JP2011035582A - Image processing apparatus and image forming apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time of image processing for removing an unnecessary region of image data obtained by reading a book document while reducing the cost required for manufacturing of an image processing apparatus. <P>SOLUTION: The image processing apparatus includes an image reading part for reading a document by irradiation with light to generate image data and an image processing part for subjecting the image data to image processing. The image processing part determines the presence or the absence of unnecessary regions within a first region having a first prescribed width from one end part in a lateral direction of a double-page spread of image data toward the inside of image data and width a second region having a second prescribed width from the other end toward the inside of image data and replaces pixels in unnecessary regions within the first region and within the second region with white. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing apparatus that performs image processing on image data obtained by reading a document. The present invention also relates to an image forming apparatus provided with the image processing apparatus.

  In reading a document, there are cases where light is irradiated on the document and image data is generated based on the reflected light of the document. The image data obtained by reading a bound document such as a book (hereinafter referred to as “book document”) includes an unnecessary image because it is a book document. For example, when a book document is placed on a document table (contact glass), the center portion (back cover portion) of the spread page may float (cannot be in close contact) with the document table. When floating from the platen, a vertical solid image appears at the center of the spread page in the image data. Also, a black solid image due to the size of the spread page being narrower than the reading range may appear at the left and right ends of the spread page of the image data. Further, as a result of reading the edge portion of each page of the book document (side surface part of the book document), a striped image may appear.

An image processing apparatus for processing such a useless image generated when a book document is read is described in Patent Document 1. Specifically, Patent Document 1 discloses a binarizing unit that binarizes an image signal read from a document reading unit with a predetermined threshold, and a region outside the document based on the binarized binary image signal. The forcible signal generator for extracting the image and the area extracted by the forcible signal generator are all output as white data, and the other areas are characters whose threshold value can be variably set to be binarized and output as image data. An image processing apparatus having a processing binarization unit is described. With this configuration, the outside of the document or the book center portion of the book document is extracted as a region outside the document, and an excellent output image is obtained in which the outside of the document or the book center portion does not become a black belt. (See Patent Document 1: Claim 1, paragraph [0042], etc.)
JP-A-10-313406

  As described above, when a book document is read, the image data includes an unnecessary image because it is a book document. In order to remove unnecessary images, for example, the image processing apparatus detects a solid black image in the image data and performs processing such as replacing the solid black image with white.

  In recent years, as the resolution of image data is increasing, for example, image processing for detecting a black solid image or the like is performed on all pixels of the image data, and thus it takes time to complete the processing. There's a problem. In order to shorten the processing time, it is necessary to increase the image processing speed. In order to increase the image processing speed, a high-speed memory, a processing circuit, and the like are required, and there is a problem that the cost required for manufacturing the image processing apparatus can be increased. Further, since image processing for erasing unnecessary images is performed for all pixels of image data, it may be necessary to mount a large-capacity memory. In this respect as well, the cost required for manufacturing the image processing apparatus is high. There is a problem that can be.

  Note that the image processing apparatus described in Patent Document 1 may certainly obtain an image in which the inside of the document does not have a black belt shape. However, in the image processing apparatus of Patent Document 1, in addition to the binarization processing for all pixels, the image data of the document is handled as n × m columns of pixels for the region determination processing of the continuous black pixels as unnecessary images. , Read by main scanning in the n direction and sub scanning in the m direction. In this scanning, one pixel row is reciprocated once in the main scanning direction in the forward and backward directions and then sub-scanned, and the next pixel row (m + 1) is similarly subjected to one reciprocating main scanning (Patent Document 1: Paragraph [0030]. , [0035] etc.). Therefore, in order to keep the processing time within a desired time, a high-speed and high-speed processing circuit may be required. In addition to the image data storage area, the memory may store the presence / absence of forcing signal output, and may require a buffer memory or line memory, resulting in a large capacity. Therefore, the invention described in Patent Document 1 cannot cope with the problem that time is required for image processing and the cost required for manufacturing the image processing apparatus can be high because unnecessary images are removed.

  In view of the above-described problems of the prior art, the present invention shortens the image processing time for removing unnecessary areas from image data obtained by reading a book document while reducing the cost required for manufacturing the image processing apparatus. The task is to continue.

  In order to achieve the above object, an image processing apparatus according to claim 1 includes an image reading unit that irradiates light and reads an original to generate image data, and an image processing unit that performs image processing on the image data. And the image processing unit includes a first region having a first predetermined width from one end in the left-right direction of the spread page of the image data toward the inside of the image data, and the other end from the other end. It is determined whether or not there is an unnecessary area in the second area having the second predetermined width toward the inside of the image data, and the unnecessary area in the first area and the pixels in the unnecessary area in the second area are determined. Replaced with white.

  According to this configuration, image processing for detecting and determining an unnecessary area in image data (open page image data) read by opening a book document is not performed on all pixels of the image data, and the first area In the second area, the presence / absence of an unnecessary area is determined, and the pixels in the unnecessary area are replaced with white. As a result, the amount of data to be processed can be reduced and the image processing time can be shortened compared to the case where image processing is performed on all the pixels of the image data. Further, it is not necessary to increase the image processing speed of the image processing unit. Also, it is not necessary to increase the amount of memory. Therefore, the cost required for manufacturing the image processing apparatus can be reduced. The first predetermined width and the second predetermined width can be arbitrarily set. For example, in the case of A3 size image data, the default values are set to 15 to 25 mm, more preferably about 20 mm, respectively. Can do. The first predetermined width and the second predetermined width may be changed according to the size of the image data.

  According to a second aspect of the present invention, in the first aspect of the present invention, the image processing unit is a third having a third predetermined width centered on a central line at a central position in the left-right direction of the spread page of the image data. A line extending in the vertical direction of the spread page in the area and having the darkest pixel in the third predetermined width area is defined as a page boundary line, and a fourth predetermined width centered on the page boundary line. The pixels in the four areas are replaced with white.

  According to this configuration, the image processing for removing the unnecessary area in the center portion caused by the floating of the back cover portion of the book document among the image data of the spread page is not performed on all the pixels of the image data. The region is limited to the range of the fourth region. As a result, the amount of data to be processed can be reduced and the image processing time can be shortened compared to the case where image processing is performed on all the pixels of the image data. Further, it is not necessary to increase the image processing speed of the image processing unit, and it is not necessary to increase the amount of memory. Therefore, the cost required for manufacturing the image processing apparatus can be reduced. The third predetermined width and the fourth predetermined width can be arbitrarily set. For example, in the case of A3 size image data, the default values are set to 10 to 20 mm, more preferably about 15 mm, respectively. Can do. The third predetermined width and the fourth predetermined width may be changed according to the size of the image data.

  According to a third aspect of the invention, in the first or second aspect of the invention, the image processing unit extends in the vertical direction of the spread page in the first area and the second area, and is darker than a predetermined pixel value. If there is a repetition of a dark color band composed of pixel values and a light color band thinner than the dark color band, the repeated area is determined as the unnecessary area.

  When the book document is opened and scanned, the side part of the book document (the edge part of each page) is scanned. According to this configuration, the side part of the book document can be checked with or without repeating the dark and light color bands. The area as a result of reading is read as an unnecessary area. As a result, the image of the side portion of the book document in the image data is removed as an unnecessary area. Although the predetermined pixel value can be set arbitrarily, it is for determining the relationship between dark and light, so it is set to a value darker than the intermediate value of the entire gradation width. For example, if the gradation is 8 bits and 256, and white is 0 and black is 255, it can be 128 or more.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the image processing unit sets an unnecessary area up to the innermost dark band in the image data in the first area and the second area. It was decided.

  In the left and right direction of the image data of the spread page, the side document, the reading result of the front cover part of the book document, and the spread of the book document than the reading range are located outside the side part of the book document. A black solid image due to being narrower than the range of the page appears. However, according to this configuration, the entire outer side than the innermost dark color band is determined as an unnecessary area, so that the reading result of the side surface part, the reading result of the cover part of the book document, and all of the solid black image Can be removed.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the image processing unit is configured to display a spread page when a plurality of pixels having the darkest pixel value exist in the third predetermined width region. In the left-right direction, a line extending in the vertical direction of the spread page at the center position of the pixel having the darkest pixel value located at both ends is defined as the page boundary line.

  According to this configuration, the page-to-page boundary in the spread page can be appropriately determined. Therefore, it is possible to appropriately remove the unnecessary area in the central portion caused by the lift of the spine portion of the book document.

  According to a sixth aspect of the present invention, in the first to fifth aspects of the invention, all or one of the first predetermined width, the second predetermined width, the third predetermined width, and the fourth predetermined width is set. It was decided to have an input part.

  According to this configuration, for example, the size of a spread page of a book document, the number of pages of the book document, the thickness of the book document, etc. The width of the unnecessary area is different. However, according to this configuration, since it is possible to input each predetermined width at the input unit, it is possible to appropriately remove unnecessary areas regardless of the type of book document.

  According to a seventh aspect of the present invention, there is provided the image forming apparatus according to any of the third to sixth aspects, further comprising an input unit for setting the predetermined pixel value.

  Depending on the value of the predetermined pixel value that has been set, it may be impossible to accurately determine whether or not the region is an unnecessary region. However, according to this configuration, the value of the predetermined pixel value can be set by the input unit, and it can be accurately determined whether or not it is an unnecessary area by changing the value of the predetermined pixel value.

  An image forming apparatus according to an eighth aspect includes the image processing apparatus according to any one of the first to seventh aspects.

  According to this configuration, printing can be performed based on the image data of the book document from which unnecessary areas have been appropriately removed, so that it is possible to provide an image forming apparatus that does not consume wasteful developer such as toner. Further, since the manufacturing cost required for the image processing apparatus mounted on the image forming apparatus can be kept low, the manufacturing cost of the image forming apparatus can also be suppressed.

  According to the present invention, image processing for removing unnecessary areas is performed only on a part of the image data obtained by reading a book document, so that image processing is performed on the entire image data. , Processing time can be shortened. Therefore, it is not necessary to increase the processing speed and the amount of memory mounted can be suppressed compared to an image processing apparatus that performs image processing on the entire image data, and the cost required for manufacturing the image processing apparatus can be reduced.

1 is a schematic cross-sectional view seen from the front showing a schematic configuration of a copier according to an embodiment. FIG. 3 is a front enlarged schematic cross-sectional view of the document conveying device and the image reading unit according to the embodiment. 1 is a block diagram illustrating an example of a configuration of a copier according to an embodiment. It is a block diagram which shows an example of a structure of the image processing apparatus which concerns on embodiment. (A) is a figure which shows an example of a book original, (b) is a perspective view which shows an example in the state which mounted the book original on the mounting reading contact glass. It is explanatory drawing which shows an example of the image data obtained by reading the book original concerning an embodiment. FIG. 5 is an explanatory diagram illustrating an example of an area for determining whether or not an unnecessary area exists in image data in the copier according to the embodiment. 4A and 4B are diagrams illustrating an example of a setting screen for image processing performed on image data obtained by reading a book document according to the embodiment, where FIG. 5A is an example of a detailed setting screen and FIG. 5B is an example of a simple setting screen. . 6 is a flowchart illustrating an example of a flow of unnecessary area removal processing for image data of a book document according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. However, each element such as configuration and arrangement described in this embodiment does not limit the scope of the invention and is merely an illustrative example.

(Outline of image forming apparatus)
First, an outline of an electrophotographic copying machine 200 (corresponding to an image forming apparatus) including an image processing apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view from the front showing a schematic configuration of a copying machine 200 according to an embodiment of the present invention.

  As indicated by a broken line in FIG. 1, an operation panel 1 (corresponding to an input unit) is provided on the front side of the copying machine 200. The operation panel 1 is of a touch panel type, and has a liquid crystal display unit 10 that displays keys for setting the copying machine 200 and receives user input. Further, the liquid crystal display unit 10 can display the status of the copying machine 200 such as an error such as a jam or out of paper. The operation panel 1 is also provided with a numeric keypad 11 for inputting numbers such as the number of copies, a start key 12 for instructing copy execution, and the like. The operation panel 1 can also make settings related to reading, such as setting the size (A3, B4, etc.) of the document to be read.

  Further, the copying machine 200 and the image processing apparatus 100 according to the present embodiment can perform image processing (unnecessary region removal processing) for removing unnecessary regions from image data obtained by reading a book document. Therefore, on the operation panel 1, it is possible to input the mode of the copying machine 200 and the image processing apparatus 100 as a removal mode for performing unnecessary area removal processing. In the removal mode, the image processing apparatus 100 performs an unnecessary area removal process, and the copying machine 200 performs printing based on the image data after the unnecessary area removal process.

  In addition, the image reading unit 2 is disposed above the copying machine 200 according to the present embodiment. The image reading unit 2 irradiates the original with light and reads the original to generate image data. A document conveying device 3 is disposed above the image reading unit 2. The document conveying device 3 conveys the document toward the conveyance reading contact glass 21 of the image reading unit 2.

  The copying machine 200 includes an image processing unit 9 that performs image processing on image data (see FIG. 3). The image processing apparatus 100 mainly includes an image reading unit 2, an image processing unit 9, an operation panel. 1 (details of the image processing unit 9 will be described later). In other words, the image processing apparatus 100 according to the present invention is included in the copying machine 200 (the copying machine 200 includes the image processing apparatus 100). The operation panel 1 also functions as an input unit of the copying machine 200.

  Next, the internal configuration and operation of the copying machine 200 will be described. The copying machine 200 includes a paper feeding unit 4, a conveyance path 5, an image forming unit 6, a fixing unit 7, and the like, and a paper discharge space is provided below the image reading unit 2. Therefore, these configurations will be described along the sheet conveyance path. In FIG. 1, a sheet conveyance path in the copying machine 200 is shown by a solid line arrow.

  First, the paper feeding unit 4 is provided at the lowermost part of the copying machine 200 and accommodates various types of papers of various sizes (A4, B5, etc.) such as copy paper, OHP paper, and label paper. The paper feed roller 41 abuts on the uppermost paper and is rotationally driven in a predetermined direction (clockwise in FIG. 1) to feed the paper one by one to the transport path 5 at the time of paper feeding.

  In the present embodiment, the conveyance path 5 is a path for conveying a sheet in the copying machine 200 and conveying the sheet from the sheet feeding unit 4 to the discharge tray 51 through the image forming unit 6. Then, along the transport path 5, a pair of transport rollers 52 that are rotationally driven by a drive mechanism (not shown), a plurality of guide plates (not shown) for guiding the paper, and a sheet that matches the formed toner image A registration roller pair 53 for feeding out the paper, a discharge roller pair 54 for discharging the paper, and the like are provided.

  In FIG. 1, the image forming unit 6 is disposed at the center left position in the copying machine 200, forms a toner image based on image data of a document read by the image processing apparatus 100, and transfers the toner image onto a sheet. . The image forming unit 6 includes a photosensitive drum 61 as an image carrier, a charging device 62, an exposure device 63, a developing device 64, a transfer roller 65, a cleaning device 66, and the like. The photoconductive drum 61 is disposed substantially at the center of the image forming unit 6, is rotationally driven in a predetermined direction (clockwise in FIG. 1) by a driving device (not shown), and has a photosensitive layer on the outer peripheral surface. The charging device 62 is disposed opposite to the upper right of the photosensitive drum 61 in FIG. 1 and charges the peripheral surface of the photosensitive drum 61 with a predetermined potential. In addition to the corona discharge type, a charging roller, a brush, or the like may be used.

  The exposure device 63 is arranged on the right side of the photosensitive drum 61 in FIG. 1, and irradiates light (for example, laser light) on the peripheral surface of the photosensitive drum 61 after charging based on image data of an image to be formed. Then, the peripheral surface is scanned and exposed to form an electrostatic latent image corresponding to the image data. The developing device 64 is provided below the photosensitive drum 61 in FIG. 1, charges the toner stored therein to a predetermined potential, supplies the toner to the electrostatic latent image, and develops the electrostatic latent image as a toner image. .

  In FIG. 1, the transfer roller 65 is rotatably supported to the lower left of the photosensitive drum 61, and transfers the toner image formed on the photosensitive drum 61 onto a sheet. Therefore, the transfer roller 65 contacts the photosensitive drum 61 to form a nip. The sheet enters the nip, and a voltage having a polarity opposite to the charging polarity of the toner is applied to the transfer roller 65 to transfer the toner image onto the sheet. In FIG. 1, the cleaning device 66 is disposed above the photosensitive drum 61, and removes and collects residual toner, dust, and the like on the peripheral surface of the photosensitive drum 61.

  In the present embodiment, the fixing unit 7 includes a heating roller 71, a pressure roller 72, and the like, and pressurizes and heats the toner image transferred to the sheet to fix it to the sheet. The heating roller 71 includes a heating element therein, and the pressure roller 72 and the heating roller 71 are pressed against each other to form a nip. A sheet on which the toner image is transferred enters the nip, and the toner is fixed. The sheet after completion of fixing is discharged to the discharge tray 51 by the discharge roller pair 54.

(Configuration of Document Feeder 3 and Image Reading Unit 2)
Next, an example of the configuration of the document conveying device 3 and the image reading unit 2 according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 is a front enlarged schematic cross-sectional view of the document conveying device 3 and the image reading unit 2 according to the embodiment of the present invention.

  The document conveying device 3 automatically and continuously conveys the document to be read one by one to a reading position (a conveyance reading contact glass 21 described later). Further, the document conveying device 3 is attached to the image reading unit 2 so that it can be opened and closed in the vertical direction with the back side of the sheet of FIG. reference).

  The document sent out from the document tray 31 is guided to a plurality of document conveyance roller pairs 32 and guides, and passes through the upper surface of the conveyance reading contact glass 21 provided on the upper surface of the image reading unit 2. During this passage, the image reading unit 2 performs reading. Then, the document that has been read is discharged from the document conveying device 3 (the document conveying path is indicated by a two-dot chain line).

  Next, the image reading unit 2 in the present embodiment will be described. As shown in FIGS. 1 and 2, the image reading unit 2 has a box-shaped housing. A transparent plate-shaped transport reading contact glass 21 is arranged on the left side of the upper surface of the image reading unit 2 in the direction perpendicular to the paper surface of FIG. 2 (main scanning direction). A transparent plate-like placement reading contact glass 22 is arranged on the right side of the upper surface of the image reading unit 2. The placement reading contact glass 22 is provided on the upper surface of the image reading unit 2, and when reading a book document such as a book one by one, the document conveying device 3 is lifted and the document is placed with the reading surface facing downward.

  As shown in FIG. 2, a first moving frame 231, a second moving frame 232, a wire 24W, a take-up drum 24D, a lens 25, and a lamp 260 for irradiating the original with light are provided in the housing of the image reading unit 2. Then, light irradiated on the original is incident, and an image sensor 27 and the like for reading the original for each line and generating image data are arranged. The image sensor 27 is constituted by, for example, a CCD (Charge Coupled Device) in which photoelectric conversion elements are arranged in a line shape, and reads the document line by line based on the reflected light of the document.

  The first moving frame 231 supports a lamp 260 (for example, a cold cathode lamp, a xenon lamp, or a fluorescent lamp) that emits light upward, and a first mirror 261 below. The lamp 260 and each mirror have a shape extending in the direction perpendicular to the paper surface of FIG. The second moving frame 232 supports the second mirror 262 on the upper side and the third mirror 263 on the lower side. Further, the first moving frame 231 is disposed above the second moving frame 232. A plurality of wires 24W are attached to the first moving frame 231 and the second moving frame 232 (only one is shown in FIG. 2 for convenience), and the other end of the wire 24W is connected to the winding drum 24D. The winding drum 24D rotates forward and backward using the winding motor 24M (see FIG. 4) as a drive source, and the first moving frame 231 and the second moving frame 232 can freely move in the horizontal direction.

  Here, an example of a specific document reading operation will be described. First, in the case of reading a document conveyed by the document conveying device 3, the first moving frame 231 and the second moving frame 232 are positioned below the conveyance reading contact glass 21 (reading position) after the winding motor 24M is driven. Is fixed, and the lamp 260 irradiates the passing document.

  The light emitted from the lamp 260 strikes the original on the conveyance reading contact glass 21, and the reflected light is guided to the lens 25 through the first mirror 261 to the third mirror 263. The lens 25 collects the reflected light and enters the image sensor 27. The image sensor 27 converts the reflected light into an analog electric signal corresponding to the image density. The original is read in units of lines in the main scanning direction (direction perpendicular to the original conveying direction), and the reading in units of lines is continuously repeated in the sub-scanning direction (original conveying direction) to read one original. It is done.

  On the other hand, when reading a document placed on the placement reading contact glass 22, the first moving frame 231 and the second moving frame 232 are moved from the home position to the right in FIG. 2 by the take-up drum 24D or the wire 24W. The entire original is read, and the original image is converted into an electrical signal.

(Hardware configuration of copying machine 200)
Next, an example of the hardware configuration of the copying machine 200 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing an example of the configuration of the copying machine 200 according to the embodiment of the present invention.

  First, the main body control unit 8 on the main control board of the copying machine 200 is provided with a CPU 81 as a central processing unit, and includes a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard disk drive), and the like. It has a storage unit 82 composed of nonvolatile and volatile memories such as a flash ROM. The storage unit 82 stores a program, data, and the like for controlling the copying machine 200. The storage unit 82 can also store image data obtained by reading by the image reading unit 2. The main body control unit 8 uses the program and data stored in the storage unit 82 to control each unit and perform printing.

  The main body control unit 8 is connected to the paper feeding unit 4, the conveyance path 5, the image forming unit 6, the fixing unit 7, and the operation panel 1, and the main body control unit 8 is configured to perform various functions such as paper conveyance and toner image formation. Perform motion control. Also, settings and copy execution instructions on the operation panel 1 are transmitted to the main body control unit 8.

  The main body control unit 8 is also connected to the image processing apparatus 100 and gives an operation instruction to the image processing apparatus 100 including the image reading unit 2 and the image processing unit 9 at the time of executing a copy (details will be described later). In FIG. 3, it is indicated by a broken line). Therefore, the main body control unit 8 can also be said to be a control unit of the image processing apparatus 100.

  Regarding the flow of image data, the image data generated by the image reading unit 2 is sent to the image processing unit 9. Note that image data may be transferred from the image reading unit 2 to the image processing unit 9 via the main body control unit 8. For example, the image processing unit 9 performs various image processing (details will be described later), and transmits the image data to the image forming unit 6. The image forming unit 6 forms a toner image based on the image data after image processing, and printing is performed (copying).

(Hardware configuration of image processing apparatus 100)
Next, an example of the hardware configuration of the image processing apparatus 100 according to the embodiment of the present invention will be described based on FIG. FIG. 4 is a block diagram showing an example of the configuration of the image processing apparatus 100 according to the embodiment of the present invention.

  As described above, the image processing apparatus 100 according to the present embodiment includes, for example, the image reading unit 2 and the image processing unit 9. The image reading unit 2 is provided with a reading control unit 20 that controls the image reading unit 2. As shown in FIG. 4, the reading control unit 20 connected to the main body control unit 8 is provided with a CPU 201, and a ROM 202 and a RAM 203 are provided as storage devices. The ROM 202 is a non-volatile memory that stores programs and data necessary for controlling the image reading unit 2. The RAM 203 is a volatile memory in which programs and data for controlling the image reading unit 2 are expanded.

  For example, when the start key 12 of the operation panel 1 is pressed and a reading execution instruction is given from the main body control unit 8, the reading control unit 20 receives an instruction from the main body control unit 8, and the operation of the image processing apparatus 100 is performed. Control is performed and data transmission control of image data obtained by reading to the image processing unit 9 and the main body control unit 8 is performed. The following components are connected to the reading control unit 20. For example, an inverter 204 that actually emits light from the lamp 260 of the image reading unit 2, a winding motor 24M that drives the winding drum 24D, an image sensor 27, and the like are connected. Then, when performing reading, the reading control unit 20 drives the inverter 204, turns on the lamp 260, moves each moving frame with the winding drum 24D, and drives the image sensor 27.

  Further, the image reading unit 2 receives an analog electrical signal of each pixel obtained by the image sensor 27, converts it into a digital signal, performs quantization, and after A / D conversion. A correction unit 28b for performing various corrections such as shading correction and γ correction, and an image memory 29 for storing the corrected image data are mounted. The corrected image data is stored in the image memory 29, and the image data in the image memory 29 is transmitted to the image processing unit 9, for example. Note that the image reading unit 2 transmits, for example, image data in which the value of each pixel is 8-bit 256 gradation (0 to 255), 0 is white, and 255 is black to the image processing unit 9.

  The image processing unit 9 includes an ASIC 91 (Application Specific Integrated Circuit) as a dedicated circuit for image processing and an image memory 92 as a work area for image data. The image processing unit 9 of the present embodiment is a circuit configured by combining an ASIC 91, an image memory 92, and the like. The image processing program can be stored in the CPU 81 or the storage unit 82 of the main body control unit 8 so that the main body control unit 8 functions as the image processing unit 9 in terms of software.

  Further, in the image processing unit 9, an unnecessary area determination unit 93 that determines an unnecessary area out of image data obtained by reading a book document, and a white color that performs white conversion processing that converts pixels in the unnecessary area to white. A conversion unit 94, an output processing unit 95 for converting the format of the image data so as to be used for exposure in the exposure apparatus 63, and the like are provided. The unnecessary area determination unit 93, the white color conversion unit 94, and the output processing unit 95 may be provided as a circuit (hardware), or may be functionally realized by the ASIC 91, the image memory 92, a program, and the like.

  The image processing unit 9 can perform various types of image processing such as enlargement / reduction processing, white conversion processing, and spatial filter processing. However, since the image processing that can be performed is various, the following description will explain image processing related to the present invention, and for other image processing, the image processing unit 9 is assumed to be able to perform known image processing, and will be described in detail. I will omit the explanation.

(Scanning book manuscripts and book manuscripts)
Next, based on FIGS. 5 and 6, reading of a book document by the copying machine 200 according to the embodiment of the present invention will be described. FIG. 5A is a diagram illustrating an example of a book document, and FIG. 5B is a perspective view illustrating an example of a state in which the book document is placed on the placement reading contact glass 22. FIG. 6 is an explanatory diagram showing an example of image data obtained by reading a book document according to the embodiment of the present invention. Note that FIG. 6 shows an example of image data when the spread page of the book document is read in accordance with the horizontal direction of the spread page in the sub-scanning direction of the image reading unit 2.

  In FIG. 6, the leftmost line on the left side of the image data is set as the start line Xs. The start line Xs is a reading start position of the image reading unit 2 in the sub-scanning direction (left and right direction of the spread page), and is a starting position of image data. The right line of the image data is set as the end line Xe. An end line Xe is a reading end position of the image reading unit 2 in the sub-scanning direction, and is an end position of the image data. The size of the image data is determined according to the input of the size of the document to be read on the operation panel 1 (the number of pixels in the main scanning direction and the sub scanning direction is determined). A central vertical line between the start line Xs and the end line Xe in the left-right direction of the spread page is set as a center line Xc. In other words, the center line Xc is a pixel row located at the center of the image data in the sub-scanning direction (horizontal direction of the spread page).

  For example, the user may copy a bookbinding document (book document) such as a dictionary or a magazine as shown in FIG. When copying a book document, the book document is opened. Then, as shown in FIG. 5A, the book document is opened. Then, in a state where the book is spread, the book document is placed on the placement reading contact glass 22 as shown in FIG.

  When reading a book document, the central portion of the book document (shown as the area F1 in FIG. 5B) is lifted. In other words, the vertical region F1 centering on the page-to-page boundary in the facing page of the book document is not in close contact with the placement reading contact glass 22. The image reading unit 2 of the present embodiment irradiates the original with light and receives the reflected light. Since the region F1 is floating, the light guided to the image sensor 27 is more than the close part. become weak. As the distance between the surface of the placement reading contact glass 22 and the original increases, the darker the reading is performed. Therefore, the page-to-page boundary in the spread page is read darkest. As a result, as shown in FIG. 6, the back cover of the book document floats, and when the book document is read, a strip-shaped solid image appears in the center portion of the image data.

  On the other hand, since the size of each page is the same, the back cover of the book document floats, so that the range (width) of the spread pages on the placement reading contact glass 22 is narrower than the normal paper reading range. Become. For example, if a book document of A4 size on one side (A4 per page is A4) is opened, ideally it will be A3 size. However, since the spine is floating, the horizontal direction of the spread page is shortened. For this reason, when reading in A3 size, the reading start position area (the area F2 is shown in FIG. 5B) at the left end of the spread page and the reading end position area (FIG. 5) in the right end of the spread page. In (b), an unnecessary image is read in the area F3.

  Specifically, in the area F2 and the area F3, the side surface and cover portion of the book document are read. Further, a cover portion of the book document or a black solid image may appear at the extreme left and right ends of the spread pages of the book document. For example, in the case of a thick book document (for example, a dictionary), if the distance between the left and right edges of the spread page of the document and the surface of the placement reading contact glass 22 exceeds the readable height, the portion becomes black solid. Image. As a result, as shown in FIG. 6, the image data includes an image obtained by reading the side of a book document (an image having a vertical stripe pattern extending in the vertical direction of a spread page by reading an edge of each page) or a black solid image. Appears.

  FIG. 6 shows an example in which the middle page of the book document is not opened, but the first half of the page is opened for reading. For this reason, the page boundary line Xc ′ at the boundary between the page and the page in this image data is closer to the Xs side than Xc. Since the first half of the middle page is opened for reading, image data obtained by reading the side of the book document exists on the inner side in the horizontal direction of the spread page of image data from the start line Xs. On the other hand, on the inner side in the horizontal direction of the spread page of image data from the end line Xe, there are an image obtained by reading a black solid image or a book original cover, and image data obtained by reading the side of the book original.

(Determining whether or not there is an unnecessary area in the image data of the book manuscript and white conversion)
Next, an example of white conversion control of an unnecessary area in the copying machine 200 according to the embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an explanatory diagram showing an example of an area for determining whether or not there is an unnecessary area in the image data in the copying machine 200 according to the embodiment of the present invention.

  First, processing at the left and right ends of the spread page will be described. The image processing unit 9 (unnecessary area determination unit 93) includes a first area FA (shown by hatching in FIG. 7) having a first predetermined width A from the start line Xs in the left-right direction (short side) of the facing page. The presence / absence of an unnecessary area is determined from a second area FB (shown by hatching in FIG. 7) having a second predetermined width B from the end line Xe in the horizontal direction (short side) of the spread page. Then, the image processing unit 9 converts the unnecessary area into white. That is, the image processing unit 9 includes the image data in the first area FA having the first predetermined width A from the one end in the horizontal direction of the spread page of the image data toward the inside of the image data, and from the other end. To determine whether or not there is an unnecessary area in the second area FB of the second predetermined width B toward the inside of the first area FA, and the unnecessary area in the first area FA and the pixels of the unnecessary area in the second area FB are white replace.

  If the side of the book document is read, the edge of each page is read. Therefore, as shown in an enlarged view in FIG. 6, when the side surface is read, in the first area FA and the second area FB, an image composed of the dark color band E1 and the light color band E2 extending in the vertical direction of the spread page. Is included. Therefore, if the dark color band E1 and the light color band E2 are repeated, it can be determined that the side of the book document is read. That is, the image processing unit 9 extends in the vertical direction of the spread page in the first area FA and the second area FB from the dark color band E1 composed of pixel values that are darker than the predetermined pixel value and the dark color band E1. If there is a repetition with the lighter color band E2, the area with the repetition is determined as an unnecessary area.

  For example, the image processing unit 9 (unnecessary region determination unit 93) confirms the existence of a dark color band E1 that exceeds a predetermined pixel value and includes a plurality of pixel lines (pixel columns). Further, the image processing unit 9 confirms whether there is a light color band E2 composed of a plurality of pixel lines (pixel columns) thinner than the dark color band E1 adjacent to the dark color band E1. Although the predetermined pixel value can be set arbitrarily, it is for determining the relationship between dark and light, and is set to a value that is darker than the intermediate value of the entire gradation width. For example, if the gradation is 8 bits and 256, and white is 0 and black is 255, it can be 128 or more.

  On the other hand, the image processing unit 9 determines whether or not the light color band E2 is a plurality of small pixel values, for example, a predetermined value or more than a predetermined pixel value (for example, a pixel value is 100 or more smaller than a predetermined pixel value) It can be determined by whether or not there is a line. Alternatively, the image processing unit 9 may determine whether there are a plurality of lines having pixel values smaller than the predetermined pixel value.

  When the image processing unit 9 (white conversion unit 94) determines that there is an unnecessary area, the image processing unit 9 (white conversion unit 94) converts all the pixel values of the pixels in the unnecessary area to white (pixel value “0”) in the first area FA. . Specifically, in the first area FA, the area from the innermost dark band E1 in the left-right direction of the spread page of image data to the outer side (start line Xs) in the left-right direction of the spread page of image data. The pixel value of each pixel is converted to white.

  Similarly, when the image processing unit 9 (white color conversion unit 94) determines that there is an unnecessary area, the pixel value of each pixel in the unnecessary area in the second area FB is all converted to white (pixel value “0”). To do. Specifically, in the second region FB, in the left-right direction of the spread page of image data, from the innermost dark band E1 toward the outer side of the spread page of image data in the left-right direction (end line Xe side). The pixel value of each pixel in the area is converted to white. That is, the image processing unit 9 determines the unnecessary area from the first area FA and the second area FB to the innermost dark color band E1 in the image data. As a result, the vertical stripe pattern image as a result of reading the side surfaces of the book document existing at both the left and right ends of the spread page, and the solid image as a result of reading the cover or the like are removed.

  Next, since the position of the page-to-page boundary can be changed depending on the position of the page opened in the book document, the image processing unit 9 has a third predetermined width C around the center line Xc in the image data. A line (pixel row) having the darkest pixel value is searched for in the region (third region FC, shown by vertical line shading in FIG. 7). This can be found by simply comparing the pixel values of the respective pixels in the third region FC. For example, when a book document is read, the pixel value of the darkest pixel in the third area FC is 256 (0 to 255). If 0 is white and 255 is black, the pixel value is about 250.

  Then, the image processing unit 9 (unnecessary region determination unit 93) sets a line that has the darkest pixel and extends in the vertical direction (vertical direction) of the spread page as a page boundary line Xc '. Then, all the pixel values of the pixels in the region having the fourth predetermined width D (fourth region FD) with the page boundary line Xc ′ as the center are converted into white (pixel value “0”). Thereby, the solid unnecessary image that appears in the center portion of the spread page due to the floating back cover is removed. That is, the image processing unit 9 is a line extending in the vertical direction of the spread page within the third area FC having the third predetermined width C with the center line Xc at the center position in the horizontal direction of the spread page of the image data as the center. The line where the darkest pixel exists in the region of the third predetermined width C is defined as the page boundary line Xc ′, and the pixels in the fourth region FD of the fourth predetermined width D are replaced with white with the page boundary line Xc ′ as the center. .

  If there are a plurality of pixels having the darkest pixel value in the third area FC and the positions of the spread pages in the left-right direction are different, a line (pixel row) including any darkest pixel value is set to the page. It may be a boundary line Xc ′. Further, the vertical line of the spread page located in the middle of the pixel having the darkest pixel value located at both ends in the horizontal direction of the spread page may be defined as the page boundary line Xc ′ (not necessarily the darkest pixel). Need not include pixels with values). That is, when there are a plurality of pixels having the darkest pixel value in the region of the third predetermined width C, the image processing unit 9 determines the center position of the pixels having the darkest pixel value located at both ends in the horizontal direction of the spread page. A line extending in the vertical direction of the spread page is defined as a page boundary line Xc ′.

(Image processing settings)
Next, an example of image processing settings applied to image data obtained by reading a book document according to the embodiment of the present invention will be described with reference to FIG. FIG. 8 is a diagram showing an example of a setting screen for image processing performed on image data obtained by reading a book document according to the embodiment of the present invention, where (a) is an example of a detailed setting screen 141, and (b). Is an example of a simple setting screen 142.

  First, a processing setting screen 14 for image data obtained by reading a book document shown in FIG. 8 is displayed on the liquid crystal display unit 10 of the operation panel 1, for example. For example, the user can repeatedly press down from the uppermost screen of the liquid crystal display unit 10 to reach the processing setting screen 14.

  In the processing setting screen 14, regardless of the detailed setting screen 141 or the simple setting screen 142, the automatic key K1, the detailed setting key K2, the simple setting key K3, the registration key K4, the cancel key K5, the OK key K6, and the original setting direction. Key K7 is arranged.

  When the automatic key K1 is pressed, the image processing unit 9 performs image processing for removing unnecessary areas using the default values of the first to fourth predetermined widths. The first predetermined width A and the second predetermined width B can be arbitrarily set. For example, in the case of A3 size image data, the default value is set to about 15 to 25 mm, more preferably about 20 mm. be able to. The third predetermined width C and the fourth predetermined width D can also be arbitrarily set. For example, in the case of A3 size image data, the default values are set to 10 to 20 mm, more preferably about 15 mm, respectively. I can leave. Each predetermined width may be changed in accordance with the size of the image data. For example, in the case of the size of A3 paper, the length of the image data in the left-right direction is about 420 mm. When the first predetermined width A is 20 mm, the second predetermined width B is 20 mm, the third predetermined width C is 15 mm, and the fourth predetermined width is 15 mm, even if each predetermined width is totaled, it is about 70 mm. When simply calculated, 70 (mm) / 420 (mm) ≈0.17, and the amount of data in the unnecessary area removal processing according to the present invention is the case where image processing for unnecessary area removal is performed on the entire image data. Compared to about 83%.

  The detail setting key K2 is pressed when setting each predetermined width in detail. The simple setting key K3 is pressed when each predetermined width is simply set. That is, the operation panel 1 can set all or any of the first predetermined width A, the second predetermined width B, the third predetermined width C, and the fourth predetermined width D. When the registration key K4 is pressed, each predetermined width set on the detailed setting screen 141 or the simple setting screen 142 is stored (for example, stored in the storage unit 82). Thereafter, unless the setting is changed, in the removal mode, the image processing unit 9 performs a removal process of unnecessary areas with each stored predetermined width.

  The cancel key K5 is pressed when the user cancels the setting. An OK key K6 is pressed when the user completes the setting. For example, when the start key 12 of the operation panel 1 is pressed, the book document is read, and the image processing unit 9 performs unnecessary area removal processing according to the setting. When the document setting direction key K7 is pressed, for example, another window (not shown) is displayed, and the direction of the document placed on the placement reading contact glass 22 can be input. For example, on the placement reading contact glass 22, when an A4 size original in the main scanning direction and an A3 size original in the sub scanning direction can be placed, if the book original is an A4 size or smaller in a spread page, the book A book document can be read regardless of whether the left-right direction of the spread page of the document is aligned with the main scanning direction or the sub-scanning direction.

  As described above, the setting direction of the original can be set on the operation panel 1 so that the horizontal direction of the spread page in the image data can be grasped. Since the book document is often read by aligning the left and right direction of the spread page of the book document with the sub-scanning direction, as a default setting, the sub-scanning direction on the placement reading contact glass 22 is the spread page of the image data. It may be predetermined that it is the left-right direction.

  When the detailed setting key K2 is pressed, the screen is switched to a detailed setting screen 141 as shown in FIG. 8A, and the image processing unit 9 uses the set values of the first to fourth predetermined widths. Then, unnecessary area removal processing is performed. Specifically, when the detailed setting key K2 is pressed, a first predetermined width display field G1 that is pressed when setting the first predetermined width A on the right side of the detailed setting key K2 and the setting result is displayed; A second predetermined width display field G2 that is pressed when setting the second predetermined width B and the setting result is displayed, and a third predetermined width that is pressed when setting the third predetermined width C and the setting result is displayed. A width display column G3 and a fourth predetermined width display column G4 that is pressed when setting the fourth predetermined width D and displays the setting result are displayed.

  The user presses one of the display fields when setting each predetermined width. The user can set each predetermined width using the plus key K8 or the minus key K9. If the numeric keypad K10 is pressed, for example, the user can set each predetermined width using the numeric keypad 11 of the operation panel 1.

  On the other hand, when the simple setting key K3 is pressed, the screen is switched to a simple setting screen 142 as shown in FIG. 8B, and an outer predetermined width display field G5 and a central predetermined width display field are displayed on the right side of the simple setting key K3. G6 is displayed. In the simple setting screen 142, when the outer predetermined width display field G5 is pressed and the length is set, it is handled that the first predetermined width A and the second predetermined width B are set by the length. In other words, the first predetermined width A and the second predetermined width B are set to the same length by the user performing input and setting in the outer predetermined width display field G5.

  Further, when the length is set by pressing the center predetermined width display field G6 on the simple setting screen 142, it is handled that the third predetermined width C and the fourth predetermined width D are set by the length. In other words, the third predetermined width C and the fourth predetermined width D are set to the same length by the user performing input and setting in the center predetermined width display field G6. Then, the image processing unit 9 performs unnecessary area removal processing using the set values of the first to fourth predetermined widths. A pixel value setting field G7 is provided on the rightmost side of the detailed setting screen 141 and the simple setting screen 142. In the pixel value setting column G7, the above-described predetermined pixel value can be set. That is, the operation panel 1 accepts setting of a predetermined pixel value.

  These user settings made on the operation panel 1 are transmitted to the main body control unit 8. Then, the main body control unit 8 is transmitted with the value of each predetermined width set in the image processing unit 9, the document setting direction, the value of the predetermined pixel value, and the like. As a result, the image processing unit 9 performs unnecessary area removal processing as set.

(Image processing control)
Next, based on FIG. 9, it is a flowchart which shows an example of the control flow of the unnecessary area | region removal process with respect to the image data of the book manuscript which concerns on embodiment of this invention. FIG. 9 is a flowchart showing an example of the flow of unnecessary area removal processing for image data of a book document according to the embodiment of the present invention.

  First, the start of FIG. 9 is a point in time when the copy mode of the book document is started by pressing the start key 12 of the operation panel 1 with the removal mode selected by the input to the operation panel 1. Then, the image reading unit 2 reads a book document (step # 1). Image data is then generated (step # 2). Thereafter, the image data is sent to the image processing unit 9, and the image processing unit 9 receives the image data (step # 3).

  Next, the image processing unit 9 confirms various settings such as each predetermined width, document set direction, and predetermined pixel value in the unnecessary area removal processing (step # 4). Then, the image processing unit 9 confirms whether or not the dark color band E1 and the light color band E2 are repeated in the first area FA. Further, the image processing unit 9 confirms whether or not there is an unnecessary area in the second area FB in which the dark color band E1 and the light color band E2 are repeated. That is, the side surface of the book document is placed in the first area FA having the first predetermined width A inward from the start line Xs of the spread page and in the second area FB having the second predetermined width B inward from the end line Xe. It is confirmed whether a reading result exists (step # 5).

  If there is an unnecessary area (Yes in Step # 5), the image processing unit 9 starts or ends the start line Xs from the darkest color band E1 in the first area FA and the second area FB. The pixel value of each pixel in the area up to the line Xe is converted to white (step # 6). On the other hand, if there is no unnecessary area (No in step # 5), the process proceeds to the next step without performing the process of converting the pixel value of the pixel to white.

  Next, the image processing unit 9 selects a page boundary line Xc ′ in which the darkest pixel exists in the third region FC. Further, if there are a plurality of lines where the darkest pixel exists in the third region FC, the center line between the two lines located at the extreme end in the left-right direction of the spread page is defined as the page boundary line Xc ′. That is, the image processing unit 9 determines the page boundary line Xc ′ (step # 7).

  Then, the image processing unit 9 converts the pixel values of all the pixels in the fourth region FD around the page boundary line Xc ′ to white (Step # 8). The image processing unit 9 performs other necessary image processing and then transmits the image data to the exposure device 63 (step # 9). Then, printing is performed based on the image data after image processing (step # 10 → end).

  As described above, according to the configuration of the image processing apparatus 100 and the copying machine 200 of the present embodiment, an unnecessary area in image data (image data of a spread page) read by opening a book document is detected and determined. Image processing is not performed on all the pixels of the image data, the presence or absence of an unnecessary area is determined in the first area FA and the second area FB, and the pixels in the unnecessary area are replaced with white. In addition, image processing for removing an unnecessary area in the central portion caused by the floating of the back cover portion of the book original in the image data of the spread page is not performed on all the pixels of the image data, and the third area FC, It is kept in the range of the four areas FD. As a result, the amount of data to be processed can be reduced and the image processing time can be shortened compared to the case where image processing is performed on all the pixels of the image data. Further, it is not necessary to increase the image processing speed of the image processing unit 9. Also, it is not necessary to increase the amount of memory. Therefore, the manufacturing cost of the image processing apparatus 100 can be reduced.

  When the book document is opened and read, the side portion (edge portion of each page) of the book document is read, but the side portion of the book document is read depending on whether or not the dark color band E1 and the light color band E2 are repeated. The resulting area is determined as an unnecessary area. Thereby, the image of the side portion of the book original in the image data is removed as an unnecessary area. Also, in the left-right direction of the image data of the spread page, the reading result of the side surface part, the reading result of the front cover part of the book document, and the book document than the reading range are located outside the side part of the book document. A black solid image due to being narrower than the range of the spread page appears. However, since all areas outside the innermost dark color band E1 are determined as unnecessary areas, the reading result of the side face part, the reading result of the cover part of the book document, and all of the solid black image can be removed. .

  Further, the page-to-page boundary in the spread page can be appropriately determined. Therefore, it is possible to appropriately remove the unnecessary area in the central portion caused by the lift of the spine portion of the book document. Also, for example, the width of the unnecessary area depends on the size of the spread page of the book manuscript, the number of pages of the book manuscript, the thickness of the book manuscript, such as the difference between a magazine of about 100 pages and a dictionary of thousands of pages. Is different. However, since it is possible to input each predetermined width using the operation panel 1 (input unit), unnecessary areas can be appropriately removed regardless of the type of book document. Further, it can be determined whether or not the area is an unnecessary area accurately based on the set value of the predetermined pixel value. However, the value of the predetermined pixel value can be set by the input unit, and by changing the value of the predetermined pixel value, it can be accurately determined whether or not it is an unnecessary area. In addition, since printing can be performed based on image data of a book document from which unnecessary areas are appropriately removed, an image forming apparatus that does not consume wasteful developer such as toner can be provided. In addition, since the manufacturing cost required for the image processing apparatus 100 mounted on the image forming apparatus can be kept low, the manufacturing cost of the image forming apparatus can also be suppressed.

  The embodiment of the present invention has been described above, but the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention is applicable to an image processing apparatus and an image forming apparatus provided with the same.

DESCRIPTION OF SYMBOLS 1 Operation panel (input part) 2 Image reading part 9 Image processing part 100 Image processing apparatus 200 Copying machine (image forming apparatus) A 1st predetermined width B 2nd predetermined width C 3rd predetermined width D 4th predetermined width E1 Dark color Belt E2 Light color belt FA First region FB Second region FC Third region FD Fourth region Xc Center line Xc 'Page boundary line

Claims (8)

An image reading unit that irradiates light and reads an original to generate image data;
An image processing unit that performs image processing on the image data;
The image processing unit
In the first area of the first predetermined width from one end in the left-right direction of the spread page of the image data to the inside of the image data, and from the other end to the inside of the image data. 2 Determine whether there is an unnecessary area in the second area of a predetermined width,
An image processing apparatus, wherein the unnecessary area in the first area and the pixel in the unnecessary area in the second area are replaced with white.   The image processing unit is a line extending in the vertical direction of the spread page within a third region having a third predetermined width centering on a central line at a center position in a horizontal direction of the spread page of the image data. The line in which the darkest pixel exists in the width region is defined as a page boundary line, and the pixels in the fourth region having the fourth predetermined width around the page boundary line are replaced with white. Image processing apparatus.   In the first area and the second area, the image processing unit extends in a vertical direction of the spread page, and includes a dark color band composed of pixel values that are darker than a predetermined pixel value, and a thin color lighter than the dark color band. 3. The image processing apparatus according to claim 1, wherein if there is a repetition with a color band, the repeated area is determined as the unnecessary area.   The image processing apparatus according to claim 3, wherein the image processing unit determines, as an unnecessary area, an innermost dark band in the image data in the first area and the second area.   When there are a plurality of pixels having the darkest pixel value in the third predetermined width region, the image processing unit is arranged at a center position of the pixels having the darkest pixel value located at both ends in the horizontal direction of the spread page. The image processing apparatus according to claim 1, wherein a line extending in a vertical direction of the spread page is defined as the page boundary line.   6. An input unit for setting all or any of the first predetermined width, the second predetermined width, the third predetermined width, and the fourth predetermined width. The image processing apparatus according to item 1.   The image processing apparatus according to claim 3, further comprising an input unit configured to set the predetermined pixel value.   An image forming apparatus comprising the image processing apparatus according to claim 1.

Images