JP5838684B2 - Image correction apparatus, image reading apparatus, image forming apparatus, and program - Google Patents

Description

  The present invention relates to an image correction apparatus, an image reading apparatus, an image forming apparatus, and a program.

  Patent Document 1 discloses a shading correction circuit that corrects white shading and black shading in an imaging apparatus, and includes white shading among reference data indicated by digital values for correcting the white shading and black shading. And an effective data extraction unit that extracts effective components for correcting black shading, a storage unit that stores the effective components extracted by the effective data extraction unit, and a normal image captured by the imaging device A shading correction circuit comprising: a correction unit that corrects the white shading and the black shading with reference to the effective component read from the storage unit with respect to input image data. .

  Patent Document 2 includes an equal-size image sensor in which a plurality of sensor chips on which a plurality of read pixels are formed are arranged, and reads normal document image data and dark output data from the equal-size image sensor. In the dark output correction device that corrects the dark output by removing the dark output data from the original image data and obtains the output of the desired true original image data, it is output from each read pixel of the same size image sensor. Dark output representative value detecting means for detecting dark output representative value for each sensor chip of dark output data is provided, and dark output representative value for each sensor chip detected by the dark output representative value detecting means is stored. Representative value storage means is provided, and the dark output representative value for each sensor chip read from the dark output representative value storage means is subtracted from the document image data for each corresponding sensor chip. Dark output correction apparatus is disclosed which is characterized in that a dark output representative value subtracting means that.

JP-A-2005-236634 Japanese Patent Laid-Open No. 7-74948

  An object of the present invention is to provide an image correction apparatus and an image reading apparatus capable of reducing a storage area (RAM area) of a circuit used at the time of shading correction of a read image as compared with a case without the configuration of the present invention. Another object is to provide an image forming apparatus and a program.

In order to achieve the above object, the invention according to claim 1 is characterized in that a specific part is obtained from a plurality of pieces of image information obtained by the obtaining unit and a plurality of pieces of image information obtained by the obtaining unit. An information selection unit that selects image information of color and type, a cumulative storage unit that accumulates and stores the image information selected by the information selection unit, and an average value of the image information that is cumulatively added by the cumulative storage unit An average value acquisition unit that acquires the average value of the image information acquired by the average value acquisition unit by color, and a target according to the type of image information acquired by the acquisition unit Each of the information selection unit, the accumulation storage unit, the average value acquisition unit, and the color-specific storage unit so that correction information or corrected image information is stored while performing calculation so that shading correction of an image is performed. An arithmetic control unit for controlling For example, together with the arithmetic control unit, when acquiring the target information to be corrected by the acquisition section performs calculation for correcting the target information using the correction information stored in the color-based storage unit, The information selection unit, the cumulative storage unit, so that the corrected image information is selected by the information selection unit, and an average value of the image information acquired by the average value acquisition unit is stored as corrected image information. The image correction apparatus performs second control for controlling each of the average value acquisition unit and the color storage unit .

  In the invention according to claim 2, when the calculation control unit acquires reference information for generating correction information by the acquisition unit, the reference information is selected by the information selection unit, and the average A first control unit that controls each of the information selection unit, the cumulative storage unit, the average value acquisition unit, and the color-specific storage unit such that an average value of image information acquired by the value acquisition unit is stored as correction information. The image correction apparatus according to claim 1, wherein the control is performed.

According to a third aspect of the invention, prior SL region of the Color storage unit in which the correction information in the first control is stored and overwrites and stores the corrected image information acquired by the second control, An image correction apparatus according to claim 2 .

According to a fourth aspect of the present invention, there is provided an image correction apparatus according to any one of the first to third aspects and a plurality of different colors and types in the image correction apparatus by optically reading an image from an object. And an image reading unit that outputs the image information.

According to a fifth aspect of the present invention, there is provided an image correction apparatus according to any one of the first to third aspects and a plurality of different colors and types in the image correction apparatus by optically reading an image from an object. The image forming apparatus includes: an image reading unit that outputs the image information; and an image forming unit that forms an image on a medium based on the corrected image information subjected to the shading correction by the image correcting device.

The invention according to claim 6 selects a plurality of pieces of image information of different colors and types, and selects image information of a specific color and type from the plurality of pieces of image information acquired by the acquisition unit. An information selection unit, a cumulative storage unit that accumulates and stores the image information selected by the information selection unit, and an average value acquisition unit that acquires an average value of the image information cumulatively added by the cumulative storage unit; A program for controlling an image correction apparatus comprising: a color-specific storage unit that stores an average value of image information acquired by the average value acquisition unit for each color, the computer being acquired by the acquisition unit According to the type of image information, calculation is performed so that shading correction of the target image is performed, and the information selection unit, the cumulative storage unit, and the average value acquisition so that correction information or corrected image information is stored Part and color To function as an arithmetic control unit for controlling each of the storage unit, the arithmetic and control unit, when obtaining the target information to be corrected by the acquisition unit, using the correction information stored in the Color storage unit The correction of the target information is performed, the corrected image information is selected by the information selection unit, and the average value of the image information acquired by the average value acquisition unit is stored as corrected image information. As described above, the program further performs second control for controlling each of the information selection unit, the cumulative storage unit, the average value acquisition unit, and the color-specific storage unit .

According to the first aspect of the present invention, it is possible to reduce the storage area (RAM area) of the circuit used for shading correction of the read image as compared with the case where the configuration of the present invention is not provided.
According to the first aspect of the present invention, the acquired target information can be corrected with the correction information, and an average value of the acquired corrected image information can be stored as corrected image information.

  According to invention of Claim 2, the average value of the acquired reference | standard information can be memorize | stored as correction information.

According to the third aspect of the present invention, the RAM area of the circuit that performs the shading correction of the read image can be further reduced as compared with the case where the configuration of the present invention is not provided.

According to the fourth aspect of the present invention, it is possible to reduce the RAM area of the circuit used at the time of shading correction of the read image as compared with the case where the configuration of the present invention is not provided.

According to the fifth aspect of the present invention, it is possible to reduce the RAM area of the circuit used at the time of shading correction of the read image as compared with the case where the configuration of the present invention is not provided.

According to the sixth aspect of the present invention, it is possible to reduce the RAM area of the circuit used at the time of shading correction of the read image as compared with the case where the configuration of the present invention is not provided.

1 is a schematic perspective view illustrating an example of a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating an example of a main configuration of an electric system of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic cross-sectional view illustrating an example of a configuration of an image reading unit illustrated in FIG. 1. It is a schematic sectional drawing which shows an example of a structure of the back surface image reading part shown in FIG. It is a functional block diagram which shows an example of a structure of the back surface image reading part shown in FIG. 6 is a functional block illustrating an example of a configuration of an average value calculation circuit illustrated in FIG. 5. 4 is a flowchart illustrating an example of a flow of “correction data acquisition processing” executed by the image reading control unit illustrated in FIG. 3. 4 is a flowchart illustrating an example of a flow of “corrected data acquisition processing” executed by the image reading control unit illustrated in FIG. 3.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

<Image forming apparatus>
First, the image forming apparatus according to the present embodiment will be described.

(Schematic configuration of image forming apparatus)
FIG. 1 is a schematic perspective view showing an example of the configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 10 according to the present exemplary embodiment includes an image reading unit 12, an image forming unit 14, a paper supply unit 16, and an operation panel 18.

  The image reading unit 12 includes an original table 22 on which an original sheet is placed, an original discharge unit 24 from which an original sheet on which an image has been read is discharged, a transport mechanism that transports the original sheet placed on the original table 22, and an image of the original sheet Is configured to include an image reading sensor for optically reading the image, a scanning mechanism for scanning the original paper, and the like. With the above-described configuration, the image reading unit 12 takes in original sheets placed on the original table 22 one by one, reads an image on the original sheet, and generates image information. Further, a reference plate 68 described later is optically read to acquire image information for performing image processing such as shading correction.

  In the present embodiment, the image reading unit 12 is configured as a “double-sided reading device” that reads a front image and a back image of a document sheet by one conveyance. The detailed configuration of the image reading unit 12 such as a transport mechanism, an image reading sensor, and a scanning mechanism will be described later. Here, an external configuration will be described.

  A pair of guides 26 </ b> A and 26 </ b> B are provided on the upper surface of the document table 22 to guide the document sheet when the document sheet placed on the document table 22 is conveyed. At least one of the pair of guides 26A and 26B is configured to move in the width direction of a document sheet placed on the document table 22 (direction perpendicular to the document sheet conveyance direction). The pair of guides 26 </ b> A and 26 </ b> B are moved according to the width of the document sheet placed on the document table 22.

  The document table 22 is provided with a sensor 30 that detects that a document sheet is placed on the document table 22. The sensor 30 is not particularly limited as long as it is a sensor that detects the presence or absence of a document. Using a reflection type optical sensor (photoreflector) that detects reflected light by irradiating light from a light source to a document, a transmission type optical sensor (photointerrupter) that detects that the light emitted from the light source is blocked, etc. Also good. Further, the sensor 30 may be configured to detect the size in the width direction of the original paper, such as A4 size, B5 size, A5 size, and letter size, as the pair of guides 26A and 26B move.

  The image forming unit 14 includes an image forming mechanism that forms an image on the paper supplied from the paper supply unit 16, a discharge mechanism that discharges the paper on which the image is formed, to the paper discharge unit 32, and the like. Yes. For example, the image forming mechanism includes an image forming unit (photosensitive drum, charging device, exposure device, developing device, transfer device, cleaning device, etc.) that forms an image by electrophotography, and a fixing device. With the above configuration, the image forming unit 14 forms an image on the paper supplied from the paper supply unit 16 and discharges the paper on which the image has been formed to the paper discharge unit 32.

  The paper supply unit 16 includes a paper storage unit that stores paper, a supply mechanism that supplies paper from the paper storage unit to the image forming unit 14, and the like. The supply mechanism is configured by a take-out roller, a transport roller, and the like that take out the paper from the paper storage unit. Depending on the type and size of the paper, a plurality of paper storage units may be provided. The paper supply unit 16 supplies paper to the image forming unit 14 with the above configuration.

  The operation panel 18 includes a touch panel 34 for displaying various screens such as a setting screen, various buttons 36 such as a start button and a numeric keypad, and the like. With the above configuration, the operation panel 18 functions as a UI (user interface) that receives user operations and displays various information to the user.

Next, the electrical configuration of the image forming apparatus 10 will be described.
FIG. 2 is a block diagram illustrating an example of a main configuration of the electrical system of the image forming apparatus 10 illustrated in FIG. As shown in FIG. 2, the image forming apparatus 10 includes a main controller 81, a secondary storage device (HDD) 90 such as a hard disk device, an image reading control unit 92, an image forming control unit 94, an external interface 96, and an operation panel 18. It has.

  The main controller 81 is configured as a computer that controls the entire apparatus and performs various calculations. The main controller 81 includes a CPU (Central Processing Unit) 84, a ROM (Read Only Memory) 86, and a RAM (Random Access Memory) 88. The CPU 84 reads a program stored in the ROM 86 or the HDD 90 and executes the program using the RAM 88 as a work area.

  The image reading control unit 92 is a control unit that is disposed in the image reading unit 12 and controls the entire image reading process. The image reading control unit 92 is configured as a computer including a CPU, a ROM, a RAM, and the like, and controls each part of the image reading unit 12 and performs various calculations. The image forming control unit 94 is a control unit that is disposed in the image forming unit 14 and controls the entire image forming process. The image formation control unit 94 is configured as a computer including a CPU, a ROM, a RAM, and the like, and controls each part of the image formation unit 14 and performs various calculations.

  The external interface 96 is an interface for communicating with an external device via a wired or wireless communication line. For example, it functions as an interface for communicating with a computer connected to a network such as a LAN (Local Area Network). The HDD 90 stores various data such as log data and various programs for controlling the entire apparatus.

  Each of the CPU 84, ROM 86, RAM 88, HDD 90, image reading control unit 92, image formation control unit 94, external interface 96, and operation panel 18 are electrically connected via a bus 98. The main controller 81 exchanges information with each of the HDD 90, the image reading control unit 92, the image formation control unit 94, and the operation panel 18 via the bus 98. Further, the main controller 81 exchanges information with an external device via the bus 98 and the external interface 96.

(Configuration of image reading unit)
Here, the configuration of the image reading unit 12 will be described in detail.
FIG. 3 is a schematic sectional view showing an example of the configuration of the image reading unit 12 shown in FIG. As described above, the image reading unit 12 is configured as a “double-sided reading device”. As shown in FIG. 3, the image reading unit 12 reads a document conveying unit 40 that conveys a document placed on the document table 22, a front image reading unit 42 that reads a front image of a document sheet, and a back image of a document sheet. A back image reading unit 66 is provided. The back image reading unit 66 is fixedly arranged in the document conveying unit 40. Further, the back image reading unit 66 is arranged on the downstream side in the document sheet transport direction with respect to the front image reading unit 42.

  The document transport unit 40 takes in the document sheets one by one by contacting the uppermost surface of the bundle of document sheets placed on the document table 22 raised by the elevation mechanism 44 and the elevation mechanism 44 that raises and lowers the document table 22. A roller 46, a supply roller 50 that supplies the original paper taken in by the take-in roller 46 to the conveyance path 48, and various conveyance rollers 52, 54, 56 that convey the original paper further downstream in the conveyance direction along the conveyance path 48. , 58, 60 and the like. The rotation shaft of each roller extends in a direction intersecting with the document sheet conveyance direction.

  Further, the document transport unit 40 includes a guide mechanism 62 that rotates around a fulcrum according to the loop state of the transported document sheet, and a discharge roller 64 that discharges the document sheet to the document discharge unit 24. Here, the loop state of the original paper means that the original paper conveyance path 48 is bent so as to form a loop, and the original paper is curved along the conveyance path 48.

  The surface image reading unit 42 includes a transparent first platen glass 70A, a transparent second platen glass 70B, a light source 72 that irradiates illumination light toward the original paper, and a reflection mirror that bends the optical path of the reflected light reflected from the original paper. 74, 76, 78, a lens 80 that forms an image of the reflected light reflected by the reflection mirror 78, an image reading sensor 82 disposed at the image forming position of the lens 80, and the like. Here, “transparent” means that each of the illumination light and the reflected light is transmitted.

  The image reading unit 12 according to the present embodiment is configured as a “double-sided reading device” that reads both front and back images from a document sheet being conveyed by the document conveying unit 40. However, when reading an image on one side of the original paper, the original paper is placed on the first platen glass 70A without using the original conveying unit 40, and the image on the side facing the first platen glass 70A is read. Also good.

  The first platen glass 70A is provided at the center of the upper surface of the surface image reading unit 42 in order to read an image on one side of the original paper placed on the first platen glass 70A. A light-shielding member (not shown) that blocks the illumination light and the reflected light is disposed around the upper surface of the surface image reading unit 42 (that is, around the first platen glass 70A).

  On the other hand, the second platen glass 70B is an opening formed in the light shielding member so as to read the surface image of the original sheet being conveyed by the original conveying unit 40. Therefore, the second platen glass 70 </ b> B is provided in a part of the peripheral portion on the upper surface of the surface image reading unit 42. In the example illustrated in FIG. 3, the second platen glass 70 </ b> B is disposed so as to face the conveyance roller 58 of the document conveyance unit 40. That is, the surface image of the original paper is read at the position where the conveying roller 58 is disposed. Hereinafter, this position is referred to as a “surface image reading position”.

  As the light source 72, a fluorescent lamp, a light source array, or the like is used. As the light source array, an LED array or the like in which a plurality of LEDs (Light Emitting Diodes) are arranged along the direction intersecting the document sheet conveyance direction may be used. Each of the light source 72 and the reflection mirrors 74, 76, 78 is mounted on the carriage and moved in the direction of arrow C together with the carriage. In the example shown in FIG. 3, the light source 72 and the reflection mirror 74 are mounted on the carriage 83A and moved in the arrow C direction together with the carriage 83A. The reflecting mirrors 76 and 78 are mounted on the carriage 83B and moved in the arrow C direction together with the carriage 83B.

  As the image reading sensor 82, an image sensor in which a plurality of light receiving elements or photoelectric conversion elements are arranged on a substrate is used. As the image sensor, a CCD line sensor or the like in which a plurality of CCDs (Charge Coupled Devices) are arranged along a direction intersecting the document sheet conveyance direction may be used. Further, a solid-state imaging device such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor may be used.

  The back image reading unit 66 is disposed between the conveyance roller 58 and the conveyance roller 60 of the document conveyance unit 40. In the present embodiment, the back surface image reading unit 66 is configured as a “contact image sensor (CIS)” that reads an image in close contact with a document sheet. Accordingly, the back image reading unit 66 is disposed so as to face the back surface of the document sheet conveyed along the conveyance path 48. That is, the back side image of the original paper is read at the position where the back side image reading unit 66 is disposed. Hereinafter, this position is referred to as a “back image reading position”. The detailed configuration of the back surface image reading unit 66 will be described later.

  A reference plate 68 for acquiring reference data for shading correction is disposed at a position facing the back image reading unit 66 across the conveyance path 48. Although various data for shading correction will be described later, correction data is generated from the acquired reference data. The reference plate 68 may be a white background plate whose surface facing the back image reading unit 66 is white. Further, the reference plate 68 may include a white reference plate for acquiring white reference data for white shading correction and a black reference plate for acquiring black reference data for black shading correction. Good.

Here, the configuration of the back surface image reading unit 66 will be described.
FIG. 4 is a schematic sectional view showing an example of the configuration of the back surface image reading unit 66 shown in FIG. As shown in FIG. 4, the back image reading unit 66 includes a light source 101 that irradiates illumination light toward the back surface of the document sheet or the reference plate 68 conveyed by the document conveyance unit 40, and the back surface of the document sheet or the reference plate 68. A lens 107 that forms an image of the reflected light that has been reflected, and an image reading sensor 100 that is disposed at the imaging position of the lens 107 are provided. Each of the light source 101, the lens 107, and the image reading sensor 100 is fixed in a predetermined position in the housing 109 and housed in the housing 109.

  As the light source 101, a light source array in which a plurality of light emitting elements are arranged on a substrate is used. As the lens 107, a lens array in which a plurality of lenses are arranged is used. As the image reading sensor 100, an image sensor such as a CCD line sensor or a CMOS image sensor is used in the same manner as the image reading sensor 82 of the surface image reading unit 42. In the present embodiment, an example in which each of the light source 101, the lens 107, and the image reading sensor 100 is configured as follows will be described.

  The light source 101 is configured as an LED array in which a plurality of LEDs (Light Emitting Diodes) are arranged along a direction that intersects the document sheet conveyance direction. The lens 107 is configured as a rod lens array in which a plurality of rod lenses are arranged along a direction intersecting the document sheet conveyance direction. The image reading sensor 100 is configured as an image sensor having an R color CCD line sensor 102, a G color CCD line sensor 104, and a B color CCD line sensor 106, and sensors corresponding to RGB colors (see FIG. 5). ).

(Operation of image reader)
Next, the operation of the image reading unit 12 will be described. The image reading unit 12 is controlled by the image reading control unit 92 to perform the following double-sided reading operation.

  When the document sheet is placed on the document table 22 with the front side facing up, the document table 22 is raised by the elevating mechanism 44. When the document table 22 rises to a predetermined position and stops, the take-in roller 46 comes into contact with the uppermost surface of the bundle of document sheets placed on the document table 22, and the take-up roller 46 takes in the document sheets one by one. It is. The original sheet that has reached the supply roller 50 is supplied to the conveyance path 48 by the supply roller 50 and the conveyance of the original sheet is started. The original sheet that has reached the conveyance roller 52 is conveyed downstream in the conveyance direction by the conveyance roller 52.

  The original sheet that has reached the conveyance roller 54 is conveyed downstream in the conveyance direction by the conveyance roller 54. Further, the leading edge of the conveyed document sheet is abutted against the stopped conveyance roller 56, and the document sheet is set in a loop state curved along the conveyance path 48. When the original paper is in a loop state, the guide mechanism 62 rotates so as to open outward with the fulcrum as a center, and guides the original paper while maintaining the original paper loop state. The transport roller 56 that has been stopped starts rotating in accordance with the start timing of image reading.

  The original sheet that has reached the conveyance roller 56 is aligned (registration adjustment) by the conveyance roller 56 and conveyed downstream in the conveyance direction. Further, the document sheet is supplied by the conveyance roller 56 to the “front image reading position” where the conveyance roller 58 is disposed. At the reading position of the front image, the surface of the original paper is in a state of facing the second platen glass 70B. The original sheet that has reached the conveying roller 58 is conveyed downstream in the conveying direction while being pressed against the second platen glass 70B by the conveying roller 58. The surface image reading unit 42 reads the surface image of the document sheet being conveyed via the second platen glass 70B.

  The original paper on which the front image has been read is transported downstream in the transport direction, and is supplied to the “back image reading position” where the back image reading unit 66 is disposed. At the back side image reading position, the back side of the document sheet faces the back side image reading unit 66. The back side image reading unit 66 reads the back side image of the document sheet being conveyed. The original sheet on which the back image has been read is conveyed downstream in the conveying direction by the conveying roller 60. The document sheet that has reached the discharge roller 64 is discharged to the document discharge unit 24 by the discharge roller 64.

  Before the original paper reaches the “back image reading position”, the back image reading unit 66 reads the reference plate 68 to acquire reference data and correction data for shading correction. In the input image from the CCD line sensor of the image reading sensor 100, density level unevenness (shading) occurs due to the characteristics of the CCD line sensor and lens aberration. By performing the shading correction using the correction data, the unevenness of the density level is removed. Various signal processing including shading correction will be described later.

  When a document sheet is placed on the upper surface of the first platen glass 70A, the image on one side of the document sheet is read by the surface image reading unit 42 as follows. While moving the light source 72 and the reflection mirrors 74, 76 and 78 in the direction of arrow C, the illumination light is emitted from the light source 72 toward the document sheet. That is, one side of the original paper is scanned with illumination light. The illumination light passes through the first platen glass 70A, is irradiated on the original paper, and is reflected by the original paper. The reflected light passes through the first platen glass 70 </ b> A, and its optical path is bent by the reflecting mirrors 74, 76 and 78, and enters the lens 80. The light incident on the lens 80 is imaged on the image reading sensor 82 by the lens 80. As a result, an image on one side of the original paper is read.

<Signal Processing in Back Image Reading Unit>
Next, signal processing in the back surface image reading unit 66 will be described.
FIG. 5 is a functional block diagram showing an example of a functional configuration of the back surface image reading unit 66 shown in FIG. As shown in FIG. 5, the back surface image reading unit 66 includes a light source 101, an image reading sensor 100, and a signal processing unit 110 that performs various signal processing on an image signal acquired by the image reading sensor 100. The light source 101 includes a light source array 103 such as an LED array, and a drive circuit 105 that drives the light source array 103. The drive circuit 105 is connected to the image reading control unit 92 and drives the light source array 103 to turn on based on a control signal from the image reading control unit 92.

  The image reading sensor 100 includes a drive circuit 108 for driving an R color CCD line sensor 102, a G color CCD line sensor 104, a B color CCD line sensor 106, and RGB color CCD line sensors. The drive circuit 108 is connected to the image reading control unit 92 and drives the CCD line sensors for each color of RGB based on a control signal from the image reading control unit 92. The RGB line CCD line sensors are driven so that image signals are output periodically.

  The signal processing unit 110 includes a sample and hold circuit 112, an output amplifier circuit 114, an A / D conversion circuit 116, and a shading correction circuit 118. Each of the sample hold circuit 112, the output amplifier circuit 114, the A / D conversion circuit 116, and the shading correction circuit 118 is connected to the image reading control unit 92 and operates based on a control signal from the image reading control unit 92. To do. The configuration of the signal processing unit 110 described above is an example, and is not limited to this configuration. Circuits may be added or deleted as necessary.

  An image signal for one line of each RGB color is input to the signal processing unit 110 from each of the CCD line sensors 102, 104, and 106 corresponding to each RGB color. The input RGB image signals are sampled by the sample and hold circuit 112, amplified to an appropriate level by the output amplifier circuit 114, and converted from an analog signal to a digital signal by the A / D conversion circuit 116.

  The RGB color image signals converted into digital signals are input to an average value calculation circuit 118 for shading correction, subjected to shading correction by the image reading control unit 92, and the corrected image signal is again input to the average value calculation circuit 118. After being processed, it is output to a subsequent processing unit (not shown) that performs color conversion processing from RGB to YMCK. The RGB color image signals converted into digital signals are image information representing pixel values for one line.

<Average value calculation circuit for shading correction>
Next, the average value calculation circuit 118 for shading correction will be described.

(Various data for shading correction)
First, various data used for shading correction will be described.
The image information when the reference plate 68 is read is referred to as “reference data”, and the image information for shading correction generated from the “reference data” is referred to as “correction data”. In addition, image information when the back side of the document sheet is read is referred to as “document data”, and image information obtained by correcting the “document data” with “correction data” is referred to as “corrected data”.

  The shading correction includes black shading correction for correcting document data based on “black correction data” and white shading correction for correcting document data based on “white correction data”. When the back image is read by the back image reading unit 66, “dirt detection processing” or the like for detecting dirt due to paper dust or the like adhering to the reference plate 68 may be performed. Prior to these white shading correction and dirt detection processing, “black corrected data” subjected to black shading correction is required.

  For example, when performing black shading correction, with the light source 101 of the back surface image reading unit 66 turned off, the reference plate 68 is read to acquire “black reference data”, and from the acquired “black reference data” to “ Black correction data "is generated. Next, with the light source 101 of the back side image reading unit 66 turned on, the back side image of the original paper is read to acquire “original data”, and the acquired “original data” is corrected with “black correction data”. Get “black corrected data”.

(Configuration and operation of average value calculation circuit)
Next, the configuration and operation of the average value calculation circuit 118 will be described.
FIG. 6 is a functional block showing an example of a functional configuration of the average value calculation circuit 118 shown in FIG. In the present embodiment, the average value calculation circuit 118 performs “correction data acquisition processing” for acquiring correction data using reference data as input data, and corrected data averaged using document data and corrected data as input data. The “corrected data acquisition process” to be acquired is selectively executed according to the type of input data.

  As illustrated in FIG. 6, the average value calculation circuit 118 includes a selection unit 120, a cumulative addition RAM 122, a division circuit 124, a selection unit 126, and a color-specific storage RAM 128. The color storage RAM 128 is provided with an R color area, a G color area, and a B color area. Each of the selection unit 120, the cumulative addition RAM 122, the division circuit 124, the selection unit 126, and the color-specific storage RAM 128 (R color region, G color region, and B color region) is connected to the image reading control unit 92. It operates based on a control signal from the reading control unit 92.

  Image data for one line of each color of RGB is input to the average value calculation circuit 118. As described above, the types of input data include reference data, document data, and corrected data. The selection unit 120 selects image information to be cumulatively added based on the control signal from the image reading control unit 92, and outputs the selected image information to the cumulative addition RAM 122. For example, image information to be cumulatively added, such as R color reference data, is specified by color and data type.

  Here, the reference data and the corrected data are subject to cumulative addition, but the document data is not subject to cumulative addition. The input document data is output to the image reading control unit 92 without being selected by the selection unit 120, and shading correction is performed.

  The cumulative addition RAM 122 cumulatively adds image information for a plurality of lines based on a control signal from the image reading control unit 92, and outputs the cumulatively added image information to the division circuit 124. The division circuit 124 calculates an average value by dividing the cumulatively added image information by the number of lines based on a control signal from the image reading control unit 92, and outputs the average value of the image information to the selection unit 126.

  Based on the control signal from the image reading control unit 92, the selection unit 126 selects an area of the color-specific storage RAM 128 that stores the average value of the image information according to the color of the image information for which the average value has been calculated. The average value of the image information is stored in the selected area of the color-specific storage RAM 128. For example, when the average value of the R color reference data is calculated, the R color area of the color-specific storage RAM 128 is selected, and the calculated average value is written to the R color area of the color-specific storage RAM 128.

  Each of the R color area, the G color area, and the B color area of the color-specific storage RAM 128 outputs an average value of stored image information based on a control signal from the image reading control unit 92. For example, the average value of the reference data for each color is output to the image reading control unit 92 as “correction data”. The average value of the corrected data for each color is output to the subsequent processing unit as “averaged corrected data”.

  For example, only the black shading correction may be performed using the average value calculation circuit 118. In this case, the “averaged black corrected data” may be output to a subsequent processing unit that performs white shading correction.

  In the present embodiment, the “correction data acquisition process” and the “corrected data acquisition process” are executed using the average value calculation circuit 118. Hereinafter, it will be described in more detail that these processes are performed using a common circuit.

(Correction data acquisition process)
Next, the “correction data acquisition process” executed by the image reading control unit 92 will be described.
FIG. 7 is a flowchart showing an example of the flow of “correction data acquisition processing”. The “correction data acquisition process” is started when the back surface image reading unit 66 reads the reference plate 68 and acquires “reference data”.

  As shown in FIG. 7, in step 100, the selection unit 120 is instructed to select “reference data” of any one of RGB as a target of cumulative addition. The selection unit 120 selects reference data for any one of RGB based on the control signal, and outputs the reference data for the selected color to the cumulative addition RAM 122.

  Next, in step 102, the cumulative addition RAM 122 is instructed to cumulatively add the reference data of the selected color. The cumulative addition RAM 122 cumulatively adds the reference data of the selected color based on the control signal, and outputs the cumulatively added reference data to the division circuit 124.

  Next, in step 104, the division circuit 124 is instructed to divide the accumulated reference data by the number of lines. The division circuit 124 divides the cumulatively added reference data by the number of lines based on the control signal, and outputs the calculated average value of the reference data to the selection unit 126. The average value of the reference data calculated here corresponds to “correction data” for shading correction.

  Next, in step 106, the selection unit 126 is instructed to select an area of the color-specific storage RAM 128 that stores correction data. The selection unit 126 selects an area corresponding to the color selected by the selection unit 120 based on the control signal.

  Next, in step 108, the correction data is written in the selected area of the color-specific storage RAM 128. In the next step 110, it is determined whether correction data has been acquired for the three colors RGB. If the determination in step 110 is affirmative, the correction data acquisition process ends.

  On the other hand, in the case of negative determination in step 110, the process returns to step 100, and the processing from step 100 to step 110 is repeated for the “reference data” of the color for which no correction data has been acquired. As a result, correction data for the three RGB colors is acquired and stored in the area corresponding to each color in the color-specific storage RAM 128.

(Corrected data acquisition process)
Next, the “corrected data acquisition process” executed by the image reading control unit 92 will be described. FIG. 8 is a flowchart showing an example of the flow of “corrected data acquisition processing”. The “corrected data acquisition process” is started when the back side image reading unit 66 reads the back side image of the original paper and acquires “original data”. As described above, “original data” is input to the image reading control unit 92 without being selected by the selection unit 120. Further, the “corrected data acquisition process” is executed following the above “correction data acquisition process”.

  As shown in FIG. 8, in step 200, shading correction is performed. Specifically, it instructs each area of the color storage RAM 128 to output the correction data to the image reading control unit 92. A predetermined calculation is performed using the acquired correction data, and shading correction of the document data is executed. The calculation procedure is set according to the shading correction method.

  For example, in the case of black shading correction, the black correction data is subtracted from the original data. In the case of white shading correction, original data that has already been subjected to black shading correction (that is, black-corrected data) is subjected to normalization processing by multiplication and then subjected to calculations such as division by white correction data. . The corrected data is output to the selection unit 120.

  Next, in step 202, the selection unit 120 is instructed to select “corrected data” of any one of RGB as a target of cumulative addition. The selection unit 120 selects corrected data of any one color of RGB based on the control signal, and outputs the corrected data of the selected color to the cumulative addition RAM 122.

  Next, in step 204, the cumulative addition RAM 122 is instructed to cumulatively add the corrected data of the selected color. The cumulative addition RAM 122 cumulatively adds the corrected data of the selected color based on the control signal, and outputs the corrected data that has been cumulatively added to the division circuit 124.

  Next, in step 206, the division circuit 124 is instructed to divide the corrected corrected data by the number of lines. The division circuit 124 divides the accumulated corrected data by the number of lines based on the control signal, and outputs the calculated average value of the corrected data to the selection unit 126. The average value of the corrected data calculated here corresponds to “averaged corrected data”.

  Next, in step 208, the selection unit 126 is instructed to select an area of the color-specific storage RAM 128 that stores the averaged corrected data. The selection unit 126 selects an area corresponding to the color selected by the selection unit 120 based on the control signal.

  Next, in step 210, the averaged corrected data is written into the selected area of the color-specific storage RAM 128. In each area of the color storage RAM 128, “correction data” acquired in “correction data acquisition processing” is stored in advance. In step 210, the averaged corrected data is overwritten on the same area, and “correction data” is rewritten to “averaged corrected data”. In the next step 212, it is determined whether or not “averaged corrected data” has been acquired for the three RGB colors. If the determination in step 212 is affirmative, the corrected data acquisition process ends.

  On the other hand, in the case of negative determination in step 212, the process returns to step 200, and the processing from step 200 to step 212 is repeated for the “corrected data” of the color for which averaged corrected data has not been acquired. As a result, “averaged corrected data” for the three colors of RGB is acquired and stored in an area corresponding to each color in the color-specific storage RAM 128.

  As described above, in the present embodiment, the “correction data acquisition process” and the “corrected data acquisition process” are executed using the average value calculation circuit 118. By executing these processes using a common circuit, a storage area (RAM area) is provided as compared with the case where the cumulative addition RAM 122 is provided for each color of RGB and the cumulative addition RAM 122 and the color-specific storage RAM 128 are provided for each process. Significantly reduced.

  Further, by setting the average value of the reference data as “correction data” and the average value of the corrected data as “averaged corrected data”, the data capacity is reduced, so that the RAM area is further reduced. .

  Here, the reduction amount of the RAM area is specifically calculated. In the conventional method, it is necessary to provide a cumulative addition RAM for each color of RGB. Further, it is necessary to provide a cumulative addition RAM and a color-specific storage RAM for each process. On the other hand, in the present embodiment, the cumulative addition RAM is common to the RGB colors. Also, the cumulative addition RAM and the color-specific storage RAM are common to the respective processes.

  The number of bits of image information is “x”, the number of bits of cumulative addition is “y”, and the number of pixels for one line is “L”. By making the cumulative addition RAM common to each color of RGB, the RAM area is reduced. The amount of RAM area reduction at this time is the difference “A” between the number of bits required in the conventional method and the number of bits required in the present embodiment, and the difference “A” is expressed by the following equation.

  A = 3L (x + y) -L [3x + (x + y)]

  That is, in the conventional method, the number of bits of “3Ly” is required for the cumulative addition RAM, and the number of bits of “3Lx” is required for the color-specific storage RAM. Therefore, the total number of bits “3L (x + y)” is required. On the other hand, in this embodiment, the cumulative addition RAM requires the number of bits “Ly + Lx”, and the color-specific storage RAM requires the number of bits “3Lx”. Therefore, the total number of bits “L [3x + (x + y)]” is sufficient. Therefore, the RAM area is reduced by the difference “A”.

  Further, by making the cumulative addition RAM and the color-specific storage RAM common to the respective processes, the number of bits of “3L (x + y)” is further reduced in addition to the difference “A”.

  For example, if the bit number “x” of the image information is 8 bits, the cumulative addition bit number “y” is 6 bits, and the number of pixels “L” for one line is 8192, the difference “A” is 32768 bits. Further, 344064 bits are reduced, resulting in a reduction of 376832 bits.

In the above-described embodiment, an example in which an average value arithmetic circuit for shading correction is provided in the back surface image reading unit of the double-sided reading device has been described, but any other device that performs shading correction on a read image may be used. You may use the circuit of the said structure as an average value calculating circuit with respect to an apparatus. For example, it may be an average value calculation circuit of a surface image reading unit of a double-sided reading device, or an average value calculation circuit of a single-sided reading device. Further, the image reading apparatus is not limited to the image reading apparatus, and may be an average value calculation circuit in shading correction of an imaging apparatus such as a camera.
Further, the configuration described in each of the above embodiments is an example, and it goes without saying that the configuration may be changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image reading part 14 Image forming part 16 Paper supply part 18 Operation panel 22 Original board 24 Original discharge part 26A, 26B Guide 30 Sensor 32 Paper discharge part 34 Touch panel 36 Various buttons 40 Original conveyance part 42 Surface image reading part 44 Elevating mechanism 46 Take-in roller 48 Conveying path 50 Supply rollers 52, 54, 56, 58, 60 Conveying roller 62 Guide mechanism 64 Discharge roller 66 Back surface image reading unit 68 Reference plate 70 A Platen glass 70 B Platen glass 72 78 Reflecting mirror 80 Lens 81 Main controller 82 Image reading sensors 83A and 83B Carriage 92 Image reading control unit 94 Image formation control unit 96 External interface 98 Bus 100 Image reading sensor 101 Light source 110 Signal processing unit 112 Sample hold circuit 114 Output Amplifier circuit 116 Conversion circuit 118 Average value calculation circuit 120 Selection unit 122 Cumulative addition RAM
124 Dividing circuit 126 Selection unit 128 Color-specific storage RAM

Claims (6)

An acquisition unit for acquiring a plurality of pieces of image information of different colors and types;
An information selection unit that selects image information of a specific color and type from a plurality of pieces of image information acquired by the acquisition unit;
A cumulative storage unit for accumulating and storing the image information selected by the information selection unit;
An average value acquisition unit for acquiring an average value of image information cumulatively added in the cumulative storage unit;
A storage unit for each color that stores an average value of the image information acquired by the average value acquisition unit for each color;
According to the type of image information acquired by the acquisition unit, the information selection unit, the accumulation so that correction information or corrected image information is stored while performing calculation so that shading correction of the target image is performed A storage unit, an arithmetic control unit that controls each of the average value acquisition unit and the color storage unit ,
The arithmetic control unit is
When the target information to be corrected is acquired by the acquisition unit, a calculation for correcting the target information is performed using the correction information stored in the color-specific storage unit and corrected by the information selection unit. The information selection unit, the cumulative storage unit, the average value acquisition unit, and the image information are selected and the average value of the image information acquired by the average value acquisition unit is stored as corrected image information. An image correction apparatus that performs second control for controlling each of the color storage units. The arithmetic control unit is
When the reference information for generating correction information is acquired by the acquisition unit, the reference information is selected by the information selection unit, and the average value of the image information acquired by the average value acquisition unit is correction information. As a first control to control each of the information selection unit, the cumulative storage unit, the average value acquisition unit and the color storage unit,
The image correction apparatus according to claim 1. Before SL region of the Color storage unit in which the correction information in the first control is stored and overwrites and stores the corrected image information acquired by the second control, the image correction apparatus according to claim 2 . An image correction apparatus according to any one of claims 1 to 3 ,
An image reading unit that optically reads an image from an object and outputs a plurality of pieces of image information of different colors and types to the image correction device;
An image reading apparatus comprising: An image correction apparatus according to any one of claims 1 to 3 ,
An image reading unit that optically reads an image from an object and outputs a plurality of pieces of image information of different colors and types to the image correction device;
An image forming unit that forms an image on a medium based on the corrected image information subjected to shading correction by the image correction device;
An image forming apparatus. An acquisition unit that acquires a plurality of pieces of image information of different colors and types, an information selection unit that selects image information of a specific color and type from a plurality of pieces of image information acquired by the acquisition unit, and the information selection Acquired by the cumulative storage unit that accumulates and stores the image information selected by the unit, the average value acquisition unit that acquires the average value of the image information cumulatively added by the cumulative storage unit, and the average value acquisition unit. A program for controlling an image correction apparatus comprising a storage unit for each color that stores an average value of the image information for each color,
Computer
According to the type of image information acquired by the acquisition unit, the information selection unit, the accumulation so that correction information or corrected image information is stored while performing calculation so that shading correction of the target image is performed Function as an arithmetic control unit for controlling each of the storage unit, the average value acquisition unit and the color-specific storage unit ,
When the acquisition control unit acquires target information to be corrected by the acquisition unit, the calculation control unit performs a calculation to correct the target information using correction information stored in the color-specific storage unit, and the information The information selection unit, the cumulative storage unit, the image information corrected by the selection unit, and the average value of the image information acquired by the average value acquisition unit is stored as corrected image information. A program for further performing a second control for controlling each of the average value acquisition unit and the color storage unit .