WO2019146859A1 - Appareil de balayage d'image pour détecter une ombre de document - Google Patents

Appareil de balayage d'image pour détecter une ombre de document Download PDF

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Publication number
WO2019146859A1
WO2019146859A1 PCT/KR2018/008672 KR2018008672W WO2019146859A1 WO 2019146859 A1 WO2019146859 A1 WO 2019146859A1 KR 2018008672 W KR2018008672 W KR 2018008672W WO 2019146859 A1 WO2019146859 A1 WO 2019146859A1
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WO
WIPO (PCT)
Prior art keywords
document
light source
image
scanning
light
Prior art date
Application number
PCT/KR2018/008672
Other languages
English (en)
Inventor
Kyoung Rok Kim
Original Assignee
Hp Printing Korea Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hp Printing Korea Co., Ltd. filed Critical Hp Printing Korea Co., Ltd.
Publication of WO2019146859A1 publication Critical patent/WO2019146859A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/024—Details of scanning heads ; Means for illuminating the original
    • H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
    • H04N1/02815—Means for illuminating the original, not specific to a particular type of pick-up head
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00681—Detecting the presence, position or size of a sheet or correcting its position before scanning
    • H04N1/00684—Object of the detection
    • H04N1/00687—Presence or absence
    • H04N1/00689—Presence
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00681—Detecting the presence, position or size of a sheet or correcting its position before scanning
    • H04N1/00684—Object of the detection
    • H04N1/00718—Skew
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00681—Detecting the presence, position or size of a sheet or correcting its position before scanning
    • H04N1/00729—Detection means
    • H04N1/00734—Optical detectors
    • H04N1/00737—Optical detectors using the scanning elements as detectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00681—Detecting the presence, position or size of a sheet or correcting its position before scanning
    • H04N1/00742—Detection methods
    • H04N1/0075—Detecting a change in reflectivity
    • H04N1/00753—Detecting a change in reflectivity of a sheet relative to a particular backgroud
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/387—Composing, repositioning or otherwise geometrically modifying originals
    • H04N1/3872—Repositioning or masking
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/387—Composing, repositioning or otherwise geometrically modifying originals
    • H04N1/3877—Image rotation
    • H04N1/3878—Skew detection or correction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/401—Compensating positionally unequal response of the pick-up or reproducing head
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
    • H04N2201/0077—Types of the still picture apparatus
    • H04N2201/0081—Image reader

Definitions

  • Image scanning apparatus refers to a device that scans original images on documents, pictures, films or the like and converts them into digital data.
  • the digital data produced as an output image may be displayed on a computer monitor, or printed by a printer.
  • Examples of the image scanning apparatus may include a scanner, a copy machine, a facsimile, or a multi-function printer (MFP) implementing functions of the above.
  • MFP multi-function printer
  • FIG. 1 is a block diagram illustrating brief configuration of an image scanning apparatus according to an example
  • FIG. 2 is a block diagram illustrating detailed configuration of an image scanning apparatus according to an example
  • FIG. 3 is a diagram illustrating a form of the scanner in FIG. 1 according to an example
  • FIG. 4 is a diagram illustrating operation of a scan unit in a flatbed form according to an example
  • FIG. 5 is a diagram illustrating operation of a scan unit in an automatic feeding device form according to an example
  • FIG. 6 is a diagram illustrating a shadow forming according to light to the document according to an example
  • FIG. 7 is a diagram illustrating operation of detecting an edge of the document using shadow according to an example
  • FIG. 8 is a diagram illustrating a shadow form when scanning document using a plurality of light sources according to an example
  • FIG. 9 is a diagram illustrating a shadow form when scanning document using one of a plurality of light sources according to an example
  • FIG. 10 is a diagram illustrating a control method for a plurality of light sources under normal condition according to an example
  • FIG. 11 is a diagram illustrating a control method for a plurality of light sources in an edge detection situation
  • FIG. 12 is a diagram illustrating a method for recognizing the front end of the document in a flatbed form according to an example.
  • FIG. 13 is a flowchart illustrating an image scanning method according to an example.
  • the scanned image When a user places documents in a misarranged order or when there is mechanical tolerance in the document transfer device, the scanned image may be in rotated or tilted state. Accordingly, a method for recognizing tilted or rotated state of the scanned image is necessary.
  • one constituent element when the specification states that one constituent element is "connected to" another constituent element, it includes a case in which the two constituent elements are 'connected to each other with another constituent element intervened therebetween' as well as a case in which the two constituent elements are 'directly connected to each other'. Further, when one constituent element "comprises (or includes)” another constituent element, unless specifically stated to the contrary, it refers to that another constituent elements may be further included rather than precluding the same.
  • image forming job may refer to various jobs related with image, such as, formation of image or generation/storage/transmission of image files (e.g., printing, scanning or faxing), and the expression “job” as used herein may refer to not only the image forming job, but also a series of processes related to performance of the image forming job.
  • the expression 'image scanning apparatus' as used herein may refer to an apparatus that scans an image of the document and generates scanned image.
  • Examples of the image scanning apparatus may include a scanner, a copy machine, a facsimile, or a multi-function printer (MFP) implementing functions of the above.
  • MFP multi-function printer
  • the image scanning apparatus when the image scanning apparatus is a copy machine, a facsimile, a multi-function printer or the like, which are capable of the image forming job, the image scanning apparatus may also be referred to as the image forming apparatus.
  • image forming apparatus refers to an apparatus that prints the printing data generated at a terminal such as a computer onto a recording medium.
  • Examples of the image forming apparatus may include a copy machine, a printer, a facsimile, or a multi-function printer (MFP) implementing functions of the above.
  • the printer, the scanner, the fax machine, the multi-function printer (MFP), a display apparatus or the like may represent any apparatus that can perform the image forming job.
  • hard copy as used herein may refer to an operation of outputting image on a recording medium such as paper
  • soft copy as used herein may refer to an operation of outputting image on a display device such as a TV, a monitor or the like.
  • content may refer to any type of data as a subject of the image forming job, such as picture, image, document file or the like.
  • printing data may refer to data converted into format that can be printed at the printer. Meanwhile, when the printer supports direct printing, the file itself may be the printing data.
  • scanned data may refer to a scanned image generated at the scanner, may be a black and white image, color image or the like, and may have various forms of file formats (e.g., BMP, JPG, TIFF, PDF, or the like).
  • main scanning direction may refer to a scanning direction of the scanner, and specifically, it may refer to a direction perpendicular to a moving direction of a printing document.
  • sub scanning direction may refer to a moving direction of a document.
  • the expression "user” as used herein may refer to a person who performs manipulation related with the image forming job using the image scanning apparatus or a device connected to the image scanning apparatus wiry or wirelessly.
  • the expression “manager” as used herein may refer to a person who has an authority to access all the functions and systems of the image scanning apparatus. The “manager” and the “user” may refer to the same person.
  • FIG. 1 is a block diagram illustrating brief configuration of an image scanning apparatus according to an example.
  • the image scanning apparatus 100 may include an image sensor 110, a first light source 120, a second light source 130, and a processor 140.
  • the image sensor 110 may scan a document. Specifically, the image sensor 110 may scan image information of the document from the light reflected from document.
  • the image sensor 110 may include charge coupled devices (CCD) disposed in a row along the main scanning direction or a plurality of CMOS image sensors (CIS).
  • CCD charge coupled devices
  • CIS CMOS image sensors
  • the image sensor 110 may be disposed on a lower end of a flatbed and disposed within an automatic document feeder (ADF).
  • ADF automatic document feeder
  • the image sensor 110 may include a convert circuit that converts scanned signal into digital signal. Specifically, CCD and the digital CIS may output scanned signals into a digital signal form, while the CIS may output the scanned signals in analog signal form. Accordingly, when the image sensor 110 includes the CIS, it may convert the scanned signal into digital signals using the convert circuit and output the converted digital signal to the processor 140.
  • the light sources 120, 130 may emit light onto a document using the light source.
  • the light sources 120, 130 may include the first light source 120 and the second light source 130 for emitting light at positions separated from each other onto a scanning region of the image sensor 110.
  • the first light source 120 may be disposed in a downstream direction
  • the second light source 130 may be disposed in an upstream direction.
  • upstream refers to a direction in which document is entered
  • downstream refers to a direction in which document is ejected.
  • the first light source 120 and the second light source 130 may be light emitting diode (LED) light sources.
  • the LED light source allows adjustment of brightness values.
  • the LED light source may output light successively or intermittently according to whether current is inputted or not.
  • the first light source 120 and the second light source 130 may receive input of control signals with respect to brightness value information or duty ratio information.
  • Such LED light source may be a W Led light source or a module combining R LED, G LED and B LED therein.
  • the first light source 120 and the second light source 130 may emit light simultaneously or emit light from only one of light sources. For example, during a normal scanning process, light may be emitted onto the document using both the first light source 120 and the second light source 130. During an edge detection process, however, the light may be emitted using the second light source 130 only, without using the first light source 120.
  • the LED light source may not only output light successively, but may also output light at a preset duty ratio. Accordingly, when it is described above that the light is emitted or not emitted, it may refer to a situation in which the image sensor is temporarily emitting light onto a scanning region where the light is scanned, or is not emitting the light onto the corresponding scanning region. In other words, the light is being emitted when it is emitted at 1 ⁇ 100 % duty ratio, but is not being emitted when duty ratio is 0 % with respect to the scanning region.
  • the duty ratio of the first light source 120 and the second light source 130 may be varied according to scanning speed of the document so that exposure can be maintained constantly during the exposure time for one line of the image sensor. For example, light may be emitted onto the document at a low duty ratio when the document is scanned at low speed, while the light may be emitted at high duty ratio when the document is scanned at high speed.
  • the scanning operation may be performed at low speed so that exposure of one line of the image sensor can be same as when the both the light sources are used.
  • the processor 140 may control each constituent element within the image scanning apparatus 100.
  • the processor 140 may be implemented as CPU, ASIC, or the like, and sense whether a scan command is inputted from a user.
  • a scan command may be inputted through a manipulation input 180 provided on the image scanning apparatus 100 or through a communicator 160 as signals from an external device.
  • the processor 140 may determine whether or not to perform the operation of detecting an edge of the document. Specifically, document misalignment often occurs when a user performs scanning operation using a flatbed.
  • the processor 140 may determine that the operation of detecting document is to be performed for a scanning job using the flatbed. In an example, for a faster scanning job, the processor 140 may proactively perform a first scanning operation for only a front region of the document upon sensing closing of a cover of the flatbed, and then perform a second scanning operation for the whole region of the document upon receiving a scan command from a user.
  • the image scanning apparatus 100 may include a sensor that senses closing of the cover of the flatbed.
  • the processor 140 may perform the first scanning operation after performing the second scanning operation, during a process in which the image sensor is returned to home position.
  • the processor 140 may determine whether or not to perform the operation of detecting an edge of the document on the basis of a predetermined cycle.
  • the processor 140 may determine that the edge detection operation is to be performed, when the edge detection operation is set to be performed by a user through the manipulation input 180.
  • the processor 140 may control the image sensor 110, the first light source 120 and the second light source 130 so that the normal scanning operation is performed. Specifically, the processor 140 may control the first light source 120 and the second light source 130 so that all of a plurality of light sources emit light onto a scanning. More specifically, the processor 140 may control the an amount of light emitted onto a document by adjusting magnitude of power provided respectively to the first light source 120 and the second light source 130 and time of applying the power.
  • the processor 140 may control a driver 150 so that document can be moved at first preset speed. Specifically, the processor 140 may control moving speed, position or the like of the document or image sensor by adjusting the power supplied to a motor that moves the document or image sensor 110.
  • the processor 140 may generate a scanned image based on signals provided from the image sensor 110. Further, the processor 140 may perform image processing with respect to the generated scanned image. For example, the processor 140 may perform various image processing such as image processing to adjust brightness of the scanned image, OCR operation to recognize texts in the scanned image or the like.
  • the processor 140 may control the first light source 120 and the second light source 130 so that only one of the first light source 120 and the second light source 130 that is adjacent to the front end of the document (specifically, light source in an upstream direction) may emit light during the scanning of the front end of the document.
  • the processor 140 may control the driver 150 so that document (or image sensor) can be moved at a second speed which is slower than scanning speed of the normal scanning operation.
  • the processor 140 may control only one light source 130 to emit light during scanning process of the front end of the document, and then control the two light sources 120, 130 to operate after scanning operation of the front end of the document finishes.
  • scanning speed may be same as in the normal scanning method.
  • the processor 140 may mask the front end of the document with a predetermined image (e.g., white image), or perform brightness compensation with respect to the front end of the document.
  • a predetermined image e.g., white image
  • the processor 140 may detect shadow of the document from the scanned image. The details of the shadow detecting operation will be described below with reference to FIG. 6.
  • the processor 140 may check at least one of tilting, width, and position of the document based on the detected shadow. Further, the processor 140 may perform compensation image processing based on at least one of the tilting, width, and position of the document.
  • the processor 140 may store the scanned image in a memory 190 or transmit it to an external device through the communicator 160. Meanwhile, when the image scanning apparatus is a multi-function printer that includes printing capability, the processor 140 may control the constituent elements in the image scanning apparatus 100 to print the scanned image.
  • the image scanning apparatus 100 may provide light using only part of a plurality of light sources during the scanning process of the front end of the document, shadow of the document may be scanned more accurately from the scanned document. Accordingly, the image scanning apparatus 100 may correctly compensate tilting, misalignment or the like of the document, and the image quality of the scanned output may be enhanced.
  • one image sensor is illustrated in the image scanning apparatus; however, when in practical implementation, a plurality of image sensors may be included in the image scanning apparatus, in which case additional light sources may be provided according to the number of the image sensors.
  • FIG. 1 illustrates and describes that the image scanning apparatus includes two light sources
  • three light sources may be used.
  • two light sources may be disposed in an upstream direction, and one light source may be disposed in a downstream direction.
  • the two light sources in the upstream direction may emit light onto a scanning region when the scanning the front end of the document, and the one light in the upstream direction and another light source in the downstream direction may simultaneously emit light after the scanning of the front end.
  • FIG. 2 is a block diagram illustrating detailed configuration of an image scanning apparatus according to an example.
  • the image scanning apparatus 100 may include an image sensor 110, a first light source 120, a second light source 130, a processor 140, a driver 150, a communicator 160, a display 170, a manipulation input 180, and a memory 190.
  • the driver 150 may move the image sensor or document. Specifically, when the image scanning apparatus 100 includes the flatbed, the driver 150 may include a mechanism and a motor to move the image sensor in a sub scanning direction. According to an example, when the image scanning apparatus 100 includes a document transfer device, the driver 150 may include a mechanism and a motor to move the document in a preset document transfer direction.
  • the communicator 160 may be connected to a terminal (not illustrated) such as mobile device (smart phone, tablet PC), PC, note book PC, PDA, digital camera or the like, and transmit the scanned image generated at the image sensor 110 or previously stored in the memory 190 to another terminal.
  • the communicator 160 may be configured to connect the image scanning apparatus 100 to an external device, and may not only be connected to a terminal through a local area network (LAN) and an internet network, but also connected through an universal serial bus (USB) port or wireless communication port (e.g., WiFi 802.11a/b/g/n, NFC, Bluetooth).
  • LAN local area network
  • USB universal serial bus
  • wireless communication port e.g., WiFi 802.11a/b/g/n, NFC, Bluetooth
  • the display 170 may display various pieces of information provided from the image scanning apparatus 100. Specifically, the display 170 may display user interface window to receive selecting of various functions provided by the image scanning apparatus 100.
  • the display 170 may be a monitor such as LCD, CRT, OLED, or the like, and may be implemented as a touch screen that can simultaneously perform a function of the manipulation input 180.
  • the display 170 may display control menu for performance of functions of the image scanning apparatus 100. Accordingly, user may input a scan command on the displayed user interface window.
  • the scan command may be a command to perform the scanning job and may be commands such as scan-to-server, scan-to-DLNA, scan-to-cloud or the like which transmit scanning job to a specific server.
  • the scan command may be a copy command that uses a scan function.
  • the scan command may be received from a terminal (not illustrated) through the communicator 160.
  • the display 170 may display the generated scanned image and information about the scanned image.
  • the displayed scanned image may be the scanned image itself or a preview image for the scanned image.
  • the manipulation input 180 may receive from a user a function selection and a control command for the function.
  • the function may include a print function, a copy function, a scan function, a fax transmission function or the like.
  • the manipulation input 180 may receive an input through the control menu displayed on the display 170.
  • the manipulation input 180 may be implemented as a plurality of buttons, keyboard, mouse or the like, and may be implemented as a touch screen that can simultaneously perform functions of the display 170 described above.
  • the manipulation input 180 may receive setting from a user with respect to whether or not to perform the edge detection operation.
  • the memory 190 may store data for image processing. Specifically, the memory 190 may store programs for performing the image processing of the processor 140, or store signals scanned at the image sensor 110 or data processed in the processor 140.
  • the memory 190 may store scanned image generated in the processor 140. Further, the memory 190 may be implemented as a storage medium within the image scanning apparatus 100 or an external storage medium such as, for example, removable disk including the USB memory, a storage medium connected to host, a web server through network, or the like.
  • FIGS. 1 and 2 illustrate and describe normal functions of the image scanning apparatus 100
  • the image scanning apparatus 100 may further include an image processor to perform the print function, a fax trans-receiver to perform the fax trans-receive function, or the like according to functions supported by the image scanning apparatus 100.
  • FIG. 3 is a diagram illustrating a form of the scan unit of FIG. 1 according to an example.
  • the image scanning apparatus 100 may include a first scanning apparatus 101 in a flatbed form, which can scan a document placed on a flat plate, and a second scanning apparatus 102 in an automatic document feeding form, which can successively scan a document placed on an automatic document feeder.
  • Each of the scanning apparatuses 101, 102 may include one image sensor and two light sources, as described in FIGS. 1 and 2.
  • the image scanning apparatus 100 includes a plurality of scanning apparatuses, in another implementation, it may include only one of the scanning apparatuses or may include three scanning apparatuses.
  • the first scanning apparatus 101 is a scanning apparatus in a flatbed form, in which a document may be placed on a flat plate and scanned as the image sensor 101 is moved under the flat plate where document is placed. Specific operation of the first scanning apparatus 101 will be described below with reference to FIG. 4.
  • the second scanning apparatus 102 is a scanning apparatus in an automatic document feeding form, in which a document may be placed on a document feeder, successively moved to a document transfer path, and scanned by the image sensor positioned on the document transfer path. Specific operation of the second scanning apparatus 102 will be described below with reference to FIG. 5.
  • the second scanning apparatus 102 may be one-side scanning apparatus that can scan one side of the document only, or double-side scanning apparatus that can scan both sides of the document.
  • first scanning apparatus 101 and the second scanning apparatus 102 respectively include image sensors, one image sensor may be commonly used in the first scanning apparatus 101 and the second scanning apparatus 102.
  • FIG. 4 is a diagram illustrating operation of a scan unit in a flatbed form according to an example.
  • the image sensor 110 of the first scanning apparatus 101 may be disposed under the flatbed including glasses 163 and moved from a home region to a document region according to a scan command. Further, the first light source 120 and the second light source 130 may be disposed above the image sensor 110. Specifically, the first light source 120 may be disposed in a downstream direction, i.e., at a left upper end of the image sensor, and the second light source 130 may be disposed in an upstream direction, i.e., at a right upper end of the image sensor.
  • the following will describe the operation of the first scanning apparatus 101 by respectively referring to a normal scanning process and a scanning process for edge detection.
  • the first light source 120 and the second light source 130 may perform operation of emitting preset an amount of light on a pixel unit basis, and this process may be repeated until the end of the document 10.
  • the first light source 120 may not emit light and the second light source 130 may perform operation of emitting light onto the front end of the document 10.
  • the scanning for edge detection may be based on three methods. Firstly, only the second light source 130 may be used to scan the entire region of the document 10 after the front end of the document 10 is scanned.
  • the image sensor 110 may be moved to a home region again, and likewise in the normal scanning process, the scanning operation of the entire region of the document 10 may be performed using both the first light source 120 and the second light source 130.
  • the scanning operation of the entire region of the document 10 may be performed using both the first light source 120 and the second light source 130, and after scanning operation of the entire region finishes, additional scanning operation of the front end of the document 10 may be performed during a returning process to a home region of the image sensor 110.
  • FIG. 5 is a diagram illustrating operation of a scan unit in an automatic document feeding form according to an example.
  • the image sensor 110 of the second scanning apparatus 102 may be positioned on a preset region of the document transfer path, and the first light source 120 and the second light source 130 may be disposed above the image sensor 110.
  • the first light source 120 may be disposed in a downstream direction, i.e., at a right upper end of the image sensor
  • the second light source 130 may be disposed in an upstream direction, i.e., at a left upper end of the image sensor.
  • the following will describe the operation of the second scanning apparatus 102 by respectively referring to a normal scanning process and an edge detection process.
  • the first light source 120 and the second light source 130 may perform an operation of emitting a preset an amount of light on a pixel unit basis at a preset time, and the above process may be repeated until the document 10 passes through the document transfer path.
  • the first light source 120 may not emit light, and only the second light source 130 may perform the operation of emitting preset an amount of light on a pixel unit basis at a preset time. Accordingly, the image sensor 110 may perform the scanning operation of the front end of the document 10 using the light of the second light source 130 only.
  • the scanning operation after scanning the front end of the document 10 may be performed with two methods. Firstly, the scanning operation of the front end of the document 10 may be performed and then the scanning of the other region may follow using both the first light source 120 and the second light source 130.
  • the scanning operation of the front end of the document 10 may be performed, but this time, the other region may then be scanned using only the second light source 130.
  • the scanning may be performed at the same speed as that of the normal scanning operation; however, because an amount of light provided to the front end of the document 10 is different from an amount of light provided to the other region, the processor 140 may be to perform a job of compensating brightness value for the front end of the scanned image.
  • scanning job may be performed at a slower speed than the method described above in order to provide sufficient amount of light using only one light source on a pixel unit basis.
  • FIG. 6 is a diagram illustrating a shadow form according to the light of the document according to an example.
  • the shadow due to the document may be detected from the scanned image and the size and deformation of the document may be sensed using the detected shadow.
  • the shadow detection may not require another physical equipment and has higher precision.
  • shadow may be formed by the document on a white background 104.
  • the image scanning apparatus 100 may detect the shadow from the document from the scanned image, and sense size and deformation of the document using the detected shadow. Specific shadow detecting method will be explained below with reference to FIG. 7.
  • FIG. 7 is a diagram illustrating an edge detection operation of the document using shadow according to an example.
  • data may be simplified through sampling 720 and averaging 730 with respect to the front end of the scanned image 710 and then an edge 740 may be extracted using a gradient filter with respect to the simplified data.
  • FIG. 8 is a diagram illustrating a shadow form when scanning document using a plurality of light sources according to an example
  • FIG. 9 is a diagram illustrating a shadow form when scanning document using only one of a plurality of light sources according to an example.
  • Recognition of the shadow may be influenced by an illumination angle of the light source that illuminates the document and arrangement of the light source.
  • the first light source 120 and the second light source 130 for emitting light at positions separated from each other may be disposed above the image sensor 110.
  • the first light source 120 may be disposed in a downstream direction and emit light onto a scanning region of the image sensor
  • the second light source 130 may be disposed in an upstream direction and emit light onto a scanning region of the image sensor.
  • shadow may be offset from the scanned image 810, and recognition rate with respect to an edge 801 may be considerably lowered.
  • contrast of shadow may increase from the scanned image 910, and recognition rate with respect to an edge 901 of the document may increase accordingly.
  • using a plurality of light sources may generally result in high quality scan because scanning for the shadow of an edge is avoided.
  • bi-directional light sources provide the effect of preventing the shadow thereof from being scanned as is, there may be an effect that the user may perceive an enhanced quality.
  • the bi-directional light source may be used when it comes to the normal image quality, but accuracy is deteriorated for the edge detection that is performed to recognize tilting of the document, size of the document, and position of the document.
  • the front end of the document which is generally non-text area, may be scanned using the light source in an upstream direction as a single light source while the light source in a downstream direction may be turned off.
  • FIG. 10 is a diagram illustrating a control method for a plurality of light sources under normal condition according to an example.
  • light may be emitted using both the second light source 130 disposed in an upstream direction and the first light source 120 disposed in a downstream direction during the scanning of the document.
  • FIG. 11 is a diagram illustrating a control method for a plurality of light sources in an edge detection case according to an example.
  • light may be emitted onto document using the second light source 130 disposed in an upstream direction during the scanning of the front end of the document.
  • the first light source 120 disposed in a downstream direction may not emit light.
  • the contrast of shadow from the front end of the document may be enhanced through the above operation, and accordingly, an edge of the document may be detected more precisely.
  • turning-off the light source in a downstream direction may reduce an amount of light to a half. Accordingly, voltage outputted from the image sensor 110 may be reduced to a half level.
  • scanning speed may be adjusted. Specifically, because lowering scanning driving speed to a half corresponds to doubling the exposure time of the image sensor, the light in the same amount as in the normal driving condition may be provided to document with a half of the amount of light.
  • turning off the light source in the downstream direction may be applied to the scanning process of the front end of the document not to other scanning processes.
  • scanning is practically performed at a state in which the light sources in upstream/downstream directions are all turned on during the scanning of image, image quality deterioration may not be generated.
  • the front end may be subject to an image processing such as masking to white color in the final scanned image.
  • masking may be performed with respect to all the four sides of the document as well as the front end of the document.
  • FIG. 12 is a diagram illustrating a method for recognizing the front end of the document in a flatbed form according to an example.
  • the image sensor may be moved to home position for scanning job as a user closes a cover of a flatbed. Thereafter, normal scanning operation may be performed using both of the two light sources based on a scan command of a user.
  • the scanning operation may be additionally performed with one light source, and the scanned image for edge detection may be additionally generated.
  • scanned image for edge detection may be generated at first using only one light source. Thereafter, the scanned image of the entire document may be generated using the two light sources based on a scan command of a user.
  • FIG. 13 is a flowchart illustrating a method for scanned image according to an example.
  • light may be emitted onto document using at least one of the first light and the second light source, at S1310. Specifically, light may be emitted onto document using only one of the first light and the second light source that is adjacent to the front end of the document (e.g., light source disposed in an upstream direction) during the scanning of the front end of the document. Further, when scanning the front end of the document finishes, light may be emitted by continuously using one light source or using all of a plurality of light sources.
  • scanned image may be generated by scanning document, at S1320. Specifically, light reflected from the document may be scanned using the image sensor and the scanned image may be generated based on signals outputted from the image sensor.
  • shadow of the document may be detected from the scanned image, at S1330. Further, at least one of tilting, width and position of the document may be checked based on the detected shadow, and image processing with respect to the scanned image may be performed based on at least one of the checked tilting, width and position. Further, when there is a change in the method of the light source between the scanning of the front end and the subsequent scanning, image processing for the masking for the front end of the scanned image may be performed.
  • the image scanning method may scan shadow of the document from the scanning document more precisely because light may be provided using some of a plurality of light sources during the scanning of the front end of the document. Accordingly, image quality of scanned output may be enhanced because tilting, skew or the like of the document may be accurately compensated.
  • the image scanning method of FIG. 13 may be performed by the image scanning apparatus having configuration of FIG. 1 or FIG. 2, or by the image scanning apparatus or the scanning device having another configuration.
  • the image scanning method according to an example described above may be implemented as a program and provided to the image scanning apparatus.
  • a program including the image scanning method may be stored and provided in non-transitory computer readable recording medium.
  • the non-transitory computer readable recording medium may store data semi-permanently and may be medium read by a device, rather than the medium storing data temporarily, such as register, cache, memory or the like.
  • various applications or programs described above may be stored and provided in non-transitory computer readable recording medium such as CD, DVD, hard disk, Blu-ray disk, USB, memory card, ROM or the like.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Facsimile Scanning Arrangements (AREA)
  • Image Input (AREA)

Abstract

L'invention concerne un appareil de balayage d'image comprenant un capteur d'image pour balayer un document à partir d'une extrémité avant du document, pour délivrer des signaux, une première source de lumière pour émettre de la lumière à une première position et une seconde source de lumière pour émettre de la lumière à une seconde position séparée de la première position, les première et seconde sources de lumière pour émettre de la lumière sur une région de balayage du capteur d'image, et un processeur pour générer une image balayée à l'aide de signaux émis par le capteur d'image et pour détecter une ombre du document sur l'image scannée, le processeur étant destiné à commander soit la première source de lumière soit la seconde source de lumière qui est adjacente à l'extrémité avant du document pour émettre de la lumière, tandis que le capteur d'image balaye l'extrémité avant du document.
PCT/KR2018/008672 2018-01-24 2018-07-31 Appareil de balayage d'image pour détecter une ombre de document WO2019146859A1 (fr)

Applications Claiming Priority (2)

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KR10-2018-0008901 2018-01-24
KR1020180008901A KR20190090252A (ko) 2018-01-24 2018-01-24 원고의 그림자 검출이 가능한 화상독취장치 및 화상독취방법

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Citations (4)

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US20090109500A1 (en) * 2007-10-31 2009-04-30 Canon Denshi Kabushiki Kaisha Image reading apparatus and control method therefor, as well as storage medium
JP2010141857A (ja) * 2008-12-15 2010-06-24 Sharp Corp 原稿読取装置およびこれを用いた画像形成装置
US20120013954A1 (en) * 2010-07-16 2012-01-19 Canon Kabushiki Kaisha Image processing method
US20170078506A1 (en) * 2015-09-16 2017-03-16 Fuji Xerox Co., Ltd. Image reading device, image forming apparatus, and image reading method

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US20090109500A1 (en) * 2007-10-31 2009-04-30 Canon Denshi Kabushiki Kaisha Image reading apparatus and control method therefor, as well as storage medium
JP2010141857A (ja) * 2008-12-15 2010-06-24 Sharp Corp 原稿読取装置およびこれを用いた画像形成装置
US20120013954A1 (en) * 2010-07-16 2012-01-19 Canon Kabushiki Kaisha Image processing method
US20170078506A1 (en) * 2015-09-16 2017-03-16 Fuji Xerox Co., Ltd. Image reading device, image forming apparatus, and image reading method

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