JP2019193160A - Image output device and image reading system - Google Patents

Abstract

To suppress a color change due to replacement of an image reading device.SOLUTION: A correction coefficient calculation unit 103 associates in units of color patches an adjustment image obtained by reading an adjustment document with a plurality of color patches with a reference image obtained by reading the same adjustment document with another image reading device. When the image to be corrected is read, an image correction unit 105 sequentially pays attention to pixels, corrects a color difference between a color of the adjustment image close to the pixel of interest and a color of the reference image corresponding to the color in addition to the pixel of interest and outputs a corrected image.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image output apparatus that corrects and outputs image data read from a document, and an image reading system including the image output apparatus.

  2. Description of the Related Art Conventionally, in an image reading apparatus that reads an image of an original while conveying the original, a CIS (Contact Image Sensor), a CCD (Charge Coupled Device), or the like can be used as an image reading sensor (see Patent Document 1).

Japanese Patent Laid-Open No. 2017-158094

  However, for example, as in Patent Document 1, when there is a difference in apparatus specifications such as different types of image reading sensors mounted on the image reading apparatus, when the image data read by each image reading apparatus is compared, it is not always necessary to change the hue, etc. Sometimes did not match.

  The present invention provides an image output apparatus and an image reading system capable of reducing a difference in color tone of output data from image data read by another image reading apparatus.

  The present invention includes an image correction unit that performs color correction on image data obtained by an image reading unit that reads an image of a document, and an image output unit that outputs an image data that has been corrected by the image correction unit. And the image correction means color-corrects the image data based on an image profile result of external data associated with an external device having a function of reading an image of a document. In the apparatus or the image reading system.

  According to the present invention, it is possible to realize an image output apparatus and an image reading system that reduce a difference in hue of output data with respect to image data read by another image reading apparatus.

FIG. 3 is a configuration diagram of an image reading unit in the present invention. 1 is a configuration diagram of an entire image reading apparatus according to the present invention. An example of an adjustment document in the present invention. The flowchart of the correction coefficient calculation process in the correction coefficient calculation part in this invention. The flowchart of the process which specifies the color sample in this invention. The flowchart of the process which specifies the color sample in this invention. 5 is a flowchart of correction processing in an image correction unit according to the present invention. The figure which shows an example of the user interface in this invention. FIG. 6 is a diagram showing a display example of a reference document and an adjustment document on the user interface according to the present invention. FIG. 6 is a diagram showing a display example of a reference document and an adjustment document on the user interface according to the present invention. The figure which shows the example of a display of the user interface in this invention.

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

<Configuration of Image Reading Apparatus and Image Reading System>
In the present embodiment, an image reading apparatus will be described as an example of an image output apparatus that corrects image data and outputs the corrected image data to the outside or a predetermined destination. FIG. 1 is a schematic sectional view of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a control block diagram of the image reading apparatus according to the embodiment of the present invention.

  As shown in FIG. 1, in the image reading apparatus 100 of the present embodiment, a paper feed tray (stacking tray) 2 on which documents (sheets) are stacked is supported so as to be openable and closable with respect to the apparatus body 1A via a hinge portion 2a. ing. That is, the paper feed tray 2 covers the document feed port (document take-in port) 13 in the closed state (broken line in FIG. 1), and the document is placed on the stacking surface 2b in the opened state (solid line in FIG. 1). Loaded.

  A plurality of documents stacked on the sheet feed tray 2 are sequentially fed while being separated one by one from the lowest document by the feed roller 4 and the separation pad 5 into the conveyance path.

  Then, the document fed to the transport path is transported to the downstream side by the transport roller pair 6, and both front and back images are read by the image reading units (image reading means) 8 and 9, and then the transport roller pair 7. It is discharged out of the device.

  As such image reading units 8 and 9, an image reading sensor such as CIS or CCD can be adopted. For example, in this embodiment, a 3-line CIS is mounted as described in detail later. did.

  The image reading apparatus 100 having such a configuration is communicably connected to an information processing apparatus 200 such as a computer, and a reading operation is controlled by an operation from the information processing apparatus 200. The image reading apparatus 100 and the information processing apparatus 200 are collectively referred to as an image reading system.

  Here, the connection between the image reading apparatus 100 and the information processing apparatus 200 can be connected by, for example, a USB cable, a SCSI cable, a LAN cable, or wirelessly.

  Further, in the information processing apparatus 200 to which the image reading apparatus 100 of the present embodiment is connected, software (a control program, for example, also called a scanner driver) that can control the image reading apparatus 100 is executed. As a result, the image reading apparatus 100 can be controlled.

  In practice, the user can select, for example, an image of resolution, number of colors, number of gradations, reading surface, reading area, and the like from a user interface such as a control screen of the image reading apparatus 100 displayed by executing the software. Reading conditions can be set.

  The setting by the user is transmitted from the information processing apparatus 200 to the image reading apparatus 100 and is referred to in an image reading process or the like. In other words, the image reading apparatus 100 is configured to execute a reading operation according to setting conditions specified by the user.

  Image data read by the image reading apparatus 100 is transmitted to the information processing apparatus 200. A display unit 201 and an operation unit 202 are connected to the information processing device 200. When the information processing device 200 executes a scanner driver, a user interface (UI) using the display unit 201 and the operation unit 202 is used. ) Is realized.

  That is, the user can check the content of the image data read by the image reading device 100 via the display unit connected to the information processing device 200.

  Further, the image reading apparatus 100 side reads the image of the document by the image reading units 8 and 9 according to the image reading conditions set by the user, and further transmits the image data read by the image reading units 8 and 9 to a predetermined destination. It is like that.

  For example, as shown in FIG. 2, the image reading apparatus 100 of the present embodiment receives image data read by the image reading units 8 and 9 externally (here, the information processing apparatus 200) by an image output unit (image output means) 106. The control unit 102 including the CPU controls so as to transmit the data.

  The control unit 102 included in the image reading apparatus 100 executes a program for realizing, for example, procedures shown in FIGS. The UI unit 107 can display UI screens such as those shown in FIGS.

  Here, although not shown, the image reading units 8 and 9 include a light irradiating unit composed of an LED or the like that irradiates a conveyed document with light of a plurality of colors, and a light receiving unit that receives reflected light from the document.

  For example, in the present embodiment, the image reading units 8 and 9 irradiate (light scan) light of R (red), G (green), and B (blue) as light of a plurality of colors irradiated on the document, The reflected light from the original is read in one line. Note that the timing of irradiating light from such a light irradiation unit is controlled by the control unit 102.

  With such a configuration, the image reading apparatus 100 scans an original image drawn on an original, converts it into full-color bitmap image data (or a compression format thereof) represented by RGB color components, and outputs the data. be able to. In this full-color image data, for example, a color is expressed by 24 bits / 1 pixel or 32 bits / 1 pixel in which RGB colors are represented by 8 bits.

  Further, as shown in FIG. 1, the control unit 102 controls driving of the feed roller 4 when receiving a document reading command from the information processing apparatus 200 such as a PC, whereby the document on the paper feed tray 2 is separated from the separation pad 5. Are separated and fed one by one to the conveyance path.

  Subsequently, the document is conveyed toward the image reading units 8 and 9 by the conveyance roller pair 6. Although not shown, a registration sensor (transmission type optical sensor) for detecting the arrival and passage of the document is provided between the conveyance roller pair 6 and the image reading units 8 and 9 in the document conveyance direction.

  Then, when the control unit 102 detects the arrival of the document by the registration sensor, the control unit 102 controls the image reading units 8 and 9 to start reading from the image reading start position P set before the image reading units 8 and 9. To do.

  Specifically, reading starts at the timing when the leading edge of the document reaches the image reading start position P. Specifically, the R (red) light is turned on from the light irradiation unit and the reflected light is read by the light receiving unit for one line, and then the G (green) light is turned on by the light irradiation unit and 1 is received by the light receiving unit. Read the line, then turn on B (blue) light with the light irradiation unit and read one line with the light receiving unit.

  Then, the image reading units 8 and 9 of this embodiment transfer the image data for one line of each RGB to the image processing unit 103 (see FIG. 2). During this time, the document is conveyed by rotating the conveyance roller pairs 6 and 7. As described above, the image reading apparatus 100 repeatedly performs the above-described operation, thereby reading the conveyed document in color and outputting image data of the document.

  The image data read by the image reading unit 8 or 9 is corrected by the image correction unit 105 serving as an image correction unit under the control of the control unit 102, and is output to the information processing apparatus 200 by the image output unit 106. The image output unit 106 has an image output mode for outputting the image data corrected by the image correction unit 105 described above, and an image output mode for outputting the image data not corrected by the image correction unit 105, It is possible to switch by user operation. The switching may be performed by the information processing apparatus 200 or the like, or by a user operation using a user interface provided in the image reading apparatus 100. These image output modes are automatically selected according to the operation, for example, the latter (second) mode is selected when a color profile for correction is generated, and the former (first) mode is selected otherwise. May be switched automatically.

  Note that the image output unit 106 has not only an image data output function in the example of the present embodiment, but also a function such as communication with the information processing apparatus 200, such as accepting a scanner setting or a scan execution instruction. You may do it.

  An image correction unit 105 shown in FIG. 2 is an example of an image correction unit having a function of performing correction processing on read image data. This correction processing includes correction processing performed by the image reading apparatus (scanner apparatus) 100 such as skew correction and color correction.

  In the present embodiment, the correction processing is described in the image reading device 100. However, for example, the correction processing may be performed by the information processing device 200 other than the image reading device 100, or the image The processing may be divided between the reading device 100 and the information processing device 200 and shared.

  Further, such an image correction unit 105 uses a correction coefficient for correcting image data. The correction coefficient is calculated and determined by the correction coefficient calculation unit 103. The correction coefficient calculation unit 103 determines a correction coefficient (also referred to as a correction parameter) used by the image correction unit 105 for color correction.

  In determining the correction coefficient described above, for example, in this embodiment, image data read by an external device is used as a reference. Here, the external device has a function and specification different from those of the image reading device 100 of the present embodiment, for example, a function of a reading method of an image reading unit (image reading sensor).

  In this embodiment, a contact image sensor (CIS) is used as the image reading units 8 and 9, and the image data read by the external device here includes, for example, image data read by a CCD. Can do.

  Even if the same original is read, the image data read by the CIS and the image data read by the CCD may not necessarily match in color. Therefore, in the present embodiment, for example, the image correction unit 105 performs the above-described image correction in order to align the color of the image data read by the image reading units 8 and 9 with respect to the image data read by the CCD.

  The image reading apparatus 100 according to the present embodiment includes a reference image input unit 104 for inputting image data (external data) read by the above-described external apparatus. The reference image input unit 104 inputs a reference image (image data of the reference image) described later, and temporarily stores it as necessary. The reference image input unit 104 may be called a reception unit that receives external data.

  The reference image can also be input through an external storage medium such as a USB memory or an application such as an email that the information processing apparatus 200 has. Therefore, when inputting from an external storage medium, the connector portion into which the external storage medium is inserted constitutes at least a part of the image input unit 104. In the case of an application such as mail, the application itself functions at least as the image input unit 104.

  Further, when the image is read for the correction coefficient determination process for color correction by the correction coefficient calculation unit 103, the color correction by the image correction unit 105 is not applied. However, skew correction may be applied.

  In the following description, as shown in FIG. 2, it is assumed that the image reading apparatus 100 has the components of the present invention.

<Example of adjustment document>
FIG. 3 shows an example of an adjustment document. A color sample image is formed on the adjustment document 301. In the color sample image, a plurality of different color patches 311 are arranged in a grid pattern.

  The reason why they are arranged in a grid is that the position of each color patch can be easily specified by scanning the read image along the main scanning direction and the sub-scanning direction.

  One color patch is a square filled with a single color, and in this example, all color patches have the same shape and the same size. In the color sample image, five color patches of the same color are arranged in a line so that the density decreases in order from the left.

  Such rows are arranged in order from the top so that the hues are different in each row. In the example of FIG. 3, black, red, green, blue, yellow, cyan, magenta and those arranged in order from top to bottom are used.

  That is, as the color patch color of the color sample image, in the example of the present embodiment, in addition to RGB which is a color component read by the image reading apparatus 100, YMC (yellow, magenta, cyan) which is a subtractive color mixture of two colors of them. ) And black (monochrome), which is a mixed color of all three colors.

  For example, assuming a color space where the vertical axis is the lightness axis, the phase around the lightness axis is hue, and the distance from the luminance axis is saturation, each color patch of the color sample image is placed at the corresponding position in the color space It shall be.

  As a result, a color solid in which the lightness axis is defined by each patch of achromatic color and the extension is defined by patches of other colors is obtained. Therefore, the color of each color patch is also called a representative color. As described above, it is desirable to select a color that can cover the color range reproduced by the image reading apparatus 100 as wide as possible.

  In the example of the present embodiment, the adjustment document 301 is output as an adjustment image using images read by the image reading units 8 and 9 of the image reading apparatus 100 (referred to as a target image reading apparatus) in FIG. In particular, an image read by an external device whose color is to be matched, specifically, an image read by another image reading device (referred to as a reference image reading device or a reference device) is used as a reference image.

  For example, the adjustment document 301 may be printed by a printing apparatus in advance, or may be prepared by providing a color sample image as image data and printing it by a color printer. Note that although the image correction units 8 and 9 may have different correction coefficients, the processing to be performed may be the same.

  The reference image may be stored in advance in a storage medium such as a USB memory, the information processing apparatus 200, or the like. Regarding the relationship with correction, the adjusted image and the reference image indicate correspondence between colors before and after correction, the adjusted image indicates a representative color before correction, and the reference image indicates a representative color after correction.

<Determination of correction factor>
Next, the creation of the correction coefficient using the adjustment image and the reference image performed by the correction coefficient calculation unit 103 will be described with reference to the flowchart of FIG. The flowchart of FIG. 4 is executed by the correction coefficient calculation unit 103 of the image reading apparatus 100.

  Note that the correction coefficient calculation unit 103 may be realized by the control unit 102 including the CPU executing the procedure of FIG. In this case, it can be said that the control unit 102 executes the procedure of the flow of FIG.

  4 is started by, for example, a predetermined button operation provided in the UI unit 107, and a user interface for the operation is first displayed on the UI unit 107. An example of the user interface screen is shown in FIG. In the initial state, neither the reference image 1101 nor the adjustment image 1102 is displayed.

  First, when the load button 1103 is pressed in this state, for example, the load instruction is transmitted to the image reading apparatus 100, and the image reading apparatus 100 stores the reference image that has been created and stored in advance based on the adjustment document 301. Reading from the medium or the information processing apparatus 200 (S401).

  The read reference image is stored in a memory (not shown) of the image reading apparatus 100 and displayed as a reference image 1101 on the UI. Next, when the adjusted original is set in the image reading apparatus 100 and the scan button 1104 is pressed, the adjusted original 301 is read using the image reading unit 8 or the image reading unit 9 (S402). The read image is called an adjusted image. Which of the image reading unit 8 and the image reading unit 9 is to be read may be determined in advance as being read by both, for example, or may be determined according to designation by an operator or the like at the time of reading. When both are read, the correction coefficient for each reading unit is determined using each adjustment image. In any case, the adjustment image is read by the image reading unit which is a target for determining the correction coefficient.

  The adjusted image is stored in the image reading apparatus 100 and displayed as the adjusted image 1102 on the user interface of FIG. Note that the layout may be a layout opposite to that of FIG. 11 as long as it is easy to compare the two images, and in the adjustment document, the color patches of the same color can be easily associated with each other. Good.

  Next, in response to pressing of the test button 1105 on the screen of FIG. 11, it is determined whether or not a color component can be acquired from each of the adjustment image and the reference image (S403). Whether or not a color component can be acquired is determined by specifying the coordinates of the square of the color patch from each of the adjustment image and the reference image and determining whether or not a predetermined number of squares can be detected in each image. Details will be described later with reference to FIGS.

  Next, when it is determined in S403 that the color components can be acquired, the respective color components are acquired from the square positions of the detected color patches, and the color components of each color patch of the adjustment image and the corresponding reference image are acquired. It is checked whether there is a large difference between the color components of the color patch (S404).

  As the color component of the color patch, the color component of one pixel at the position of the detected color patch may be used as the color component of the color patch. Alternatively, the color components of pixels within a predetermined range of the pixels may be acquired, and the average value may be used as the color component of the color patch.

  The correspondence between the reference image and the color patch of the adjusted image is determined based on the correspondence of the position in each image. The large difference may be determined as follows, for example.

For example, the color components of the i-th color patch from the left and the j-th color patch from the top are extracted from the adjusted image and the reference image, respectively. When this is set to (R _ij , G _ij , B _ij ) and (R ′ _ij , G ′ _ij , B ′ _ij ), the color difference D _ij is expressed as follows.
D _ij = | R _ij -R ' _ij | + | G _ij -G' _ij | + | B _ij -B ' _ij |
At this time, if the color difference D _ij is equal to or greater than a predetermined threshold value, the adjustment image and the reference image are treated as errors such as a difference in orientation, and the input of the adjustment image and the reading of the reference image are obtained again.

  For example, as shown in FIG. 10, when the reference image and the adjusted image 1001 are upside down, the process is repeated from S401 in the determination of S404.

  On the other hand, if there is no significant difference in the square color component of each color patch in the determination of S404, the color component of the color patch at the corresponding position is associated and stored as a correction coefficient (correction parameter or mapping) (S405). ). For example, a name specified by the user may be added to the correction coefficient.

  At this time, if a negative determination result is obtained in S403 or S404, a message to that effect may be displayed on the UI to prompt confirmation.

  Further, when both of the determination results are positive, the correction parameter may be saved in response to pressing of the set button 1106. When storing a plurality of correction parameters, an identification name may be input.

  As described above, the correction coefficient for correcting the image data read by the image reading units 8 and 9 can be calculated and stored from the adjusted image and the reference image. The determined correction coefficient is used for color correction of image data read by the image reading apparatus 100, and color correction is executed.

  As a result of the correction, the color of the read image data is converted into a color output by the reference image reading apparatus and output. As a result, the same image can be output in the same color even between different image reading apparatuses.

  Note that S404 is a process provided to correct a difference in colors that should be output as the same color. Therefore, by skipping S404, it is possible to convert the color of the adjusted image into the reference image without performing this process.

<Identification of color patch location>
Next, the process for determining whether or not the color component can be acquired in step S403 will be described with reference to the flowcharts of FIGS. FIG. 5 is a procedure for determining the positions of the upper and lower sides of each color patch.

  Even in the case of each color patch, in this example, the color patches of the same hue are arranged in one line and share the vertical coordinate (vertical coordinate), so for example, the patch in the leftmost column of the adjustment document. Therefore, each position may be specified.

  In this description, it is assumed that the scanned image data has been subjected to skew correction. In the following description, the object to be handled is image data, which is called an image. Since the processing target of the processing in FIG. 5 is both the reference image and the adjustment image, the processing described below may be performed on both images. The same applies to the procedure of FIG.

  First, attention is paid to pixels that are shifted to the right by a predetermined number of pixels from the upper left end of the image obtained by reading the adjustment document shown in FIG. 3 (S501).

  That is, when the upper left corner of the image is the head position of the image data, attention is paid to pixels that are a predetermined number of pixels away from the head position in the main scanning direction. Here, the predetermined number of pixels is the number of pixels that are highly likely to be a column included in the leftmost patch.

  Next, it is checked whether the brightness of the pixel of interest is below a predetermined threshold (S502). If not below the threshold value, the pixel of interest is shifted downward by a predetermined line, for example, one line (S503). This is repeated until a pixel whose brightness is less than or equal to the threshold is found. If a pixel below the threshold is found, the vertical coordinate at this time is stored (S504).

  Here, the threshold value is a value for distinguishing the color patch from the background, and since it is considered that the lightness of the background is the highest, the value between the color patch of the maximum lightness and the lightness of the background is selected as the threshold value. The

  The coordinate value stored in S504 indicates the coordinate value of the upper row of the color patch. The coordinate value can be indicated by the number of lines from the upper end, for example.

  Next, it is checked whether the brightness of the pixel of interest is above the threshold (S505). If not above the threshold value, the pixel of interest is shifted downward, for example, by one pixel (S506). This is repeated until a pixel whose brightness is above the threshold is found.

  If a pixel above the threshold is found, the vertical coordinate at this time is stored (S507). The coordinates stored in S507 indicate the coordinate values of the lower line of the color patch. The above is repeated until a predetermined number of coordinates are stored (S508).

  The prescribed number here is the number of color patches arranged in the vertical direction, and is seven in the example of FIG. If it is determined Yes in S508, the coordinates of the upper and lower sides of each color patch have been identified.

  Next, detection of the coordinates of the left and right sides of the color patch will be described with reference to the flowchart of FIG. In this procedure, the coordinates of the left and right sides of each color patch are identified in the same manner as the coordinates of the upper and lower sides of each color patch in FIG.

  First, a pixel shifted downward by a predetermined pixel from the upper left end of the image is noticed (S601). Next, it is examined whether the brightness of the pixel of interest is below a threshold value (S602). This threshold value may be the same value as the threshold value used in the processing of FIG.

  If it is not less than the threshold value in S602, the pixel of interest is shifted to the right (S603). This is repeated until a pixel whose brightness is less than or equal to the threshold is found. If a pixel below the threshold is found, the horizontal coordinate at this time is stored (S604). The coordinates stored here indicate the coordinate values of the column on the left side of each color patch.

  Next, it is checked whether the brightness of the pixel of interest is above the threshold (S605). If not above the threshold value, the pixel of interest is shifted to the right (S606). This is repeated until a pixel whose brightness is above the threshold is found.

  If a pixel above the threshold is found in S605, the horizontal coordinate at this time is stored (S607). The coordinates stored here indicate the coordinate values of the column on the right side of each color patch.

  The above processing is repeated until a predetermined number of coordinates are stored (S608). The prescribed number here is the number of color patches arranged in the horizontal direction, and is 5 in the example of FIG. If YES in S608, the coordinates of the left and right sides of each color patch have been identified.

  Thereby, the coordinates of each square in the adjusted document can be detected. That is, each color patch is a rectangular area surrounded by the upper and lower rows specified in the procedure of FIG. 5 and the left and right columns specified in the procedure of FIG.

  The above is performed on the adjustment image and the reference image, and when the coordinates corresponding to the number of color patches included in each image cannot be stored, it is determined that the color component could not be acquired.

  That is, if the coordinates of the number of color patches included in each image cannot be stored, it is determined that there is a problem with the input adjustment image or the read reference image, and the adjustment image is input again to the user, Request reading of reference image.

  For example, as shown in FIG. 9, if the adjustment image 901 is tilted, the color components could not be acquired unless 5 × 7 = 35 color patches can be identified from the adjustment image 901 by the above-described procedure. Determined.

  Now, the colors of the color patches of the reference image and the adjustment image whose position and range are specified in the above manner can be associated, for example, in the following manner. When specifying the position and range of the color patch, numbers are assigned sequentially in the horizontal and vertical directions.

  Then, in the reference image and the adjustment image, the color patches specified by the same horizontal number and vertical number may be used as the corresponding color patches, and the respective colors may be stored in association with each other.

  Of course, the above-described example is merely an example. For example, when the reference image and the adjustment image are overlapped with the upper left corner as a reference, the color patch having the largest overlapping area is associated with the corresponding color patch. May be.

  In this way, the data that associates the color of each color patch of the adjustment image with the color of each color patch of the reference image is an image profile (image profile result) described later, and is correction coefficient data or a correction coefficient. Also called a correction parameter or mapping.

  The image profile is data output from the correction coefficient calculation unit 103. The correction coefficient calculation unit 103 uses the image reading units 8 and 9 to read the same original as the original image (adjusted original 301) of the reference image (data) input by the reference image input unit 104 (adjustment). Image) and the reference image input by the reference image input unit 104 are compared in units of color patches or in units of pixels, and correction coefficient data for bringing the adjusted image closer to the reference image is generated as an image profile. Therefore, the correction coefficient calculation unit 103 is sometimes called an image profile generation unit.

  Note that the color patch identifiers may be associated with each other without directly relating the colors. The identifier of the color patch may be information indicating the position of the specified color patch, for example. In this way, the correction coefficient is calculated in S405 of FIG. 4 and stored in the image correction unit 105, for example.

<Color correction processing>
Next, correction processing in the present embodiment will be described with reference to the flowchart of FIG. This process is executed by the image correction unit 105.

  Note that the image correction unit 105 may be realized by executing a program for realizing the flow of FIG. Alternatively, this program is not limited to software, and may be realized by hardware by configuring a logic circuit capable of executing the procedure of FIG. 7 using an ASIC or the like.

  First, it is confirmed whether the image profile result (that is, the correction coefficient) is stored (S701). This correction coefficient is determined by the procedure of FIG. 4 and stored in S405. In S701, if a correction coefficient is stored, for example, the name of the correction coefficient is displayed as identification information of the stored correction coefficient (S702). If a plurality of correction coefficients are stored together with their names, the list may be displayed as an option.

  FIG. 8 is an example of a screen displayed by the scanner driver when the document is read by the image reading apparatus 100. This UI screen includes a column for selecting a correction coefficient.

  The UI 801 may be displayed on the display unit 201 in response to a user operation, for example, when an information processing apparatus 200 executes an application program that performs image reading.

  In the UI 801, a list of correction coefficients is displayed in a list box 814. The user selects a desired correction coefficient therefrom and presses an OK button 816, whereby the selected correction coefficient is used for subsequent correction.

  When the preset mode 813 is checked, a list of correction coefficients preset at the time of factory shipment is displayed on the image reading apparatus 100 in the list box 814, and the list can be selected from the list.

  The preset correction coefficient may be created based on a reference image obtained by reading the adjustment document 301 with another commercially available image reading apparatus, for example.

  When using a correction coefficient created by the user according to the procedure of FIG. 4, for example, the preset mode may be unchecked, or only one correction coefficient is stored, or a correction coefficient used in advance If the setting is fixed, the correction coefficient to be used may be determined without displaying the option.

  The UI 801 includes a brightness adjustment bar 811, a contrast adjustment bar 812, a gamma setting button 815, and the like, and can be adjusted.

  When the correction coefficient used for correction is determined in S702, ON / OFF of the correction processing function is confirmed (S703). If the function is set to be turned ON, the correction coefficient selected in S702 is loaded (S704).

  Conversely, if it is determined that the correction coefficient is not stored in S701, or if the correction processing function has been selected to be turned off in S703, the default correction coefficient that disables the correction is loaded. (S705).

  The default correction coefficient here may be such that all the RGB values associated in the adjusted image and the reference image have the same value.

  Note that the correction on / off switching may be performed from the UI 801. Instead of performing step S703, the correction may be performed using the selected correction coefficient.

  When the correction coefficient to be used is loaded, the original is scanned (S706). Then, correction processing using the mapped color components is performed on the scanned image (S707).

  The correction process using the mapped color component (that is, correction coefficient) performed by the image correction unit 105 performed in S707 will be described. In S707, the read image is corrected as follows based on the color components mapped to each pixel of the image.

  First, attention is focused on the first pixel of the input image data (that is, read in S706). The order of interest may be the raster scanning order. Then, the color having the smallest color difference from the RGB value of the pixel of interest is identified among the colors of the color patches of the adjusted image. The determination of the color difference may be performed in the same manner as S404 in FIG.

Here, the RGB value of the pixel of interest is (R _S , G _S , B _S ), and the color component having the smallest color difference from the color of the pixel of interest among the colors of each color patch in the adjusted image is (R _i , G _i , B _i ).

Next, the color components of the reference image associated with the color components (R _i , G _i , B _i ) are identified based on the correction coefficient, and the values are determined as (R ′ _i , G ′ _i , B ′ _i ) And

At this time, the corrected RGB values (R _D , G _D , B _D ) are output under the following conditions.
R _D = R ' _i −R _i + R _s
G _D = G ' _i −G _i + G _s
B _D = B ' _i −B _i + B _s
That is, each color component of the pixel of interest is corrected by adding the color difference between the color of the adjustment image closest to the pixel of interest and the color of the reference image corresponding to the color component of the pixel of interest. The above-described color correction processing is executed over the entire image while sequentially proceeding with the pixel of interest. As described above, the correction coefficient or the image profile can be referred to as color information including (or indicating) the color difference of the corresponding colors of the reference image and the adjustment image. It is realized using.

  As described above, the input image is corrected based on the correction coefficient created in S105. The color correction method described here is merely an example, and other methods may be used for correction.

  For example, specify two or more colors instead of one from the color patch of the adjustment image, and specify colors corresponding to those colors from the reference image, and select a color between the corresponding colors. The average of the color differences may be corrected by adding each color component to the target pixel. As this average, not a simple average but a weighted average weighted by the reciprocal of the distance to the target pixel may be used. Taking an average value makes it difficult to produce an extreme value in the output value.

  Further, by using only the color component having a small color difference with respect to the color component of the input pixel for calculation, it is possible to prevent the result from being shifted due to the influence of the color component having a large color difference.

  As described above, according to the present embodiment, the color (particularly the color value) of image data that is read by an external device or the like having a different reading specification such as an image reading method and input to the image reading apparatus 100 of the present embodiment. Therefore, the image data read by the image reading units 8 and 9 included in the image reading apparatus 100 according to the present embodiment is corrected and output, so that the image data serving as a reference and the image data output from the image reading apparatus 100 are output. It is possible to reduce a difference in hue from image data.

  Therefore, according to the image reading apparatus 100 of the present embodiment, when reading the same single document, even if the image reading apparatus has different reading specifications such as a sensor and a light source, image data with substantially the same color can be output. Can do.

[Other Embodiments]
In the above embodiment, as illustrated in FIG. 2, the image reading apparatus 100 has been described as including the components necessary for the present invention. However, in the present invention, some of the components may be included in the information processing apparatus 200.

  For example, the image reading apparatus 100 includes image reading units 8 and 9, a control unit 102, an image correction unit 105, and an image output unit 106. Other components, that is, the UI unit 107, the correction coefficient calculation unit 103, and the reference image input unit 104 are realized on the information processing apparatus 200 side by, for example, an application or a scanner driver.

  In this case, the correction coefficient generated by the information processing apparatus 200 in the procedure of FIGS. 4 to 6 is downloaded to the image reading apparatus 100, and the image reading apparatus 100 executes the correction process.

  In this way, the correction coefficient determination process of FIGS. 4 to 6 is executed by the information processing apparatus 200, and in the above-described embodiment, the screens of FIGS. Are displayed by a user interface realized by the display unit 201 and the operation unit 202. In this case, the UI unit 107 is unnecessary.

  Furthermore, since the information processing apparatus 200 executes the processes in FIGS. 4 to 6, it is not necessary to store the reference image and the adjusted image in the image reading apparatus 100. In this case, the correction coefficient calculated in S405 of FIG. 4 may be transmitted to the image reading apparatus 100. With this configuration, for example, even if the image reading apparatus 100 is not provided with a display unit, a user interface similar to that of the above-described embodiment can be provided.

  In the example of the present embodiment, an example in which rectangular color patches as shown in FIG. 3 are arranged in a grid pattern as an adjustment document has been described. However, the adjustment document may have a format different from the example of FIG.

  In the correction process, the output value is determined using the color component acquired from the adjustment image for the color component of each pixel of the input image. For this reason, the greater the number of types of color components in the adjustment document, the smaller the deviation between the color components of the input pixels and the color components used to calculate the output value, thus increasing the accuracy. Therefore, the correction accuracy can be further improved by further increasing the number of colors of the adjustment document.

  Further, the format of the adjustment document is not limited to a document in which squares filled with a single color are arranged as shown in FIG. 3, and any format can be used as long as the color component and its position can be acquired.

  Further, in the example of this embodiment, one adjustment image and one reference image are used, but there may be a plurality of combinations of pairs. For example, a plurality of types of adjustment documents are prepared, an adjustment image and a reference image are created for each adjustment document, and mapping is acquired. Then, all the acquired mappings may be combined as one mapping and used for the correction process.

  In the example of the present embodiment, the reference image is an image obtained by reading the adjustment document using another image reading device. However, any image may be used as long as it is the same format as the image obtained by reading the adjustment document.

  For example, an adjustment document may be measured using a calibrated colorimeter, and an adjustment image corrected based on the result may be used as a reference image. In this case, it is possible to match the image read by the image reading device with the result measured by the colorimeter.

  Further, an image obtained by correcting a specific color component with respect to the adjusted image may be used as the reference image. In this case, an image in which only a specific color component is corrected can be output in the same manner as when the reference image is created.

  Furthermore, in the case where an image read by another image reading apparatus is used as the reference image, the reference image may be generated using the adjustment document used to read the adjustment image.

  The document may be deteriorated depending on the storage condition, or the printing may be misaligned. If images obtained by reading different originals for the adjusted image and the reference image are used, these differences may have an adverse effect.

  Therefore, by causing the image reading apparatus to read the same document when creating the adjustment image and the reference image, it is possible to eliminate an adverse effect that may occur due to different documents.

  In the example of the present embodiment, the mapping in which the color component on the adjusted image and the color component on the reference image are associated with each other is used as it is for the correction process. However, the mapping may be adjusted for the correction process.

  For example, mapping may be performed by associating a group of predetermined RGB values with an output value obtained by performing correction processing on each element of the group of RGB values. As an example of a group of RGB values determined in advance, lattice points in an RGB-3D space may be used. In this case, a color component having a small color difference can be specified from the RGB value of the input pixel.

  In this way, by fixing the color components of the adjustment image used for the correction processing in advance, it is possible to speed up the processing for calculating which color component and color difference are small, and to speed up the entire correction processing. .

  In the example of the present embodiment, the correction process is not performed when the adjustment image is read. When correction is performed, the RGB value before correction processing from the adjusted image is obtained by back-calculating the correction coefficient when the adjusted image is read, and the result is associated with the result of the reference image.

  In the present embodiment, the case where image correction is performed in the image reading apparatus 100 serving as an image processing apparatus has been described. However, the present invention is not limited to this, and a mode in which an image is corrected by an application in the information processing apparatus is also described. Widely targeted.

  In other words, the present invention reads an image in an image output apparatus that corrects the read image data and outputs corrected image data, or an image reading system that includes the image reading apparatus 100 and the information processing apparatus 200 described above. A configuration having image output means for correcting the image data and outputting the corrected image data can be widely used.

  In the above-described embodiment, the sheet-through type image reading apparatus 100 that reads an image of a document while conveying the document has been described as an example. However, the present invention is of course not limited thereto, and for example, a document is placed. The present invention can also be applied to correction of image data read by a flat bed type image reading apparatus that reads an image of a placed original while moving the image reading unit along the placement glass while being placed on the glass.

  DESCRIPTION OF SYMBOLS 100 Image reader, 103 Correction coefficient calculation part, 105 Image correction part, 200 Information processing apparatus

Claims (17)

Image correction means for color correcting image data obtained by an image reading means for reading an image of a document;
Image output means having an image output mode for outputting the corrected image data corrected by the image correction means,
The image output device, wherein the image correction unit performs color correction on the image data based on an image profile result of external data associated with an external device having a function of reading an image of a document. Receiving means for receiving the external data;
Image profile generation means for generating image profiles of the external data by comparing image data obtained by reading the same original as the original original of the external data with the image reading means and the external data in pixel units;
The image output apparatus according to claim 1, further comprising:   The image profile result of the external data includes color information indicating a color difference between image data obtained by reading the same original document as the external data by the image reading unit and the external data. The image output apparatus according to claim 1 or 2.   The image output apparatus according to claim 1, wherein the image output unit has an image output mode in which the image data read by the image reading unit is output without being corrected by the image correction unit. Further comprising a specifying means for specifying a correction parameter based on the image profile result of the external data;
5. The image correction unit according to claim 1, wherein the image correction unit corrects the image data read by the image reading unit based on the correction parameter specified by the specifying unit. 6. Image output device. A user interface;
The image output apparatus according to claim 5, wherein the correction parameter is designated by a user on the user interface. The correction parameter includes color correspondence before and after correction by the image correction unit,
The image output apparatus according to claim 6, wherein an image in which colors before and after the correction are associated is displayed on the user interface. The image in which the color before and after correction is associated includes a reference image and an adjustment image in which a plurality of colors are arranged before and after correction by the image correction unit,
8. The image output apparatus according to claim 7, wherein the reference image and the adjustment image are an image obtained by reading an original document by the external device and an image read by the image reading unit, respectively.   The user interface displays, as the adjustment image, color image data obtained by reading the original document in which a plurality of colors are arranged by the image reading unit, and as the reference image, at a position corresponding to each color of the original document. 9. The image output apparatus according to claim 8, wherein a color image in which corresponding colors are arranged is displayed.   The image output apparatus according to claim 9, wherein the user interface displays a color image obtained by reading the original document with an external image reading apparatus as the reference image.   11. The image output apparatus according to claim 9, wherein the original document includes a plurality of monochrome samples having different densities and a plurality of color samples having different hues.   The user interface displays, as the reference image, one reference image selected from a plurality of different reference images stored in the image reading system in association with the adjustment image. The image output device according to claim 8.   The image correction means is a color difference between the focused color of the image data obtained by reading the original document with the image reading means and the focused color of the image data obtained by the image reading means. The image output apparatus according to claim 2, wherein the focused color is corrected by adding a color difference between the color having the smallest color and the color of the external data corresponding to the color of the image data.   When the color difference between the color of the image data obtained by reading the original document with the image reading unit and the color of the external data corresponding to the color exceeds a threshold, the image profile generation unit 14. The image output apparatus according to claim 2, wherein no correction parameter is generated. An image output device according to any one of claims 1 to 5 and an information processing device communicably connected to the image reading device,
The information processing apparatus has a user interface;
An image reading system in which the correction parameter is designated by a user on the user interface. The image output device includes an image reading device and an information processing device communicably connected to the image reading device,
The image reading system according to claim 15, wherein the image reading apparatus includes the image reading unit, the image correction unit, the image output unit, and the user interface.   The image reading system according to claim 16, wherein an image in which colors before and after correction by the image correction unit are associated is displayed on the user interface.