 11. This document reference plate serves as an index indicating the size and placement direction of the document placed on the first contact glass 11. Therefore, the operator of the image forming apparatus can easily place the document on the first contact glass 11 according to the document reference plate.

  The second reading unit 23 reads an image of a document placed on the document set tray 22, and includes a document conveyance unit 31, an image sensor unit 32, a document conveyance path 33, and a document discharge unit 34.

  The document transport unit 31 takes in a document placed on the document set tray 22 and transports it on the document transport path 33. The image sensor unit 32 reads an image of a document being conveyed. The document discharge unit 34 discharges the document after the image is read by the image sensor unit 32 to the sheet discharge tray 3.

  The document transport unit 31 includes a feeding auxiliary roller 61, a document set detection sensor 62, a document pressing plate 63, a friction pad 64, a feeding timing sensor 65, a feeding roller 66, and an alignment roller pair 67.

  The auxiliary feeding roller 61 and the document holding plate 63 draw the document detected by the document set detection sensor 62 into the second reading unit 23. The friction pad 64, the feeding roller 66, and the alignment roller pair 67 are configured to guide the drawn originals to the image sensor unit 32 one by one based on the detection result of the feeding timing sensor 65.

  The alignment roller pair 67 has an electromagnetic clutch (not shown) on its drive shaft, and can control the transmission of driving force from a drive motor (not shown), and stops when there is no document. is doing. When the leading edge of the document comes into contact with the feeding timing sensor 65 and a predetermined signal is transmitted from this sensor, the document is set to rotate in the direction of transporting the document downstream.

  When the alignment roller pair 67 is stopped, the leading edge of the document conveyed from the upstream side by the friction pad 64 and the feeding roller 66 contacts the nip portion of the alignment roller pair 67 to form a predetermined deflection in the document. After that, the document is rotated so as to be conveyed downstream. At this time, the leading edge of the document is aligned by the nip portion of the alignment roller pair 67 so as to be perpendicular to the conveyance direction. Further, the alignment roller pair 67 forms a part of the document conveyance path 33 with the second contact glass 16.

  The document discharge unit 34 includes a document discharge roller pair 69 and a document discharge sensor 59. The upper roller of the document discharge roller pair 69 is a driving roller, and is integrally provided on the left side of the upper housing 2 and is driven by a driving mechanism in the upper housing 2. The upper roller of the document discharge roller pair 69 sandwiches and conveys the document that has passed through the document conveyance path 33 with the lower roller (driven roller) of the document discharge roller pair 69 that is rotatably provided on the lower housing 1 side. To be discharged onto the paper discharge tray 3.

  The document discharge sensor 59 is disposed on the downstream side of the document discharge roller pair 69, and transmits the discharge of the document to a reading control unit described later.

  An image sensor unit (CIS: Contact Image Sensor) 32 is provided in the upper housing 2 and reads an upper image in a document traveling on the document conveyance path 33. The open door 24 can open a space above the image sensor unit 32.

Next, the operation of the image input apparatus 111 configured as described above will be described.
The image input device 111 can select only the single-sided mode in the stationary reading mode, and only the first reading unit 10 is used for reading a document. At this time, the first scanning unit 12 of the first reading unit 10 is first arranged at the home position (Pos0 between Pos3 and Pos1 in FIG. 2). Then, in accordance with an instruction from the reading control unit, the document placed on the first contact glass 11 is moved from the position Pos1 to the Pos2 side together with the second scanning unit 13 while scanning. As a result, the CCD 15 can receive the reflected light corresponding to the document image. As described above, the first reading unit 10 reads an image formed on the lower surface (front surface) of a stationary document.

  In the traveling reading mode, both the single-sided reading mode and the double-sided reading mode can be selected. In the single-sided reading mode of the traveling reading mode, only the first reading unit 10 is used for reading a document. When there is an instruction for this mode, the first scanning unit 12 of the first reading unit 10 moves from the position of the home position Pos0 to the position of Pos3 and stops. I do. Then, in response to an instruction from the reading control unit, the CCD 15 reads the image of the document conveyed on the document conveyance path 33 from the lower side through the second contact glass 16. That is, the first reading unit 10 reads an image formed on the lower surface (front surface) of the document.

  In the double-sided reading mode of the traveling reading mode, both the first reading unit 10 and the image sensor unit 32 are used for reading a document. At this time, the first scanning unit 12 of the first reading unit 10 is stopped at the position Pos3 as in the single-sided reading mode of the traveling reading mode.

  Then, in response to an instruction from the reading control unit, the first reading unit 10 reads an image of the document conveyed through the document conveyance path 33 from the lower side through the second contact glass 16. Similarly, the image sensor unit 32 reads an image formed on the upper surface (back surface) of the conveyed document from above.

  As described above, in the double-sided reading mode of the present reading apparatus, the first reading unit 10 and the image sensor unit 32 read the images on both the front and back sides of the transported document at a time from the vertical direction.

  When reading an image of a single-sided document having an image formed only on the front side, the front side and the back side of the document may be read, and a streak image may be detected for the read image data on the back side of the document. . In this case, reading of the front side of the document is performed by the first reading unit 10, and reading of the back side of the document is performed by the second reading unit 23.

Next, the streak detection processing unit 129 included in the image processing apparatus 112 will be described.
FIG. 3 is a block diagram showing the configuration of the streak detection processing unit 129 shown in FIG.

  As shown in FIG. 3, the streak detection processing unit 129 includes a determination region extraction unit 201, an adjacent pixel density difference calculation unit (edge pixel detection unit) 202, a rising / falling edge detection unit (edge pixel detection unit) 203, Pixel determination unit 204, streak pixel counting unit (streaked pixel number counting unit) 205, edge pixel counting unit (edge pixel number counting unit) 206, plain region determining unit 207, streak presence / absence determining unit 208, edge threshold setting unit 209, plain An area determination threshold setting unit 210 and a streak presence / absence determination threshold setting unit 211 are provided.

  The determination area extraction unit 201 extracts several lines on the reading leading edge side of the original or several lines on the reading rear end side of the original reading image data (RGB image) as the determination area. As described above, the number of lines on the read leading end side of the read image data or the number of lines on the read back end side of the original is set as the determination area. Generally, the original image is drawn on the end of the original. This is because there are few areas. By setting the determination area in this way, it is possible to prevent erroneous determination that a line or an edge intentionally drawn on a document is erroneously determined as a streak.

  The streak detection processing unit 129 determines the attribute of the determination region extracted by the determination region extraction unit 201 for each pixel included in the document image data with each pixel as a target pixel. In this determination, an n × m pixel block centered on the target pixel is used. n · m is a natural number, for example, 7.

  The adjacent pixel density difference calculation unit 202 calculates a density difference between each pixel included in the n × m pixel block and a pixel adjacent to each pixel.

  The rising / falling edge detection unit 203 compares the density difference calculated by the adjacent pixel density difference calculation unit 202 with an edge threshold (for example, 10), and determines whether each pixel is an edge pixel. For those determined to be edge pixels, whether the pixel is a rising edge pixel or a falling edge pixel is determined from the density difference value calculated by the adjacent pixel density difference calculating unit 202. In this determination, when the density value of the pixel adjacent to the right side of the pixel is subtracted from the density value (pixel value) of the left pixel, the rising edge pixel is set when the density value is negative, and the falling value is set when the density value is positive. It is determined as an edge pixel. The edge threshold (for example, 10) is set in the edge threshold setting unit 209.

  The edge pixel counting unit 206 counts the pixel of interest that is the center of the n × m pixel block that is determined as the edge pixel.

  The streak pixel determination unit 204 determines whether or not the pixel of interest at the center of the n × m pixel block is a streak pixel. In this determination, the pixel of interest is determined to be a streak pixel when all of the following first to third conditions are satisfied.

  The first condition is that the pixel of interest at the center of the n × m pixel block is an edge pixel, and the second condition is that for each line in the main scanning direction in the n × m pixel block, a rising edge pixel and One set of falling edge pixels exists, and the third condition is that edge pixels (edge pixels in the horizontal direction) do not exist in all lines in the sub-scanning direction. As a result, there are one pair of edges having a density difference in the main scanning direction, and no edge having a density difference exists in the sub scanning direction. It can be determined that one vertical stripe exists. Note that the edge pixels in the vertical direction are detected under the first condition and the second condition.

  The streak pixel counting unit 205 counts the pixel of interest, which is the center of the n × m pixel block, determined by the streak pixel determination unit 204 as a streak pixel.

  The plain area determination unit 207 intentionally draws the determination area extracted by the determination area extraction unit 201 on the document by comparing the edge pixel count number in the edge pixel count unit 206 with the plain area determination threshold value. It is determined whether the line is a plain area where no line exists. In this determination, the plain area determination threshold value is set to the number of sub-scan lines in the determination area × a predetermined value (for example, 5). When the edge pixel count number <the plain area determination threshold value, the determination area is determined as a plain area. On the other hand, when the edge pixel count number ≧ the plain area determination threshold value, the determination area is determined not to be a plain area.

  When the plain area determination unit 207 determines that the determination area is a plain area where a line intentionally drawn on the document does not exist, the streak pixel determination unit 208 performs the streak pixel count in the streak pixel count unit 205. By comparing the number and the streak presence / absence determination threshold, it is determined whether or not a streak that does not exist in the document has occurred in the determination region determined to be a plain region. In this determination, the streak presence / absence determination threshold is set to the number of pixels in the sub-scanning direction of the determination region × a predetermined value (for example, 2). When the streak pixel count number> the streak presence / absence determination threshold value, it is determined that a streak that does not exist in the document has occurred in the read image data of the document, that is, the determination region. On the other hand, when the streak pixel count number ≦ the streak presence / absence determination threshold, it is determined that no streak that does not exist in the document has occurred in the read image data of the document, that is, the determination region.

  Regarding the setting of the streak presence / absence determination threshold value, for example, when a vertical streak composed of three pixels in the sub-scanning direction exists in the determination region, the streak pixel is usually a rising pixel and a falling pixel in the main scanning direction for each vertical streak. Two pixels are detected. On the other hand, among the vertical stripes composed of three pixels, the central vertical stripe pixel may not be determined as an edge pixel due to the density difference between the adjacent vertical stripe pixels. Accordingly, the streak presence / absence determination threshold value is determined by taking into account that there are at least two streak pixels, ie, rising and falling pixels in the main scanning direction, and the number of pixels in the sub-scanning direction (number of lines in the sub-scanning direction) in the determination region The value is doubled. The streak presence / absence determination threshold is compared with the number of streak pixels counted by the streak pixel counting unit 205, and the streak presence / absence determination unit 208 compares the streak presence / absence determination unit 208 with the streak presence / absence determination threshold. It is determined that an image exists.

  As described above, the streak presence / absence determination threshold value is the minimum of the number of streak pixels expected to be generated in one line in the main scanning direction of the determination region, compared to the number of pixels in the sub scanning direction in the determination region (number of lines in the main scanning direction). It is preferable to set the value multiplied by the value.

  In the above configuration, the operation of the streak detection processing unit 129 of the image processing apparatus 112 will be described below. FIG. 4 is a flowchart showing the streak detection operation in the streak detection processing unit 129 shown in FIG.

  When the document image data is input, the determination area extraction unit 201 extracts several lines at the leading edge or several lines at the trailing edge as the determination area (S11). This determination area is, for example, 300 lines of document image data at a resolution of 600 dpi.

  Next, the adjacent pixel density difference calculating unit 202 calculates a density difference (ab) between each pixel a of the n × m pixel block centered on the target pixel and its adjacent pixel b (right adjacent pixel). Calculate (S12).

  Next, the rising / falling edge detecting unit 203 compares the absolute value of the adjacent density difference (ab) calculated by the adjacent pixel density difference calculating unit 202 with the edge threshold value, and each pixel is an edge pixel. It is determined whether or not there is (S13). In this determination, when the absolute value of the adjacent density difference (ab)> the edge threshold value, the pixel is determined as an edge pixel.

  Next, the edge pixel counting unit 206 counts, as edge pixels, pixels in which the target pixel that is the center of the n × m pixel block is determined as the edge pixel (S14).

  Also, the rising / falling edge detection unit 203 determines whether or not the adjacent density difference (ab)> 0 (S15). In this determination, if the adjacent density difference is negative (ab−0 <0), it is determined as a rising pixel (S16), and if the adjacent density difference is positive (ab−0), the falling pixel is determined. (S17). The rising / falling edge detection unit 203 and the edge pixel count unit 206 perform the processing of S12 to S17 for all the pixels in the n × m pixel block.

  Next, the streak pixel determination unit 204 determines that the target pixel at the center of the n × m pixel block is a streak pixel only when all of the first to third conditions are satisfied in the n × m pixel block. (S18). That is, the pixel of interest at the center of the n × m pixel block is an edge pixel (first condition), and the rising edge pixel and the falling edge pixel are determined for each line in the main scanning direction in the n × m pixel block. Only when there is one set (second condition) and no edge pixel (horizontal edge pixel) exists in all lines in the sub-scanning direction (third condition), at the center of the n × m pixel block. It is determined that a certain pixel of interest is a streak pixel (S18).

  Next, the streak pixel counting unit 205 counts the pixel of interest that is the center of the n × m pixel block as a streak pixel as a streak pixel (S19).

  The streak detection processing unit 129 repeats the above processing of S12 to S19 until it finishes for all the pixels in the RGB image of the determination area (S20), and if the processing ends, it proceeds to S21.

  Next, the plain area determination unit 207 compares the edge pixel count number in the edge pixel count unit 206 with the plain area determination threshold value, and determines whether the determination area for performing streak detection is a plain area where there is no writing other than streak. It is determined whether or not (S21).

  In the determination of S21, the plain area determination threshold value is the number of sub-scan lines in the determination area × a predetermined value (for example, 5). In the determination of S21, if the edge pixel count number <the plain area determination threshold value, the determination area is determined as a plain area. In this case, the determination area is a determination target of whether or not streaks are generated in the RGB image.

  On the other hand, when the edge pixel count number ≧ the plain area determination threshold value, it is determined that the determination area is not a plain area (S22). In this case, it is determined that an area (line or the like) intentionally drawn on the document exists in the determination area, and the determination area is not a target for determining whether or not a streak has occurred. In this case, the continuous number of originals with streaks described later is not reset.

  The streak presence / absence determination unit 208 determines the streak pixel count number and the streak presence / absence determination in the streak pixel count unit 205 when the determination region is determined to be a plain region in S21 (when the edge pixel count number <the plain region determination threshold value). The threshold value is compared to determine whether or not a streak that does not exist in the document has occurred in the determination area (S23).

  In the determination of S23, the streak presence / absence determination threshold value is the number of pixels in the sub-scanning direction of the determination region × a predetermined value (for example, 2). In the determination of S23, if the streak pixel count number> the streak presence / absence threshold, it is determined that a streak that does not exist in the document has occurred in the read image data of the document (S25). On the other hand, if the streak pixel count number ≦ the streak presence / absence threshold, it is determined that no streak that does not exist in the original has occurred in the read image data of the original (S24).

  Next, the operation of the image processing apparatus 112 that issues a warning when the streaked original data in which a streak image that does not exist in the original is detected in the read image data will be described. FIG. 5 is a flowchart showing the operation of the image forming apparatus that issues a warning when streaked document data is detected.

  The streak detection processing unit 129 of the image processing device 112 performs a detection operation for streaked document data when the operator selects the travel reading mode (using the ADF function) of the image input device 111. The determination as to whether or not the data is streaked document data is performed not on the entire read image data of the document but on the determination region corresponding to the leading edge or the trailing edge of the document as described above. Further, for example, the control unit 116 counts the number of read image data (continuous number of streaked originals) that is continuously determined to be streaked original data in the streak detection processing part 129. Furthermore, the control unit 116 displays a warning on the display unit of the operation unit 117, for example, when the continuous number of streaked originals exceeds a streak generation warning threshold. The streak occurrence warning threshold is set to 3, for example. Note that the method of warning the streak generation for the operator may be performed by voice or by display and voice in addition to the warning display on the display unit (streaks generation warning device) of the operation unit 117. When the warning is performed by voice, the warning should be simply sounded or the contents to be displayed on the display unit may be conveyed by synthesized voice.

  As shown in FIG. 5, in the image processing apparatus 112, when the ADF function, that is, the traveling reading mode is selected in the image input apparatus 111 (S51), each read image data of the original sequentially read and read by the ADF function. The line detection processing unit 129 performs the line detection process (S52). That is, the streak detection processing unit 129 determines whether or not the read image data of the document is streaked document data.

  As a result of the streak detection process in S52, if the determination area of the read image data is not a plain area (S53), the process proceeds to S59. On the other hand, as a result of the streak detection processing in S52, if the determination area of the read image data is a plain area, it is determined whether or not the read image data is streaked document data (S54).

  If the result of determination in S54 is that the read image data is not streaked document data, the control unit 116 resets the continuous streaked document count (S58), and proceeds to S59.

  On the other hand, if the result of determination in S54 is that the read image data is streak-generated document data, the control unit 116 increases the counted number of streak-generated documents by 1 (S55), and the streak-generated document continuous number is a streak generation warning. It is determined whether or not it has become larger than a threshold value (for example, 3) (S56).

  If the result of determination in S56 is that the streak-generated document continuous number is not larger than the streak generation warning threshold value, the process proceeds to S59. On the other hand, if the streak occurrence document continuous number is larger than the streak occurrence warning threshold, the control unit 116 displays a streak occurrence warning on the display unit of the operation unit 117, for example (S57).

  The processes of S51 to S57 described above are repeated until the process for the read image data of all the originals set in the image input device 111 is completed (S59), and the process for the read image data of all the originals is completed. If so, the process ends.

  As described above, in the image processing apparatus 112 according to the present embodiment, the streak presence / absence determination unit 208 determines that the target pixel is a streak pixel when all of the first to third conditions are satisfied. Can be performed with high accuracy. Accordingly, it is possible to accurately detect the occurrence of a streak image that does not exist in the original in the read image data of the original due to the presence of dust or dirt when the image input device 111 (ADF) is used.

  Further, the image processing apparatus 112 warns the operator that a streak has occurred in the read image data when a streak image that does not exist in the original has continuously occurred in the read image data of the original. It is like that. As a result, the operator can remove the dust and dust that cause the streak image that does not exist in the document from the read region of the document, and can solve the problem of the generation of the streak image in the read image data of the document.

  The reason for determining whether or not a streak generation warning is necessary is based on the continuous number of pieces of streak-generated document data. First, in order to reduce the possibility of erroneously determining a line intentionally drawn on a document as a streak. It is. Second, in the image input device 111, streaked images generated in the read image data due to dust and dirt attached when using the ADF may be removed while the ADF is used. This is because the streak occurrence warning is prevented even in such a case.

  Further, the continuous document generation number of streaks is stored in the transmission / reception unit / storage unit 115 without being reset even when the reading operation of a part of a document (a series of documents) set in the image input device 111 is completed. It is inherited when the next document is read. As a result, the operator can be warned early of the occurrence of a streak image in the read image data without depending on only the number of streaks generated when the image input device 111 (ADF) is used once.

  Further, when the image input device 111 (ADF) is compatible with double-sided scanning of a document, the streak-generated document continuous count is counted on each of the front and back surfaces. Even when the operator selects only one side of the original document, both sides of the original document are read and the continuous number of streaked originals for the scanned image data on the back side is continuously counted. A streak warning may be made when double-sided scanning of a document is selected.

  In addition, the image input apparatus 111 may include the function of the image processing apparatus 112, particularly the function of the streak detection processing unit 129 as an image reading apparatus.

  Next, a hardware configuration of the image forming apparatus according to the embodiment of the present invention will be described. FIG. 6 is a block diagram illustrating an example of a hardware configuration in the image forming apparatus according to the embodiment of the present invention.

  As shown in FIG. 6, the image forming apparatus 900 includes an image processing unit 910 (corresponding to the image processing apparatus 112 and the control unit 116 in FIG. 1), a scanner 920 (corresponding to the image input apparatus 111 in FIG. 1), and a hard disk device ( Hereinafter, it is referred to as a unit HDD (corresponding to the transmission / reception unit / storage unit 115 in FIG. 1) 930, a drive device 940, and a printer 980 (corresponding to the image output device 113 in FIG. 1). The image processing unit 910 controls each unit connected to the image processing unit 910 and processes image data output from the image forming apparatus 900.

  The image processing unit 910 includes a CPU 901, ROM 902, RAM 903, image processing ASIC 904, scanner interface (hereinafter simply referred to as scanner I / F) 912, HDD interface (hereinafter simply referred to as HDD-I / F) 913, drive interface ( Hereinafter, it has a printer interface (hereinafter simply referred to as printer I / F) 918 and a communication interface (hereinafter simply referred to as communication I / F) 919.

  The CPU 901 controls each unit of the image processing unit 910 and each unit connected to the image processing unit 910 by executing a computer program. The ROM 902 stores a computer program executed by the CPU 901, for example.

  The CPU 901 may also have a function of performing automatic document determination processing, drawing command generation processing, and image generation processing with non-display content added.

  The RAM 903 stores image data to be processed when the image processing ASIC 904 and the CPU 901 execute a computer program. Note that this image data may be stored in the ROM 902.

  The image processing ASIC 904 performs various processes on the image data. The image processing ASIC 904 performs, for example, at least one of region separation processing, background removal processing, color correction processing, black generation / undercolor removal processing, spatial filter processing, output tone correction processing, and halftone generation processing. You may do it.

  The scanner I / F 912 receives image data input from the scanner 920 and performs image processing according to the characteristics of the scanner 920. The HDD-I / F 913 inputs and outputs image data stored in the HDD 930 based on the control of the CPU 901. The drive I / F 914 inputs / outputs data to / from the portable recording medium 941 inserted into the drive device 940.

  A printer I / F 918 is an interface for outputting image data processed by the image processing unit 910 to the printer 980. The communication I / F 919 is an interface for communicating image data or control signals with other apparatuses from the image processing unit 910 via the network 990.

  The scanner 920 optically reads a document on which an image is formed and outputs read image data. The read image data output from the scanner 920 may be an analog signal or a digital signal converted from the analog signal.

  The HDD 930 stores image data processed by the image processing unit 910. The HDD 930 stores, for example, image data input from the scanner 920, image data input from the communication I / F 919, and intermediate image data generated by processing of the CPU 901 and the image processing ASIC 904. The drive device 940 writes and reads data to and from the portable recording medium 941 by inserting the portable recording medium 941. The portable recording medium 941 stores a computer program executed by the CPU 901, for example.

  The printer 980 forms and outputs the image data processed by the image processing unit 910 on a medium such as paper.

  Each block of the image forming apparatus, in particular, the image processing apparatus 112 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the image processing apparatus 112 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is a recording medium in which program codes (execution format program, intermediate code program, source program) of a control program of the image processing apparatus 112, which is software that realizes the above-described functions, are recorded so as to be readable by a computer. This can also be achieved by supplying the image processing apparatus 112 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the image processing apparatus 112 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in the embodiments are also included. It is included in the technical scope of the present invention.

  The present invention can be used for a scanner, a printer, an image processing apparatus, a copying machine, and a multifunction machine.

111 Image input device (image reading device)
DESCRIPTION OF SYMBOLS 112 Image processing apparatus 113 Image output apparatus 116 Control part 117 Operation part (streaks generation | occurrence | production warning apparatus)
129 Line detection processing unit 201 Determination region extraction unit 202 Adjacent pixel density difference calculation unit (edge pixel detection unit)
203 Rising / falling edge detection unit (edge pixel detection unit)
204 streak pixel determining unit 205 streak pixel counting unit (streaked pixel number counting unit)
206 Edge Pixel Counting Unit (Edge Pixel Counting Unit)
207 Solid region determination unit 208 Line presence / absence determination unit 209 Edge threshold setting unit 210 Plain region determination threshold setting unit 211 Line presence / absence determination threshold setting unit

Claims (11)

In an image processing apparatus including a streak detection processing unit that detects read image data including a streak image with respect to read image data read from a document,
The streak detection processing unit
For the determination region set in the read image data read from the document, the edge pixel included in the determination region is detected, and the pixel density of the detected edge pixel is increased toward the main scanning direction in reading the document. An edge pixel detection unit that determines whether the rising edge pixel is a falling edge pixel that has a pixel density that decreases in the main scanning direction in reading a document;
Each pixel in the determination area is set as a pixel of interest, a block including a plurality of pixels in the main scanning direction and the sub-scanning direction is set around the pixel of interest, and the first condition is that the pixel of interest is an edge pixel. For each line in the main scanning direction, there are all the second conditions in which one set of rising edge pixels and falling edge pixels exists, and the third condition in which no edge pixels exist in all lines in the sub-scanning direction in the block. An image processing apparatus comprising: a streak pixel determining unit that determines that the target pixel is a streak pixel when the target pixel is satisfied. The streak detection processing unit
A determination area extraction unit that sets an area on the reading front end side or the reading rear end side of the document in the read image data as the determination area;
An edge pixel number counting unit that counts the number of edge pixels included in the determination region detected by the edge pixel detection unit;
A plain area determination threshold value in which the number of edge pixels for determining whether or not the determination area is a plain area is compared with the number of edge pixels counted by the edge pixel number counting unit, and whether the determination area is a plain area. A plain area determination unit for determining whether or not,
A streak presence / absence determining unit that determines whether or not a streak image is included in the determination region when the determination region is determined to be a plain region by the plain region determination unit. The image processing apparatus according to claim 1. The streak detection processing unit
A streak pixel number counting unit that counts the number of pixels determined to be streak pixels by the streak pixel determination unit;
The streak presence / absence determination unit includes a streak presence / absence determination threshold value that sets the number of streak pixels for determining that a streak image is included in the determination region, and the number of streak pixels counted by the streak pixel number counting unit. The image processing apparatus according to claim 2, wherein the image processing apparatus compares and determines whether or not a streak image is included in the determination area. A streak generation warning device for performing a streak generation warning notifying that a streak image has occurred in the read image data;
A control unit that causes the streak generation warning device to perform a streak generation warning device when the streak presence / absence determination unit determines that a plurality of continuous read image data includes a streak image; The image processing apparatus according to claim 2, wherein: The control unit counts the continuous number of streaked document data that is read image data determined to include a streak image by the streak presence / absence determining unit, and the continuous number exceeds a streak generation warning threshold To cause a streak occurrence warning by the streak occurrence warning device,
When a streak generation document data is generated in a first job including processing of a plurality of read image data, and a continuous number of streak generation document data is equal to or less than the streak generation warning threshold, a streak is generated in the first job. When the number of continuous streaked document data from the first job exceeds the streak generation warning threshold in a second job that holds the continuous number of document data and includes processing of a plurality of read image data, The image processing apparatus according to claim 4, wherein a streak generation warning is issued by the generation warning apparatus.   An image reading apparatus comprising the image processing apparatus according to claim 1, wherein the image reading apparatus acquires the read image data by reading an image of the original while conveying the original to a reading position. When reading an image of a single-sided document with an image only on the front side, scan the front and back sides of the document,
The image reading apparatus according to claim 6, wherein the image processing apparatus detects a streak image of the read image data on the back side of the document.   An image forming apparatus comprising the image reading apparatus according to claim 7, wherein an image is printed based on the read image data processed by the image processing apparatus. In an image processing method for performing streak detection processing for detecting read image data including a streak image with respect to read image data read from a document,
The streak detection process
For the determination region set in the read image data read from the document, the edge pixel included in the determination region is detected, and the pixel density of the detected edge pixel is increased toward the main scanning direction in reading the document. An edge pixel detection step for determining whether the pixel is a rising edge pixel or a falling edge pixel whose pixel density decreases in the main scanning direction in reading a document;
Each pixel in the determination area is set as a pixel of interest, a block including a plurality of pixels in the main scanning direction and the sub-scanning direction is set around the pixel of interest, and the first condition is that the pixel of interest is an edge pixel. For each line in the main scanning direction, there are all the second conditions in which one set of rising edge pixels and falling edge pixels exists, and the third condition in which no edge pixels exist in all lines in the sub-scanning direction in the block. An image processing method comprising: a streak pixel determining step that determines that the target pixel is a streak pixel when the target pixel is satisfied.   The program for functioning a computer as each said part of the image processing apparatus of any one of Claim 1 to 5.   The computer-readable recording medium which recorded the program of Claim 10.

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