JP2019080169A - Image processing device and image processing method - Google Patents

Abstract

To detect double feed when feeding originals, without using a mechanism dedicated to detection of double feed.SOLUTION: The device detects image density of an original expressed by image information on the basis of the image information. In a case where a difference between a first image density being an image density related with a first original detected on the basis of first image information and second image density being an image density related with a second original detected on the basis of second image information is larger than a predetermined value, the device detects occurrence of overlapping of the first original or the second original.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image processing apparatus and an image processing method.

  In recent years, computerization of information tends to be promoted, and image processing apparatuses such as printers and facsimiles used for outputting computerized information and scanners used for computerizing documents have become indispensable devices. Such an image processing apparatus is often configured as a multifunction peripheral that can be used as a printer, a facsimile, a scanner, and a copier by including an imaging function, an image forming function, a communication function, and the like.

  Among such image processing apparatuses, there is one which conveys a document to a scanner by an ADF (Auto Document Feeder) and generates a read image. When the document is conveyed to the scanner by the ADF, a so-called "multi-feed" may occur in which a plurality of documents are conveyed in an overlapping state, and it may not be possible to read the target document.

  On the other hand, a double feed detection technique using a reflective or transmissive sensor is known (see, for example, Patent Document 1). Patent Document 1 discloses a technique in which a sensor of reflection type or transmission type is disposed in a conveyance path of a document, and it is determined whether double feeding of a document is occurring or not based on the relationship between the reflected light amount and the transmitted light amount. ing.

  However, in the technology disclosed in Patent Document 1, it is necessary to dispose a mechanism dedicated to double feed detection such as a reflective or transmissive sensor.

  An object of the present invention is to detect double feeding during document conveyance without using a mechanism dedicated to double feeding detection.

  In order to solve the above problems, one aspect of the present invention is an image processing apparatus that reads an original and generates image information, and an image density detection unit that detects an image density of the original based on the image information A first image density that is an image density related to a first document detected based on the first image information, and a second image density that is an image density related to a second document detected based on the second image information And a duplication detection unit that detects that duplication of a document has occurred in either the first document or the second document when the difference of is larger than a predetermined value.

  According to the present invention, double feeding at the time of document conveyance can be detected without using a mechanism dedicated to double feeding detection.

FIG. 1 is a block diagram showing a hardware configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 1 is a block diagram showing a functional configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing an internal configuration of an image processing unit according to the embodiment of the present invention. The flowchart which shows the flow of the whole process which the duplication detection part which concerns on embodiment of this invention performs. FIG. 6 is a view showing a read image generated by reading one original according to the embodiment of the present invention. FIG. 6 is a view showing a read image generated by reading a plurality of originals according to the embodiment of the present invention. The flowchart which shows the flow of the 1st concentration detection processing concerning the embodiment of the present invention. FIG. 6 is a view showing a read image in which the shadow of an overlapping original according to the embodiment of the present invention is expressed. The flowchart which shows the flow of the 2nd density detection processing concerning an embodiment of the invention. 5 is a flowchart showing a flow of shadow detection processing according to the embodiment of the present invention. The flowchart which shows the flow of the 3rd density detection processing concerning an embodiment of the invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, the present invention is applied to an image processing apparatus such as an MFP (Multi Function Peripheral: multifunction device) equipped with an ADF (Auto Document Feeder) as a sheet feeding unit for feeding a document to be read to a scanner unit. An example will be described.

  First, the hardware configuration of the entire image processing apparatus 1 according to the present embodiment will be described. FIG. 1 is a block diagram showing the hardware configuration of the image processing apparatus 1 according to the present embodiment. The image processing apparatus 1 has a configuration in which the controller 100 and the engine unit 23 are connected by a PCI (Peripheral Component Interface) bus.

  The controller 100 is a controller that controls the entire image processing apparatus 1 and performs drawing, communication, and input from the operation unit. The engine unit 23 is a printer engine or the like connectable to the PCI bus, and is, for example, a black-and-white plotter, a 1-drum color plotter, a 4-drum color plotter, a scanner or a fax unit. The engine unit 23 includes an image processing unit such as error diffusion and gamma conversion in addition to a so-called engine unit such as a plotter.

  The controller 100 includes a CPU 11, a north bridge (NB) 13, a system memory (MEM-P) 12, a south bridge (SB) 14, a local memory (MEM-C) 17, an application specific integrated circuit (ASIC) 16, a hard disk drive HDD) 103 is included. Further, the north bridge (NB) 13 and the ASIC 16 are connected by an accelerated graphics port (AGP) bus 15. Further, the MEM-P 12 includes a ROM (Read Only Memory) 12 a and a RAM (Random Access Memory) 12 b.

  The CPU 11 controls the entire operation of the image processing apparatus 1 and includes a chip set including the NB 13, the MEM-P 12, and the SB 14, and is connected to other devices via the chip set. The NB 13 is a bridge for connecting the CPU 11 to the MEM-P 12, the SB 14, and the AGP bus 15, and includes a memory controller that controls reading and writing to the MEM-P 12, a PCI master and an AGP target. The MEM-P 12 is a system memory used as a memory for storing programs and data, a memory for expanding programs and data, a memory for drawing a printer, and the like, and includes a ROM 12a and a RAM 12b.

  The ROM 12a is a read-only memory used as a storage memory for programs and data, and the RAM 12b is a writable and readable memory used as a development memory for programs and data, a drawing memory for a printer, and the like. The SB 14 is a bridge for connecting the NB 13 to PCI devices and peripheral devices. The SB 14 may be connected to the NB 13 via the PCI bus, and a network interface (I / F) unit may be connected to the PCI bus.

  The ASIC 16 is an IC (Integrated Circuit) for image processing application having a hardware element for image processing, and realizes a function of a bridge connecting the AGP bus 15, the PCI bus, the HDD 125 and the MEM-C 17 respectively. The ASIC 16 includes a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 16, a memory controller that controls the MEM-C 17, and a plurality of DMACs (Direct Memory Access) that rotate image data by hardware logic. Controller) and a PCI unit that transfers data between the engine unit 23 via the PCI bus.

  Connected to the ASIC 16 are an FCU (Facsimile Control Unit) 18, a USB (Universal Serial Bus) 19, and an IEEE 1394 (the Institute of Electrical and Electronics Engineers 1394) interface 21 through the PCI bus. The operation display unit 24 is directly connected to the ASIC 16. The MEM-C 17 is a local memory used as a copy image buffer and a code buffer.

  The HDD 25 is a storage for storing image data, storing programs, storing font data, and storing forms, and stores a program file of application software executed in the image processing apparatus 1. The AGP bus 15 is a bus interface for a graphics accelerator card proposed to accelerate graphics processing, and makes the graphics accelerator card faster by directly accessing the MEM-P 12 with high throughput. .

  In such a hardware configuration, the software control unit is configured by the CPU 11 performing operations according to the steps of the program stored in the ROM 12 a and the steps of the program loaded to the RAM 12 b from the storage medium such as the HDD 25 or the optical disk. Ru. The combination of the software control unit configured as described above and hardware configures a functional block that implements the function of the image processing apparatus 1 according to the present embodiment, and an image processing method and an image processing program are implemented. .

  Next, the functional configuration of the image processing apparatus 1 according to the present embodiment will be described with reference to FIG. As shown in FIG. 2, the image processing apparatus 1 according to the present embodiment includes a controller 100, an ADF (Auto Document Feeder) 101, a scanner unit 102, a sheet discharge tray 103, a display panel 104, and a sheet feeding table. A print engine 106, a discharge tray 107, and a network I / F 108 are provided.

  The controller 100 also includes a main control unit 110, an engine control unit 120, an image processing unit 130, an operation display control unit 140, and an input / output control unit 150. As shown in FIG. 2, the image processing apparatus 1 according to the present embodiment is configured as a multifunction machine having a scanner unit 102 and a print engine 106. In FIG. 2, the electrical connection is indicated by a solid arrow and the flow of the sheet is indicated by a broken arrow.

  The display panel 104 is a display unit for visually displaying the state of the image processing apparatus 1 and as a touch panel, when the user directly operates the image processing apparatus 1 or inputs information to the image processing apparatus 1 It is also an input part of That is, the display panel 104 includes a function of displaying an image for receiving an operation by the user. The display panel 104 is realized by the operation display unit 24 shown in FIG.

  A network I / F 108 is an interface for the image processing apparatus 1 to communicate with another device via the network 4, and an Ethernet (registered trademark) or a USB (Universal Serial Bus) interface or the like is used. The network I / F 108 can communicate by the TCP / IP protocol. The network I / F 108 also functions as an interface for executing facsimile transmission when the image processing apparatus 1 functions as a facsimile. Therefore, the network I / F 108 is also connected to the telephone line. The network I / F 108 is realized by the USB 19 and the IEEE 1394 interface 21 shown in FIG.

  The controller 100 is configured by a combination of software and hardware. Specifically, a program stored in a non-volatile storage medium such as the ROM 12a or non-volatile memory, HDD 25 or an optical disk is loaded into a volatile memory (hereinafter memory) such as the RAM 12b, and the CPU 11 executes an operation according to the program It is comprised by the software control part comprised by performing, and hardwares, such as ASIC16. The controller 100 functions as a control unit that controls the entire image processing apparatus 1.

  The main control unit 110 plays a role of controlling each unit included in the controller 100, and gives an instruction to each unit of the controller 100. The engine control unit 120 plays a role as a driving unit that controls or drives the print engine 106, the scanner unit 102, and the like. The image processing unit 130 generates drawing information based on image information to be printed out under the control of the main control unit 110. The drawing information is raster data which is information for drawing an image to be formed in the image forming operation by the print engine 106 which is an image forming unit.

  The image processing unit 130 also processes imaging data input from the scanner unit 102 to generate image data. The image data is information that is stored as a result of the scanner operation in the storage area of the image processing apparatus 1 or transmitted to another information processing terminal or storage device via the network I / F 108.

  The operation display control unit 140 displays information on the display panel 104 or notifies the main control unit 110 of information input through the display panel 104. The input / output control unit 150 inputs information input via the network I / F 108 to the main control unit 110. Further, the main control unit 110 controls the input / output control unit 150, and accesses other devices connected to the network via the network I / F 108.

  When the image processing apparatus 1 operates as a printer, first, the input / output control unit 150 receives a print job via the network I / F 108. The input / output control unit 150 transfers the received print job to the main control unit 110. When the main control unit 110 receives the print job, the main control unit 110 controls the image processing unit 130 to generate drawing information based on document information or image information included in the print job.

  When drawing information is generated by the image processing unit 130, the engine control unit 120 controls the print engine 106, and executes image formation on the sheet conveyed from the sheet feeding table 105 based on the generated drawing information. Let As a specific aspect of the print engine 106, it is possible to use an image forming mechanism by an ink jet method, an image forming mechanism by an electrophotographic method, or the like. A document on which an image has been formed by the print engine 106 is discharged to the discharge tray 107.

  When the image processing apparatus 1 operates as a scanner, the operation display control unit 140 or the input / output control according to a user's operation on the display panel 104 or a scan execution instruction input from another terminal via the network I / F 108. The unit 150 transfers the scan execution signal to the main control unit 110. The main control unit 110 controls the engine control unit 120 based on the received scan execution signal.

  The engine control unit 120 drives the ADF 101, and transports the document to be imaged set in the ADF 101 to the scanner unit 102. Further, the engine control unit 120 drives the scanner unit 102 to capture an image of a document conveyed from the ADF 101. Further, when a document is not set in the ADF 101 and is directly set in the scanner unit 102, the scanner unit 102 captures an image of the set document according to the control of the engine control unit 120.

  In an imaging operation, an optical element such as a contact image sensor (CIS) or a charge-coupled device (CCD) included in the scanner unit 102 optically scans a document, and imaging information is generated based on optical information. These optical elements scan the document conveyed to the scanner unit 102 for each area divided in the main scanning direction, and generate imaging information for each area scanned.

  In the present embodiment, the area divided in the main scanning direction is hereinafter referred to as "line". The engine control unit 120 transfers the imaging information generated by the scanner unit 102 to the image processing unit 130. The image processing unit 130 generates image information based on the imaging information received from the engine control unit 120 according to the control of the main control unit 110.

  The main control unit 110 acquires the image information generated by the image processing unit 130, and the main control unit 110 stores the image information in a storage medium mounted on the image processing apparatus 1 such as the HDD 40. That is, the scanner unit 102, the engine control unit 120, and the image processing unit 130 work together to function as an image input unit. Image information generated by the image processing unit 130 is stored as it is in a storage medium such as the HDD 40 according to a user's instruction, or is transmitted to an external device via the input / output control unit 150 and the network I / F 108. .

  When the image processing apparatus 1 operates as a copying machine, the image processing unit 130 generates drawing information based on imaging information received from the scanner unit 102 by the engine control unit 120 or image information generated by the image processing unit 130. Do. The engine control unit 120 drives the print engine 106 based on the drawing information as in the printer operation. In addition, when the information format of drawing information and imaging information is the same, it is also possible to use imaging information as drawing information as it is.

  The image processing apparatus 1 according to the present embodiment detects, based on imaging data input from the scanner unit 102, whether a so-called “double feed” in which originals are transported in duplicate is generated. Next, an internal function of the image processing unit 130 that performs control to process imaging data will be described.

  FIG. 3 is a functional block diagram showing internal functions of the image processing unit 130 according to the present embodiment. As shown in FIG. 3, the image processing unit 130 includes a read image generation unit 131, an overlap detection unit 132, a γ conversion processing unit 133, a filter processing unit 134, a color conversion processing unit 135, and a halftone processing unit 136.

  The read image generation unit 131 generates imaging information based on optical information obtained by the optical element scanning a document. The read image generation unit 131 generates, for example, a read image which is digital image data in which RGB are each represented by 8-bit values (0 to 255) as imaging information.

  Based on the read image generated by the read image generation unit 131, the overlap detection unit 132 detects whether duplication of a document in the read image has occurred. In addition, the aspect of the specific process which the duplication detection part 132 performs is mentioned later.

  The γ conversion processing unit 133 executes a process of correcting the gradation characteristic on the read image generated by the read image generation unit 131. Then, the γ conversion processing unit 133 transmits the read image obtained by converting the gradation characteristics to the filter processing unit 134.

  The filter processing unit 134 performs filter processing such as cooperation and smoothing on the read image acquired from the γ conversion processing unit 133. Then, the filter processing unit 134 transmits the read image subjected to the filter processing to the color conversion processing unit 135.

  The color conversion processing unit 135 converts color information represented by RGB data into CMYK (Cyan, Magenta, Yellow, Key plate) data with respect to the read image acquired from the filter processing unit 134. Then, the color conversion processing unit 135 transmits the read image subjected to the color conversion to the halftone processing unit 136.

  The halftone processing unit 136 performs dither processing, error diffusion processing, and the like on the read image acquired from the color conversion processing unit 135 to convert the number of gradations. The read image whose tone number has been converted by the halftone processing unit 136 is the drawing information.

  With the configuration as described above, the image processing apparatus 1 according to the present embodiment performs image processing on the acquired image to generate drawing information, and executes image formation output. In addition, when the image processing apparatus 1 according to the present embodiment generates a read image, the overlap detection unit 132 determines whether duplication is occurring in the document to be read.

  Next, with reference to FIG. 4, the flow of the double feed detection process performed by the duplicate detection unit 132 according to the present embodiment will be described. FIG. 4 is a flowchart showing the entire flow of the process performed by the duplication detection unit 132.

  The overlap detection unit 132 executes the first density detection process on the read image acquired from the read image generation unit 131 (S401). The overlap detection unit 132 calculates and stores the density of the paper of the ground portion of one original sheet as the first density detection process. Details of the first concentration detection process will be described with reference to FIG.

  Next, the overlap detection unit 132 executes a second density detection process on the read image acquired from the read image generation unit 131 (S402). The overlap detection unit 132 calculates the density of the background portion in the image area corresponding to the current line and several lines, that is, M lines, as the second density detection process. Details of the second concentration detection process will be described with reference to FIG.

  Next, the overlap detection unit 132 executes shadow detection processing on the read image (S403). The overlap detection unit 132 determines whether or not a shadow area that is an image area of a shadow portion is detected in the read image as the shadow detection process. In addition, the duplication detection unit 132 updates the value of “status” based on the result of the shadow detection process.

  Note that “status” is a parameter indicating whether or not a shadow area has been detected. “Status = 0” indicates that a shadow area is not detected. Also, “status = 1” indicates that the area is switched from the shadow area to the background area. “Status = 2” indicates that “status = 1” and that regions in the vicinity of the shadow region can be compared in density. Details of the shadow detection process will be described with reference to FIG.

  When the shadow detection process ends, the duplication detection unit 132 determines whether the value of “status” is 1 (S404). When it is determined that “status = 1” (S404 / YES), in the image area of the current line and the previous line, the pixel is switched from the shadow area to the background area, ie, from the shadow area to the background area It is an area.

  If YES in S404, the overlap detection unit 132 executes the third density detection process (S405). The overlap detection unit 132 calculates and stores the paper density of the background region of several lines as the third density detection process. In addition, the overlap detection unit 132 updates the value of status based on the result of the third concentration detection process. Details of the third density detection process will be described with reference to FIG.

  When the third concentration detection process is completed, the duplication detection unit 132 determines whether the value of “status” is 2 (S406). When it is determined that "status = 2" (S406 / YES), the background area of several lines is a line in which pixels are switched from the shadow area to the background area, and the lines of the shadow area where the density can be compared Is an area configured to include

  On the other hand, when it is not determined that “status = 2” (S406 / NO), the duplication detection unit 132 executes the processing from S401 again for the next line. Before and after the shadow area, when the change in density is smaller than a predetermined value, it is determined that “status = 2”.

  If YES in S406, the duplicate detection unit 132 determines whether the difference between “L2sum”, which is the result of the second density detection process, and “L3sum”, which is the result of the third density detection process, is larger than “Fth”. It determines (S407).

  The value of “Fth” changes its optimum value depending on the paper thickness and paper type of the document. Therefore, the value of “Fth” may be stored in advance in controller 100 as a data table for each sheet thickness and sheet type of the document, or may be configured to input an arbitrary value from the display panel 104 by the user.

  If the difference between “L2sum” and “L3sum” is larger than “Fth” (S 407 / YES), the duplication detection unit 132 detects duplication of the originals, and indicates that double feeding of the originals is occurring. The generation information is transmitted to the main control unit 110 (S408). When the double control occurrence information is received, the main control unit 110 controls the operations of the ADF 101 and the scanner unit 102, and stops the reading of the document (S409).

  When the reading of the document is stopped, the main control unit 110 causes the operation display control unit 140 to display on the display panel 104 that the double feed has been detected (S410). The duplication detection unit 132 ends the present process when the main control unit 110 executes the display in which the double feed is detected.

  When the difference between “L2sum” and “L3sum” is smaller than “Fth” (S407 / NO), the duplication detection unit 132 updates the status to 0 (S411). In the case of S411, double feed of the document has not occurred.

  Then, when the duplication detection unit 132 executes a series of processing from S401 on all the lines included in the document (S412 / YES), this processing ends. As described above, in the present embodiment, it is possible to detect whether double feed of a document has occurred based on a change in the density of pixels in the image area of the document included in the read image.

  FIG. 5 shows a read image P1 generated by reading one original document according to the present embodiment. The information indicating the density of the read image P1 may be stored in advance in the ROM 12a or the HDD 25 according to the size of the document, the paper quality, and the paper type.

  Even if the original is a document from which the read image P1 is generated if it is read normally, if the document is sent twice, the density of the area where the document overlaps is different. This example will be described using the read image P2 shown in FIG. As shown in FIG. 6, when a plurality of originals are double-fed, the plurality of originals overlap, so the image of the original represented in the read image P2 has a thickness obtained by overlapping the plurality of originals. The density corresponds to that of paper.

  Therefore, since the density of the read image P2 is higher than the density of the read image P1, double feeding can be detected by comparing the densities of a plurality of read images.

  Next, the first concentration detection process performed by the overlap detection unit 132 in S401 will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of the first concentration detection process according to the present embodiment.

  In the first density detection process, first, the density of the read image P1, which is the first image information corresponding to the background portion of one original, is calculated. The background portion is an area on the document where characters and images are not expressed, and in the read image P1, an area expressed by the color of the first original which is the origin of the read image P1. . Alternatively, the density of the image of the read image P1, that is, the first image density may be stored in advance in the ROM 12a, the HDD 25, or the like, and may be configured as a density information storage unit.

  Then, by comparing the density of the read image P1 with the density of the read image P2, which is the second image information, it is determined whether double feed of the document has occurred. In the first density processing, double feeding in a read image in which the four sides of the document overlap and are transported can be detected.

  First, the process of calculating the density of the read image P2, that is, the second image density by the overlap detection unit 132 will be described. The read image P2 is generated by the read image generation unit 131 based on the imaging information of the second document read by the scanner unit 102. Therefore, the overlap detection unit 132 functions as an image density detection unit that detects the image density of the document expressed in the read image P2.

  The overlap detection unit 132 divides the read image P2 acquired from the read image generation unit 131 at regular intervals in the main scanning direction, and flattens the image density for each of the divided image DIV1, the image DIV2, ..., DIVn. Flatness determination, achromatic determination, and brightness determination are respectively executed based on the change of the color, the change of the color component, and the change of the lightness (S701). Here, the image divided in the main scanning direction will be described as the image DIV1, the image DIV2,..., DIVn, respectively. Further, the image DIV1 is an image of a background region, and the image DIVX is an image which is not a background region.

  The overlap detection unit 132 extracts the maximum value and the minimum value of the image signal in the image DIV1 for each of the RGB color components as the density flatness determination. Then, the overlap detection unit 132 determines that the density of the image DIV1 is flat if the difference between the maximum value and the minimum value of the image signal in the extracted image DIV1 is smaller than the predetermined value TH for all color components of RGB. judge.

  That is, the overlap detection unit 132 sets (maximum value of image signal of red component in image DIV1−minimum value of image signal of red component in image DIV1) <TH_R, and (maximum value of image signal of green component in image DIV1 -The minimum value of the image signal of the green component in the image DIV1 <TH_G, and (the maximum value of the image signal of the blue component in the image DIV1-the minimum value of the blue component image signal in the image DIV1) <TH_B It is determined that the density of DIV1 is flat.

  The overlap detection unit 132 compares representative value color components, which are image signal values representing the image DIV1, with each other as achromatic color determination, and extracts the maximum value and the minimum value. At this time, the overlap detection unit 132 detects an average value or an intermediate value of the image signals in the image DIV1 (arranged in order of the size of the image signals and indicates a signal value located in the middle) or the image DIV1 and its periphery An average value or an intermediate value of the image signal may be calculated as a representative value color component.

  Then, if the difference between the maximum value and the minimum value of the extracted representative value color components is smaller than a predetermined value TH_N, the overlap detection unit 132 determines that the color is achromatic. That is, the overlap detection unit 132 determines that the image DIV1 is achromatic when (maximum value of representative value color components−minimum value of representative value color components) <TH_N.

  The overlap detection unit 132 performs a process of determining that each color component of the representative value in the image DIV1 is brighter than the predetermined threshold TH_L as the brightness determination. That is, the overlap detection unit 132 generates an image when red component of the representative value in the image DIV1> TH_L, green component of the representative value in the image DIV1> TH_L, and blue component of the representative value in the image DIV1> TH_L. It is determined that DIV1 is bright.

  Next, the overlap detection unit 132 determines whether or not it is a ground area for each of the divided images, based on the results of density flatness determination, achromatic color determination, and brightness determination (S702). Generally, in an original, an image is formed on white paper, so in the background area, the variation in color and the variation in brightness and darkness are small, and the lightness is bright. Therefore, in the image DIV1, when the density of the image DIV1 is flat, the image DIV1 is achromatic, and the image DIV1 is bright, the overlap detection unit 132 determines that the image DIV1 is a background region. .

  In the case of YES in S702, the duplication detection unit 132 sets “ground = 1” for the image DIV1 (S703). Note that "ground" is a parameter indicating whether the image is a background region. If NO in S702, the duplication detection unit 132 sets “ground = 0” for the image DIVX (S704).

  Next, the overlap detection unit 132 executes density average value addition processing. As one of the density average value addition processing, the overlap detection unit 132 determines the density of the image in the case of “ground = 1” as in the case of the image DIV1, for example, with respect to the images DIV1,. The average D of the image is calculated and added to the density L of the read image P2. In the case of “ground = 0”, the duplication detection unit 132 does nothing, but also in that case, it is included in one form of density average value addition processing.

  In addition, each time it is determined that the background area is determined as in the image DIV1, the overlap detection unit 132 indicates “the number of images DVIn determined to be the background area as one of the density average value addition processing. The value of "ground" is added to (S705).

  The density value L is initialized, for example, when processing is performed on the first line of the read image. In addition, “groundAsum” is also initialized when processing is performed on the first line of the read image, and the value is always stored in the RAM 12 b or the HDD 25 when processing of the line downstream in the sub scanning direction is performed. ing.

  Next, the duplication detection unit 132 determines whether or not the processing up to S705 has been performed on the image area of the read image P2 corresponding to all in the main scanning direction, that is, one line (S706). In the case of YES in S706, the overlap detection unit 132 adds the density value L to the density value LG of the background of the read image P2 (S707).

  Note that the density value LG is initialized, for example, when processing is performed on the first line of the read image, and the value is always stored in the RAM 12 b or the HDD 25 when processing of the line downstream in the sub scanning direction is performed. It is done. Next, the duplication detection unit 132 determines whether or not the processing up to S707 has been performed for all the lines constituting the read image P2 (S708), and executes the processing from S701 to S707 for all the lines. .

  In the case of YES in S707, the overlap detection unit 132 divides the sum of the density values LG of the background of the paper by the sum “groundAsum” of the number of the images DIVn determined to be the ground area and included in the read image P2. The average value "LGave" of the density of the background area is calculated (S709).

  Next, the overlap detection unit 132 determines whether the difference between “LGave” and the average value “L (G−1) ave” of the density of the background region included in the read image P1 one page before is larger than “Tth”. (S710). At this time, if the read image P2 is the first document, there is no document of one page before. Therefore, for the first page among a plurality of originals, it is determined that "Tth" or less.

  The optimum value of "Tth" changes depending on the paper thickness and paper type. Therefore, the value of "Tth" may be stored in advance as a data table in the ROM 12a or the HDD 25 for each sheet thickness or sheet type, or the user may set an arbitrary value from the display panel 104.

  If YES in S710, that is, if the difference between the average value of the density in the read image P2 and the average value of the density in the read image P1 is large, the overlap detection unit 132 determines that the document overlaps in the read image P1 or the read image P2. It detects that it is doing (S711). If the duplication detection unit 132 detects duplication of documents, the main control unit 110 stops reading of the documents by the scanner unit 102 (S 712), and displays a screen notifying that the documents are duplicates on the display panel 104. Let

  In the case of NO at S710, that is, when the difference between the average value of the density in the read image P2 and the average value of the density in the read image P1 is small, duplication of the document does not occur in the read image P1 or the read image P2. . At this time, the duplication detection unit 132 updates the value designated by “L (G−1) ave” in preparation for the next document as the value of “LGave” (S713).

  As described above, in the first density detection process, it is possible to detect double feeding in the read image in which the four sides of the document overlap and are transported. However, when a plurality of originals are conveyed in a shifted state, as shown in FIG. 8, a read image P3 may be generated in which the shadows of the overlapping originals are expressed.

  In FIG. 8, the originals do not overlap in the background portion in the line downstream of the shadow region in the sub scanning direction, and the originals overlap in the background portion of the line upstream in the sub scanning direction from the shadow region. Therefore, in a portion where a plurality of originals overlap, the density corresponds to a sheet of paper having a thickness in which the plurality of originals overlap, so the density of the background portion and the shadow area on the line downstream of the shadow area in the sub scanning direction The density of the image is different in the background portion in the line upstream in the sub scanning direction.

  Therefore, in the present embodiment, the density of the read image P3 of the background portion of several lines downstream in the current line and the sub scanning direction is calculated. The density calculated at this time is the density of the background area in the image area of the shadow of the overlapped original, that is, the line upstream of the shadow area in the sub scanning direction. The overlap detection unit 132 performs, as the second density detection process, the density of the background portion in the vicinity of the shadow region, that is, the line upstream of the shadow region in the sub scanning direction and the background portion of the line downstream of the shadow region in the sub scanning direction. It is determined whether or not double feeding is made by comparing the concentration.

  Next, the second concentration detection process performed by the overlap detection unit 132 in S402 will be described with reference to FIG. The duplication detection unit 132 determines whether “status” of the read image P3 acquired from the read image generation unit 131 is “status = 0” (S901).

  If “status = 0” is not satisfied (S901 / NO), the duplication detection unit 132 ends this processing. This is because if the status is not “status = 0”, the shadow area S has already been detected, and the image density in the line downstream in the sub scanning direction is detected to compare the image density.

  If “status = 0” (S901 / YES), the overlap detection unit 132 performs density flatness determination, achromatic determination, and brightness determination on the read image P3 as in S701 (S902). Therefore, the overlap detection unit 132 functions as an image density detection unit that detects the image density of the document expressed in the read image P3.

  At this time, if the shadow area S is not detected in the read image P3 and the image density in the line downstream in the sub scanning direction is not detected, it is unknown whether the shadow area S exists in the read image P3. It is.

  Next, the overlap detection unit 132 controls the value of “ground” for each of the images DIVn for which the background determination has been performed, based on the result of the background determination in S902 (S903). When it is determined in S902 that the ground is the ground, that is, in the case of YES in S903, the duplication detection unit 132 sets “ground” of the image DIVn as “ground = 1” (S904).

  If it is determined in S902 that the image is not the ground, that is, NO in S903, the overlap detection unit 132 sets “ground” of the image DIVn to “ground = 0” (S905).

  Next, the overlap detection unit 132 executes density average value addition processing. The overlap detection unit 132 calculates the average value D of the image density in the case of “ground = 1” as in the image DIV1 for the images DIV1 to DIVn subjected to the background determination, for example, and reads the image Add to the density value L of P3. In the case of “ground = 0”, the duplication detection unit 132 does nothing, but this process is also one of the density average value addition processes.

  In addition, each time it is determined that the background area is the image DIV1, the overlap detection unit 132 indicates “the number of images DVIn determined to be the background area as one of the density average value addition processing. The value of "ground" is added to (S906).

  The density value L is initialized, for example, when processing is performed on the first line of the read image P3. In addition, “groundBsum” is also initialized when processing is performed on the first line of the read image, and the value is always stored in the RAM 12 b or the HDD 25 when processing of the line downstream in the sub scanning direction is performed. ing.

  Next, the duplication detection unit 132 determines whether or not the processing up to S906 has been performed on the image area of the read image P3 corresponding to all lines in the main scanning direction, that is, one line (S907). In the case of YES in S907, the duplication detection unit 132 adds the density value L to the image density value LN of the background area of the read image P3 and divides it by "groundBsum" to calculate an average value (S908).

  The image density value LN is initialized when processing is performed on the first line of the read image P3. Next, the duplication detection unit 132 calculates “L2sum” which is the total sum from “L0” to “LN” (S909). “L2sum” is the sum of image density in the image DIVn determined to be the line being processed and the background region.

  Then, the duplication detection unit 132 sets “L (N−1) = LN”, “L (N−2) = L (N−1)”,..., “L0 = L1”,. The information for executing the process for the next line is updated (S910), and the process ends.

  At this time, in the read image P3, as shown in FIG. 8, a shadow area S which is a shadow of the overlapping original is represented. The overlap detection unit 132 detects the boundary between the shadow area S and the background area E1 (or background area E2), and compares the density in the images before and after the shadow area, that is, the background area E1 and the background area E2. Shadow detection processing for detecting a shadow area S in the read image P3 is executed. Therefore, the overlap detection unit 132 functions as a shadow area detection unit. Next, the shadow detection process performed by the overlap detection unit 132 in step S403 will be described with reference to FIG.

  The duplication detection unit 132 determines whether “status” of the read image P3 acquired from the read image generation unit 131 is “status = 0” (S1001). If “status = 0” is not satisfied (S1001 / NO), the duplication detection unit 132 ends this processing. At this time, the shadow area S is already detected in the read image P3.

  If “status = 0” (S1001 / YES), the overlap detection unit 132 performs density flatness determination, achromatic determination, and brightness determination on the read image P3 as in S701 (S1002 to S1004). . At this time, in order to detect the shadow area S, the overlap detection unit 132 reduces the lightness threshold value in the brightness determination in S1002 so that a color close to black can be detected.

  The overlap detection unit 132 controls the value of “Black_M” to “Black_M = 0” for the line determined to be the background region in the processing in any of S1002 to S1004 (S1007). Note that “Black_M” is a value indicating whether or not it is a shadow area S, and in the case of “Black_M = 0”, it is not the shadow area S, but in the case of “Black_M = 1”, the shadow area S To indicate that

  Next, the overlap detection unit 132 determines whether or not the processing up to S1004 has been performed on the image area of the read image P3 corresponding to all the main scanning directions, that is, one line (S1005). In the case where S1005 is YES, the duplication detection unit 132 controls the value of “Black_M” to “Black_M = 1” (S1006).

  Next, the overlap detection unit 132 determines the value of “Black_M” for the first line of the area corresponding to M lines, in order to determine whether the image area corresponding to M lines is a shadow area S, That is, it is determined whether the sum of "Black_0" to "Black_M" is M (S1008).

  For this reason, the value of M of paper thickness and paper type may be stored as a data table in the RAM 12 b or the HDD 25, and an arbitrary M value of the user may be set from the display panel 104.

  If S1008 is YES, that is, if the sum of “Black_0” to “Black_M” is M, the overlap detection unit 132 sets the value of “Shadow_M” of the image area corresponding to M lines as “Shadow_M = 1”. Control is performed (S1009). "Shadow_M" is a value indicating whether the image area corresponding to M lines is a shadow area S, "Shadow_M = 1" indicates a shadow area S, and "Shadow_M = 0" is a value. It indicates that it is not a shadow area S.

  If S1008 is NO, that is, if the sum of "Black_0" to "Black_M" does not become M, the overlap detection unit 132 sets the "Shadow_M" value of the image area corresponding to M lines as "Shadow_M = 0". To do (S1010). Further, in the case of “Black_M = 0” in the M line, since the M-th line is not the shadow area S, the overlap detection unit 132 sets “Shadow_M = 0”.

  Next, the duplication detection unit 132 determines whether “Shadow_M = 0” and “Shadow_ (M−1) = 1” (S1011). “Shadow_ (M−1)” indicates whether all the lines of the image area corresponding to M lines are the shadow area S or not.

  In S1011, when “Shadow_M = 0” and “Shadow_ (M−1) = 1” (S1011 / YES), the image area corresponding to the M line corresponds to the shadow area S to the background area E1 (or background area E2) It is a switching part to Therefore, in the case of YES in S1101, the duplication detection unit 132 sets “status” of the image area corresponding to M lines to “status = 1” (S1012), and ends this processing.

  In S1011, when “Shadow_M = 0” and “Shadow_ (M−1) = 1” are not (S1011 / NO), the duplication detection unit 132 determines that “Shadow_ (M−1) = Shadow_M”, “Black_ (M−1) The information is updated as “Black_M”, “Black_ (M−2) = Black_ (M−1)”,..., “Black_0 = Black_1” (S1013), and this process ends.

  Then, the overlap detection unit 132 calculates, for the detected shadow area S, the density of the background area E2 for several lines downstream of the shadow area in the sub scanning direction, and the line upstream of the shadow area in the sub scanning direction. A third density detection process is performed to compare with the density of the background area E1. The overlap detection unit 132 overlaps the original by comparing the density of the background area E2 of several lines downstream of the shadow area in the sub scanning direction with the density of the background area E1 of the line upstream of the shadow area in the sub scanning direction. It is determined whether the

  Next, the third concentration detection process performed by the overlap detection unit 132 in S405 will be described with reference to FIG. FIG. 11 is a flowchart showing the flow of the third concentration detection process according to the present embodiment.

  In the overlap detection unit 132, the overlap detection unit 132 performs the density flatness determination, the achromatic determination, and the brightness determination on the read image P3 as in S701 (S1101). The overlap detection unit 132 determines, for each of the divided images, whether it is a ground area or not based on the results of the density flatness determination, the achromatic determination, and the brightness determination (S1102).

  In the case of YES in S1102, the duplication detection unit 132 sets “ground = 1” for the image DIV1 (S1103). On the other hand, in the case of NO in S1102, the duplication detection unit 132 sets “ground = 0” for the image DIVX (S1104).

  Next, the overlap detection unit 132 executes density average value addition processing. As one of the density average value addition processing, the overlap detection unit 132 determines the density of the image in the case of “ground = 1” as in the case of the image DIV1, for example, with respect to the images DIV1,. The average D of the image is calculated and added to the density L of the read image P3. In the case of “ground = 0”, the duplication detection unit 132 does nothing, but this process is also one of the density average value addition processes.

  In addition, each time it is determined that the background area is the image DIV1, the overlap detection unit 132 indicates “the number of images DVIn determined to be the background area as one of the density average value addition processing. The value of “ground” is added to “(S1105)”.

  The density value L is initialized, for example, when processing is performed on the first line of the read image. In addition, “groundBsum” is also initialized when processing is performed on the first line of the read image, and the value is always stored in the RAM 12 b or the HDD 25 when processing of the line downstream in the sub scanning direction is performed. ing.

  Next, the overlap detection unit 132 determines whether or not the processing up to S1105 has been performed for the image area of the read image P3 corresponding to all the main scanning directions, that is, one line (S1106). In the case of YES in S1106, the overlap detection unit 132 divides the density value L of the background area of the read image P3 by "groundCsum" to calculate the average value of the density of the background area of the read image P3 (S1107).

  The density value L is the sum of the densities of the images determined to be background regions in the image region corresponding to M lines, and “groundCsum” is a line determined to be a background region in the image regions corresponding to M lines The number of has been counted. Density values L and "groundCsum" are initialized when processing the first line of the read image P3.

  Next, the overlap detection unit 132 adds the calculated average value of the density of the background region of the read image P3 to “L3sum”. “L3sum” is the density value of the image of the background area E2 in the image area corresponding to N lines in the sub scanning direction from the shadow area S (S1108).

  Next, the overlap detection unit 132 determines whether the processing from S1101 to S1108 has been executed in the image area corresponding to N lines in the sub scanning direction from the shadow area S (S1109). In the case of NO at S1109, the duplication detection unit 132 executes the processing from S1101 on the remaining lines. In the case of YES in S1109, the duplication detection unit 132 sets the value of “status” to “status = 2”, and ends this processing.

  As described above, in the present embodiment, by comparing the densities of a plurality of read images, it is possible to detect double feeding without providing a dedicated mechanism for detecting double feeding of a document. Therefore, the housing of the image processing apparatus 1 can be miniaturized, and furthermore, the manufacturing cost of the image processing apparatus 1 can be reduced.

  Misalignment of the document due to duplication of the document often appears as a difference in image density at the end of the read image. Therefore, the overlap detection unit 132 may detect the overlap of the originals by detecting the image density of the originals in an area of, for example, 5 cm from the end of the read image.

1 Image processing device 11 CPU
12 MEM-P
13 NB
14 SB
16 ASIC
17 MEM-C
18 FCU
19 USB
21 IEEE 1394
22 NFC
23 Engine 24 Operation Display 25 HDD
100 Controller 101 ADF
102 scanner unit 103 output tray 104 display panel 105 paper feed table 106 print engine 107 output tray 108 network I / F
110 main control unit 120 engine control unit 130 image processing unit 131 read image generation unit 132 overlap detection unit 133 γ conversion processing unit 134 filter processing unit 135 color conversion processing unit 136 halftone processing unit 140 operation display control unit 150 input / output control unit

JP, 2009-292549, A

Claims (10)

An image processing apparatus that reads an original and generates image information,
An image density detection unit that detects an image density of the document based on the image information;
A first image density, which is the image density of the first document detected based on the first image information, and a second image density, which is the image density of the second document detected based on the second image information A duplication detection unit that detects that duplication of a document occurs in either the first document or the second document when the difference is larger than a predetermined value;
An image processing apparatus including: A density information storage unit storing information on the first image density;
The duplicate detection unit
The image processing apparatus according to claim 1, wherein when the difference between the first image density and the second image density is larger than a predetermined value, it is detected that an overlap of originals occurs in the second original.   The first image density is a density calculated from a background area of the first document, and the second image density is a density calculated from the background area of the second document. The image processing apparatus according to claim 1. An image processing apparatus that reads an original and generates image information,
An image density detection unit that detects an image density of a document expressed in the image information based on the image information;
A shadow area detection unit that detects a shadow area of the document included in the image information based on a change in the image density;
When the difference between the image density in each of a plurality of different image areas in the vicinity of the shadow area is larger than a predetermined value when the shadow area is detected in the image information, the duplication of the document occurs. A duplicate detection unit that detects
An image processing apparatus including: The shadow area detection unit
The image processing apparatus according to claim 4, wherein the shadow area is detected based on a change in lightness in the image information. The image density detection unit
The image processing apparatus according to any one of claims 1 to 5, wherein the image density of the area in which the flatness of the density is smaller than a predetermined value is detected as the image density of the document in the area included in the image information. The image density detection unit
7. The image processing apparatus according to claim 6, wherein an image density of an area in which a change in color component is smaller than a predetermined value in an area included in the image information is detected as an image density of the document. The image density detection unit
The image processing apparatus according to claim 7, wherein an image density of an area in which a change in lightness is smaller than a predetermined value in an area included in the image information is detected as an image density of the document. An image processing method for reading an original and generating image information, comprising:
Detecting an image density of the document based on the image information;
A first image density, which is the image density of the first document detected based on the first image information, and a second image density, which is the image density of the second document detected based on the second image information When the difference is larger than a predetermined value, it is detected that duplication of documents occurs in either the first document or the second document,
Image processing method. An image processing method for reading an original and generating image information, comprising:
Detecting an image density of the document based on the image information;
A shadow area of the document included in the image information is detected based on a change in the image density;
When the difference between the image density in each of a plurality of different image areas in the vicinity of the shadow area is larger than a predetermined value when the shadow area is detected in the image information, the duplication of the document occurs. To detect that
Image processing method.