JP2012124562A - Image reading device, image reading method, and program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly feed a document and also suppress the generation of a difference between an image read by placing the document and an image read by automatically feeding the document.SOLUTION: A transparent sheet 35, that is roughened and regulates the movement direction of a document, is arranged in an automatic document feeder (ADF) reading area 34 concerning a scanner unit 40. In-placement shading correction processing is performed through the use of black reference data K and white reference data W with respect to reading data obtained by reading a document placed on a flat bed part 31. Meanwhile, in-feeding shading correction processing where a correction amount becomes larger in the dark range of reading data than in the bright range is performed with respect to the reading data which is obtained by reading a document automatically fed by an ADF unit 61. In this case, the in-feeding shading correction processing is performed through the use of black reference data K' for correcting a bright-black phenomenon, which is obtained by moving the black reference data K to the side of the white reference data and is different from the black reference data K, and the white reference data W.

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). Due to the difference in the method of reading the document, for example, a transparent sheet that restricts the moving direction of the document to the conveyance path is provided between the automatic conveyance device and the document reading area. May be different.

  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;
The placement correction process is performed on the read data obtained by reading the original placed on the placement unit, while the bright portion range of the read data obtained by reading the original conveyed by the automatic conveying unit and the read data Correction execution means for executing a correction process at the time of conveyance, which is a larger correction amount in the dark part range than in the bright part range, with respect to the dark part range that is darker than the bright part range;
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. In addition, the correction processing at the time of placement is executed for the read data obtained by reading the document placed on the placement portion, while the read data obtained by reading the automatically conveyed document is compared with the bright portion range. In the dark part range, a correction process at the time of conveyance that is a larger correction amount is executed. 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. Unlike the reading by the placement unit, the black correction state can be corrected because the correction processing at the time of conveyance, which is a larger correction amount in the dark part range than in the bright part range, is executed. 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 “dark part range” may be, for example, a range in which the black floating state becomes noticeable visually. Further, in the conveyance correction process, for example, the relationship between the read data read in the placement reading area and the read data read in the conveyance reading area is empirically obtained, and correction is performed so that these read data are more approximate. It may be a thing. The “correction amount” may be, for example, a difference value between the read data value before correction and the output data value after correction. At this time, the correction execution means may execute the above-mentioned correction process at the time of darkness and the correction process at the time of conveyance in which the correction amount is larger than that of the bright part range.

  In the image reading apparatus according to the aspect of the invention, the correction execution unit performs the correction processing at the time of conveyance in which the correction amount becomes larger as the color becomes darker in the dark portion range of the read data obtained by reading the document conveyed by the automatic conveyance unit. It may be executed. Since the black floating state becomes more prominent near black, this makes it possible to more effectively correct the black floating state. Here, the “dark color side” may be a side having lower brightness and saturation, for example, a black side.

  In the image reading apparatus according to the aspect of the invention, the correction execution unit may include first black reference data and white reference data for read data obtained by reading the document placed on the placement unit with the reading unit. The first shading reference data is used as white reference data for the dark area of the read data obtained by reading the original transported by the automatic transport means by the reading means while executing the shading correction process at the time of placement. The shading correction process at the time of conveyance may be executed using the second black reference data and the white reference data shifted to the side. 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. Further, since 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, it is possible to relatively easily correct the black floating state generated by the roughened transparent sheet. At this time, the first black reference data may be used for a bright portion range of read data obtained by reading the original conveyed by the automatic conveyance unit by the reading unit. In addition, when executing the above-described placement shading correction process, the correction execution unit calculates a difference value between the read data and the first black reference data, the white reference data, and the 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. A value divided by the difference value with the 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.

  Alternatively, in the image reading apparatus according to the present invention, the correction execution unit may perform a predetermined gamma correction process on the read data obtained by reading the document placed on the placement unit when executing the placement correction process. On the other hand, when the conveyance correction process is performed, the correction amount is larger in the dark portion range than in the bright portion range with respect to the read data obtained by reading the document conveyed by the automatic conveyance unit. A gamma correction process may be executed. By so doing, it is possible to relatively easily correct the black floating state caused by the roughened transparent sheet using the gamma correction process.

  Alternatively, in the image reading apparatus according to the present invention, the correction execution unit may perform a predetermined look-up table on the read data obtained by reading the document placed on the placement unit when executing the placement correction process. When performing the conveyance correction process, the dark portion is compared with the bright portion range with respect to the read data obtained by reading the document conveyed by the automatic conveyance means. The predetermined color conversion process having a larger correction amount in the range may be executed. By so doing, it is possible to relatively easily correct the black floating state caused by the roughened transparent sheet by using color conversion processing using a lookup table.

  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) performing a placement correction process on the read data obtained by reading the document placed on the placement portion;
(B) The dark portion compared to the bright portion range with respect to the bright portion range of the read data obtained by reading the document conveyed by the automatic conveying unit and the dark portion range that is darker than the bright portion range A step of performing a correction process at the time of conveyance, which is a larger correction amount in the range;
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, unlike the case of placement reading, the conveyance correction process is performed at the time of conveyance reading, which is a larger correction amount in the dark area than in the bright area, so that 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 one computer or if each computer executes the steps in a shared manner, 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 correction type | mold 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 other approximation method of FB reading mode and ADF reading mode. 7 is a flowchart illustrating an example of another image reading processing routine. Explanatory drawing which shows an example of the black floating correction by gamma correction. 7 is a flowchart illustrating an example of another image reading processing routine. Explanatory drawing which shows an example of the black float correction | amendment by a color conversion process.

  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. Note that ASIC is an abbreviation for Application Specific Integrated Circuit.

  As shown in FIG. 2, the scanner engine 60 includes an ADF unit 61 that automatically conveys a document set in the ADF insertion port 26 to the ADF reading area 34, and a belt 79 spanned between a carriage motor 78 a and a driven roller 78 b. And a CIS module 76 that reciprocates by being driven by a 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 rough surface processing (non-glare processing, anti-glare processing) that scatters light by forming irregularities on the surface on the ADF reading region 34 side. 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 flash 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. And an internal communication interface (I / F) 87 that communicates with the panel 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 inserted 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. The main controller 80 includes a background removal processing unit 88 that performs background removal, which is a process for preventing show-through that may occur during printing, and a gamma correction unit 89 that performs gamma correction on image data read by the scanner unit 40. It is equipped with. The background removal processing unit 88 performs a process of changing the colors of the shadow part and the highlight part included in the image data using a lookup table (LUT) that associates the relationship between the input color and the output color. The LUT is stored in the flash ROM 84. The gamma correction unit 89 performs a process of adjusting the brightness of the image based on the gamma curve.

  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 correction formula 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 as an approximate curve (step S140), and the black float correction equation is calculated based on the obtained approximate curve equation. This is calculated and stored in the HDD (step S150), and 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 an approximate expression of a curve connecting the plotted points, such as a quadratic function or a logarithmic function, is given as a relationship between these. I wanted it. 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 the present embodiment, the following description will be made on the assumption that the black reference data K is adjusted to adjust the image difference between the FB reading mode and the ADF reading mode. Here, based on the obtained approximate expression, the black floating correction expression f (Da) for calculating the black reference data K ′ for black reference correction is obtained. Although details will be described later, here, a black floating correction formula is set such that the value of the black reference data K ′ increases as the color becomes darker. In this way, a model-specific black float correction formula is obtained as information on the difference between read data in the FB read mode and the ADF read mode, and the black float correction formula is stored in advance in the read processing unit 51 of the scanner ASIC 50. It was. The black float correction type 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. 6 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, the shading correction processing unit 53, the background removal processing unit 88, the gamma correction unit 89, and the like of the reading processing unit 51. did.

  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 CIS module 76 and the white reference plate 36 face each other, and all the 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. In the detection of the black reference data K, at the position where the CIS module 76 and the white reference plate 36 face each other, all the color LEDs 72R, 72G, 72B of the light source unit 71 are turned off to scan the white reference plate 36 and receive each light. The output voltage obtained by the element 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 reading is completed, background removal processing is executed on the obtained image data (step S270). Here, it is assumed that the background removal processing unit 88 executes a process of skipping the shadow part and the highlight part included in the image data using the LUT (see the solid line in FIG. 12 described later). Subsequently, gamma correction is performed on the obtained image (step S280). Here, it is assumed that the gamma correction unit 89 executes a process of applying a density adjustment gamma curve to the input image data. Then, a predetermined process selected by the user is performed on the obtained image data (step S290), 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 document reading method is the ADF reading mode in step S210, the shading correction formula for the ADF in the bright portion range exceeding the predetermined value d1 of the read data and the ADF for the dark portion range not exceeding the predetermined value d1 of the read data. And a correction coefficient Ca is set (step S300). Since the black floating state caused by the transparent sheet 35 is conspicuous in the dark area of the read data, the read data in the ADF read mode performs shading correction that provides a larger correction amount in the dark area than in the bright area. To do. Specifically, among the read data in the ADF reading mode, for the shading correction formula for the ADF in the bright area, the formula (2) obtained by changing the correction coefficient of the shading correction formula in the FB reading mode is used. . The correction coefficient Ca for ADF in the expression (2) is a coefficient for matching the output result between the output image in the FB reading mode and the output image in the ADF reading mode without taking the transparent sheet 35 into consideration, and is obtained empirically. Can be. In this way, when applied to a model that does not include the transparent sheet 35, the image quality in the FB reading mode and the ADF reading mode can be matched by the ADF correction coefficient Ca, and the application becomes easy. On the other hand, among the reading data in the ADF reading mode, the shading correction formula for the ADF in the dark part range uses the formula (3) in which the black reference data is changed in addition to the correction coefficient. In the expressions (2) and (3), the reading data in the ADF is Da, the white reference data is W, the ADF correction coefficient is Ca, the black reference data is K, the black reference data for black floating correction is K ′, and the ADF. The output data at is Da ′. That is, in 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 calculated as the white reference data W and the black floating correction in the dark area of the read data. The value divided by the difference value from the black reference data K ′ for correction is used. In this way, large correction can be executed by changing the black reference data in the dark range of the read data, and the read image in the FB read mode can be unified. The black reference data K ′ for black float correction is shifted (increased) to the white reference side by adding the black float correction expression f (Da) as shown in Expression (4). It is a value. Further, the black reference data K ′ has a larger correction amount as it becomes darker in the dark part range. Here, it is assumed that black reference data K ′ for black floating correction in which the black reference data K is shifted to the white reference data W side is output using the equation (4) when Da as read data is given. As described above, 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. 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 is good also as what is adjusted and determined so that it may become such a value. The “dark range” may be a range in which the black floating state is noticeable in the read data read in the ADF reading mode. For example, each of RGB values (up to 255) is 100. Pixels (read data) satisfying the following and satisfying an average of RGB values of 70 or less can be determined.

Da ′ = Ca × (Da−K) / (W−K) (2)
Da ′ = Ca × (Da−K ′) / (W−K ′) (3)
K ′ = K + f (Da) (4)

  Next, it is determined whether or not the user has instructed to start reading based on whether or not a start button (not shown) displayed on the operation panel 46 has been pressed (step S310). 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 S320). 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, it is determined whether or not the read data is in the dark part range (step S330). This determination is made based on whether or not the read data satisfies the dark range condition. If the read data is not in the dark area, correction processing is executed using the shading correction formula for the bright area in the ADF reading mode (step S340). On the other hand, when the read data is in the dark area, correction processing is executed using the shading correction formula for the dark area in the ADF reading mode (step S350).

  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 correction formula 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 illustrating an example of a shading correction process during conveyance that takes into account black float correction. As shown in FIG. 7, the shading correction process is executed using the black reference data K in the bright area of the ADF reading mode, but the white area is shifted to the white side using the black floating correction formula f (Da) in the dark area. By using the black reference data K ′ for black floating correction, 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. Further, in the bright area, by using the black reference data K, it is possible to prevent the black float correction from being applied to the bright area. In the dark range of the shading correction process during conveyance, a larger correction amount is corrected than the shading correction process during placement.

  Now, after step S340 or step S350, it is determined whether or not reading has been completed (step S360). If reading has not been completed, the processing from step S320 is repeatedly executed. On the other hand, when reading is completed, background removal processing is executed in step S270, gamma correction processing is executed in step S280, and predetermined processing selected by the user is performed on the obtained image data in step S290. This routine is terminated. As described above, when the original is read through the transparent sheet 35, black reference data K ′ for black floating correction is obtained using the black floating correction formula, and shading is performed on the dark area of the read data using this. Correction processing is executed.

  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 the transparent sheet, the shading correction processing unit 53 corresponds to the correction execution unit, and the control unit 52 corresponds to the control unit. The white reference data W corresponds to white reference data, the black reference data K corresponds to first black reference data, and the black reference data K ′ for black floating correction is the second black reference for black floating correction. It corresponds to data, the ADF reading area 34 corresponds to the conveyance reading area, and 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 according to 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, on-read shading correction processing is executed for read data obtained by reading a document placed on the flat bed section 31, while on-load shading is performed on read data obtained by reading an automatically conveyed document. The shading correction process at the time of conveyance which becomes a larger correction amount in the dark part range than the correction process and the bright part range is executed. As described above, since the transparent sheet for restricting the moving direction of the document is provided, the document can be conveyed smoothly. Moreover, since the transparent sheet 35 is roughened, Newton rings can be prevented from being generated. Further, when reading data is obtained via the roughened transparent sheet 35, unlike the reading in the flat bed portion 31, the shading during conveyance is a larger correction amount in the dark portion range than in the bright portion range. Since the correction process is executed, this black floating state can be corrected. Therefore, it is possible to further suppress the occurrence of a difference between the image in the FB reading mode and the image in the ADF reading mode.

  Also, in the dark area of the read data in the ADF reading mode, the shading correction process at the time of conveyance, which is a larger correction amount is executed as the dark color side where the black floating state becomes conspicuous, and the black floating state is corrected more effectively. can do. Further, for the read data in the FB reading mode, the black reference data K and the white reference data W are used to perform the shading correction process at the time of placement, while the dark data range of the read data in the ADF read mode is applied. Uses the black reference data K ′ for black float correction and the white reference data W to execute the shading correction process at the time of conveyance. Therefore, the transparent sheet 35 roughened using the black reference data for black float correction is used. It is possible to correct the black floating state caused by the above relatively easily. Since black reference data K ′ for black float correction in which the black reference data K is shifted to the white reference data W side is used for the dark range of the shading correction process during conveyance, the difference between the black reference data and the read data is Since the reading data becomes smaller, that is, the read data is shifted to the dark color side, it is possible to relatively easily correct the black floating state generated by the roughened transparent sheet. 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 relatively determined by using the black reference data K ′ for black floating correction using the black floating correction formula. Correction can be performed easily and relatively 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 float correction formula is obtained by plotting the read data in the FB read mode and the read data in the ADF read mode to obtain the black float correction formula as a curve approximation formula. However, it is not particularly limited to this. For example, as shown in FIG. 8, different straight line 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 floating correction black color calculated using these linear approximation equations is obtained. The shading correction process during conveyance may be executed using the reference data K ′. 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 reference data K ′ for black floating correction obtained using the black floating correction formula f (Da) is used for the dark part range of the read image in the shading correction processing during conveyance. As long as it is different from the black reference data in the bright area range in the ADF reading mode, the present invention is not particularly limited to this, and the black float correction is capable of eliminating the black floating state in the dark area caused by the presence of the transparent sheet 35. The black reference data K ′ may be used. Further, in the above-described embodiment, the black reference data K ′ for correcting the black float that uses the black reference data K on the white reference data W side is used. However, the present invention is not limited to this. 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, 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 in the dark area of the shading correction process during conveyance. However, it is not particularly limited to this.

  In the above-described embodiment, the black float correction is performed in the shading correction, but is not particularly limited thereto. For example, while performing a predetermined gamma correction process on the read data in the FB reading mode, the gamma correction that provides a larger correction amount in the dark area than in the bright area for the read data in the ADF reading mode. It is good also as what performs a process. FIG. 9 is a flowchart illustrating an example of an image reading processing routine for performing black floating correction by gamma correction. FIG. 10 is an explanatory diagram of an example of black float correction by gamma correction. As shown in FIG. 9, in this process, after the reading process in the ADF reading mode is executed in step S320, the shading correction process (for example, the above equation (2)) in the ADF reading mode is executed (step S400). After the reading is completed (step S410), the background removal process similar to that in step S270 is executed in step S420, and the correction amount is larger in the dark area than in the bright area for the read data in the ADF reading mode. A gamma correction process is executed (step S430, see FIG. 10). By so doing, it is possible to relatively easily correct the black floating state caused by the roughened transparent sheet using the gamma correction process.

  Alternatively, a predetermined color conversion process is performed on the read data in the FB reading mode using a lookup table, while the read data in the ADF reading mode is larger in the dark area than in the bright area. It is also possible to execute a color conversion process as a correction amount. FIG. 11 is a flowchart illustrating an example of an image reading processing routine that performs black float correction by color conversion processing in the background removal processing. FIG. 12 is an explanatory diagram showing an example of black float correction by color conversion processing. As shown in FIG. 11, in this process, after the process up to step S410 described above is performed, the color that has a larger correction amount in the dark area than the bright area for the read data in the ADF reading mode. A background removal process is executed by the conversion process (step S500). By so doing, it is possible to relatively easily correct the black floating state caused by the roughened transparent sheet by using color conversion processing using a lookup table. It should be noted that in the dark part range, a color conversion process in which the correction amount increases as the dark side is reached may be performed.

  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 dark part range is corrected with a larger correction amount than the bright part range in the ADF reading mode, the function sharing, etc. The main 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 correction type setting processing routine is performed in the manufacturing process. However, the present invention is not limited to this, and the step chart 30 is attached to the multi-function printer 20 and sold. The expression setting process routine may be executed. Further, the serviceman may execute a black float correction formula setting processing routine at irregular or periodic maintenance, and rewrite the black float correction formula values, correction coefficients Cf, Ca, and the like.

  In the above-described embodiment, the multifunction 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. For example, a scanner device may be used and a FAX function may be provided. 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, 71 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 driven roller, 78a carriage motor, 79 belt 80, main controller, 82 CPU, 84 ROM, 86 RAM, 87 internal communication interface (I / F), 88 background removal processing unit, 89 gamma correction unit, MC memory card.

Claims (9)

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;
The placement correction process is performed on the read data obtained by reading the original placed on the placement unit, while the bright portion range of the read data obtained by reading the original conveyed by the automatic conveying unit and the read data Correction execution means for executing a correction process at the time of conveyance, which is a larger correction amount in the dark part range than in the bright part range, with respect to the dark part range that is darker than the bright part range;
An image reading apparatus comprising:   2. The correction execution unit executes the correction processing at the time of conveyance in which the correction amount becomes larger as the color becomes darker in a dark part range of read data obtained by reading the document conveyed by the automatic conveyance unit. Image reading apparatus.   The correction execution means uses the first black reference data and the white reference data for the read data obtained by reading the original placed on the placement unit by the reading means, and performs a shading correction process during placement. On the other hand, for the dark part range of the read data obtained by reading the original conveyed by the automatic conveying unit with the reading unit, the second black is obtained by shifting the first black reference data to the white reference data side. The image reading apparatus according to claim 1, wherein the shading correction process during conveyance is performed using the reference data and the white reference data.   The correction execution means, when executing the above-described placement shading correction processing, calculates a difference value between the read data and the first black reference data, and a difference between the white reference data and the first black reference data. While the value divided by the value 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 used as the difference between the white reference data and the second black reference data. The image reading apparatus according to claim 3, wherein a value obtained by dividing a difference value with data is used.   The correction execution means performs a predetermined gamma correction process on the read data obtained by reading the document placed on the placement unit when executing the placement correction process, while performing the conveyance correction process. 2. The gamma correction processing for executing a correction amount larger in the dark area than in the bright area is performed on the read data obtained by reading the document conveyed by the automatic conveying unit when executing. Or the image reading apparatus of 2.   The correction execution means executes a predetermined color conversion process using a predetermined look-up table for the read data obtained by reading the original placed on the mounting unit when executing the above-described correction processing. On the other hand, when the conveyance correction process is executed, the predetermined correction amount which is larger in the dark portion range than the bright portion range with respect to the read data obtained by reading the document conveyed by the automatic conveyance unit. The image reading apparatus according to claim 1, wherein the color conversion process is executed. The image reading apparatus according to any one of claims 1 to 6,
The reading means is controlled to read the original placed on the placement reading area of the placement section at the time of placing and reading, and the automatic conveying means is controlled to carry the original at the time of carrying and reading. 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. 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) performing a placement correction process on the read data obtained by reading the document placed on the placement portion;
(B) The dark portion compared to the bright portion range with respect to the bright portion range of the read data obtained by reading the document conveyed by the automatic conveying unit and the dark portion range that is darker than the bright portion range A step of performing a correction process at the time of conveyance, which is a larger correction amount in the range;
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 8.

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