JP4897637B2 - Image processing apparatus, image forming apparatus provided with image processing apparatus, image processing method, image processing program, and computer-readable recording medium storing the program - Google Patents

Description

  The present invention relates to an image processing apparatus, an image forming apparatus provided with an image processing apparatus, an image processing method, an image, and the like, which are used when a double-sided original is printed using an electrophotographic method and the image of the double-sided original is reproduced. The present invention relates to a processing program and a computer-readable recording medium on which the program is recorded.

  In general, in the reproduction of an image of an original in an electrophotographic image forming apparatus, first, reflected light obtained by scanning while irradiating light exposed from a slit is used as the image information as an optical / electric conversion element. The original image is read by receiving (CCD: Charge Coupled Device), converting the voltage and converting the obtained analog image information into a digital signal. Then, the digital signal is optically converted, and an electrostatic latent image corresponding to the original image is formed on a uniformly electrostatically charged photoreceptor. Thereafter, the electrostatic latent image formed on the photoreceptor is developed with toner (also referred to as “developer”). The toner image on the photosensitive member is transferred onto the recording paper by electricity of reverse polarity. The toner image transferred to the recording paper is heated and pressed to be fixed.

  If there are images on both the front and back sides of the document, the density of the other side may be read when the scanner reads one side of the document. In such a case, so-called show-through occurs in which even the image information on the other side that is not necessary is printed.

  In order to avoid such a problem, various techniques for suppressing the show-through in the image forming apparatus have been proposed.

  For example, in Patent Document 1, image information on one side and the other side of a double-sided document is read, the image information on the other side is inverted, and the image information on one side is combined and combined. There has been proposed an image processing apparatus configured to remove show-through in image information of a surface.

  Further, in Patent Document 2, a show-through prevention mode can be set. When the show-through prevention mode is set, a show-through level is determined based only on image information of one side that has been read, and binarization processing is performed. Thus, an image forming apparatus configured to suppress show-through has been proposed.

JP-A-10-304204 JP 2005-277886 A

  However, the following problems have been pointed out in the image forming apparatuses disclosed in Patent Documents 1 and 2.

  In the technique described in Patent Document 1, the image information on one surface is basically left untouched, and the image is synthesized in consideration of the intensity of information on the other surface. Therefore, since the show-through is uniformly removed by the threshold value in the obtained image, there is a detrimental effect on the portion that is not show-through on one side.

  In the technique described in Patent Document 2, the image processing itself is simple, but since the determination is based on the image information of only one surface, the accuracy of the show-through detection is not high.

  The present invention has been made in view of the above technical problem, and enables an image processing apparatus, an image forming apparatus provided with an image processing apparatus, and an image processing apparatus capable of highly accurate image processing without show-through upon image reproduction of a double-sided document. It is an object of the present invention to provide a processing method, an image processing program, and a computer-readable recording medium on which the program is recorded.

  When the present invention is viewed from the first aspect, image reproduction of one side of the double-sided document read by the image information reading unit and / or image information of the other side is performed (in other words, the image information reading unit). An image processing apparatus for performing image reproduction of image information on one side of the double-sided document read in step 1 or image information on the other side), and an image on one side input from the image information reading unit First region separation processing means for separating information, and a first specific region having a component that can be influenced by the show-through component of the other surface from the region separation result by the first region separation processing unit Region extraction processing means, second region separation processing means for separating the image information of the other surface input from the image information reading unit, and region separation results by the second region separation processing means Show-through from one side to the other Second region extraction processing means for extracting a second specific region having a possible component, extraction information obtained by the first region extraction processing means, and obtained by the second region extraction processing means An image processing apparatus including a comparison determination processing means for determining the presence or absence of show-through from comparison of both pieces of extracted information, and a density conversion processing means for performing density conversion according to a determination result of the comparison determination processing means. is there.

  In the above configuration, image reproduction of the image information on one side of the read double-sided document or the image information on the other side is performed. At this time, the image information of one surface read and input is subjected to region separation, and a first specific region having a component that can be influenced by the show-through component of the other surface is extracted from the region separation result. In parallel with this, the image information of the other surface read and input is subjected to region separation, and a second specific region having a component that can be show-through to one surface is extracted from the region separation result. Then, the presence / absence of show-through is determined by comparing both the extracted information related to the first specific area and the extracted information related to the second specific area, and density conversion is performed according to the determination result. In this way, for the detection of show-through on one side of a double-sided document, it is possible to accurately determine the presence or absence of show-through on a double-sided document by directly using the area separation extraction process information of the image information on the other side of the document. be able to. As a result, it is possible to obtain a reproduced image without show-through with a simple configuration.

  The image processing apparatus includes: a threshold value calculation processing unit for calculating a threshold value based on density for the first specific region extracted by the first region extraction processing unit; Binarization processing means for performing binarization processing using the calculation result is further included. The comparison determination processing means is obtained by the processing information obtained by the binarization processing means and the second region extraction processing means. The presence or absence of show-through is determined by comparing the extracted information.

  In the above configuration, a threshold value related to the first specific area is calculated, and binarization processing is performed using the calculated threshold value. Thereafter, the presence or absence of show-through is determined from a comparison between the binarization processing information and the extracted information related to the second specific area. Thereby, it is possible to easily determine the presence or absence of show-through in the double-sided document.

  Further, the image processing apparatus is configured to detect a background on the one surface from the image information on one surface input from the image information reading unit, and according to a detection result by the background detection processing unit. The image processing apparatus further includes background portion extraction processing means for extracting a background portion of one surface, and the first area extraction processing means includes a region separation result obtained by the first area separation processing means and an extraction result obtained by the background portion extraction processing means. To extract the first specific region.

  In the above configuration, the background is detected from the image information of the one surface read and input, and the background portion is extracted according to the detection result of the background. The background portion extraction information is taken into account when the first specific region is subjected to region extraction processing. As described above, since the background information is taken into consideration in advance, it is possible to set the background removal amount in consideration of show-through.

  Further, in the image processing apparatus, the density conversion processing means selects a density conversion table corresponding to the input image density, and performs density conversion processing with reference to the selected density conversion table.

  In the above configuration, the density conversion process is changed according to the density information in the region separation extraction process, and the density conversion process according to the situation of the background and show-through information becomes possible. As a result, a reproduced image without show-through is obtained.

  It should be noted that density information is referred to when the first specific area is extracted by the first area extracting means. In one aspect, the second specific area is extracted by the second area extracting means. The density information is also referred to when the area is extracted. In this case, it is possible to detect show-through with higher accuracy.

  Viewed from a second aspect, the present invention is an image forming apparatus provided with the image processing apparatus.

  According to the above configuration, since the optimum density conversion process is performed according to the strength of show-through, it is possible to improve the image quality when forming an image.

  When the present invention is viewed from the third aspect, the image information of one side and / or the image information of the other side of the double-sided document read by the image information reading unit is reproduced (in other words, the image information reading unit). Image processing method for performing image reproduction of one side of the double-sided document read in step 1 or image information on the other side of the original, and an image on one side input from the image information reading unit A first region separation processing step for separating information, and a first specific region having a component that can be influenced by a show-through component of the other surface from the region separation result in the first region separation processing step. 1 region extraction processing step, a second region separation processing step for region separation of the image information of the other surface input from the image information reading unit, and a region separation result in the second region separation processing step to one surface back A second region extraction processing step for extracting a second specific region having a component that can be different, extraction information obtained in the first region extraction processing step, and extraction obtained in the second region extraction processing step The image processing method includes a comparison determination processing step for determining the presence or absence of show-through from a comparison of both information, and a density conversion processing step for performing density conversion according to the determination result of the comparison determination processing step.

  According to the above configuration, presence / absence of show-through is obtained by comparing information obtained by performing region separation / extraction processing on image information of one side read and input and information obtained by region separation / extraction of image information on the other side read and input Is determined, and density conversion is performed based on the determination result. Therefore, it is possible to obtain a reproduced image without show-through in a double-sided document.

  When the present invention is viewed from the fourth aspect, image reproduction of one side of the double-sided document read by the image information reading unit and / or image information of the other side is performed (in other words, the image information reading unit). The image information on one side of the double-sided document read in step S1 or the image information on the other side is reproduced. A first region separation processing unit for extracting the first specific region having a component that can be influenced by the show-through component of the other surface from the region separation result by the first region separation processing unit. One region extraction processing unit, a second region separation processing unit for region separation of the image information of the other surface input from the image information reading unit, and one surface from the region separation result by the second region separation processing unit Can be a show-through to Second region extraction processing means for extracting a second specific region having a component, extraction information obtained by the first region extraction processing means, and extraction information obtained by the second region extraction processing means Is an image processing program which functions as a comparison determination processing means for determining the presence or absence of show-through from the comparison of the two, and a density conversion processing means for performing density conversion according to the determination result of the comparison determination processing means. .

  In the above configuration, the computer performs image reproduction of the image information on one side of the double-sided document read by the image information reading unit or the image information on the other side. At this time, when the computer executes processing according to the image processing program, information obtained by performing region separation extraction processing on the image information of one side read and input, and region separation extraction of image information on the other surface read and input The presence or absence of show-through is determined by collating with the processed information, and density conversion is performed based on the determination result. Therefore, it is possible to obtain a reproduced image without show-through in a double-sided document.

  When the present invention is viewed from the fifth aspect, the image information of one side and / or the image information of the other side of the double-sided document read by the image information reading unit is reproduced (in other words, the image information reading unit). The image information on one side of the double-sided document read in step S1 or the image information on the other side is reproduced. A first region separation processing unit for extracting the first specific region having a component that can be influenced by the show-through component of the other surface from the region separation result by the first region separation processing unit. One region extraction processing unit, a second region separation processing unit for region separation of the image information of the other surface input from the image information reading unit, and one surface from the region separation result by the second region separation processing unit Can be a show-through to Second region extraction processing means for extracting a second specific region having a component, extraction information obtained by the first region extraction processing means, and extraction information obtained by the second region extraction processing means A comparison determination processing means for determining the presence or absence of show-through from the comparison of the two, and an image processing program that functions as a density conversion processing means for performing density conversion according to the determination result of the comparison determination processing means is recorded. The computer-readable recording medium.

  According to the above configuration, the image processing program recorded on the recording medium by the computer when performing image reproduction of the image information on one side of the double-sided document read by the image information reading unit or the image information on the other side. By performing the processing according to the above, the information obtained by performing the region separation extraction process on the image information of one side read and input is collated with the information obtained by performing the region separation extraction process on the image information of the other side read and input. Since the presence or absence of the reflection is determined and the density conversion is performed based on the determination result, a reproduced image without show-through can be obtained in the double-sided document.

  As the recording medium, for example, a memory itself for processing by a CPU (Central Processing Unit) such as a RAM (Random Access Memory) and a ROM (Read Only Memory) may be a recording medium. Alternatively, it may be a recording medium provided with a program reading device as an external storage device of a computer and readable by being inserted into this device. In any case, the recorded image processing program is executed when the CPU accesses the recording medium. Further, the CPU may read out the image processing program from the recording medium, copy the read image processing program to the program storage area, and execute it. The CPU comprehensively controls each part of the computer so as to form a predetermined image according to the installed image processing program.

  Further, the recording medium readable by the program reader includes (1) magnetic tape, (2) tape system such as cassette tape, magnetic disk such as flexible disk (FD) and hard disk (HDD), or CD-ROM ( Disc systems such as compact disc-read only memory (MO), magneto optical disc (MO), mini disc (MD), DVD (digital versatile disc), etc. (3) IC (integrated circ card) including memory card, integrated optical card (4) Mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrical) y Erasable Programmable Read Only Memory), can be exemplified medium or the like for recording fixedly programmed, including a semiconductor memory such as a flash memory.

  Furthermore, the computer may be configured to be connectable to a communication network including the Internet, and may be a medium that fluidly carries the program so as to download an image processing program from the communication network. When the image processing program is downloaded from the communication network as described above, the download program may be stored in the computer in advance. Moreover, you may install from another recording medium.

  As an example of a computer system that executes an image processing program read from the recording medium, (1) an image reading device such as a flatbed scanner, a film scanner, and a digital camera; and (2) the above various programs by executing various programs. (3) an image display device such as a CRT (Cathode Ray Tube) display or a liquid crystal display for displaying the processing results of the computer, and (4) the processing results of the computer An image output apparatus such as a printer that outputs the image to paper or the like is connected to each other. Further, the computer system is provided with a network interface or a modem for connecting to a server or the like via a communication network and transmitting and receiving various programs including an image processing program and various information such as image information. Preferably it is.

  In the present invention, the area separation extraction processing information on both the one side and the other side of the double-sided document is used for judging the presence or absence of show-through. Can be executed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the drawings attached to the present specification, the same reference numerals are assigned to the same functional parts. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[First embodiment]
<Mechanical configuration>
FIG. 1 is a diagram showing an overall configuration of an image forming apparatus 20 according to the first embodiment of the present invention.

  Referring to FIG. 1, an image forming apparatus 20 according to the present embodiment is an electrophotographic multifunction machine that functions as, for example, a copying machine, a printer, a facsimile machine, and the like. 2) an image information reading unit 24 that reads image information of a document; 2) an image forming unit 26 that forms an image based on the image information processed by the image processing circuit 82 shown in FIG. 2; A paper supply unit 30 for supplying recording paper from the cassette 28 to the image forming unit 26; (4) a fixing unit 32 for fixing the image transferred to the recording paper on which the image is formed in the image forming unit 26; A paper discharge unit 36 for discharging the recording paper on which the image is fixed to the paper discharge tray 34; and (6) a control device 38 for controlling the entire image forming apparatus 20.

  In the image forming apparatus 20, recording paper is also supplied to the image forming unit 26 from the manual feed tray 40 and the automatic paper feed cassette 42 outside the apparatus main body 22 via the paper supply unit 30. The manual feed tray 40 is disposed on the side opposite to the paper discharge tray 34. The automatic paper feed cassette 42 can accommodate a large amount of recording paper, and is connected to the apparatus main body 22 by an external attachment below the manual feed tray 40.

  The image information reading unit 24 includes an optical system 44 capable of reading a monochrome image or color image of a document, and a document table 46 made of a transparent glass body is disposed above the optical system 44.

  The optical system 44 includes a document scanning unit, an optical lens, a CCD line sensor, and the like, and performs an operation of the document placed on the document table 46 by an operation related to the automatic document feeder 48 provided on the document table 46. A black and white image or a color image is relatively read at a predetermined exposure position (reading position). The document image information read by the optical system 44 is output to the image processing circuit 82.

  The automatic document feeder 48 is supported by the apparatus main body 22 so as to be rotatable at a predetermined angle so that one end portion of the automatic document feeder 48 can directly place a document on the document table 46. The automatic document feeder 48 includes a document feed tray 50, a reversing path path 52, a document discharge tray 54, and the like, and a plurality of documents placed on the document feed tray 50 are one sheet. Each sheet is automatically fed onto the document reading position on the document table 46.

  In the image information reading unit 24, when the document placed on the document feeding tray 50 of the automatic document feeder 48 is a double-sided document, the double-sided document is removed from the document feeding tray 50 of the automatic document feeder 48. The image is fed with the surface facing down on the document reading position of the document table 46, and image information on the surface of the double-sided document placed on the document reading position of the document table 46 is read by the optical system 44. When the reading of the image information on the front side is completed, the front and back sides are reversed by the reverse path path 52 in the automatic document feeder 48, and the double-sided document is fed on the reading position of the document table 46 with the back side facing downward. Image information on the back side of the double-sided document placed on the document reading position of the document table 46 is read again by the optical system 44. When the reading of the image information on both the front and back sides of the document is completed in this way, the double-sided document is discharged to the document discharge tray 54 of the automatic document feeder 48.

  The image forming unit 26 includes a photosensitive drum 56, a charger 58, a laser scanning unit (hereinafter referred to as “LSU”) 60 that functions as an exposure unit, a developing unit 62, a transfer unit 63, a cleaning unit 64, and a toner supply unit 66. Including. The charger 58 charges the photosensitive drum 56 to a predetermined potential. The LSU 60 performs laser processing according to image data read by the image information reading unit 24 or image data such as image information transferred from an external device such as a client personal computer (hereinafter referred to as “client PC”) 88 shown in FIG. Light is irradiated to form an electrostatic latent image on the photosensitive drum 56. The developing device 62 supplies toner to the electrostatic latent image formed on the photosensitive drum 56 via a developing roller to visualize the toner image. The transfer unit 63 transfers the toner image formed on the photosensitive drum 56 onto the recording paper. The cleaning device 64 collects the toner remaining on the photosensitive drum 56 after the transfer process is completed. The toner supplier 66 supplies toner into the developing device 62.

  The photosensitive drum 56 is supported by the apparatus main body 22 so as to be rotatable clockwise. A charger 58, an LSU 60, a developing device 62, a transfer unit 63, and a cleaning device 64 are arranged in this order along the rotation direction of the photosensitive drum 56.

  The fixing unit 32 includes a pair of roller pairs of an upper pressure roller 68 and a lower heating roller 70. The heating roller 70 has a built-in heater, and the temperature of the heating roller 70 is detected by a fixing temperature sensor.

<Hardware configuration>
FIG. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus 20.

  As shown in FIG. 2, the control device 38 is substantially a computer, and includes a CPU 72, ROM 74, RAM 76, HDD (Hard Disk Drive) 78, an image memory 80, and an image processing circuit 82. Therefore, in the present embodiment, the control device 38 functions as an image processing device.

  A common BUS line 38L is connected to the CPU 72, and a ROM 74, a RAM 76, an HDD 78, an image memory 80, and an image processing circuit 82 are connected to the BUS line 38L.

  The CPU 72 realizes the functions of the respective units of the image processing circuit 82 shown in FIG. 3 by executing a computer program for realizing the image processing of the present embodiment. A program executed by the CPU 72 is stored in the ROM 74 or the HDD 78.

  The program stored in the ROM 74 or the HDD 78 is read from the ROM 74 or the HDD 78 and stored in the RAM 76 at the time of execution, and is read from an address in the RAM 76 indicated by a register functioning as a program counter in the CPU 72. Executed. Data necessary for execution is read from an address specified by the above-mentioned register in the CPU 72, the RAM 76 or the HDD 78. Similarly to this, the result of the execution is also stored at the address specified by the above-mentioned register in the CPU 72, the RAM 76 or the HDD 78.

  In addition to the image information reading unit 24, the image forming unit 26, the paper supply unit 30, the fixing unit 32, the paper discharge unit 36, the automatic paper feed cassette 42, and the automatic document feeder 48, the common BUS line 38L includes the main image forming unit. An NIC (Network Interface Card) 90 that interfaces with a client PC 88 or the like, which is one of external devices, is also connected via an operation panel 84 of the apparatus 20 and a LAN (Local Area Network) line 86. Therefore, the CPU 72 controls the image information reading unit 24, the image forming unit 26, the paper supply unit 30, the fixing unit 32, the paper feeding device 42, the automatic document feeder 48, and the NIC 90 to read the document, output the document, and the client. A desired operation such as communication with an external device such as the PC 88 is executed, and data is stored in and read out from the RAM 76, HDD 78, and image memory 80.

  In the image forming apparatus 20, the control device 38 functioning as an image processing apparatus converts image information input from an external device such as the image information reading unit 24 or the client PC 88 into an electrical signal of each color, and Output to LSU 60 respectively.

  The image processing program according to the present embodiment is transmitted from another device to the control device 38 functioning as an image processing device via the LAN line 86 and the NIC 90 and stored in the ROM 74 or the HDD 78.

<Configuration of Image Processing Circuit 82>
FIG. 3 is a functional block diagram of the image processing circuit 82.

  Referring to FIG. 3, the image processing circuit 82 is a circuit for performing image reproduction of the image information on one side of the double-sided document read by the image information reading unit 24 or the image information on the other side. The first region separation processing unit 92, the first region extraction processing unit 94, the second region separation processing unit 96, the second region extraction processing unit 98, the comparison determination processing unit 100, and the density conversion processing unit 102 Including.

  The first region separation processing unit 92 separates the image information of one side input from the image information reading unit 24 into regions. The region separation result obtained by the region separation processing unit 92 is given to the first region extraction processing unit 94.

  The first region extraction processing unit 94 extracts a first specific region having a component that can be influenced by the show-through component of the other surface from the region separation result by the first region separation processing unit 92. The extraction information obtained by the region extraction processing unit 94 is given to the comparison determination processing unit 100. A specific example of the first specific area will be described later.

  The second region separation processing unit 96 separates the image information of the other surface input from the image information reading unit 24. The region separation result by the region separation processing unit 96 is given to the second region extraction processing unit 98.

  The second region extraction processing unit 98 extracts a second specific region having a component that can be a show-through to one surface from the region separation result by the second region separation processing unit 96. The extraction information obtained by the region extraction processing unit 98 is given to the comparison determination processing unit 100. A specific example of the second specific area will be described later.

  The comparison determination processing unit 100 determines the presence or absence of show-through from the comparison between the extraction information obtained by the first region extraction processing unit 94 and the extraction information obtained by the second region extraction processing unit 98. The comparison determination result by the comparison determination processing unit 100 is given to the density conversion processing unit 102.

  The density conversion processing unit 102 performs density conversion according to the determination result of the comparison determination processing unit 100.

  The image processing circuit 82 outputs the image reproduction information obtained by the series of processes from the CPU 72 to the LSU 60 of the image forming unit 26 via the common BUS line 38L.

<Software configuration>
When the image forming apparatus 20 performs image reproduction of image information on one side of a double-sided document, or image information on the other side of the double-sided document, region separation extraction processing on both one side and the other side of the double-sided document is performed. It is programmed to determine the presence or absence of show-through based on information.

  As described above, this program is stored in the ROM 74 or the HDD 78 in the control device 38 of the image forming apparatus 20, and realizes an image processing function of the image forming apparatus 20 described below. Realization of this function is achieved by the CPU 72 in the control device 38, which is substantially a computer, controlling the image processing circuit 82 in accordance with the program.

  FIG. 4 is a flowchart showing a program structure for realizing the image processing function of the image forming apparatus 20. In FIG. 4, the control flow assumes a case where image reproduction on the surface of a double-sided document is performed.

  When the image information reading unit 24 finishes reading (scanning) the front and back sides of the double-sided document, the image information on the front side and the image information on the back side are stored in the image memory 80 by the CPU 72 and input to the image processing circuit 82 from the CPU 72. Is done.

  Referring to FIG. 4, when the image information on the front surface and the image information on the back surface are input to the image processing circuit 82, first, the first region separation processing unit 92 performs region separation on the input image information on the front surface. Processing is performed (step S100), and the second region separation processing unit 96 performs region separation processing on the input back side image information (step S104). In the present embodiment, the image information on both the front and back surfaces is separated into four areas: a character area, a dot area, a high density photographic area, and a low density photographic area.

  Here, the region separation processing in steps S100 and S104 will be described in detail.

  FIG. 5 is a flowchart showing the program structure of a routine for realizing the region separation processing function.

Referring to FIG. 5, halftone dot determination is first performed for region separation (step S200). In this halftone dot determination process, an image is divided into blocks each consisting of 9 pixels, and an average value (D _ave ) of signal levels is obtained for 9 pixels in each block, and each pixel in the block is obtained using the average value. Is binarized. Also, the maximum pixel signal level (D _max ) and the minimum pixel signal level (D _min ) are obtained at the same time. Thereafter, the halftone dot region is identified as a halftone dot region by utilizing the fact that the fluctuation of the image signal in the small region is large and the density is higher than the background. Specifically, for the binarized data, the number of change points from “0” to “1” and the number of change points from “1” to “0” are obtained in the main scanning and sub-scanning directions, respectively. Te, respectively and K _H and K _V, when both compared with a threshold value T _H and T _V are both above the threshold a dot region. In order to prevent erroneous determination with the background, the maximum value _{Dmax of} the pixel signal level, the minimum value _{Dmin of} the pixel signal level, and the average value _Dave of the pixel signal level are set to the maximum value and the average value of the pixel signal level. comparing the threshold value B ₂ with respect to the difference between the average value and the minimum value of the threshold B _1, and a pixel signal level for the difference between the.

  When the above halftone dot determination is completed, character edge determination is performed next (step S202). In this character edge determination process, in the 3 × 3 pixel block centered on the pixel of interest, the density difference between the pixel of interest and its neighboring pixels is obtained, and any one of them is one of the threshold values THc, THm, and THy. If it is larger than one, it is determined as a character edge region, and if it is smaller than any one of the threshold values THc, THm, and THy, it is determined as a photo region. For a pixel determined to be a photographic area, a threshold value THd is further used. If the above density difference is equal to or greater than THd, it is determined as a high density photographic area, and if it is less than THd, it is determined as a low density photographic area. Is done.

  Referring to FIG. 4 again, when the region separation process for the image information on both the front and back surfaces is completed, the control proceeds to steps S102 and S106.

  In step S102, the first specific region having a component that can be influenced by the show-through component on the back surface is extracted from the region separation result in step S100 by the first region extraction processing unit 94 with reference to the density information. Done. In the present embodiment, a portion that is not any of a character region, a halftone dot region, and a high-density photo region is extracted as the first specific region. Thereafter, the control proceeds to steps S108 and S110.

  On the other hand, in step S106, the second specific region having a component that can be exposed to the surface is extracted from the region separation result in step S104 by the second region extraction processing unit 98. In the present embodiment, at least one of a character area, a halftone dot area, and a high-density photo area is extracted as the second specific area. For example, when a character area, a halftone dot area, and a high density photographic area exist in the back side document, all of the character area, the halftone area, and the high density photographic area are extracted, and the high density photographic area is extracted from the back side document. If no exists, it means that a character area and a halftone dot area excluding a high density photographic area are extracted. Thereafter, the control proceeds to steps S108 and S110.

  When the control proceeds to steps S108 and S110, the comparison determination processing unit 100 compares the image information of the first specific area and the image information of the second specific area to determine whether there is show-through. Specifically, if the overlap between the first specific area and the second specific area is a predetermined ratio or more, it is determined that there is show-through, and otherwise, it is determined that there is no show-through. Control branches according to the determination result.

  If it is determined that there is show-through, the density conversion processing unit 102 selects a density conversion table from which show-through is removed, and performs density conversion processing with reference to the selected density conversion table (steps S112 and S116). ). At this time, as the density conversion table, a table that reproduces the low density portion brighter than the original input image density included in the surface image information according to the show-through information is selected in FIG. For example, the table tb1 rising from the input image density D1 is selected as the density conversion table.

  On the other hand, when it is determined that there is no show-through, the density conversion processing unit 102 selects a density conversion table that does not consider show-through, and performs density conversion with reference to the selected density conversion table (step S114 and step S114). S116). At this time, the density conversion table in FIG. 6 is selected as the input image density without selecting the table that reproduces the lower density part brighter than the original input image density included in the surface image information. For example, a table tb0 that rises from the input image density D0 is selected as the density conversion table.

  In the case of performing image reproduction on the back side of a double-sided document, image information on the back side is input to the first area separation processing unit 92 and image information on the front side is input to the second area separation processing unit 96. The image processing from step S100 to S116 is executed.

<Operation>
In the image forming apparatus 20, the image information of one side of the double-sided document read by the image information reading unit 24 or the image information of the other side is further reproduced.

  At this time, image information on both sides of the read double-sided document is input to the image processing circuit 82. When image information on both the front and back surfaces is input to the image processing circuit 82, the input image information on one surface is separated by the first region separation processing unit 92, and further, the first information is referred to while referring to the density information. The region extraction processing unit 94 extracts a first specific region having a component that can be influenced by the show-through component of the other surface from the region separation result in the first region separation processing unit 92. In parallel with this, the input image information of the other surface is subjected to region separation by the second region separation processing unit 96, and further by the second region extraction processing unit 98. A second specific region having a component that can be a show-through to one surface is extracted from the region separation result.

  Then, both the extracted information related to the first specific area and the extracted information related to the second specific area are compared by the comparison determination processing unit 100, and the presence or absence of show-through is determined based on the comparison result.

  A density conversion process for removing the show-through is performed by the density conversion processing unit 102 on the image determined to have show-through. On the other hand, the density conversion processing without considering the show-through is performed by the density conversion processing unit 102 on the image determined to have no show-through.

<Action and effect>
According to the present embodiment, the following operations and effects are achieved.

  (1) Since the area separation extraction process information of the image information on the other side of the document is directly used to detect the show-through on one side of the double-sided document, it is possible to accurately determine the presence or absence of the show-through in the double-sided document. Can do. As a result, it is possible to obtain a reproduced image without show-through with a simple configuration. As described above, by using the region separation extraction processing information on both the one side and the other side of the double-sided document for judging the presence or absence of show-through, high-accuracy image processing without show-through can be achieved. It becomes executable.

  (2) Since the density conversion process is changed according to the density information in the region separation / extraction process, the density conversion process according to the situation of the show-through information becomes possible, and as a result, a reproduced image without show-through is obtained.

  (3) As described above, since the optimum density conversion process is performed according to the strength of show-through, the image quality is improved when an image is formed.

[Second Embodiment]
A feature of the present embodiment is that a threshold relating to density is calculated from a first specific region having a component that can be influenced by a show-through component on the other surface, and the first specific is calculated using this threshold. The binarization process is performed, and the presence / absence of show-through is determined by comparing the binarization processing result with the extracted information on the second specific area having a component that can be show-through to one surface. There are other configurations similar to those of the first embodiment.

<Configuration of Image Processing Circuit 82>
FIG. 7 is a functional block diagram of an image processing circuit 82 applied to the image forming apparatus 20 according to the second embodiment of the present invention.

  Referring to FIG. 7, in the present embodiment, the image processing circuit 82 includes a first region separation processing unit 200, a first region extraction processing unit 200, a second region separation processing unit 96, and a second region separation processing unit 96. In addition to the region extraction processing unit 98, the comparison determination processing unit 100, and the density conversion processing unit 102, a threshold value calculation processing unit 104 and a binarization processing unit 106 are provided.

  The threshold value calculation processing unit 104 uses the threshold value based on the density for the first specific region extracted by the first region extraction processing unit 200 and having a component that can be influenced by the show-through component of the other surface. Is calculated. The threshold value calculated by the threshold value calculation processing unit 104 is given to the binarization processing unit 106.

  The binarization processing unit 106 performs binarization processing using the calculation result of the threshold value calculation processing unit 104. The binarization result in the binarization processing unit 106 is given to the comparison determination processing unit 100.

  The comparison determination processing unit 100 determines the presence or absence of show-through from the comparison of both the processing information obtained by the binarization processing unit 106 and the extraction information obtained by the second region extraction processing unit 98.

  In the first region extraction processing unit 200, the threshold value calculation processing unit 104 in the next stage calculates the threshold value related to the density from the first specific region. Therefore, the first specific extraction processing unit 200 does not refer to the density information. Region extraction is performed.

<Software configuration>
In the present embodiment, in particular, a threshold value related to the first specific area is calculated, and after binarization processing is performed using the calculated threshold value, binarization processing information and The program is programmed such that the presence or absence of show-through is determined from the comparison with the extracted information related to the second specific area.

  Similar to the first embodiment, this program is stored in the ROM 74 or the HDD 78 in the control device 38 of the image forming apparatus 20, and realizes the image processing function of the image forming apparatus 20 described below. Realization of this function is achieved by the CPU 72 in the control device 38, which is substantially a computer, controlling the image processing circuit 82 in accordance with the program.

  FIG. 8 is a flowchart showing a program structure for realizing the image processing function of the image forming apparatus 20. In FIG. 8, the flow of control assumes a case where image reproduction on the surface of a double-sided document is performed.

  Referring to FIG. 8, when surface image information is input, first region separation processing unit 92 performs region separation processing on the surface image information (step S300), and first region extraction processing unit In step S302, the first specific region having a component that can be influenced by the show-through component on the back surface is extracted from the region separation result in step S300. Thereafter, control proceeds to steps S304 and S306.

  When the control proceeds to steps S304 and S306, the threshold value calculation processing unit 104 calculates a threshold value based on the density based on the first specific region extracted in step S302, and a binarization processing unit. 106 binarizes the extraction region related to the first specific region using the threshold value. Thereafter, control proceeds to steps S312 and S314.

  On the other hand, when the back side image information is input, the second region separation processing unit 96 performs region separation processing on the back side image information (step S308), and the second region extraction processing unit 98 performs step S308. The second specific region having a component that can be a show-through to the surface is extracted from the region separation result (step S310). Thereafter, control proceeds to steps S312 and S314.

  When the control proceeds to steps S312 and S314, the comparison determination processing unit 100 uses the binarization result of the first specific area in step S306 and the image information of the second specific area obtained in step S310. The presence or absence of show-through is determined by comparison. Specifically, if the overlap of the second specific area with respect to the value indicating the binarization result of the first specific area is greater than or equal to a predetermined ratio THr, it is determined that there is show-through, and less than the predetermined ratio THr. If there is, it is determined that there is no show-through. Control branches according to the determination result.

  When it is determined that there is show-through, the density conversion processing unit 102 selects a density conversion table that reproduces a lower density part than the input image density and removes show-through in FIG. A density conversion process is performed with reference to the density conversion table (steps S316 and S320). For example, the table tb1 rising from the input image density D1 is selected as the density conversion table.

  On the other hand, if it is determined that there is no show-through, the density conversion processing unit 102 does not select the table for removing the show-through by reproducing the low-density part brighter than the input image density in FIG. A density conversion table that does not take into account is selected, and density conversion is performed with reference to the selected density conversion table (steps S318 and S320). For example, a table tb0 that rises from the input image density D0 is selected as the density conversion table.

  In the case of performing image reproduction on the back side of a double-sided document, image information on the back side is input to the first area separation processing unit 92 and image information on the front side is input to the second area separation processing unit 96. The image processing from step S300 to S320 is executed.

<Operation>
When image information on both the front and back surfaces is input to the image processing circuit 82, the input image information on one surface is separated by the first region separation processing unit 92, and further by the first region extraction processing unit 200. A first specific region having a component that can be influenced by the show-through component of the other surface is extracted from the region separation result in the first region separation processing unit 92. For this extracted information, a threshold value for the density is calculated by the threshold value calculation processing unit 104, and the first specific area is binarized using the threshold value. In parallel with this, the input image information of the other surface is subjected to region separation by the second region separation processing unit 96, and further by the second region extraction processing unit 98. A second specific region having a component that can be a show-through to one surface is extracted from the region separation result.

  Both the binarized information on the first specific area and the image information on the second specific area are compared by the comparison determination processing unit 100 to determine whether there is show-through.

  The density conversion processing unit 102 performs density conversion processing for removing the show-through on the image determined to have show-through, and performs density conversion processing without considering the show-through on the image determined to have no show-through. Done.

<Action and effect>
According to this embodiment, in addition to the same operations and effects as (1) to (3) of the first embodiment, the following operations and effects are achieved.

  After the threshold value for the first specific region having a component that can be influenced by the show-through component of the other surface is calculated and binarization processing is performed using this threshold value, the binarization processing is performed. The presence or absence of show-through is determined by comparing the information with the extracted information related to the second specific area having a component that can be show-through on one side. Judgment can be made.

[Third embodiment]
The feature of the present embodiment is that the background of one side is detected and extracted from the image information of one side of the double-sided document, and the background part extraction result is also a component that can be influenced by the show-through component of the other side The other features are the same as those of the second embodiment.

<Configuration of Image Processing Circuit 82>
FIG. 9 is a functional block diagram of an image processing circuit 82 applied to the image forming apparatus 20 according to the third embodiment of the present invention.

  Referring to FIG. 9, in the present embodiment, the image processing circuit 82 includes a first region separation processing unit 92, a first region extraction processing unit 200, a second region separation processing unit 96, a second region separation processing unit 96, and a second region separation processing unit 96. In addition to the region extraction processing unit 98, the comparison determination processing unit 100, the density conversion processing unit 102, the threshold value calculation processing unit 104, and the binarization processing unit 106, a background detection processing unit 108 and a background part extraction processing unit 110 are provided. It has been.

  The background detection processing unit 108 detects the background of the one surface from the image information of one surface input from the image information reading unit 24. The detection result in the background detection processing unit 108 is given to the background part extraction processing unit 110.

  The background portion extraction processing unit 110 extracts the background portion of one surface according to the detection result by the background detection processing unit 108. The extraction result by the background portion extraction processing unit 110 is given to the first region separation processing unit 92.

  The first region extraction processing unit 200 includes a component that can be influenced by the show-through component of the other surface from the region separation result by the first region separation processing unit 92 and the extraction result by the background portion extraction processing unit 110. One specific area is extracted.

<Software configuration>
In the present embodiment, in particular, for the image information on one side of a double-sided document, the background of one side is detected and extracted, and the detection and extraction result is combined with the region separation result on one side and the above-mentioned first information. It is programmed to be used when extracting specific areas.

  Similar to the first embodiment, this program is stored in the ROM 74 or the HDD 78 in the control device 38 of the image forming apparatus 20, and realizes the image processing function of the image forming apparatus 20 described below. Realization of this function is achieved by the CPU 72 in the control device 38, which is substantially a computer, controlling the image processing circuit 82 in accordance with the program.

  FIG. 10 is a flowchart showing a program structure for realizing the image processing function of the image forming apparatus 20. In FIG. 10, the flow of control assumes a case where image reproduction on the surface of a double-sided document is performed.

  In the present embodiment, when the image information on the front surface and the image information on the back surface are input, the image processing circuit 82 gives the image information on the front surface to the first region separation processing unit 92 and the background detection processing unit 108, and Is supplied to the second region separation processing unit 96.

  Referring to FIG. 10, when surface image information is input, first region separation processing unit 92 performs region separation processing on the surface image information (step S400). Thereafter, control proceeds to step S406.

  When the surface image information is input, the background detection processing unit 108 performs background detection of the surface image information (step S402). That is, the background density of the surface image information is detected from the histogram information. Various background detection methods have been proposed, but the method disclosed in Japanese Patent Application Laid-Open No. 2003-51946 is applied in the present embodiment. Specifically, the search is started from the dark side of the created histogram, and the level first exceeding a predetermined threshold is detected as a background candidate level, and the frequency of the background candidate level and the level adjacent to the bright side are detected. By comparing with the frequency, the level with the higher frequency is determined as the base level. When the background detection processing is completed, the background portion extraction processing unit 110 extracts the background portion according to the background detection result in step S402 (step S404). Specifically, a portion that falls within a range obtained by adjusting the density by a predetermined ratio with respect to the detected background density level (for example, a range of background density ± α%) is extracted as a background portion. Thereafter, control proceeds to step S406.

  When the control proceeds to step S406, the first region extraction processing unit 200 includes a first component having a component that can be influenced by the show-through component on the back surface from the region separation result in step S400 and the background portion extraction result in step S404. Extract a specific area. At this time, a portion that is not a character region, a halftone dot region, or a high-density photo region and falls within a range in which the density is adjusted by a predetermined ratio with respect to the background density (for example, a range of background density ± α%). Are extracted as the first specific region. Thereafter, the control proceeds to steps S408 and S410.

  When the control proceeds to steps S408 and S410, the threshold value calculation processing unit 104 calculates a threshold value based on the density based on the first specific region extracted in step S406, and a binarization processing unit. 106 binarizes the extraction region related to the first specific region using the threshold value. Thereafter, control proceeds to steps S416 and S418.

  When the back side image information is input, the second region separation processing unit 96 performs region separation processing on the back side image information (step S412), and the second region extraction processing unit 98 performs the step S412. A second specific region having a component that can show through to the surface is extracted from the region separation result (step S414). Thereafter, control proceeds to steps S416 and S418.

  When the control proceeds to steps S416 and S418, the comparison determination processing unit 100 uses the binarization result of the first specific area in step S410 and the image information of the second specific area obtained in step S414. The presence or absence of show-through is determined by comparison. At this time, if the overlap of the second specific area with respect to the value indicating the binarization result of the first specific area is greater than or equal to a predetermined ratio THr, it is determined that there is show-through, and if it is less than the predetermined ratio THr It is determined that there is no show-through. Control branches according to the determination result.

  When it is determined that there is show-through, the density conversion processing unit 102 detects the density-conversion table for removing the show-through and background in FIG. 6 by reproducing the lower-density part brighter than the input image density. A table having a background removal amount larger than the background density is selected, and density conversion processing is performed with reference to the density conversion table (steps S420 and S424). For example, the table tb2 rising from the input image density D2 is selected as the density conversion table.

  On the other hand, when it is determined that there is no show-through, the density conversion processing unit 102 uses a density conversion table that removes only the background without considering show-through in FIG. A table that is reproduced brightly and has a background removal amount corresponding to the detected background density is selected, and density conversion is performed with reference to the density conversion table (steps S422 and S424). For example, the table tb1 rising from the input image density D1 is selected as the density conversion table.

  Note that, when image reproduction on the back side of a double-sided document is performed, image information on the back side is input to the first region separation processing unit 92 and the background detection processing unit 108, and image information on the front side is input to the second region separation processing unit. 96, and the above-described image processing from step S400 to S424 is executed.

<Operation>
When image information on both front and back sides is input to the image processing circuit 82, the input image information on one side is a component that can be influenced by the show-through component on the other side by the first region extraction processing unit 200. Before the region extraction process of the first specific region is performed, the region is separated by the first region separation processing unit 92 and the background information is extracted by the background detection processing unit 108 and the background portion extraction processing unit 110. Is done. With respect to the extraction information related to the first specific area, the threshold value calculation processing unit 104 calculates a threshold value for the density, and the first specific area is binarized using the threshold value. In parallel with this, the input image information of the other surface is subjected to region separation by the second region separation processing unit 96, and further by the second region extraction processing unit 98. A second specific region having a component that can be a show-through to one surface is extracted from the region separation result.

  Both the binarized information on the first specific area and the image information on the second specific area are compared by the comparison determination processing unit 100 to determine whether there is show-through. If it is determined that there is show-through, the density conversion processing that provides a background removal amount larger than the background density detected for the image by the density conversion processing unit 102 (that is, density conversion processing for removing show-through and background). If it is determined that there is no show-through, the density conversion processing unit 102 converts the density of the background removal amount corresponding to the background density to the image (that is, the background without considering the show-through). Density conversion processing) is performed.

<Action and effect>
According to the present embodiment, in addition to the same operations and effects as those of the second embodiment, the show-through component of the other side extracted from the image information of one side of the double-sided original is separated and extracted. Since the first specific area having a component that can be affected is based on the background information in advance, it is possible to set the background removal amount in consideration of show-through. As a result, a highly accurate reproduced image without show-through can be obtained.

[Fourth embodiment]
FIG. 11 is a functional block diagram of an image processing circuit 82 applied to the image forming apparatus 20 according to the fourth embodiment of the present invention.

  Referring to FIG. 11, the feature of the present embodiment is that the second region extraction processing unit 300 can be a show-through to one surface from the region separation result obtained by the second region separation processing unit 96. The second specific region having the above is extracted, but at this time, the second region extraction processing unit 300 refers to the density information to perform the region extraction processing, and the other configuration is the third embodiment. It is the same as the form.

<Software configuration>
In the present embodiment, in particular, when performing region extraction processing on image information on the other side of a double-sided document, it is programmed to refer to density information.

  Similar to the first embodiment, this program is stored in the ROM 74 or the HDD 78 in the control device 38 of the image forming apparatus 20, and realizes the image processing function of the image forming apparatus 20 described below. Realization of this function is achieved by the CPU 72 in the control device 38, which is substantially a computer, controlling the image processing circuit 82 in accordance with the program.

  FIG. 12 is a flowchart showing a program structure for realizing the image processing function of the image forming apparatus 20. In FIG. 12, the flow of control assumes a case where image reproduction on the surface of a double-sided document is performed.

  Referring to FIG. 12, when surface image information is input, first region separation processing unit 92 performs region separation processing on the surface image information (step S500). Thereafter, the control proceeds to step S506.

  When the surface image information is input, the background detection processing unit 108 performs background detection of the surface image information (step S502), and the background part extraction processing unit 110 determines the background part according to the background detection result in step S502. Is extracted (step S504). At this time, a portion that falls within a range obtained by adjusting the density by a predetermined ratio with respect to the detected background density level (for example, a range of background density ± α%) is extracted as a background portion. Thereafter, the control proceeds to step S506.

  When the control proceeds to step S506, the first region extraction processing unit 200 includes a component that can be influenced by the show-through component on the back surface from the region separation result in step S500 and the background portion extraction result in step S504. One specific area is not a character area, a halftone dot area, or a high density photographic area, and a range in which the density is adjusted by a predetermined ratio with respect to the background density (for example, a range of background density ± α%). The part that fits in is extracted. Thereafter, control proceeds to steps S508 and S510.

  When the control proceeds to steps S508 and S510, the threshold value calculation processing unit 104 calculates a threshold value based on the density based on the first specific region extracted in step S506, and a binarization processing unit. 106 binarizes the extraction region related to the first specific region using the threshold value. Thereafter, control proceeds to steps S516 and S518.

  When the back side image information is input, the second region separation processing unit 96 performs region separation processing on the back side image information (step S512), and the second region extraction processing unit 300 refers to the density information. Then, the second specific region having a component that can be a show-through to the surface is extracted from the region separation result in step S512 (step S514). Thereafter, control proceeds to steps S516 and S518.

  When the control proceeds to steps S516 and S518, the comparison determination processing unit 100 uses the binarization result of the first specific area in step S510 and the image information of the second specific area obtained in step S514. When the comparison result is that the overlap of the second specific area with respect to the value indicating the binarization result of the first specific area is equal to or greater than a predetermined ratio THr, it is determined that there is show-through, and the predetermined ratio If it is less than THr, it is determined that there is no show-through. Control branches according to the determination result.

  After that, when it is determined that there is show-through, the density conversion processing unit 102 reproduces the low-density portion brighter than the input image density as a density conversion table for removing show-through and background in FIG. A table having a background removal amount larger than the detected background density is selected, density conversion processing is performed with reference to this density conversion table (steps S520 and S524), and if it is determined that there is no show-through, FIG. As a density conversion table that removes only the background without considering show-through, select a table that reproduces the low-density part brighter than the input image density and provides the background removal amount according to the detected background density. Density conversion is performed with reference to the density conversion table (steps S522 and S524). For example, when it is determined that there is show-through, the table tb2 rising from the input image density D2 is selected as the density conversion table, and when it is determined that there is no show-through, the table tb1 rising from the input image density D1 is selected as the density conversion table. .

  Note that, when image reproduction on the back side of a double-sided document is performed, image information on the back side is input to the first region separation processing unit 92 and the background detection processing unit 108, and image information on the front side is input to the second region separation processing unit. 96, and the above-described image processing from step S500 to S524 is executed.

<Operation>
When image information on both front and back sides is input to the image processing circuit 82, the input image information on one side is a component that can be influenced by the show-through component on the other side by the first region extraction processing unit 200. Before the region extraction process of the first specific region is performed, the region is separated by the first region separation processing unit 92 and the background information is extracted by the background detection processing unit 108 and the background portion extraction processing unit 110. Is done. With respect to the extraction information related to the first specific area, the threshold value calculation processing unit 104 calculates a threshold value for the density, and the first specific area is binarized using the threshold value. In parallel with this, the input image information of the other surface is subjected to region separation by the second region separation processing unit 96 and further to the second region by the second region extraction processing unit 300 while referring to the density information. A second specific region having a component that can be a show-through to one surface is extracted from the region separation result in the separation processing unit 96.

  Both the binarized information on the first specific area and the image information on the second specific area are compared by the comparison determination processing unit 100 to determine whether there is show-through. If it is determined that there is show-through, density conversion processing (that is, density conversion processing for removing show-through and background) is performed with a background removal amount larger than the background density detected by the density conversion processing unit 102, and there is no show-through. If it is determined, the density conversion processing unit 102 performs background conversion amount density conversion processing according to the background density (that is, density conversion processing for removing only the background without considering show-through).

<Action and effect>
According to the present embodiment, in addition to the same operation and effect as the third embodiment, the region extraction process for the image information on the other surface is executed with reference to the density information. More accurate show-through detection is possible.

  The present invention is not limited to the above embodiment. In the above-described embodiment, the configuration in which the image processing program is transmitted from another device to the control device functioning as the image processing device via the LAN line and the NIC and stored in the ROM or HDD is described. However, the present invention is not limited to such a configuration. For example, in place of the NIC, various disk drives such as a DVD drive, a CD-ROM drive, and an FD drive, a memory port, and the like are provided, whereby an image processing program recorded on an external recording medium is stored in the image forming apparatus. You may make it introduce. Even in this case, the object of the present invention can be sufficiently achieved. It goes without saying that various design changes and modifications can be made within the scope of the claims attached to this specification.

  That is, the embodiment disclosed in this specification is merely an example, and the present specification is not limited to the embodiment described above. The scope of the present invention is indicated by the claims in the appended claims in consideration of the description of the present specification, and all modifications within the meaning and scope equivalent to the words described therein are included. Including.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus. FIG. It is a functional block diagram of an image processing circuit. FIG. 2 is a diagram showing a program structure for realizing an image processing function of the image forming apparatus in a flowchart format. It is a figure which shows the program structure of the routine for implement | achieving an area | region isolation | separation processing function in the flowchart format. It is a figure which shows a density | concentration conversion table as a graph. FIG. 6 is a functional block diagram of an image processing circuit applied to an image forming apparatus according to a second embodiment of the present invention. FIG. 2 is a diagram showing a program structure for realizing an image processing function of the image forming apparatus in a flowchart format. FIG. 10 is a functional block diagram of an image processing circuit applied to an image forming apparatus according to a third embodiment of the present invention. FIG. 2 is a diagram showing a program structure for realizing an image processing function of the image forming apparatus in a flowchart format. FIG. 10 is a functional block diagram of an image processing circuit applied to an image forming apparatus according to a fourth embodiment of the present invention. FIG. 2 is a diagram illustrating a program structure for realizing an image processing function of an image forming apparatus in a flowchart format.

Explanation of symbols

20 Image forming device 24 Image information reading unit 38 Control device 60 LSU
72 CPU
74 ROM
76 RAM
78 HDD
80 image memory 82 image processing circuit 92 first region separation processing unit 94, 200 first region extraction processing unit 96 second region separation processing unit 98, 300 second region extraction processing unit 100 comparison determination processing unit 102 density Conversion processing unit 104 Threshold value calculation processing unit 106 Binary processing unit 108 Background detection processing unit 110 Background part extraction processing unit

Claims (8)

An image processing apparatus for performing image reproduction of image information on one side and / or image information on the other side of a double-sided document read by an image information reading unit,
The image information of the one surface that is input from the image information reading unit, a character region, a halftone dot region, the high concentration photographic region, and the low-concentration photo area for separation into a first region separating means,
Segmentation results or found by the first region separating means, pre SL have a effect can undergo components of show-through components of the other surface, and the character area, the halftone dot area, and the high concentration photos First area extraction processing means for extracting a first specific area that is not any of the areas;
The image information of the other side that is input from the image information reading unit, a character region, a halftone dot region, the high concentration photographic region, and the low-concentration photo area for separation in the second region separating means,
The second region separating means by the segmentation results or al, have a will obtain components and show-through of the previous SL one side, and the character area, the halftone dot area, and of the high concentration photograph area Second region extraction processing means for extracting a second specific region which is at least one region ; and
The extraction information of the first specific area obtained by the first area extraction processing means is compared with the extraction information of the second specific area obtained by the second area extraction processing means. A comparison for determining that there is show-through if the overlap between the first specific area and the second specific area is greater than or equal to a predetermined ratio, and that there is no show-through if the overlap is smaller than the predetermined ratio. including determination processing hand stage, the image processing apparatus. Threshold value calculation processing means for calculating a threshold value based on density for the first specific area extracted by the first area extraction processing means, and a calculation result of the threshold value calculation processing means And further includes binarization processing means for performing binarization processing using
The comparison determination processing unit compares the processing information obtained by the binarization processing unit and the extraction information obtained by the second region extraction processing unit, and compares the first specific region with the first region. 2. The image processing apparatus according to claim 1 , wherein if the overlap with a specific area of 2 is equal to or greater than a predetermined ratio, it is determined that there is show-through, and if it is smaller than the predetermined ratio, it is determined that there is no show-through . A background detection processing unit for detecting a background of the one surface from the image information of the one surface input from the image information reading unit, and the detection of the one surface according to a detection result by the background detection processing unit. It further includes a ground part extraction processing means for extracting the ground part,
The first area extracting processing unit, the first region separating means further separated the character regions in the dot region, an area not one of the high density photographic region, and the underlying The image processing apparatus according to claim 2 , wherein an area that falls within a range that is adjusted by a predetermined ratio with respect to the background density extracted by the partial extraction processing unit is extracted as the first specific area . If the result of the comparison / determination processing means is show-through, the density conversion of the one surface is performed using a density conversion table that reproduces a lower density part brighter than the input image density, and the determination result 4. The apparatus according to claim 1 , further comprising density conversion processing means for performing density conversion on the one surface using a density conversion table that does not consider show-through when no show-through occurs . The image processing apparatus according to item 1.   An image forming apparatus comprising the image processing apparatus according to claim 1. An image processing method for performing image reproduction of image information on one side and / or image information on the other side of a double-sided original read by an image information reading unit,
The image information of the one surface that is input from the image information reading unit, a character region, a halftone region, the first segmentation process step of separation high concentration photograph area, and the low-concentration photo region,
Segmentation results or found in the first segmentation process step, pre SL have a effect can undergo components of show-through components of the other surface, and the character area, the halftone dot area, and the high concentration photos A first region extraction processing step for extracting a first specific region that is not one of the regions;
The image information of the other side that is input from the image information reading unit, a character region, a halftone dot region, the second region separating process step of separation into a high density photographic region, and the low-concentration photo region,
It said second segmentation process segmentation results or et at step have a will obtain components and show-through of the previous SL one side, and the character area, the halftone dot area, and of the high concentration photograph area A second region extraction processing step for extracting a second specific region that is at least one region ; and
The extraction information of the first specific area obtained in the first area extraction processing step is compared with the extraction information of the second specific area obtained in the second area extraction processing step. Comparison determination processing for determining that there is show-through if the overlap between the first specific area and the second specific area is equal to or greater than a predetermined ratio, and that there is no show-through if the overlap is smaller than the predetermined ratio. step including flop, image processing method. In order to perform image reproduction of the image information on one side and / or the image information on the other side of the double-sided document read by the image information reading unit,
The image information of the one surface that is input from the image information reading unit, a character region, a halftone dot region, the high concentration photographic region, and the low-concentration photo area for separation into a first region separating means,
Segmentation results or found by the first region separating means, pre SL have a effect can undergo components of show-through components of the other surface, and the character area, the halftone dot area, and the high concentration photos First area extraction processing means for extracting a first specific area that is not any of the areas;
The image information of the other side that is input from the image information reading unit, a character region, a halftone dot region, the high concentration photographic region, and the low-concentration photo area for separation in the second region separating means,
The second region separating means by the segmentation results or al, have a will obtain components and show-through of the previous SL one side, and the character area, the halftone dot area, and of the high concentration photograph area Second region extraction processing means for extracting a second specific region which is at least one region ; and
The extraction information of the first specific area obtained by the first area extraction processing means is compared with the extraction information of the second specific area obtained by the second area extraction processing means. A comparison for determining that there is show-through if the overlap between the first specific area and the second specific area is greater than or equal to a predetermined ratio, and that there is no show-through if the overlap is smaller than the predetermined ratio. determination processing hand stage and to be functional, the image processing program. In order to perform image reproduction of the image information on one side and / or the image information on the other side of the double-sided document read by the image information reading unit,
The image information of the one surface that is input from the image information reading unit, a character region, a halftone dot region, the high concentration photographic region, and the low-concentration photo area for separation into a first region separating means,
Segmentation results or found by the first region separating means, pre SL have a effect can undergo components of show-through components of the other surface, and the character area, the halftone dot area, and the high concentration photos First area extraction processing means for extracting a first specific area that is not any of the areas;
The image information of the other side that is input from the image information reading unit, a character region, a halftone dot region, the high concentration photographic region, and the low-concentration photo area for separation in the second region separating means,
The second region separating means by the segmentation results or al, have a will obtain components and show-through of the previous SL one side, and the character area, the halftone dot area, and of the high concentration photograph area Second region extraction processing means for extracting a second specific region which is at least one region ; and
The extraction information of the first specific area obtained by the first area extraction processing means is compared with the extraction information of the second specific area obtained by the second area extraction processing means. A comparison for determining that there is show-through if the overlap between the first specific area and the second specific area is greater than or equal to a predetermined ratio, and that there is no show-through if the overlap is smaller than the predetermined ratio. determination processing hand stage and to be functional, a computer readable recording medium recording an image processing program.

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