JP7141973B2 - Image reading device, image processing system, control method and control program - Google Patents

Description

The present invention relates to an image reading device, an image processing system, a control method and a control program.

An image reading device such as a general image scanner uses an imaging unit such as a line sensor to capture an image while conveying a medium. Therefore, if foreign matter such as paper dust, dust, or glue adheres to the glass surface of the imaging unit, vertical streak noise may occur in the input image obtained by imaging the medium.

For example, in the image reading apparatus disclosed in Patent Document 1, by passing the medium once, the first reading means reads the image on the first side of the medium at the reading position A and the image on the second side of the medium is read at the reading position B. and a second reading means for reading with. The medium on which the images on both sides have been read in the first pass is turned over, and in the second pass, the image on the second side is read by the first reading means, and the image on the first side is read by the second reading means. is read by The image reading device compares the image data of the same surface read by the reading means and outputs the image data with less line noise.

JP 2010-226361 A

Image reading apparatuses are desired to detect, with high accuracy, vertical streaks to be removed in an input image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus capable of detecting, with high accuracy, vertical streaks to be removed in an input image.

An image reading apparatus according to one aspect of the present embodiment includes a transport unit that transports a medium, an imaging unit that captures an image of the medium transported by the transport unit and generates an input image, and a medium that is transported by the transport unit. a control unit for generating a second input image by causing the image capturing unit to capture the same surface as the first input image while causing the transport unit to transport the medium again after the image capturing unit generates the first input image; a vertical-stripe candidate detection unit that detects vertical-stripe candidates from the first input image and the second input image; positions of the vertical-stripe candidates on the medium in the first input image; a removal determination unit that determines that the vertical streak candidate is to be removed if the position of the vertical streak candidate on the medium is different from that of the vertical streak candidate.

An image processing system according to one aspect of the present embodiment is an image processing system including an image reading device and an information processing device. an imaging unit that captures an image of a medium and generates an input image; and an imaging unit that generates a first input image while conveying the medium by the conveying unit and then conveys the medium again by the conveying unit. and a control unit for generating a second input image by imaging the same surface as the first input image by and a vertical stripe candidate detection unit that detects a vertical stripe candidate when the position of the vertical stripe candidate on the medium in the first input image is different from the position of the vertical stripe candidate on the medium in the second input image. and a removal determination unit that determines that the is to be removed.

Further, a control method according to one aspect of the present embodiment provides control of an image reading apparatus having a transport unit that transports a medium and an imaging unit that captures an image of the medium transported by the transport unit and generates an input image. In the method, after the first input image is generated by the imaging unit while the medium is conveyed by the conveying unit, the same surface as the first input image is captured by the imaging unit while the medium is conveyed again by the conveying unit. imaging is performed to generate a second input image; vertical stripe candidates are detected from the first input image and the second input image; If the position of the vertical stripe candidate on the medium in the input image is different from that of the vertical stripe candidate, it is determined that the vertical stripe candidate is to be removed.

A control program according to one aspect of the present embodiment controls an image reading device having a transport unit that transports a medium and an imaging unit that captures an image of the medium transported by the transport unit and generates an input image. The program causes the imaging unit to generate a first input image while conveying the medium by the conveying unit, and then reproduces the same surface as the first input image by the imaging unit while conveying the medium again by the conveying unit. imaging is performed to generate a second input image; vertical stripe candidates are detected from the first input image and the second input image; If the position of the vertical streak candidate on the input image is different from that of the vertical streak candidate, the image reading device determines that the vertical streak candidate is to be removed.

According to this embodiment, there is provided an image reading apparatus capable of detecting with high accuracy vertical streaks to be removed in an input image.

1 is a configuration diagram of an example of an image processing system according to an embodiment; FIG. FIG. 3 is a diagram for explaining a conveying path inside the image reading apparatus; FIG. 10 is a diagram illustrating an example of an operation of generating a first input image by an imaging device while transporting a medium by a transport unit; FIG. 10 is a diagram showing an example of an operation of generating a second input image by the imaging device while causing the medium to be conveyed again by the conveying unit; 1 is a block diagram showing a schematic configuration of an image reading device and an information processing device; FIG. 3 is a diagram showing a schematic configuration of a first storage device and a first CPU; FIG. 4 is a flow chart showing an example of the operation of the overall processing of the image reading apparatus; 9 is a flowchart showing an example of vertical streak detection processing; FIG. 10 is a schematic diagram showing an example of an input image in which vertical streaks are generated due to a foreign substance present in the imaging device; FIG. 4 is a schematic diagram showing an example of an input image including vertical streaks present on a medium; 9 is a flow chart showing another example of the operation of the overall processing of the image reading apparatus; FIG. 10 is a schematic diagram for explaining medium shift processing; FIG. 10 is a schematic diagram for explaining medium shift processing; FIG. 10 is a schematic diagram for explaining medium shift processing; FIG. 11 is a diagram showing a schematic configuration of still another processing circuit; FIG. 4 is a diagram showing a schematic configuration of another second storage device and a second CPU; FIG. 11 is a flowchart showing an example of the operation of another vertical streak detection process; FIG. FIG. 11 is a block diagram showing a schematic configuration of another second processing circuit;

An image processing system according to one aspect of the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the invention described in the claims and equivalents thereof.

FIG. 1 is a configuration diagram of an example of an image processing system 1 according to an embodiment.

The image processing system 1 includes an image reading device 100 and an information processing device 200 . The image reading device 100 is an image scanner or the like that captures an image of a medium while conveying the medium. The image reading device 100 may be a copier, facsimile machine, MFP (Multifunction Peripheral), or the like. The medium may be paper, cardboard, card, booklet, passport, or the like. The image reading device 100 may be a facsimile machine, a copier, a printer complex machine (MFP, Multifunction Peripheral), or the like. The information processing device 200 is a personal computer, a multifunctional mobile terminal, a mobile phone, or the like. The image reading device 100 and the information processing device 200 are connected to each other.

The image reading device 100 includes a lower housing 101, an upper housing 102, an insertion slot 103, a first display device 104, a first operating device 105, and the like.

The upper housing 102 is arranged to cover the upper surface of the image reading apparatus 100 and engages with the lower housing 101 . A medium insertion port 103 is provided between the upper housing 102 and the lower housing 101 . In FIG. 1, the direction A1 indicates the insertion direction of the medium, and the direction A2 opposite to the direction A1 indicates the ejection direction of the medium. Direction A1 is an example of a first direction, and direction A2 is an example of a second direction.

The first display device 104 has an LED (Light Emitting Diode) and an interface circuit for controlling the LED, and turns on or off the LED according to the state of the device.

The first operating device 105 has an input device such as a button and an interface circuit that acquires signals from the input device, receives user operations, and outputs signals corresponding to user inputs.

FIG. 2 is a diagram for explaining the transport path inside the image reading apparatus 100. As shown in FIG.

A conveying path inside the image reading apparatus 100 includes a first light emitter 111a, a first light receiver 111b, first conveying rollers 112a and 112b, second conveying rollers 113a and 113b, an imaging device 114, a second light emitter 115a, a second It has a light receiver 115b, third transport rollers 116a and 116b, fourth transport rollers 117a and 117b, and the like.

Hereinafter, the first conveying rollers 112a and 112b may be collectively referred to as the first conveying rollers 112 in some cases. Also, the second conveying rollers 113a and 113b may be collectively referred to as the second conveying rollers 113 in some cases. Also, the third conveying rollers 116 a and 116 b may be collectively referred to as the third conveying roller 116 . Also, the fourth conveying rollers 117a and 117b may be collectively referred to as the fourth conveying roller 117 in some cases.

The lower surface of the upper housing 102 forms an upper guide 106a for the medium transport path, and the upper surface of the lower housing 101 forms a lower guide 106b for the medium transport path. The upper guide 106a and the lower guide 106b form the insertion opening 103 and the evacuation opening 107 for the medium. The insertion port 103 is an opening for inserting a medium to be read into the image reading apparatus 100 , and the evacuation port 107 is an opening for temporarily withdrawing the medium to be read from the image reading apparatus 100 . is. In the following, upstream means upstream in the direction A1 in which the medium is inserted, and downstream means downstream in the direction A1 of the medium.

The first light emitter 111 a and the first light receiver 111 b are arranged upstream of the first transport roller 112 and the second transport roller 113 . The first light emitter 111a and the first light receiver 111b are arranged in the vicinity of the medium transport path so as to face each other with the transport path interposed therebetween. The first light emitter 111a emits light toward the first light receiver 111b. When no medium is present in the transport path, the first light receiver 111b detects light emitted from the first light emitter 111a. On the other hand, when the medium exists in the transport path, the light emitted from the first light emitter 111a is blocked by the medium existing in the transport path, and the first light receiver 111b receives the light emitted from the first light emitter 111a. Not detected. The first light receiver 111b detects whether or not a medium exists between the first light emitter 111a and the first light receiver 111b according to the intensity of the received light, and indicates whether or not the medium exists. A first medium detection signal is generated and output. Hereinafter, the first light emitter 111a and the first light receiver 111b may be collectively referred to as the first medium sensor 111 in some cases.

A first conveying roller 112 and a second conveying roller 113 are provided downstream of the first light emitter 111 a and the first light receiver 111 b and upstream of the imaging device 114 to move the medium relative to the imaging device 114 . The first conveying roller 112 and the second conveying roller 113 are provided to rotate forward and reverse.

The image pickup device 114 is an example of an image pickup unit, and has a 1:1 optical system type CIS (Contact Image Sensor) that includes image pickup elements that are CCDs (Charge Coupled Devices) linearly arranged in the main scanning direction. In addition, the imaging device 114 has a lens that forms an image on the imaging device, and an A/D converter that amplifies an electrical signal output from the imaging device and performs analog/digital (A/D) conversion. The imaging device 114 captures an image of the medium conveyed by the first conveying roller 112, the second conveying roller 113, the third conveying roller 116, and the fourth conveying roller 117, generates an input image, and outputs it.

A CMOS (Complementary Metal Oxide Semiconductor) may be used instead of the CCD. Also, a reduction optics type imaging sensor may be used instead of the CIS.

The second light emitter 115a and the second light receiver 115b are arranged downstream of the imaging device 114 and upstream of the third transport roller 116 and the fourth transport roller 117, respectively. The second light emitter 115a and the second light receiver 115b are arranged in the vicinity of the medium transport path so as to face each other with the transport path interposed therebetween. The second light emitter 115a emits light toward the second light receiver 115b. The second light receiver 115b detects whether or not a medium exists between the second light emitter 115a and the second light receiver 115b according to the intensity of the received light, and indicates whether or not the medium exists. A second detection signal is generated and output. Hereinafter, the second light emitter 115a and the second light receiver 115b may be collectively referred to as the second medium sensor 115 in some cases.

A third conveying roller 116 and a fourth conveying roller 117 are provided downstream of the imaging device 114 , the second light emitter 115 a and the second light receiver 115 b to move the medium relative to the imaging device 114 . The third conveying roller 116 and the fourth conveying roller 117 are provided to be rotatable forward and backward. Thus, the first transport roller 112 and the second transport roller 113, and the third transport roller 116 and the fourth transport roller 117 are provided at both ends of the imaging device 114 in the medium transport direction. The first conveying rollers 112, the second conveying rollers 113, the third conveying rollers 116, and the fourth conveying rollers 117 are an example of a conveying unit that conveys the medium.

FIG. 3A is a diagram illustrating an example of an operation of generating a first input image by the imaging device 114 while transporting the medium by the transport unit.

The medium D inserted into the insertion port 103 is guided by the upper guide 106 a and the lower guide 106 b and fed between the first transport rollers 112 and the second transport rollers 113 . The medium is conveyed in the direction A1 by the rotation of the first conveying roller 112 in the direction A4 and the rotation of the second conveying roller 113 in the direction A5, and is sent under the reading surface of the imaging device 114. FIG. After that, the medium D read by the imaging device 114 is retracted to the outside of the image reading device 100 through the evacuation port 107 by the rotation of the third transport roller 116 in the direction A4 and the rotation of the fourth transport roller 117 in the direction A5. be done. The image of the medium D read by the imaging device 114 is output as the first input image.

FIG. 3B is a diagram showing an example of the operation of causing the imaging device 114 to generate the second input image while causing the transport unit to transport the medium again.

When the trailing edge of the medium D passes under the reading surface of the imaging device 114, the third conveying roller 116 rotates in the direction A6 opposite to the direction A4, and the fourth conveying roller 117 rotates in the direction A7 opposite to the direction A5. do. As a result, the medium D is transported (switched back) in the direction A<b>2 and fed again under the reading surface of the imaging device 114 . After that, the medium D read again by the imaging device 114 is transported from the insertion slot 103 to the outside of the image reading device 100 by the rotation of the first conveying roller 112 in the direction A6 and the rotation of the second conveying roller 113 in the direction A7. Ejected. The image of the medium D read again by the imaging device 114 is output as the second input image.

FIG. 4 is a block diagram showing a schematic configuration of the image reading device 100 and the information processing device 200. As shown in FIG.

The image reading apparatus 100 further includes a first interface device 131, a first storage device 140, a first CPU (Central Processing Unit) 150, a first processing circuit 160, and the like, in addition to the configuration described above.

The first interface device 131 is an example of an output unit, and has an interface circuit conforming to a serial bus such as USB (Universal Serial Bus). The first interface device 131 communicates with the information processing device 200 to transmit and receive various images and information. Also, instead of the first interface device 131, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface circuit for transmitting and receiving signals through a wireless communication line according to a predetermined communication protocol may be used. good. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network).

The first storage device 140 includes memory devices such as RAM (Random Access Memory) and ROM (Read Only Memory), fixed disk devices such as hard disks, or portable storage devices such as flexible disks and optical disks. The first storage device 140 also stores computer programs, databases, tables, and the like used for various processes of the image reading apparatus 100 . The computer program may be installed in the first storage device 140 from a computer-readable portable recording medium using a known setup program or the like. Portable recording media include, for example, CD-ROMs (Compact Disc Read Only Memory) and DVD-ROMs (Digital Versatile Disc Read Only Memory). Various images are stored as data in the first storage device 140 .

The first CPU 150 operates based on a program pre-stored in the first storage device 140 . A DSP (Digital Signal Processor), an LSI (Large Scale Integration), or the like may be used instead of the first CPU 150 . Also, instead of the first CPU 150, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like may be used.

The first CPU 150 includes the first display device 104, the first operating device 105, the first medium sensor 111, the second medium sensor 115, the imaging device 114, the driving device 121, the first interface device 131, the first storage device 140 and the first It is connected to the processing circuit 160 and the like via a bus 180 . The first CPU 150 controls these units. The first CPU 150 performs driving control of the driving device 121, medium reading control of the imaging device 114, and the like.

The first CPU 150 receives signals output from the first medium sensor 111 and the second medium sensor 115 via the bus 180 . Each of the first medium sensor 111 and the second medium sensor 115 has an analog-to-digital conversion circuit, but an analog-to-digital conversion circuit may be provided between each sensor and the first CPU 150 .

The first processing circuit 160 performs predetermined image processing such as correction processing on the image acquired from the imaging device 114 . Note that an LSI, DSP, ASIC, FPGA, or the like may be used as the first processing circuit 160 .

The information processing device 200 has a second display device 201, a second operating device 202, a second interface device 203, a second storage device 210, a second CPU 220, a second processing circuit 230, and the like.

The second display device 201 has a display composed of liquid crystal, organic EL (Electro-Luminescence), etc. and an interface circuit for outputting image data to the display, and displays image data on the display according to instructions from the second CPU 220 . .

The second operation device 202 further includes an input device and an interface circuit that acquires signals from the input device, receives operations by the user, and outputs signals according to the user's input to the second CPU 220 .

The second interface device 203 has an interface circuit or a wireless communication interface circuit similar to that of the first interface device 131, and communicates with the image reading device 100 to transmit and receive various images and information.

The second storage device 210 includes memory devices such as RAM and ROM, fixed disk devices such as hard disks, portable storage devices such as flexible disks and optical disks, and the like. The second storage device 210 also stores computer programs, databases, tables, and the like used for various processes of the information processing device 200 . The computer program may be installed in the second storage device 210 from a computer-readable portable recording medium such as CD-ROM, DVD-ROM, etc. using a known setup program or the like. Various images are stored as data in the second storage device 210 .

The second CPU 220 operates based on a program pre-stored in the second storage device 210 . A DSP, LSI, ASIC, FPGA, or the like may be used instead of the second CPU 220 .

The second CPU 220 is connected to the second display device 201, the second operation device 202, the second interface device 203, the second storage device 210, the second processing circuit 230, etc. via the bus 240, and controls these components. The second CPU 220 controls each device and executes image processing on an image acquired from the image reading device 100 .

The second processing circuit 230 performs predetermined image processing such as correction processing on the image acquired from the image reading device 100 . Note that an LSI, DSP, ASIC, FPGA, or the like may be used as the second processing circuit 230 .

FIG. 5 is a diagram showing a schematic configuration of the first storage device 140 and the first CPU 150 of the image reading device 100. As shown in FIG.

As shown in FIG. 5, the first storage device 140 stores programs such as a control program 141, a vertical streak candidate detection program 142, a removal determination program 143, an image correction program 144, an output control program 145, and a medium shift program 146. remembered. Each of these programs is a functional module implemented by software running on a processor. The first CPU 150 reads each program stored in the first storage device 140 and operates according to each read program. Thereby, the first CPU 150 functions as a control section 151 , a vertical streak candidate detection section 152 , a removal determination section 153 , an image correction section 154 , an output control section 155 and a medium shift section 156 .

FIG. 6 is a flow chart showing an example of the overall processing operation of the image reading apparatus 100 . An example of the operation of the overall processing of the image reading apparatus 100 will be described below with reference to the flowchart shown in FIG. The operation flow described below is executed mainly by the first CPU 150 in cooperation with each element of the image reading apparatus 100 based on a program stored in the first storage device 140 in advance.

First, the control unit 151 detects that a medium has been inserted from the insertion slot 103, and waits until an operation signal instructing reading of the medium is received from the first operation device 105 (step S101). Based on the first medium detection signal received from the first medium sensor 111, the control unit 151 determines whether or not the medium exists at the position where the first medium sensor 111 is arranged. If the control unit 151 determines that the medium exists at that position, the control unit 151 determines that the medium is inserted from the insertion port 103 . Further, the control unit 151 receives an operation signal from the first operation device 105 when the user uses the first operation device 105 to perform an operation to instruct reading of the medium.

Next, the controller 151 drives the driving device 121 to rotate the first conveying roller 112 and the third conveying roller 116 in the direction A4 in FIG. 2 is rotated in the direction A5. Thereby, the control unit 151 causes the medium to be transported in the direction A1 by the first transport rollers 112, the second transport rollers 113, the third transport rollers 116, and the fourth transport rollers 117 (step S102). That is, the medium moves under the reading surface of the imaging device 114 so that it can be read by the imaging device 114 from the upper end (downstream end in direction A1) to the lower end (upstream end in direction A1) of the medium. .

Next, the control unit 151 moves the medium in the direction A1 by the first conveying roller 112, the second conveying roller 113, the third conveying roller 116, and the fourth conveying roller 117, and causes the imaging device 114 to image the medium. A first input image is generated. Then, the control unit 151 acquires the generated first input image from the imaging device 114 (step S103). That is, the first input image is an image obtained by photographing each line of the medium extending in the main scanning direction of the imaging device 114 in order from the top end to the bottom end in the sub-scanning direction.

Next, based on the second medium detection signal received from the second medium sensor 115, the control unit 151 determines whether the trailing edge of the medium has passed the position of the imaging device 114 (step S104). When the second medium detection signal changes from the state indicating the presence of the medium to the state indicating the absence of the medium, the controller 151 detects that the trailing edge of the medium has passed the position of the second medium sensor 115 . It is determined that the position of the imaging device 114 has been passed. If the trailing edge of the medium has not passed the imaging device 114 , the control unit 151 moves the medium until the trailing edge of the medium passes the imaging device 114 .

On the other hand, when the trailing edge of the medium has passed the imaging device 114, the control unit 151 causes the medium to be conveyed in the direction A2 opposite to the direction A1. The controller 151 drives the driving device 121 to rotate the first conveying roller 112 and the third conveying roller 116 in the direction opposite to the direction A4 in FIG. Rotate in a direction opposite to direction A5 in FIG. As a result, the control unit 151 directs the medium by the first transport roller 112, the second transport roller 113, the third transport roller 116, and the fourth transport roller 117 after the imaging device 114 generates the first input image. The sheet is conveyed to A2 (step S105). That is, the medium moves under the reading surface of the imaging device 114 so that it can be read by the imaging device 114 from the lower end (upstream end in direction A1) to the upper end (downstream end in direction A1) of the medium. .

Next, the control unit 151 causes the first conveying roller 112, the second conveying roller 113, the third conveying roller 116, and the fourth conveying roller 117 to convey the medium in the direction A2, while the imaging device 114 captures the first input image. , to generate a second input image. Then, the control unit 151 acquires the generated second input image from the imaging device 114 (step S106). That is, the second input image is an image obtained by photographing each line of the medium extending in the main scanning direction of the imaging device 114 in order from the lower end to the upper end in the sub-scanning direction. Note that the lines of the second input image are rearranged so that the vertical medium orientations of the first input image and the second input image match.

Next, the vertical streak candidate detection unit 152, the removal determination unit 153, and the image correction unit 154 execute vertical streak detection processing (step S107). In the vertical stripe detection process, the vertical stripe candidate detection unit 152, the removal determination unit 153, and the image correction unit 154 detect vertical stripe candidates from each input image, correct the vertical stripe candidates determined to be removed, and generate a corrected image. to generate Details of the vertical streak detection process will be described later.

Next, the output control unit 155 outputs the input image or the corrected image by transmitting it to the information processing device 200 via the first interface device 131 (step S108), and ends the series of steps. The output control unit 155 outputs the corrected image to the information processing apparatus 200 when the corrected image is generated in the vertical streak detection process, and outputs the input image to the information processing apparatus when the corrected image is not generated in the vertical streak detection process. 200. The information processing apparatus 200 acquires the corrected image or the input image via the second interface device 203 and displays the acquired image on the second display device 201 .

Note that the method of generating the first input image and the second input image is not limited to the above method. For example, after generating the first input image while conveying the medium in direction A1, the image reading apparatus 100 temporarily ejects the medium to the evacuation port 107, and the user inserts the medium into the evacuation port 107 again. The second input image may be generated while transporting the medium in direction A2.

Alternatively, the image reading apparatus 100 may generate the first input image and the second input image while conveying the medium in the same direction. For example, after the image reading apparatus 100 generates the first input image while conveying the medium in the direction A1, the medium is once ejected to the evacuation port 107, and the user inserts the medium into the insertion port 103 again. The second input image may be generated while transporting the medium in direction A1.

Alternatively, the image reading apparatus 100 may be provided with a transport path for transporting the medium ejected from the evacuation port 107 to the insertion port 103 . In this case, after generating the first input image while conveying the medium in the direction A1, the image reading apparatus 100 returns the medium to the insertion port 103 via the conveying path, and conveys the medium in the direction A1 again to produce the second input image. generates an input image of .

FIG. 7 is a flowchart showing an example of vertical streak detection processing in step S107 of FIG.

First, the vertical-stripe candidate detection unit 152 detects vertical-stripe candidates from the first input image and the second input image (step S201).

The vertical streak candidate detection unit 152 calculates, for example, the average value of the gradation values of each pixel for each horizontal line in the input image, and compares the gradation value of the target pixel with the average value calculated for the horizontal line to which the target pixel belongs. A pixel whose absolute value of the difference between is equal to or greater than a predetermined threshold value is extracted as a vertical streak candidate pixel. Next, among the extracted vertical-stripe candidate pixels, the vertical-stripe candidate detection unit 152 selects vertical-stripe candidate pixels that are connected in the vertical direction by a predetermined number (for example, 90% of the number of pixels in the vertical direction of the input image) or more as vertical stripes. To detect. The vertical-stripe candidate detection unit 152 determines whether each of the extracted vertical-stripe candidate pixels is connected in the vertical direction (whether adjacent vertical-stripe candidate pixels exist). The vertical-stripe candidate detection unit 152 collects mutually connected vertical-stripe candidate pixels into one group, and detects the group as a vertical stripe when the number of pixels in the vertical direction of each group is equal to or greater than a predetermined number.

FIG. 8A is a schematic diagram showing an example of a first input image 810 and a second input image 820. FIG. FIG. 8B is a schematic diagram showing another example of the first input image 830 and the second input image 840. FIG.

A first input image 810 and a second input image 820 shown in FIG. 8A include media 811 and 821 and vertical streaks 812 and 822, respectively. The vertical streaks 812 and 822 are generated when paper dust, dust, glue, or other foreign matter adheres to the reading surface of the imaging device 114 and the foreign matter is imaged by the imaging device 114 . On the other hand, a first input image 830 and a second input image 840 shown in FIG. 8B include media 831 and 841 and vertical streaks 832 and 842, respectively. The vertical streaks 832 and 842 are originally described in medium 831 and medium 841 .

In addition, every time the medium is conveyed, a slip occurs between the medium and the conveying rollers, or the gears are disengaged. Not a little difference occurs in the inclination. Therefore, in the first input image 810 and the second input image 820, the position of the medium 821 changes with respect to the position of the medium 811, and in the first input image 830 and the second input image 840, the position of the medium 831 changes. The position of medium 841 is changing with respect to position. The image reading apparatus 100 has a reading resolution that can identify such slight deviations.

Vertical stripes 812 and 822 are detected as vertical stripe candidates from the first input image 810 and the second input image 820 shown in FIG. 8A, and the first input image 830 and the second input image shown in FIG. 8B are detected. From 840, a vertical stripe 832 and a vertical stripe 842 are detected as vertical stripe candidates.

Next, the vertical streak candidate detection unit 152 detects medium regions from each of the first input image and the second input image (step S202).

First, the vertical stripe candidate detection unit 152 extracts edge pixels from the input image. The vertical streak candidate detection unit 152 calculates the absolute value of the difference between the luminance values of the pixels adjacent to each pixel in the input image in the horizontal or vertical direction (hereinafter referred to as the adjacent difference value). Pixels exceeding the threshold are extracted as edge pixels. Note that the vertical stripe candidate detection unit 152 may calculate the absolute value of the difference between the luminance values of pixels separated by a predetermined distance in the horizontal or vertical direction from each pixel as the adjacent difference value. Further, the vertical stripe candidate detection unit 152 may calculate the adjacent difference value using the color value (R value, G value, or B value) of each pixel instead of the luminance value of each pixel. Further, the vertical stripe candidate detection unit 152 may extract edge pixels by comparing the luminance value or color value of the input image with the first threshold. For example, the vertical streak candidate detection unit 152 detects that the luminance value or color value of a specific pixel is less than the first threshold, and the luminance value of a pixel adjacent to the specific pixel or a pixel separated from the specific pixel by a predetermined distance. Or if the color value is greater than or equal to the first threshold, then the particular pixel is taken as the edge pixel.

Next, the vertical stripe candidate detection unit 152 detects straight lines from the extracted edge pixels. The vertical stripe candidate detection unit 152 detects straight lines using Hough transform. Note that the vertical stripe candidate detection unit 152 may detect a straight line using the least squares method. Next, the vertical streak candidate detection unit 152 detects a medium region from the detected straight line. The vertical streak candidate detection unit 152 extracts a plurality of medium region candidates composed of four straight lines, two of which are substantially perpendicular to each other, out of the plurality of detected straight lines. Then, the vertical stripe candidate detection unit 152 detects, as a medium area, a circumscribing rectangle or an inscribed rectangle of the medium area candidate having the largest area among the extracted medium area candidates.

A medium 811 and a medium 821 are detected as medium areas from the first input image 810 and the second input image 820 shown in FIG. 8A, and from the first input image 830 and the second input image 840 shown in FIG. 8B Medium 831 and medium 841 are detected as medium areas.

Next, the removal determining unit 153 determines whether the position of the vertical stripe candidate on the medium in the first input image is different from the position of the vertical stripe candidate on the medium in the second input image. (step S203).

The removal determination unit 153 identifies the position of each vertical stripe candidate on each medium area detected from each input image. For example, the removal determining unit 153 determines the position of the vertical streak candidate in a coordinate system whose origin is the pixel at the upper left corner of each medium area, and whose coordinate axes are a straight line corresponding to the upper end portion and a straight line corresponding to the left end portion of each medium region. Identify (coordinates). The removal determination unit 153 calculates the total value of the difference (distance) between the upper end positions and the difference (distance) between the lower end positions of the vertical streak candidates in the medium area detected from the first input image and the second input image. calculate. If the calculated total value is equal to or greater than the second threshold, the removal determining unit 153 determines the position of the vertical stripe candidate on the medium in the first input image and the vertical stripe candidate on the medium in the second input image. is determined to be different from the position of On the other hand, if the calculated total value is less than the second threshold, the removal determination unit 153 removes the position of the vertical stripe candidate on the medium in the first input image and the vertical stripe candidate on the medium in the second input image. It is determined that the positions of the muscle candidates are the same.

Note that the removal determination unit 153 calculates the total value as the difference in intersection positions where each vertical stripe intersects with the upper end of each medium region when each vertical stripe is stretched in each medium region along the stretching direction of the vertical stripe. (distance) and the difference (distance) between intersection positions where each vertical stripe intersects with the lower end of each medium region may be calculated.

In the first input image 810 and the second input image 820 shown in FIG. 8A, the position of the medium 821 is changed with respect to the position of the medium 811, but the vertical line candidate 822 position has not changed. Therefore, it is determined that the position of the vertical streak candidate 812 on the medium 811 and the position of the vertical streak candidate 822 on the medium 821 in the second input image 820 are different. On the other hand, in the first input image 830 and the second input image 840 shown in FIG. 8B, the position of the medium 841 varies with respect to the position of the medium 831, and the , the position of the vertical stripe candidate 842 with respect to the position of the vertical stripe candidate 832 is changed. Therefore, it is determined that the position of the vertical stripe candidate 832 on the medium 831 and the position of the vertical stripe candidate 842 on the medium 841 in the second input image 840 are the same.

In this way, the removal determination unit 153 compares the positional relationship between the vertical streak candidate and the medium in the two input images to determine whether the vertical streak candidate is caused by a foreign object adhering to the reading surface of the imaging device 114 . , it is possible to determine with high accuracy whether the information is written on the medium from the beginning.

If the position of the vertical streak candidate on the medium in the first input image is different from the position of the vertical streak candidate on the medium in the second input image, the removal determination unit 153 determines that the vertical streak candidate is to be removed. (step S204).

Next, the image correction unit 154 generates a corrected image by correcting the input image so as to remove vertical streaks from the rectangular area in the input image (step S205), and ends the vertical streak detection process.

The image correction unit 154 corrects the vertical streak candidate on the medium in one of the first input image and the second input image, which are determined to be removed by the removal determination unit 153, on the medium in the other image. Correction is performed by replacing with pixel data at the corresponding position. The image correction unit 154 converts the pixel value of the pixel related to the vertical streak candidate in the input image to be corrected to the pixel of the pixel in the other input image whose coordinate position in the coordinate system related to the medium area is the same as that pixel. Replace with value. Thereby, the image correction unit 154 can completely remove vertical streaks generated in one input image using the other input image.

Note that if pixels in the other input image that correspond to pixels related to vertical streak candidates in the input image to be corrected are also included in the vertical streak candidates, the image correction unit 154 uses, for example, a known linear interpolation technique. Then, the vertical streak area may be corrected using the gradation values of pixels surrounding the vertical streak area. As a result, the image correction unit 154 can bury the vertical stripes in the background when the background around the vertical stripes is monotonous.

An image 850 shown in FIG. 8A is an example of a corrected image obtained by correcting the first input image 810 using the second input image 820 . In the corrected image 850, the vertical streaks 812 are well removed.

On the other hand, when the position of the vertical streak candidate on the medium in the first input image is the same as the position of the vertical streak candidate on the medium in the second input image, removal determination section 153 determines that the vertical streak candidate is It is determined that it is not to be removed (step S206), and the vertical streak detection process ends. In this case, the image correction unit 154 does not correct the input image.

In the example shown in FIG. 8B, either the first input image 830 or the second input image 840 is transmitted to the information processing apparatus 200 as it is.

As described above, the image reading apparatus 100 uses the same image sensor to read the same medium twice. It is determined that the streak candidate is caused by a foreign substance adhering to the imaging device 114 . As a result, the image reading apparatus 100 can detect the vertical streaks to be removed in the input image with high accuracy.

Further, the image reading apparatus 100 switches back the medium to read the same medium twice. As a result, the image reading apparatus 100 can read the same medium twice without providing a transport path for returning the imaged medium to the insertion slot 103 side, which increases the size or cost of the apparatus. can be suppressed. In addition, the image reading apparatus 100 can read the same medium twice without having the user convey the medium twice, thereby improving convenience for the user.

The above-described embodiments are merely examples of specific implementations of the present invention, and the technical scope of the present invention should not be construed to be limited by these. That is, the present invention can be embodied in various forms without departing from its technical concept or main features.

For example, in order to make it easier to determine whether or not a vertical streak candidate is to be removed, the image reading apparatus 100 may perform The position or angle of the medium in the width direction with respect to the reading surface of the imaging device 114 may be shifted.

FIG. 9 is a flow chart showing another example of the operation of the overall processing of the image reading apparatus 100. As shown in FIG. The flow of operations shown in FIG. 9 is executed instead of the flow of operations shown in FIG. In this embodiment, the third conveying roller 116a and the third conveying roller 116b are configured to be independently rotatable. Steps S301 to S304 and S306 to S309 in FIG. 9 are the same as steps S101 to S104 and S105 to S108 in FIG. 6, respectively, so detailed description thereof will be omitted.

In step S305, the medium shifting unit 156 performs medium shifting processing for shifting the position or angle of the medium in the width direction with respect to the reading surface of the imaging device 114 (step S305). The medium shifting unit 156 executes the medium shifting process by driving the driving device 121 such that, for example, only one of the third conveying rollers 116a and 116b is rotated and the other is stopped.

10A to 10C are schematic diagrams for explaining the medium shifting process.

In step S302, as shown in FIG. 10A, the control unit 151 rotates all of the first transport rollers 112a and 112b and the third transport rollers 116a and 116b to transport the medium D in the direction A1. On the other hand, in step S305, the medium shifting unit 156 shifts the position and angle of the medium D by rotating only one of the third conveying rollers 116a and 116b and stopping the other, as shown in FIG. 10B. Thereafter, in step S306, as shown in FIG. 10C, the control unit 151 rotates all of the first transport rollers 112a and 112b and the third transport rollers 116a and 116b again to transport the medium D in the direction opposite to the direction A1. Convey in direction A2.

In this manner, the medium shift unit 156 executes medium shift processing from the generation of the first input image to the generation of the second input image. As a result, the position of the medium D in the width direction with respect to the reading surface of the imaging device 114 is reliably shifted between when the medium D is conveyed in the direction A1 and when the medium D is conveyed in the direction A2. As a result, the position of the vertical streak noise generated in the first input image and the position of the vertical streak noise generated in the second input image due to dirt or the like on the reading surface of the imaging device 114 are surely shifted. , the removal determination unit 153 can more accurately determine whether or not the vertical streak candidate is to be removed.

In step S<b>305 , the medium shifting unit 156 may perform the medium shifting process by transporting the medium until it separates from the third transport roller 116 and the fourth transport roller 117 . In that case, a discharge table inclined so that the imaging device 114 side faces downward is provided at the evacuation port 107 . The medium is once separated from the third transport rollers 116 and the fourth transport rollers 117 and is discharged from the evacuation port 107 onto the discharge table. It is pinched by the conveying rollers 117 . Therefore, in step S306, the media is re-transported toward the imaging device 114. FIG. In this case as well, when the medium is conveyed in the direction A1 and when it is conveyed in the direction A2, the position of the medium in the width direction with respect to the reading surface of the imaging device 114 certainly deviates. , it is possible to more accurately determine whether or not the vertical streak candidate is to be removed.

FIG. 11 is a diagram showing a schematic configuration of a processing circuit 400 in a medium transporting device according to still another embodiment. The processing circuit 400 is used instead of the first processing circuit 160 of the image reading apparatus 100, and instead of the first CPU 150, executes medium reading processing, vertical streak candidate detection processing, removal determination processing, image correction processing, and output control processing. do. The processing circuit 400 includes a control circuit 401, a vertical streak candidate detection circuit 402, a removal determination circuit 403, an image correction circuit 404, an output control circuit 405, and the like. Each of these units may be composed of an independent integrated circuit, microprocessor, firmware, or the like.

The control circuit 401 is an example of a control section and has the same function as the control section 151 . The control circuit 401 receives the first medium detection signal from the first medium sensor 111 and the first medium detection signal from the second medium sensor 115, and drives the driving device 121 based on the received signals. The control circuit 401 also receives an input image from the imaging device 114 and outputs it to the vertical stripe candidate detection unit 152 .

The vertical stripe candidate detection circuit 402 is an example of a vertical stripe candidate detection unit and has the same function as the vertical stripe candidate detection unit 152 . The vertical stripe candidate detection circuit 402 receives an input image from the control circuit 401 , detects vertical stripe candidates, and outputs the detection result to the removal determination circuit 403 .

The removal determination circuit 403 is an example of a removal determination unit and has the same function as the removal determination unit 153 . The removal determination circuit 403 receives the detection result of the vertical stripe candidate from the vertical stripe candidate detection circuit 402 , determines whether or not the vertical stripe candidate is to be removed, and outputs the determination result to the image correction circuit 404 .

The image correction circuit 404 is an example of an image correction section and has the same function as the image correction section 154 . The image correction circuit 404 receives the removal target determination result from the removal determination circuit 403 , generates a corrected image from the input image, and outputs the corrected image to the output control circuit 405 .

The output control circuit 405 is an example of an output control section and has the same function as the output control section 155 . The output control circuit 405 receives the corrected image from the image correction circuit 404 and outputs it to the information processing apparatus 200 via the first interface device 131 .

FIG. 12 is a diagram showing a schematic configuration of the second storage device 210 and the second CPU 220 of the information processing device 200 according to yet another embodiment.

In this embodiment, instead of the image reading apparatus 100, the information processing apparatus 200 executes the vertical streak detection process.

As shown in FIG. 12, the second storage device 210 stores programs such as a reception program 211, a vertical streak candidate detection program 212, a removal determination program 213, an image correction program 214, an output control program 215, and the like. Each of these programs is a functional module implemented by software running on a processor. The second CPU 220 reads each program stored in the second storage device 210 and operates according to each read program. Thereby, the second CPU 220 functions as a receiving section 221 , a vertical streak candidate detecting section 222 , a removal determining section 223 , an image correcting section 224 and an output control section 225 . Note that in the present embodiment, the image reading apparatus 100 does not have the vertical streak candidate detection unit 152 , the removal determination unit 153 and the image correction unit 154 .

FIG. 13 is a flow chart showing an example of the operation of the vertical streak detection process of the information processing apparatus 200 . An example of the operation of the vertical streak detection process of the information processing apparatus 200 will be described below with reference to the flowchart shown in FIG. 13 . The operation flow described below is executed mainly by the second CPU 220 in cooperation with each element of the information processing apparatus 200 based on a program stored in the second storage device 210 in advance.

In this embodiment, the vertical streak detection process in step S107 is omitted in the overall process of the image reading apparatus 100 shown in FIG. Also, in step S<b>108 , the output control unit 155 transmits the first input image and the second input image to the information processing apparatus 200 via the first interface device 131 .

First, the receiving unit 221 receives a first input image and a second input image from the image reading device 100 via the second interface device 203 (step S401). The processing of steps S402 to S407 is the same as the processing of steps S201 to S206 in FIG. However, the processing of steps S402 to S403 is executed by the vertical streak candidate detection unit 222, the processing of steps S404 to S405 and S407 is executed by the removal determination unit 223, and the processing of step S406 is executed by the image correction unit 224. be done.

In step S408, the output control unit 225 outputs the input image or the corrected image by displaying it on the second display device 201 (step S408), and ends the vertical streak detection process. Note that the output control unit 225 may output the input image or the corrected image by transmitting it to a server or the like (not shown) via the second interface device 203 .

The image processing system according to this embodiment can also achieve the same effects as the above-described effects.

FIG. 14 is a block diagram showing a schematic configuration of a second processing circuit 500 according to yet another embodiment.

The second processing circuit 500 is used in place of the second processing circuit 230 of the information processing device 200, and performs vertical streak detection processing and the like instead of the second CPU 220. FIG. The second processing circuit 500 includes a receiving circuit 501, a vertical stripe candidate detection circuit 502, a removal determination circuit 503, an image correction circuit 504, an output control circuit 505, and the like. Each of these units may be composed of an independent integrated circuit, microprocessor, firmware, or the like.

The receiver circuit 501 is an example of a receiver and has the same function as the receiver 221 . The vertical stripe candidate detection circuit 502 is an example of a vertical stripe candidate detection unit and has the same function as the vertical stripe candidate detection unit 222 . The removal determination circuit 503 is an example of a removal determination unit and has the same function as the removal determination unit 223 . The image correction circuit 504 is an example of an image correction section and has the same function as the image correction section 224 . The output control circuit 505 is an example of an output control section and has the same function as the output control section 225 .

The image processing system according to this embodiment can also achieve the same effects as the above-described effects.

It should be noted that it is possible to appropriately change in which of the image reading device and the information processing device each part of the image reading device and the information processing device is arranged. Also, in order to provide image processing services in the form of cloud computing, a plurality of information processing devices may be distributed over a network, and each information processing device may work together to share each process. good.

1 image processing system 100 image reader 112 first conveying roller 113 second conveying roller 114 imaging device 116 third conveying roller 117 fourth conveying roller 131 first interface device 151 control section 152 vertical 153 removal determination unit 154 image correction unit 155 output control unit 156 medium shifting unit 200 information processing apparatus;

Claims (7)

a transport unit that transports the medium;
an imaging unit that captures an image of the medium conveyed by the conveying unit and generates an input image;
After the first input image is generated by the imaging unit while the medium is transported by the transport unit, the same surface as the first input image is captured by the imaging unit while the medium is transported again by the transport unit. a control unit that captures and generates a second input image;
a vertical-stripe candidate detection unit that detects vertical-stripe candidates from each of the first input image and the second input image;
Positions of the vertical stripe candidates in a coordinate system based on mutually orthogonal edges of the medium in the first input image and mutually orthogonal edges of the medium in the second input image a removal determination unit that determines that the vertical stripe candidate is to be removed when the position of the vertical stripe candidate is different from the position of the vertical stripe candidate in a coordinate system ;
An image reading device comprising: The control unit causes the medium to be conveyed in the first direction by the conveying unit, causes the imaging unit to generate the first input image, and then conveys the medium in the first direction again by the conveying unit. Generate the second input image by imaging the same surface as the first input image by the imaging unit while conveying in the opposite second direction;
The image reading device according to claim 1. The vertical streak candidate on the medium in one of the first input image and the second input image that has been determined to be removed by the removal determining unit is moved to a corresponding position on the medium in the other image. further comprising an image correction unit that replaces and corrects with the pixel data of
The image reading device according to claim 1 or 2. Further comprising a medium shifting unit that shifts the position or angle of the medium in the width direction with respect to the reading surface of the imaging unit from the generation of the first input image to the generation of the second input image,
The image reading device according to any one of claims 1 to 3. An image processing system having an image reading device and an information processing device,
The image reading device is
a transport unit that transports the medium;
an imaging unit that captures an image of the medium conveyed by the conveying unit and generates an input image;
After the first input image is generated by the image pickup unit while the medium is conveyed by the conveyance unit, the same surface as the first input image is captured by the image pickup unit while the medium is conveyed again by the conveyance unit. a control unit that captures and generates a second input image;
has
The information processing device is
a vertical-stripe candidate detection unit that detects vertical-stripe candidates from each of the first input image and the second input image;
Positions of the vertical stripe candidates in a coordinate system based on the mutually orthogonal edges of the medium in the first input image and based on mutually orthogonal edges of the medium in the second input image a removal determination unit that determines that the vertical stripe candidate is to be removed when the position of the vertical stripe candidate is different from the position of the vertical stripe candidate in a coordinate system ;
An image processing system comprising: A control method for an image reading device having a transport unit that transports a medium and an imaging unit that captures an image of the medium transported by the transport unit and generates an input image,
After the first input image is generated by the imaging unit while the medium is transported by the transport unit, the same surface as the first input image is captured by the imaging unit while the medium is transported again by the transport unit. imaging to generate a second input image;
detecting vertical stripe candidates from the first input image and the second input image;
Positions of the vertical stripe candidates in a coordinate system based on the mutually orthogonal edges of the medium in the first input image and based on mutually orthogonal edges of the medium in the second input image determining that the vertical-stripe candidate is to be removed if the position of the vertical-stripe candidate differs from the position of the vertical-stripe candidate in a coordinate system ;
A control method characterized by: A control program for an image reading device having a transport unit that transports a medium and an imaging unit that captures an image of the medium transported by the transport unit and generates an input image,
After the first input image is generated by the imaging unit while the medium is transported by the transport unit, the same surface as the first input image is captured by the imaging unit while the medium is transported again by the transport unit. imaging to generate a second input image;
detecting vertical stripe candidates from the first input image and the second input image;
Positions of the vertical stripe candidates in a coordinate system based on mutually orthogonal edges of the medium in the first input image and mutually orthogonal edges of the medium in the second input image determining that the vertical-stripe candidate is to be removed if the position of the vertical-stripe candidate differs from the position of the vertical-stripe candidate in a coordinate system ;
A control program that causes the image reading device to execute:

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