JP5703724B2 - Image reading apparatus, image reading method and program thereof - Google Patents

Description

  The present invention relates to an image reading apparatus, an image reading method, and a program thereof.

  Conventionally, as an image reading apparatus, a difference between an output level when reading and scanning an all black image and an output level when reading and scanning at zero incident light is stored in advance, and an output when reading and scanning at zero incident light is stored. A technique has been proposed in which the level is stored, the stored values are added, and this is calculated by an operational amplifier with respect to the image signal output of the image sensor, thereby removing black level floating (for example, Patent Documents). 1). This apparatus is capable of correcting the black level float that changes with time without scanning an all-black document every time the document is read by the image sensor.

JP-A-8-98017

  By the way, in the above-described apparatus or the like, there is a case where an original is placed and read, or an original is conveyed and read by an automatic document feeder (auto document feeder: ADF). The reading state of the image sensor differs depending on the method of reading the original, for example, a transparent sheet that restricts the moving direction of the original to the conveying path is provided between the automatic conveying device and the reading area. Sometimes.

  The present invention has been made in view of the above problems, and facilitates the conveyance of the original, and there is a difference between the image read by placing the original and the image read by automatically conveying the original. It is a main object of the present invention to provide an image reading apparatus, an image reading method, and a program thereof that can further suppress the occurrence.

  The present invention adopts the following means in order to achieve the main object described above.

The image reading apparatus of the present invention includes:
A reading means for reading the document, comprising: a light emitting unit for irradiating light on the document; and a light receiving unit having a light receiving element for receiving the reflected light reflected by the document.
Automatic conveying means for conveying a document along a conveyance path to a conveyance reading area readable by the reading means;
A placement unit that has a placement reading area that can be read by the reading unit and places the document;
A transparent sheet that is provided in the conveyance and reading region so that the light emitted from the light-emitting unit is transmitted and reaches the original, and is roughened to regulate the moving direction of the original;
For the read data obtained by reading the document placed on the placement unit with the reading unit, the first black reference data and the white reference data are used to perform a placement shading correction process, Shading correction during conveyance using second black reference data and white reference data different from the first black reference data for the read data obtained by reading the original conveyed by the automatic conveyance unit by the reading unit Shading correction means for executing processing;
It is equipped with.

  In this image reading apparatus, a transparent sheet that is roughened and regulates the moving direction of the document is provided in the transport reading area. Further, for the read data obtained by reading the document placed on the placement unit, the first black reference data and the white reference data are used to execute the placement shading correction process, while the automatically fed document The reading shading correction process is performed on the read data using the second black reference data and the white reference data different from the first black reference data. As described above, since the transparent sheet for restricting the moving direction of the document is provided, the document can be conveyed smoothly. In addition, when a transparent sheet is present, the light reflected from both sides of the gap between the transparent sheets may interfere to generate a concentric ring (Newton ring) in the read image, but the transparent sheet is roughened. Therefore, the occurrence of this Newton ring can be prevented. Furthermore, when a roughened transparent sheet is used, a black floating state in which the black region becomes more white due to scattered light may occur, but when reading data is obtained via the roughened transparent sheet. Since the shading correction process during conveyance is executed using the second black reference data different from the reading by the placement unit, it is possible to correct this black floating state. Therefore, it is possible to further suppress the occurrence of a difference between the image read by placing the original and the image read by automatically conveying the original. Here, the second black reference data may be such that the read data shifts to the black side with respect to the first black reference data. The second black reference data is determined so that, for example, the relationship between the read data read in the placement reading area and the read data read in the transport reading area is obtained empirically and these read data are more approximate. It may be a thing.

  In the image reading apparatus according to the aspect of the invention, the shading correction unit uses the second black reference data obtained by shifting the first black reference data to the white reference data side when executing the conveyance shading correction process. It is good. In this way, the difference between the black reference data and the read data becomes smaller, that is, the read data is shifted to the dark color side, so that it is possible to relatively easily correct the black floating state caused by the roughened transparent sheet. it can. The “dark color side” may be a side having lower brightness and saturation, for example, a black side.

  In the image reading apparatus of the present invention, when the shading correction unit executes the above-described placement shading correction process, the difference value between the read data and the first black reference data is calculated as the white reference data and the white reference data. While the value divided by the difference value with the first black reference data is used, when the shading correction process during conveyance is executed, the difference value between the read data and the second black reference data is set as the white reference data. A value obtained by dividing the difference between the data and the second black reference data may be used. By so doing, it is possible to relatively easily correct the black floating state generated by the roughened transparent sheet using the second black reference data.

  In the image reading apparatus of the present invention, when the shading correction unit performs the shading correction process during conveyance, the shading correction unit has a bright area of read data obtained by reading the original with the reading unit and a range darker than the bright area. The second black reference data that has a larger correction amount in the dark area than in the bright area may be used in a certain dark area. Since the black floating state becomes prominent in the dark range of the image, this makes it possible to correct the black floating state more effectively. Here, the “correction amount” may be, for example, a difference value between the read data value before correction and the output data value after correction. The “dark part range” may be, for example, a range in which the black floating state becomes noticeable visually. At this time, when executing the shading correction process during conveyance, the shading correction unit is larger in a dark portion range of read data obtained by reading the original conveyed by the automatic conveyance unit by the reading unit as it becomes darker. The second black reference data serving as a correction amount may be used. Since the black floating state becomes more prominent near black, this makes it possible to more effectively correct the black floating state.

  The image reading apparatus of the present invention controls the reading unit so as to read the document placed in the placement reading area of the placement unit at the time of placement reading, and the automatic conveyance to convey the document at the time of conveyance reading. Control means for controlling the reading means so as to read the transported document in the transport reading area may be provided.

The image reading method of the present invention includes:
A reading unit that includes a light emitting unit that irradiates light on a document and a light receiving unit that receives light reflected from the document, and a reading unit that reads the document, and a conveyance reading region that can be read by the reading unit An automatic conveyance unit that conveys the original along the conveyance path, a placement reading area that can be read by the reading unit, a placement unit that places the document, and the light emitted from the light emitting unit is transmitted. An image reading method using an image reading apparatus provided with a transparent sheet that is provided in the conveyance reading area so as to reach the original and that regulates the moving direction of the original.
(A) A placement shading correction process is executed using the first black reference data and the white reference data on the read data obtained by reading the original placed on the placement unit by the reading unit. Steps,
(B) The second black reference data and the white reference data different from the first black reference data are used for the read data obtained by reading the original conveyed by the automatic conveyance unit by the reading unit. Execute shading correction processing during conveyance,
Steps,
Is included.

  In this image reading method, as with the image reading apparatus described above, for example, since the transparent sheet that regulates the moving direction of the document is provided, the document can be smoothly conveyed. Moreover, since the transparent sheet is roughened, Newton's rings can be prevented from occurring. Further, when reading data is obtained through the roughened transparent sheet, since the shading correction process at the time of conveyance is executed using the second black reference data that is different from reading by the loading unit, the black floating state Can be corrected. Therefore, it is possible to further suppress the occurrence of a difference between the image read by placing the original and the image read by automatically conveying the original. In this image reading method, various aspects of the above-described image reading apparatus may be adopted, and steps for realizing each function of the above-described image reading apparatus may be added.

  The program of the present invention is for causing one or more computers to realize each step of the above-described image reading method. This program may be recorded on a computer-readable recording medium (for example, hard disk, ROM, FD, CD, DVD, etc.) or from a computer via a transmission medium (communication network such as the Internet or LAN). It may be distributed to another computer, or may be exchanged in any other form. If this program is executed by a single computer or if each step is shared and executed by a plurality of computers, each step of the above-described image reading method is executed, so that the same effect as the control method can be obtained. It is done.

FIG. 2 is a configuration diagram illustrating an outline of a configuration of a multifunction printer 20. FIG. 2 is a configuration diagram showing an outline of the configuration of a scanner unit 40. Explanatory drawing which shows an example of the step chart 30. FIG. The flowchart which shows an example of a black floating ratio setting process routine. Explanatory drawing of the correspondence of the reading result of FB reading mode and ADF reading mode. 6 is a flowchart illustrating an example of an image reading processing routine. The conceptual diagram of an example of the shading correction process at the time of conveyance. Explanatory drawing of the setting of other black float correction. 7 is a flowchart illustrating an example of another image reading processing routine. Explanatory drawing of the other approximation method of FB reading mode and ADF reading mode.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of the configuration of a multifunction printer 20 according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing an outline of the configuration of a scanner unit 40.

  The multi-function printer 20 according to the present embodiment includes a housing 21 and a housing cover 22 that can open and close the upper surface of the housing 21, and a scanner unit 40 that optically reads a document and generates image data. A printer unit 42 that feeds, prints, and discharges paper set in the cassette 23 to the paper discharge tray 24, an operation panel 46 that allows various operations by the user, and a main unit that controls the entire apparatus. And a controller 80. A flat bed portion 31 having a glass table 32 as a placement reading area for placing and reading a document is arranged on the upper surface of the housing 21 (see FIG. 2). An original can be optically read by the scanner unit 40 (hereinafter, this operation mode is referred to as a flat bed (FB) reading mode). The housing cover 22 incorporates an auto document feeder unit 61 (hereinafter referred to as an ADF unit) (see FIG. 2), and is guided by a document guide 29 and set in the ADF insertion slot 26. Can be optically read by the scanner unit 40 while being automatically and continuously conveyed (hereinafter, this operation mode is referred to as an ADF reading mode).

The scanner unit 40 includes a scanner ASIC 50 and a scanner engine 60. The scanner ASIC 50 is an integrated circuit that controls the scanner engine 60. Upon receiving a scan command from the main controller 80, the scanner ASIC 50 reads the document as image data in either the FB reading mode or the ADF reading mode. To control. In addition, ASIC is Application Specific.
Abbreviation for Integrated Circuit.

As shown in FIG. 2, the scanner engine 60 places a document set on the ADF insertion port 26 and a flat bed portion 31 having a glass table 32 as a placement reading area where a document can be placed and read. An ADF unit 61 that automatically conveys to the ADF reading area 34, and a CIS module 76 that reciprocates by driving a belt 79 spanned between a carriage motor 78a and a driven roller 78b by the carriage motor 78a. The ADF unit 61 is configured as an automatic conveyance device that conveys the document S along the conveyance path 62 to the ADF reading area 34 that can be read by the CIS module 76. The ADF unit 61 includes a pickup roller 63 disposed in the vicinity of the ADF insertion port 26, a plurality of transport rollers 64 disposed in the transport path 62, and a discharge roller 65 disposed in the vicinity of the ADF discharge tray 28. The rollers 63, 64, 65 are driven to rotate by the conveyance motor 66, whereby the documents set in the ADF insertion port 26 are taken one by one and automatically conveyed onto the conveyance path 62. The CIS module 76 includes a light source unit 71 that irradiates light to the glass table 32 or the ADF reading area 34, and a CIS 74 that reads reflected light from the original and stores it as electric charges to read the original. The light source unit 71 includes light sources of three colors, a red LED 72R that turns on red light, a green LED 72G that turns on green light, and a blue LED 72B that turns on blue light. And irradiating the glass table 32 or the ADF reading area 34 (see FIG. 1). The ADF reading area 34 is formed of a transparent material (for example, a film) so that light emitted from the light source unit 71 is transmitted and reaches the original, and a transparent sheet that restricts the moving direction of the original S to the conveyance path 62. 35 is provided. As shown in FIG. 2, the transparent sheet 35 is subjected to a rough surface process (non-glare process, anti-glare process) that makes the surface uneven and scatters light. In general, when an image is read through a transparent sheet, the light reflected from both sides of the gap between the transparent sheets may interfere to generate a concentric ring (Newton ring) in the read image. By roughening the surface, this Newton ring can be prevented from occurring. The CIS 74 is configured such that a plurality of light receiving elements (for example, CMOS image sensors) 75 for one line are arranged in the main scanning direction, and the reflected light is changed to one color while sequentially turning on the LEDs 72R, 72G, and 72B of the respective colors. Color image data is generated by reading each one.

  The scanner ASIC 50 includes a reading processing unit 51 including a control unit 52 that controls each device and a shading correction processing unit 53 that performs shading correction on the read data. Although the shading correction process will be described in detail later, the black reference data K and the white reference data W are used, and each pixel is caused by variations in light emission of the light source unit 71 and sensitivity characteristics of the light receiving elements 75 in each element. Is a process of removing density unevenness (shading correction) occurring in the image. A white reference plate 36 is provided at the end of the glass table 32 in the sub-scanning direction. The black reference data K is an output voltage obtained by the light receiving element 75 when scanning is performed with all the light sources turned off with the CIS module 76 and the white reference plate 36 facing each other. The white reference data W is an output voltage obtained by the light receiving element 75 when scanning is performed with the LEDs 72R, 72G, and 72B of each color turned on with the CIS module 76 and the white reference plate 36 facing each other. The scanner ASIC 50 includes an LED driving unit 54 that individually turns on and off the LEDs 72R, 72G, and 72B, an A / D conversion unit 56 that inputs an analog signal generated by the CIS 74 via an amplifier (not shown), and converts the analog signal into a digital signal. A motor driving unit 58 that receives a control signal from the reading processing unit 51 and drives the carriage motor 78a and the conveyance motor 66a.

  As shown in FIG. 1, the printer unit 42 includes a printer ASIC 44 and a printer engine 45. The printer ASIC 44 is an integrated circuit that controls the printer engine 45. Upon receiving a print command from the main controller 80, the printer ASIC 44 controls the printer engine 45 to print an image on recording paper based on an image file that is a target of the print command. . The printer engine 45 is configured as a well-known inkjet color printer mechanism that performs printing by ejecting ink from a print head onto paper. Since the printer unit 42 does not form the gist of the present invention, detailed description thereof is omitted.

  The operation panel 46 includes a display unit 47 disposed in the center and a power button 48 disposed on the left side of the display unit 47. The display unit 47 is configured as a touch panel type liquid crystal display, a mode button for selecting a mode, a selection / setting button for selecting a menu or an item by touching according to a guide displayed on the display, copying or printing Display a start button or the like to start the touch and accept a touch operation. Here, as modes that can be selected by the mode selection button, printing is performed using a copy mode in which an original placed on the glass table 32 is scanned and copied, or an image stored in the memory card MC of the memory card slot 49. There are a memory card mode in which a document is scanned and converted into data and stored in the memory card MC, and a film mode in which a photographic film is scanned and printed or data is stored in the memory card MC.

The main controller 80 is configured as a microprocessor centered on the CPU 82, and includes a ROM 84 that stores various processing programs, various data, various tables, a RAM 86 that temporarily stores scan data and print data, and an operation panel. And an internal communication interface (I / F) 87 that communicates with 46. The main controller 80 inputs various operation signals and various detection signals from the printer unit 42 and the scanner unit 40, and inputs operation signals generated in response to a touch operation on the operation panel 46. In addition, an image file is read from the memory card MC installed in the memory card slot 49, a command is output to the printer unit 42 to execute printing of image data, and a document is read based on a scan command from the operation panel 46. A command is output to the scanner unit 40 to read as image data, or a control command for the display unit 47 is output to the operation panel 46.

  Next, the operation of the multi-function printer 20 of the present embodiment configured as described above, first, the process of adjusting the image difference between the FB reading mode and the ADF reading mode will be described. In the multi-function printer 20, in the ADF reading mode, black floating occurs due to the transparent sheet 35 disposed in the ADF reading area 34, so adjustment with the FB reading mode is performed. In this process, the scanner unit 40 is used, a predetermined chart is read in the FB reading mode and the ADF reading mode, and a process for obtaining the correspondence relationship of the output data is performed. Here, it is assumed that the scanner unit 40 performs a process of reading an achromatic stepwise density chart. FIG. 3 is an explanatory diagram showing an example of the step chart 30. In this process, the step chart 30 is placed at a predetermined position on the glass table 32 as output data in the read FB read mode, and is placed at a predetermined position in the ADF read area 34 to read the output data in the read ADF read mode. To do. FIG. 4 is a flowchart showing an example of the black float ratio setting processing routine. This routine is, for example, a routine executed in the manufacturing process of the multifunction printer 20, and is stored in the HDD of a management personal computer (PC) (not shown). The multifunction printer 20 is connected to the management PC, and a step chart 30 is displayed. It is executed after being placed on the glass table 32 and the ADF reading area 34.

  When this routine is executed, the CPU provided in the controller of the management PC executes the reading process of the step chart 30 placed on the glass table 32 in the FB reading mode (step S100). Here, processing for storing the read position (representing the density of the chart) and the read data (output voltage) in association with each other in the storage device (HDD) is performed. Next, it is determined whether or not the reading process in the FB reading mode is finished (step S110). When the reading process is not finished, the reading process is continued. When the reading process is finished, ADF reading is performed in the ADF reading mode. The reading treatment of the step chart 30 placed in the area 34 is executed (step S120). Also here, the process of storing the read position (representing the density of the chart) and the read data (output voltage) in association with each other is performed. Subsequently, it is determined whether or not the reading process in the ADF reading mode is completed (step S130). If the reading process is not completed, the reading process is continued. On the other hand, when the reading process is completed, the relationship between the reading data in the FB reading mode and the reading data in the ADF reading mode is obtained (step S140), and the black floating ratio E is calculated and stored in the HDD (step S150). This routine is terminated. In step S140, the read data in the ADF read mode is plotted with respect to the read data in the FB read mode, and a linear approximation expression (straight line) is obtained as a relationship between them. FIG. 5 is an explanatory diagram illustrating an example of a correspondence relationship between read data in the FB read mode and read data in the ADF read mode. In step S150, the reading data in the FB reading mode is set as the X axis, the reading data in the ADF reading mode is set as the Y axis, the intercept b is obtained using a linear approximation formula of Y = aX + b, and the black floating ratio E is calculated. The average value of RGB values was obtained from the equation E = b / 255 × 100 (%). The black floating ratio E is used when reading the document S in the ADF reading mode, and will be described in detail later. In this way, the model-specific black floating ratio E as information on the difference between the read data in the FB reading mode and the ADF reading mode is obtained, and the obtained black floating ratio E is stored in the reading processing unit 51 in advance. . The black float ratio setting process routine is automatically executed by the CPU of the management PC. However, the present invention is not particularly limited to this, and the operator may manually execute the same work.

Next, an operation when scanning a document with the scanner unit 40 will be described. FIG.
5 is a flowchart showing an example of an image reading processing routine executed by the main controller 80. In this process, for example, the copy mode or the memory card mode is selected by the mode selection button, and the scanning condition is set by the user when the original is set in the ADF insertion slot 26 or the original is set on the glass table 32. This is executed when the confirmation operation is performed. In this image reading processing routine, the main controller 80 performs reading processing using the control unit 52 of the reading processing unit 51, the shading correction processing unit 53, and the like.

  When the original reading processing routine is executed, the CPU 82 outputs a command to the scanner ASIC 50 to execute processing for detecting the white reference data W and the black reference data K used for shading correction (step S200). Here, in the detection of the white reference data W, the carriage motor 78a is driven and controlled to move to a position where the carriage 76 and the white reference plate 36 face each other, and all the color LEDs 72R, 72G, 72B of the light source unit 71 are turned on. The white reference plate 36 is scanned, and the output voltage obtained by each light receiving element 75 is stored for the number of pixels in the main scanning direction. Further, in the detection of the black reference data K, the white reference plate 36 is scanned at the position where the carriage 76 and the white reference plate 36 face each other with all the color LEDs 72R, 72G, 72B of the light source unit 71 turned off. The output voltage obtained in 75 is stored for the number of pixels in the main scanning direction. Here, in this embodiment, each reference data is set as an average value of data obtained by repeating scanning a predetermined number of times to obtain a predetermined number of times.

  When the white reference data W and the black reference data K are thus detected, it is determined based on the reading condition set by the user whether the document reading method is the FB reading mode or the ADF reading mode (step S210). ). When in the FB reading mode, a shading correction formula and correction coefficient Cf for a flat bed are set (step S220). Here, for example, the reading data on the flat bed is Df, the black reference data is K, the white reference data is W, the flatbed correction coefficient for matching the output result between the original and the output image is Cf, and the flatbed is corrected. When the output data is Df ′, the shading correction formula shown in the following formula (1) is used. That is, when executing the mounting shading correction processing in the FB reading mode, the difference value between the read data Df and the black reference data K is divided by the difference value between the white reference data W and the black reference data K. Values were used. The flatbed correction coefficient Cf is a coefficient for matching the output results of the original and the output image, and can be obtained empirically.

  Df ′ = Cf × (Df−K) / (W−K) (1)

Next, it is determined whether or not the start of reading has been instructed by the user based on whether or not a start button (not shown) displayed on the operation panel 46 has been pressed (step S230). Wait as it is. On the other hand, when the start of reading is instructed, the CIS module 76 serving as a reading sensor is scanned, and the CIS module 76 is controlled so as to read a document placed on the glass table 32 (placement reading area). Is executed (step S240). In the image reading process, each color LED 72R, 72G, 72B is turned on to emit light to the original, and the output voltage obtained by receiving the reflected light from the original by the light receiving element 75 is stored for the number of pixels in the main scanning direction. Data was to be acquired. Next, the placement shading correction process is executed using the set shading correction formula for the FB reading mode (step S250), and it is determined whether or not the reading is completed (step S260). When the reading is not completed, the processes after step S240 are repeatedly executed. On the other hand, when the reading is completed, predetermined processing selected by the user is performed on the obtained image data (step S270), and this routine is terminated. As this predetermined processing, for example, storage processing for saving the obtained image data in the memory card MC, printing processing for printing the obtained image data by the printer unit 42, and display of the obtained image on the operation panel 46. Display processing to be performed.

  On the other hand, when the original reading method is the ADF reading mode in step S210, the black floating ratio E stored in the scanner ASIC 50 is read (step S280), and the shading correction formula for ADF in consideration of the black floating ratio E is read. And the correction coefficient Ca is set (step S290). Here, for example, assuming that the black reference data is K, the white reference data is W, and the black floating ratio E is, the black reference data K ′ for black floating correction can be obtained by Expression (2). Further, when the reading data in the ADF is Da, the black reference data K ′ for black floating correction, the white reference data W, the correction coefficient for ADF is Ca, and the output data in the ADF is Da ′, the following equation (3) is obtained. The shading correction in the ADF reading mode is performed using the shading correction formula shown. That is, when carrying out the shading correction process during conveyance in the ADF reading mode, the difference value between the read data Da and the black reference data K ′ for black floating correction is used as the difference value between the white reference data W and the black floating correction black. The value divided by the difference value from the reference data K ′ is used. As will be described in detail later, the black reference data K ′ for black floating correction is a value obtained by raising (shifting) the black reference data K to the white reference side by adding the black floating ratio E. Here, the ADF correction coefficient Ca is a coefficient for matching the output results of the output image in the FB reading mode and the output image in the ADF reading mode without taking the transparent sheet 35 into account, and is obtained empirically. can do. The black reference data K ′ for black float correction is obtained, for example, by empirically obtaining the relationship between the read data read by the glass table 32 and the read data read by the ADF read area 34, and these read data are more approximate. It may be determined by adjusting the value of the black floating ratio E so as to achieve such a value. In this way, the conveyance shading correction process in the ADF reading mode is used to correct the difference in image quality between the read image in the FB reading mode and the read image in the ADF reading mode. It is.

K ′ = K + (W−K) × E / 100 (2)
Da ′ = Ca × (Da−K ′) / (W−K ′) (3)

  Next, it is determined whether or not the start of reading has been instructed by the user based on whether or not a start button (not shown) displayed on the operation panel 46 has been pressed (step S300). Wait as it is. On the other hand, when the start of reading is instructed, the CIS module 76 is fixed to the ADF reading area 34, and the ADF unit 61 is driven to transport the original S, and the CIS module 76 is controlled to read the original in the ADF reading area 34. Then, an image reading process is executed (step S310). In the image reading process, each color LED 72R, 72G, 72B is turned on to emit light to the original, and the output voltage obtained by receiving the reflected light from the original by the light receiving element 75 is stored for the number of pixels in the main scanning direction. Data was to be acquired. Next, the shading correction process during conveyance is executed using the set shading correction formula for the ADF reading mode (step S320).

Here, the conveyance shading correction process will be described in detail. The ADF reading area 34 is provided with a transparent sheet 35 that restricts the conveyance direction of the document S to the conveyance path 62 so that the document S is not sandwiched between the glass gap of the ADF reading area 34 or the conveyance roller 64. . In general, if both surfaces of the transparent sheet are smooth, light reflected by a gap between the glass and the transparent sheet in the ADF reading area 34 interferes to generate a concentric ring (Newton ring) in the read image. There is. Here, a transparent sheet 35 having a roughened surface is used on the surface on the ADF reading area 34 side, and the occurrence of this Newton ring can be prevented. However, when the transparent sheet is roughened, a black floating state in which the black region is shifted to the white side due to light scattered by the roughened surface may occur. In this state, there is a difference between an image read in the FB reading mode and an image read in the ADF reading mode. Therefore, here, the black floating ratio E is further used, and the black reference data K ′ for black floating correction and the white reference data W which are different from the black reference data K in the FB reading mode are used. Is executed to correct this black floating state. FIG. 7 is a conceptual diagram of an example of the shading correction process during conveyance. As shown in FIG. 7, in the FB reading mode, shading correction processing is executed using the black reference data K. In the ADF reading mode, black floating correction black that has shifted to the white side using the black floating ratio E is used. By using the reference data K ′, the difference between the read data Da and the black reference data is reduced, that is, the read data is shifted to the dark color side. Thereby, the discomfort which may arise in the dark part range containing black can be suppressed more. Here, the black reference data K ′ for black floating correction is obtained using the black floating ratio E obtained from the intercept b, and this black reference data K ′ is used. Therefore, not only the dark part range including black but also white. The black float correction is also applied to the read data on the side. However, since the visual influence is smaller in the bright area than in the dark area, here, the black floating correction is further performed using the black floating ratio E obtained by the intercept b and the shading correction formula for ADF. It was supposed to be executed easily.

  Now, after step S320, it is determined whether or not the reading has been completed (step S330). If the reading has not been completed, the processes after step S310 are repeatedly executed. On the other hand, when the reading is completed, in step S270, predetermined processing selected by the user is performed on the obtained image data, and this routine is ended. As described above, when the original is read through the transparent sheet 35, the black reference data K ′ for black floating correction is obtained using the black floating ratio E, and the shading correction processing is executed using the black reference data K ′.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In this embodiment, the light source unit 71 corresponds to a light emitting unit, the CIS 74 corresponds to a light receiving unit, the CIS module 76 corresponds to a reading unit, the ADF unit 61 corresponds to an automatic conveying unit, and the flat bed unit 31 is placed. The transparent sheet 35 corresponds to a transparent sheet, the shading correction processing unit 53 corresponds to a shading correction unit, and the control unit 52 corresponds to a control unit. Further, the white reference data W corresponds to the white reference data, the black reference data K corresponds to the first black reference data, the black reference data K ′ for black floating correction corresponds to the second black reference data, The ADF reading area 34 corresponds to the conveyance reading area, and the placement reading area of the glass table 32 corresponds to the placement reading area. In the present embodiment, an example of the image reading method of the present invention is also clarified by describing the operation of the multifunction printer 20.

  In the multi-function printer 20 of the present embodiment described in detail above, the transparent sheet 35 that is roughened and restricts the moving direction of the document is provided in the ADF reading area 34. In addition, for the read data obtained by reading the document placed on the flat bed portion 31, the black reference data K and the white reference data W are used to perform the placement shading correction process, while the automatically conveyed document Is read using the black reference data K ′ for black float correction and the white reference data W which are different from the black reference data K, and the shading correction process during conveyance is executed. Thus, since the transparent sheet 35 that regulates the moving direction of the document is provided, the document can be smoothly conveyed. In addition, when a transparent sheet having a smooth surface is present, Newton rings may occur. However, since the transparent sheet 35 is roughened, the generation of Newton rings can be prevented. Further, a black floating state may occur through the roughened transparent sheet 35. In the ADF reading mode in which reading data is obtained through the transparent sheet 35, black floating correction different from the FB reading mode is performed. Since the shading correction process during conveyance is executed using the black reference data K ′ for use, this black floating state can be corrected. Therefore, it is possible to further suppress the occurrence of a difference between the image read by placing the original and the image read by automatically feeding the original.

Further, when executing the shading correction process during conveyance, the black reference data K ′ for black floating correction in which the black reference data K is shifted to the white reference data side is used, so that the difference between the black reference data and the read data is smaller. In other words, since the read data is shifted to the dark color side, it is possible to relatively easily correct the black floating state caused by the roughened transparent sheet. Further, when executing the placement shading correction process, a value obtained by dividing the difference value between the read data Df and the black reference data K by the difference value between the white reference data W and the black reference data K is used. When executing the shading correction process, the difference value between the read data Da and the black reference data K ′ for black floating correction is divided by the difference value between the white reference data W and the black reference data K ′ for black floating correction. Since the value is used, the black floating state caused by the roughened transparent sheet can be corrected relatively easily using the black reference data K ′ for black floating correction. Furthermore, the black floating state caused by the transparent sheet 35 that is difficult to be corrected by the correction coefficient Ca for the ADF reading mode is expressed by using the black floating ratio E and black reference data K ′ for black floating correction using the black floating ratio E. Correction can be performed relatively easily and relatively reliably. Furthermore, the rough adjustment between the FB reading mode and the ADF reading mode is attempted using the ADF correction coefficient Ca, and the black floating state generated by the transparent sheet 35 is further improved using the black reference data K ′ for black floating correction. It can be corrected reliably.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the black floating ratio E is obtained by plotting the read data in the FB reading mode and the read data in the ADF reading mode, and obtaining an intercept b as an approximate expression of a straight line. However, the present invention is not limited to this. For example, when executing the shading correction process at the time of conveyance, the dark part range is compared with the bright part range in the bright part range of the read data read by the CIS module 76 and the dark part range that is darker than the bright part range. Then, it is good also as what uses the black reference data for black floating correction used as a bigger correction amount. This “dark part range” may be a range in which the black floating state becomes noticeable visually. For example, each of RGB values (up to 255) satisfies 100 or less, and the average of RGB values is 70. A pixel that satisfies the following conditions may be used. FIG. 8 is an explanatory diagram of other black float correction settings using an approximate expression of a curve. As shown in FIG. 8, the reading data in the FB reading mode and the reading data in the ADF reading mode are plotted, and in the dark part range, a curve approximation expression is obtained by a polynomial approximation expression Y = f (X). For example, when reading data in the ADF reading mode is input using an expression, the value of the reading data in the FB reading mode may be output. This dark part range may be determined empirically, for example, in a range where the black float is more conspicuous. In this way, the black float correction can be corrected more appropriately in the dark range, and the influence of the black float correction can be further reduced in the bright range, and the black float correction can be corrected more effectively. it can. In the dark part range, black reference data for black float correction, which has a larger correction amount on the darker color side, may be used. Since the black floating state becomes more prominent near black, this makes it possible to more effectively correct the black floating state.

At this time, the shading correction process during conveyance can be executed as follows. FIG. 9 is a flowchart illustrating an example of another image reading processing routine. For convenience of description, description of the same parts as those in the above-described embodiment is omitted. Here, in the dark part range shown in FIG. 8 with the predetermined value d1 as a boundary, the black floating point determined in a quadratic function so that the read data Da in the ADF reading mode becomes larger black reference data as it becomes darker. A case where the black reference data K ′ for correction is used will be described. The “dark color side” may be a side having lower brightness and saturation, for example, a black side. When this image reading processing routine is executed, after step S300 of the above-described image reading processing routine, the CPU 82 uses the reading processing unit 51 to execute the following processing. When the start of reading is instructed in step S300, the CIS module 76 is fixed to the ADF reading area 34, the ADF unit 61 is driven to transport the original S, and the CIS module 76 is read so as to read the original in the ADF reading area 34. The image reading process is executed (step S310). Next, it is determined whether or not the read value of the read data is in the dark part range (step S400). This determination may be made, for example, in a range where each of the RGB values (with 255 as the upper limit) is 100 or less and the average value of RGB is 70 or less. When the value of the read data is not in the dark part range, the shading correction process is executed using the bright part range correction formula in the ADF reading mode (step S410). For example, the shading correction formula shown in the following formula (4) may be used as the bright range correction formula. That is, the black reference data K is used as it is, and correction for adjusting the image quality in the FB reading mode and the ADF reading mode is performed by the ADF correction coefficient Ca. On the other hand, when the value of the read data is in the dark part range in step S400, the black reference data K ′ corresponding to the read data in the dark part range is used, and at the time of conveyance using the above-described equations (3) and (5). A shading correction process is executed (step S420). Then, after step S410 or after step S420, it is determined whether or not reading has been completed (step S330). If reading has not been completed, the processing after step S310 is repeatedly executed. On the other hand, when the reading is completed, the processing after step S270 is executed. In this way, since the black reference data K ′ for black float correction determined in a quadratic function so that the black reference data becomes larger as the read data Da becomes darker, the read data is relatively read on the dark color side. Move to the black side. In this way, the black float correction can be corrected more appropriately in the dark range, and the influence of the black float correction can be further reduced in the bright range, and the black float correction can be corrected more effectively. it can.

Da ′ = Ca × (Da−K) / (W−K) (4)
K ′ = K + f (Da) (5)

  In the above-described embodiment, the black floating ratio E is obtained by plotting the read data in the FB reading mode and the read data in the ADF reading mode, obtaining an intercept b as an approximate expression of a straight line, and obtaining from the intercept b. For example, as shown in FIG. 10, different linear approximation equations are obtained for the bright portion range and the dark portion range on the darker side than the bright portion range, and the black reference data is obtained using these approximation equations. When K ′ is calculated and transported using the black reference data K ′ for black float correction in the bright part range for the bright part range and the black reference data K ′ for black float correction in the dark part range for the dark part range The shading correction process may be executed. At this time, for example, in the dark part range, the black reference data K ′ for black float correction obtained by the intercept b ′ of the linear approximation formula of the dark part range is used, and in the bright part range, the intercept of the linear approximation formula of the bright part range. The shading correction process during conveyance may be executed using the black reference data K ″ obtained by b ″. Even in this way, it is possible to correct the black floating state that may occur due to the transparent sheet 35.

  In the above-described embodiment, the black shading correction black reference data K ′ obtained using the black floating ratio E is used in the conveyance shading correction processing. However, the placement shading correction processing in the FB reading mode is used. If the black reference is different from the black reference, the black reference data K ′ for black floating correction that can eliminate the black floating state caused by the presence of the transparent sheet 35 may be used. Further, in the above-described embodiment, the black reference data K ′ for correcting black floating is used in which the black reference data K is shifted to the white reference data side. However, the present invention is not particularly limited thereto. In the above-described embodiment, when the placement shading correction process is executed, the difference value between the read data Df and the black reference data K is divided by the difference value between the white reference data W and the black reference data K. On the other hand, when executing the shading correction process during conveyance, a value obtained by dividing the difference value between the read data Da and the black reference data K ′ by the difference value between the white reference data W and the black reference data K ′ is used. However, the present invention is not limited to this.

  In the above-described embodiment, the transparent sheet 35 is fixed to the ADF reading area 34 side of the flat bed portion 31, but roughening is performed between the conveyed document S and the ADF reading area 34. If the transparent sheet 35 exists, it will not specifically limit, The transparent sheet 35 may be fixed to the conveyance path 62 side of the ADF unit 61. FIG.

  In the embodiment described above, the same white reference data W is used in the FB reading mode and the ADF reading mode. However, the present invention is not particularly limited to this, and different white reference data is used in the FB reading mode and the ADF reading mode. It may be a thing.

  In the above-described embodiment, the main controller 80 and the scanner ASIC 50 are provided. However, if the shading correction process using the black reference data can be executed, the function sharing and the like are not limited to this. The controller 80 and the scanner ASIC 50 may be integrated, or another ASIC may be further provided to further share functions.

  In the above-described embodiment, the black float ratio setting processing routine is performed in the manufacturing process. However, the present invention is not limited to this. The step chart 30 is attached to the multifunction printer 20 and sold, and the user sets the black float ratio. A processing routine may be executed. Further, the serviceman may execute a black float ratio setting processing routine at irregular or regular maintenance, and rewrite the value of the black float ratio E, correction coefficients Cf, Ca, and the like.

  In the above-described embodiment, the multi-function printer 20 has been described. However, there is no particular limitation as long as the FB reading mode and the ADF reading mode can be performed by the scanner unit. A FAX apparatus may be used. In addition, the printer unit 42 is an inkjet color printer mechanism, but is not particularly limited thereto, and may be an electrophotographic color printer, a dot impact color printer, or a monochrome printer of these. It is good.

  In the above-described embodiment, the multi-function printer 20 has been described. However, an image reading method or a program for executing this method may be used.

20 Multi-function printer, 21 Case, 22 Case cover, 23 Cassette, 24 Paper discharge tray, 26 ADF insertion slot, 28 ADF paper output tray, 29 Document guide, 30 Step chart, 31 Flatbed section, 32 Glass stand, 34 ADF reading area, 35 transparent sheet, 36 white reference plate, 40 scanner unit, 42 printer unit, 46 operation panel, 49 memory card slot, 50 scanner ASIC, 51 reading processing unit, 52 control unit, 53 shading correction processing unit, 54 LED drive unit, 56 A / D conversion unit, 58 motor drive unit, 60 scanner engine, 61 ADF unit, 62 transport path, 63 pickup roller, 64 transport roller, 65 paper discharge roller, 66 transport motor, 66a transport motor, 1 light source unit, 72B blue LED, 72G green LED, 72R red LED, 73 light guide, 74 CIS, 75 light-receiving element, 76 CIS module, 78B driven roller, 78b
Followed roller, 78a Carriage motor, 79 belt, 80 main controller, 82 CPU, 84 ROM, 86 RAM, 87 Internal communication interface (I / F), MC memory card.

Claims (7)

A reading means for reading the document, comprising: a light emitting unit for irradiating light on the document; and a light receiving unit having a light receiving element for receiving the reflected light reflected by the document.
Automatic conveying means for conveying a document along a conveyance path to a conveyance reading area readable by the reading means;
A placement unit that has a placement reading area that can be read by the reading unit and places the document;
A transparent surface that is provided in the transport reading area so that the light emitted from the light emitting section is transmitted and reaches the original, and the surface on the side of the transport reading area is roughened to regulate the moving direction of the original. Sheet,
For the read data obtained by reading the document placed on the placement unit with the reading unit, the first black reference data and the white reference data are used to perform a placement shading correction process, the second black reference data and the white reference data with respect to the reading data read by the reading means the document conveyed by the automatic conveying means moves said first black reference data in the white reference data side Shading correction means for performing a shading correction process during conveyance using
An image reading apparatus comprising: The shading correction means, when performing a pre-described standing time shading correction process, a difference value between the the read data of the first black reference data, and the white reference data with said first black reference data On the other hand, when executing the shading correction process during conveyance, the difference value between the read data and the second black reference data is used as the difference value between the white reference data and the second reference data. The image reading apparatus according to claim 1, wherein a value divided by a difference value with respect to black reference data is used. When performing the shading correction process during conveyance, the shading correction unit is configured such that each of the RGB values with an upper limit of 255 among reading pixels obtained by reading the original with the reading unit is equal to or less than a certain number and the RGB value The second black reference data, which has a larger correction amount in the dark part range than the bright part range, is used in the dark part range where the average of the dark part range satisfies a certain number or less and the bright part range other than the dark part range. the image reading apparatus according to any one of claims 1-2. When the shading correction unit performs the on-conveying shading correction process, the darker range of the read data obtained by reading the original conveyed by the automatic conveyance unit with the reading unit has a larger correction amount as it becomes darker. The image reading apparatus according to claim 3 , wherein the second black reference data is used. The image reading apparatus according to any one of claims 1 to 4 ,
The reading means is controlled so as to read the original placed on the placement reading area of the placement unit at the time of placement reading, and the automatic conveying means is controlled so as to convey the original at the time of transport reading and the transported. An image reading apparatus comprising: control means for controlling the reading means so as to read the original document in the transport reading area. A reading unit that includes a light emitting unit that irradiates light on a document and a light receiving unit that receives light reflected from the document, and a reading unit that reads the document, and a conveyance reading region that can be read by the reading unit An automatic conveyance unit that conveys the original along the conveyance path, a placement reading area that can be read by the reading unit, a placement unit that places the document, and the light emitted from the light emitting unit is transmitted. And a transparent sheet that is provided in the conveyance reading area so as to reach the original and that has a rough surface on the surface of the conveyance reading area and restricts the movement direction of the original. An image reading method,
(A) A placement shading correction process is executed using the first black reference data and the white reference data on the read data obtained by reading the original placed on the placement unit by the reading unit. Steps,
(B) the the automatic transfer means reading data read by the reading means the document conveyed by the the migrated second black reference data the first black reference data in the white reference data side Execute shading correction processing during conveyance using white reference data
Steps,
An image reading method including: A program for causing one or more computers to execute each step of the image reading method according to claim 6 .