JP2005184660A - Image reading apparatus, color correction original, color correction method and color correction program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus, color correction original, color correction method and color correction program in which a labor for correcting color reproducibility using the color correction original is reduced. <P>SOLUTION: An image reading apparatus comprises: a colorimetric value specifying means for recognizing color information based on a digital image outputted from a reading means by reading a color correction document describing a color sample patch and color information for specifying a colorimetric value of the color sample patch, and specifying a colorimetric value based on the recognized color information; a correction value setting means for setting a correction value based on a gradation value of a pixel representing the color sample patch of the digital image outputted by reading the color correction original and the colorimetric value specified by the colorimetric value specifying means; and a correction means for correcting the gradation value of the digital image outputted by reading an arbitrary original using the reading means based on the correction value set by the correction value setting means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus, a color correction document, a color correction method, and a color correction program.

It is known that an image reading apparatus such as an image scanner deteriorates in color reproducibility due to aging of a fluorescent tube used as a light source. It is also known that color reproducibility varies depending on individual differences even in a state where there is no secular change.
As a method for easily correcting the difference in color reproducibility due to secular change or individual difference, a method using a color correction document on which a color sample patch is written is known. In this method, a color correction document is read and a digital image is output, and the gradation value of the pixel representing the color sample patch in the output digital image and the color sample patch written on the color correction document are spectrally converted. A colorimetric value previously measured by a colorimeter such as a meter is compared, and correction is performed by increasing or decreasing the gradation value of the digital image according to the difference. It is possible to correct the image reading device by recreating the profile used for color space conversion of the digital image. However, according to the simple method described above, the correction value can be set with simpler processing than when the profile is recreated from scratch. it can.

  However, in conventional image reading apparatuses, colorimetric values are generally stored in a file and recorded on a recording medium such as an attached CD-ROM in many cases. The file may be written in a predetermined area when the attached application program recorded on the recording medium is installed in a personal computer (PC). For this reason, the operator has to read the file storing the colorimetric values from a predetermined area of the recording medium or the PC when performing correction, and there is a problem that work is troublesome. In addition, the color correction original lot targeted by the colorimetric values stored in the file may be different from the color correction original lot attached to the image reading apparatus. In this case, work such as downloading a file storing colorimetric values corresponding to the lot via a communication network is troublesome.

  The present invention has been made in view of such problems, and an image reading apparatus, a color correction document, a color correction method, and a color correction device that reduce the labor of correcting color reproducibility using a color correction document. An object is to provide a correction program.

  To achieve the above object, an image reading apparatus according to the present invention includes a reading unit that reads a document and outputs a digital image, a digital image output from the reading unit, and a color sample patch and a color sample patch. The color information is recognized based on a digital image output by reading a color correction document on which color information for specifying a colorimetric value is written, and the colorimetric value is specified based on the recognized color information. Based on a colorimetric value specifying unit, a gradation value of a pixel representing the color sample patch of a digital image output by reading the color correction document, and a colorimetric value specified by the colorimetric value specifying unit. A correction value setting means for setting a correction value and a gradation value of a digital image output by reading an arbitrary document by the reading means based on the correction value set by the correction value setting means. Characterized in that it comprises a correction means for correcting Te. According to this image reading apparatus, since the colorimetric values are specified from the color information written on the color correction document, the operator only needs to read the color correction document and store the colorimetric values. There is no need to read the read file or input the read colorimetric value to the image reading apparatus. Further, it is difficult for the color correction document lot and the lot targeted by the colorimetric value to be shifted, and it is difficult to perform operations such as downloading. Therefore, according to this image reading apparatus, it is possible to reduce the labor of correcting the color reproducibility using the color correction document.

  To achieve the above object, an image reading apparatus according to the present invention reads a document to create a digital image, and converts the color space of the created digital image to another color space based on a predetermined color space conversion table. A color correction document including a color sample patch and color information for specifying a colorimetric value of the color sample patch, which is a digital image output from the reading unit. A colorimetric value specifying means for recognizing the color information based on the output digital image and specifying a colorimetric value based on the recognized color information; and a digital image output by reading the color correction document. Conversion table updating means for correcting the color space conversion table based on the gradation value of the pixel representing the color sample patch and the colorimetric value specified by the colorimetric value specifying means; Characterized in that it comprises. According to this image reading apparatus, since the colorimetric values are specified from the color information written on the color correction document, the operator only needs to read the color correction document and store the colorimetric values. There is no need to read the read file or input the read colorimetric value to the image reading apparatus. In addition, the difference between the color correction original lot and the colorimetric value is unlikely to occur, and operations such as downloading are unlikely to occur. Therefore, according to this image reading apparatus, it is possible to reduce the labor of correcting the color reproducibility using the color correction document.

Furthermore, in the image reading apparatus according to the present invention, the color correction document is characterized in that the color information is represented by a barcode. According to this image reading apparatus, since a known technique for reading a barcode can be used, color information can be easily recognized.
Furthermore, in the image reading apparatus according to the present invention, the color correction document has the color information written in characters. According to this image reading apparatus, the operator can interpret the color information.

Further, in the image reading apparatus according to the present invention, the character is a URL for acquiring a colorimetric value via a communication network. According to this image reading apparatus, even if there is an error in the colorimetric value, it is only necessary to correct the colorimetric value on the server side, and correction of the colorimetric value is facilitated.
Furthermore, in the image reading apparatus according to the present invention, the color correction document includes a plurality of color sample patches representing different colors, and the color information specifies an average value of colorimetric values of the plurality of color sample patches. The correction means sets a correction value based on the average value and an average value of a plurality of gradation values corresponding to the plurality of color sample patches. The difference between the gradation value representing the color sample patch and the colorimetric value may differ depending on the color represented by the color sample patch. Setting correction values based on multiple color sample patches that represent different colors allows you to set correction values that can bring more colors closer to the colorimetric values compared to a single color sample patch. . Therefore, the effect of correction can be obtained more reliably.

  Further, in the image reading apparatus according to the present invention, the color correction document is written such that the expiration date of the color sample patch is readable, and the expiration date is recognized based on a digital image output by reading the color correction document. And an expiration date recognizing unit for warning and a warning unit for issuing a warning when the expiration date recognized by the expiration date recognition unit has passed. According to this image reading apparatus, it is possible to prevent an inappropriate correction value from being set by using a faded color correction document.

In order to achieve the above object, a color correction document according to the present invention is characterized in that a color sample patch and color information for specifying a colorimetric value of the color sample patch are readable. And According to this color correction document, the labor of correcting the color reproducibility using the color correction document can be reduced.
The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

  The present invention can be specified not only as an apparatus invention but also as a program invention, a recording medium recording the program, and a method invention.

Hereinafter, the best mode for carrying out the present invention will be described based on examples.
(First Example)
The image reading apparatus according to the first embodiment of the present invention includes a personal computer (PC) and an image scanner connected to the PC.
FIG. 2 is a block diagram showing a hardware configuration of the PC 2 constituting the image reading apparatus. The PC 2 includes a CPU 81, a ROM 82, a RAM 83, an operation unit 84, a display unit 85, an external storage unit 86, and a device I / F 87, which are connected to each other via a bus 88. The operation unit 84 includes a mouse, a keyboard, and the like. The display unit 85 includes a display such as a CRT or LCD, a display controller, and the like, and is used as a warning unit. The external storage unit 86 includes a hard disk, a hard disk controller, and the like, and stores an operating system (OS), a device driver for controlling the image scanner 1, correction values, and various other data. The device I / F 87 is configured based on a communication standard such as RS-232C, Bluetooth, USB, and the like, and is connected to the image scanner 1 so as to be communicable. The CPU 81 controls the entire PC 2 by executing a program stored in the ROM 82 or the external storage unit 86. In the first embodiment, the color correction program is mounted as a part of the device driver, and the CPU 81 executes the device driver stored in the external storage unit 86 to thereby read the color measurement value specifying means, the correction value setting means, It also functions as a correction unit, an expiration date recognition unit, and a warning unit. The ROM 82 is a memory that stores various programs and data in advance, and the RAM 83 is a memory that temporarily stores various programs and data. These various programs and data may be downloaded and input from a predetermined server via a network, or may be read and input from a computer-readable storage medium such as a removable memory.

FIG. 3 is a schematic diagram showing the image scanner 1 constituting the image reading apparatus.
The document cover 11 is connected to the housing 10 so as to be swingable from a posture in which the plate surface of the document table 12 is opened by a hinge to a posture in which the plate surface of the document table 12 is covered. The document cover 11 presses the document M placed on the surface of the document table 12 and covers the document table 12 so that light other than the light emitted from the light source 14 does not illuminate the document M.

The document table 12 is formed of a glass plate or the like, and closes a rectangular opening formed in the housing 10. There is a step between the upper surface of the document table 12 and the upper surface of the housing 10, and the document is positioned by contacting the step.
The linear image sensor 17 is mounted on the carriage 13 in such a manner that light receiving elements such as photodiodes are arranged in a straight line in the direction perpendicular to the paper surface in FIG. The linear image sensor 17 accumulates charges obtained by photoelectric conversion of light in a predetermined wavelength region such as visible light, infrared light, and ultraviolet light in a light receiving element for a certain time, and an electric signal corresponding to the amount of light received for each light receiving element. Is output using a CCD (Charge Coupled Device), a MOS transistor switch, or the like.

  The optical system 21 (see FIG. 4) includes a light source 14, a mirror 15, a lens 16, and the like as shown in FIG. The light source 14 is composed of a fluorescent tube lamp or the like. The mirror 15 and the lens 16 form an optical path for causing the linear image sensor 17 to form an optical image of the original M irradiated to the light source 14. As a result, an optical image of the original M on the main scanning line is formed on the linear image sensor 17.

FIG. 4 is a block diagram showing the image scanner 1.
The main scanning drive unit 24 is a drive circuit that outputs drive pulses necessary for driving the linear image sensor 17 to the linear image sensor 17. The main scanning drive unit 24 includes, for example, a synchronization signal generator, a drive timing generator, and the like.

  The sub-scanning drive unit 25 includes a slide shaft that is installed perpendicularly to the longitudinal axis of the linear image sensor 17 and that holds the carriage 13 slidably, a stepping motor, a drive belt, a drive circuit, and the like. When the stepping motor pulls the carriage 13 with the drive belt, the linear image sensor 17 and the original M move relative to each other in the α direction (sub-scanning direction) shown in FIG. 3, so that a two-dimensional image can be scanned.

  The AFE (analog front end) unit 22 includes an analog signal processing unit, an A / D converter, and the like. The analog signal processing unit subjects the electrical signal output from the linear image sensor 17 to analog signal processing such as amplification and noise reduction processing, and outputs the result. The A / D converter quantizes the electrical signal output from the analog signal processing unit into an output signal in a digital representation having a predetermined bit length, and outputs the output signal.

  The digital image processing unit 23 performs processing such as gamma correction, interpolation of defective pixels by a pixel interpolation method, shading correction, image signal sharpening, color space conversion, and the like on the output signal output from the AFE unit 22 A digital image expressed in a Lab color space that is an independent color space is generated. The various processes performed by the digital image processing unit 23 may be replaced with processes by a computer program executed by the control unit 26.

The interface (I / F) unit 20 is configured based on a communication standard such as RS-232C, Bluetooth, or USB, and is communicably connected to the PC 2.
The control unit 26 includes a CPU 27, a ROM 28, and a RAM 29. The CPU 27 executes computer programs stored in the ROM 28 and controls each unit of the image scanner 1. The ROM 28 is a memory that stores various programs and data, and the RAM 29 is a memory that temporarily stores various programs and data.

Next, the color correction document will be described.
FIG. 1 is a schematic diagram showing a color correction document. On the color correction document 30, a plurality of color sample patches representing different colors, a plurality of barcodes 32 as color information, and a number 33 representing an expiration date are printed. Here, the color sample patch refers to rectangular areas 31 a to 31 t painted with a specific color on the color correction document 30. In the first embodiment, 14 color sample patches from approximately black to light gray are arranged so that the color gradually becomes lighter from left to right and from top to bottom. The bar code 32 represents an average value of colorimetric values of a plurality of color sample patches. Each of the plurality of color sample patches is measured using a colorimeter, and one colorimetric value is obtained for one color sample patch. The average value of the color measurement values of the color sample patch means the average value of the plurality of color measurement values. Since the gradation value and the colorimetric value of the digital image need to be compared in the same color space, the colorimetric value is expressed in the Lab color space like the digital image. For this reason, three barcodes 32L, 32a, and 32b corresponding to the L component, a component, and b component of the average value of the colorimetric values are printed on the color correction document 30. Note that another device-independent color space such as the XYZ color space may be used as the reference color space. In the case of a device-dependent color space such as RGB, the result may differ between the image scanner 1 and the colorimeter even in a state where there is no secular change, which is not preferable because some kind of correspondence is necessary. The expiration date 33 indicates a time limit during which correction values can be set using the color correction document 30. In the first embodiment, a number “2003” is printed, which means that the period within the year 2003 is within the expiration date. The printed color sample patch fades with time, and an accurate correction value cannot be set. When the period when the color fading period or the degree of fading is within the allowable range expires is described as the expiration date, the user can visually recognize whether the color correction document 30 is valid or invalid, and the correction value is not accurate. Can be prevented from being set.

Next, the color correction program will be described.
FIG. 5 is a block diagram showing a logical configuration of the color correction program. The correction program includes a reading unit 41, an expiration date recognition unit 42, a warning unit 43, a colorimetric value specifying unit 44, a correction value setting unit 45, and a correction unit 46. In the drawing, two reading units 41 are shown for convenience, but they are the same.

The reading unit 41 controls the image scanner 1 and executes processing for reading a digital image.
The expiration date recognizing unit 42 executes processing for recognizing the expiration date based on the digital image output by reading the color correction document 30. Specifically, the expiration date is recognized by performing image processing similar to so-called OCR (Optical Character Reader) on the region corresponding to the region where the expiration date of the output digital image is written.

  The warning unit 43 executes a process for issuing a warning when the expiration date recognized by the expiration date recognition unit 42 has passed. If the recognized expiration date is “2003” and today is 2004, the warning unit 43 displays, for example, a warning message “This color correction document 30 has expired” on the display unit 85. To do. In addition, when a sound reproduction means is provided, you may warn by reproducing an audio | voice file or sounding a sound. Further, when the image scanner 1 includes an LCD, a warning may be given by displaying on the LCD, or when the image scanner 1 includes an LED, a warning may be given by turning on the LED. If today is 2003, no warning is issued because the expiration date has not yet passed. By recognizing the expiration date and giving a warning, it is possible to prevent an inappropriate correction value from being set even when a color correction document that has been faded without noticing the written expiration date is used. The expiration date may be represented by a barcode.

  The colorimetric value specifying unit 44 recognizes color information based on the digital image output by the reading unit 41 and output by reading the color correction document 30, and measures color based on the recognized color information. A process for specifying a color value is executed. Specifically, the bar and space patterns of the barcode 32 are analyzed by performing image processing similar to that of a so-called barcode reader, and converted into specific characters corresponding to the pattern. In the first embodiment, a number representing a colorimetric value is printed as a bar code, and thus converted into a number representing a colorimetric value. Therefore, in the first embodiment, the color information can be recognized and the colorimetric values can be identified at a time by recognizing the barcode 32. When the color information is represented by a bar code, a known technique for reading the bar code can be used, so that the color information can be easily recognized.

  The correction value setting unit 45 performs correction based on the gradation value of the pixel representing the color sample patch of the digital image output by reading the color correction document 30 and the colorimetric value specified by the colorimetric value specifying unit 44. Execute the process to set the value. Specifically, the correction value is set based on the average value of the colorimetric values and the average value of a plurality of gradation values corresponding to a plurality of color sample patches.

  FIG. 6A is a schematic diagram showing the colorimetric values specified by the colorimetric value specifying unit 44, and FIG. 6B shows the gradation values of the pixels representing the color sample patches in the digital image for each color sample patch. It is a schematic diagram shown in FIG. Since one color sample patch is represented by a plurality of pixels, for example, an average value for the plurality of pixels is set as a gradation value of the color sample patch. FIG. 6C is a schematic diagram showing correction values. In the bottom line of FIG. 6B, the average value of the gradation values of the color sample patch is shown for each of the L component, the a component, and the b component. The correction value is obtained by subtracting the average value of the tone values of the color sample patches shown in the bottom row of FIG. 6B from the colorimetric values shown in FIG. As a result, as shown in FIG. 6C, correction values are obtained for each of the L component, the a component, and the b component. The obtained correction value is stored in the external storage unit 86. Thereby, a correction value is set.

  The correction unit 46 executes processing for correcting the gradation value of the digital image output by reading an arbitrary document by the reading unit 41 based on the correction value set by the correction value setting unit 45. Specifically, the correction is performed by adding correction values for each of the L component, the a component, and the b component to the pixel of the digital image output by reading an arbitrary document. For example, if the correction value of the L component is −5, the correction value of the a component is 1, and the correction value of the b component is 3, all the pixels of the output digital image are uniformly added with −5, 1 is uniformly added to the a component of the pixel, and 3 is uniformly added to the b component of all the pixels.

Next, the flow of processing for setting a correction value will be described.
FIG. 7A is a flowchart showing a flow of processing for setting a correction value.
In S <b> 105, the image scanner 1 reads the color correction document 30 and outputs a digital image to the PC 2.
In S110, the PC 2 recognizes the expiration date based on the output digital image, and determines whether or not the expiration date has passed. If the time limit has passed, the process proceeds to S115, and if not, the process proceeds to S120.

In S115, a warning is issued and the process is stopped.
In S120, color information is recognized based on the output digital image, and a colorimetric value is specified based on the recognized color information.
In S125, a correction value is set based on the output digital image and the colorimetric value.

Next, the flow of processing for correcting the gradation value of a digital image will be described.
FIG. 7B is a flowchart showing a flow of processing for correcting the gradation value of the digital image.
In S205, the image scanner 1 reads an arbitrary document and outputs a digital image to the PC 2.

In S210, the PC 2 corrects the gradation value of the output digital image based on the correction value. The corrected digital image is converted into, for example, a YCbCr color space and stored in the external storage unit 86.
According to the image reading apparatus according to the first embodiment of the present invention described above, the color reproducibility can be easily returned to the initial state by performing correction when the color reproducibility is deteriorated due to secular change. Further, when there are a plurality of image scanners 1, a difference in color reproducibility due to individual differences can be easily absorbed by correcting the plurality of image scanners 1. In the correction, since the colorimetric value is specified from the color information written on the color correction document 30, the operator only needs to read the color correction document 30, and the colorimetric value is stored. It is not necessary to perform the operation of reading the read file or inputting the read colorimetric value to the image reading apparatus. Further, there is no deviation between the lot of the color correction original 30 and the lot of the color correction original targeted by the colorimetric value, and the operation such as downloading does not occur. Therefore, according to this image reading apparatus, it is possible to reduce the labor of correcting the color reproducibility using the color correction document 30.

  In this embodiment, the case where the image reading apparatus is configured by the PC 2 and the image scanner 1 has been described as an example. However, the image reading apparatus is configured only by the image scanner by executing a color correction program on the image scanner side. Also good.

(Second embodiment)
The second embodiment is an example of correcting a color space conversion table.
The color space conversion table is a table used for performing color space conversion, and is a table that associates a gradation value expressed in one color space with a gradation value in another color space. For example, in the case of a color space conversion table that associates the RGB color space with the Lab color space, when the combination of R, G, and B values is determined, the corresponding combination of L, a, and b values is uniquely determined by the color space conversion table. Can be identified. Therefore, in the case of a digital image expressed in the RGB color space, the R, G, and B values for each pixel can be converted into L, a, and b values to convert them into a digital image expressed in the Lab color space. it can. The color space conversion table is the central existence of the ICC profile. An ICC profile is a file defined by an international standard for color management technology, and is a file used for matching a device-dependent color space with a device-independent color space. Also in the second embodiment, color space conversion is performed using an ICC profile.

The CPU 27 of the second embodiment also functions as a conversion table update unit by executing a color correction program stored in the ROM 28.
Next, the color correction program of the second embodiment will be described.
FIG. 8 is a block diagram showing a logical configuration of the color correction program of the second embodiment. The color correction program includes a reading unit 51, a colorimetric value specifying unit 52, and a conversion table updating unit 53. In the drawing, two reading units 51 are shown for convenience, but they are the same. The color correction program of the second embodiment also includes the same expiration date recognition unit 42 and warning unit 43 as in the first embodiment, but is omitted in FIG. 8 for easy understanding.

  The reading unit 51 executes processing for reading each digital image by controlling each unit. The reading unit 51 according to the second embodiment reads a document to create a digital image represented by an RGB color space, which is a device-dependent color space, and converts the color space of the created digital image into a device based on a color space conversion table. It is converted into a Lab color space which is an independent color space and output.

Since the colorimetric value specifying unit 52 is substantially the same as the colorimetric value specifying unit 44 of the first embodiment, description thereof is omitted.
The conversion table updating unit 53 reads the color correction document and outputs the color space based on the gradation value of the pixel representing the color sample patch of the digital image output and the colorimetric value specified by the colorimetric value specifying unit 52. Execute processing to update the conversion table. Specifically, the correction is performed by adding a correction value for each of the L component, the a component, and the b component of the color space conversion table. For example, if the correction value of the L component is -5, the correction value of the a component is 1, and the correction value of the b component is 3, -5 is uniformly added to the L component of the color space conversion table, and the a component is uniformly added. Add 1 and add 3 to b component uniformly. For example, it is assumed that the RGB value (100, 64, 227) is associated with the Lab value (96, 69, 84) in the color space conversion table. In this case, the conversion table update unit 53 updates (96, 69, 84) to (91, 70, 87) (= (96-5, 69 + 1, 84 + 3)). In this way, by updating all the Lab values associated with each RGB uniformly, the RGB value (100, 64, 227), for example, is converted into the Lab value (91, 70, 87) in the next reading. As a result, the difference from the colorimetric value is eliminated.

(Third embodiment)
The third embodiment is an example of a color correction document in which color information is written in characters.
FIG. 9 is a schematic diagram showing the color correction document 60 of the third embodiment. As shown in the drawing, the color correction document 60 is printed with color information 61, 62, and 63 representing the L component, a component, and b component of the colorimetric value instead of the barcode.
The colorimetric value specifying unit of the third embodiment recognizes a number by performing image processing on the output digital image, and sets a value represented by the recognized number as a colorimetric value.

(Fourth embodiment)
The fourth embodiment is an example of a color correction document in which a URL for acquiring a colorimetric value via a communication network is described.
FIG. 10A is a schematic diagram showing a color correction document of the fourth embodiment, and FIG. 10B is a schematic diagram showing a text file in which colorimetric values are recorded. The text file 72 in which the colorimetric values are recorded is stored in a predetermined server connected to the communication network, and the URL 73 of the text file 72 is printed on the color correction document 71.

  The colorimetric value specifying unit of the fourth embodiment recognizes the URL 73 by performing image processing on the output digital image. Next, the text file 72 specified by the recognized URL 73 is downloaded via the communication network, and the colorimetric values are specified by reading the data recorded in the text file 72.

According to the color correction document of the fourth embodiment, even if there is an error in the colorimetric value, it is only necessary to correct the colorimetric value on the server side, and the colorimetric value can be easily corrected. Further, since the image reading apparatus executes the download, the user does not need to perform an operation for downloading, and the time and effort required for the download can be reduced.
In the first to fourth embodiments, the case where the color information is represented by a barcode, a number, a URL, or the like has been described as an example. However, the color information may be, for example, a predetermined figure.

1 is a schematic diagram of a color correction document according to a first embodiment of the present invention. FIG. 1 is a block diagram of a PC according to a first embodiment of the present invention. 1 is a schematic diagram of an image scanner according to a first embodiment of the present invention. 1 is a block diagram of an image scanner according to a first embodiment of the present invention. 1 is a block diagram of a color correction program according to a first embodiment of the present invention. (A) is a schematic diagram illustrating an example of a colorimetric value according to the first embodiment of the present invention, (B) is a schematic diagram illustrating an example of a gradation value of a pixel representing a color sample patch, and (C) is a correction value. The schematic diagram which shows an example. (A) And (B) is a flowchart which shows the flow of the process which concerns on 1st Example of this invention. The block diagram of the color correction program which concerns on 2nd Example of this invention. FIG. 10 is a schematic diagram of a color correction document according to a third embodiment of the present invention. (A) is a schematic diagram of a color correction document according to a fourth embodiment of the present invention, and (B) is a schematic diagram of a file in which colorimetric values are recorded.

Explanation of symbols

1 image scanner (reading means), 2 personal computer, 81 CPU (reading means, colorimetric value specifying means, correction value setting means, correction means, expiration date recognition means, warning means, conversion table update means), 30 color correction Original, 31 color sample patch, 32 color information, 60 color correction original, 61, 62, 63 color information, 71 color correction original, 73 color information 85 Display section (warning means)

Claims (10)

Reading means for reading a document and outputting a digital image;
A digital image output from the reading unit and read out from a color correction document in which a color sample patch and color information for specifying a colorimetric value of the color sample patch are read. A colorimetric value specifying means for recognizing the color information based on the color information and specifying a colorimetric value based on the recognized color information;
A correction value for setting a correction value based on a gradation value of a pixel representing the color sample patch of the digital image output by reading the color correction document and a colorimetric value specified by the colorimetric value specifying unit Setting means;
Correction means for correcting a gradation value of a digital image output by reading an arbitrary document by the reading means based on a correction value set by the correction value setting means;
An image reading apparatus comprising: Reading means for reading a document to create a digital image, converting the color space of the created digital image into another color space based on a predetermined color space conversion table, and
A digital image output from the reading unit and read out from a color correction document in which a color sample patch and color information for specifying a colorimetric value of the color sample patch are read. A colorimetric value specifying means for recognizing the color information based on the color information and specifying a colorimetric value based on the recognized color information;
The color space conversion table is corrected based on the gradation value of the pixel representing the color sample patch of the digital image output by reading the color correction document and the colorimetric value specified by the colorimetric value specifying means. Conversion table updating means to
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the color information of the color correction document is represented by a barcode.   The image reading apparatus according to claim 1, wherein the color information is written in characters in the color correction document.   The image reading apparatus according to claim 4, wherein the character is a URL for acquiring a colorimetric value via a communication network. The color correction document has a plurality of color sample patches representing different colors,
The color information is information for specifying an average value of colorimetric values of the plurality of color sample patches,
6. The correction unit according to claim 1, wherein the correction unit sets a correction value based on the average value and an average value of a plurality of gradation values corresponding to the plurality of color sample patches. The image reading apparatus described. The color correction document is written so that the expiration date of the color sample patch can be read.
Expiration date recognizing means for recognizing the expiration date based on a digital image output by reading the color correction document;
The image reading apparatus according to claim 1, further comprising a warning unit that issues a warning when the expiration date recognized by the expiration date recognition unit has passed. A color sample patch,
Color information for specifying a colorimetric value of the color sample patch;
Is a color correction document characterized by being readable. A color correction method for an image reading apparatus comprising reading means for reading a document and outputting a digital image,
An output step of reading a color correction document in which a color sample patch and color information for specifying a colorimetric value of the color sample patch are written by the reading unit and outputting a digital image;
A colorimetric value specifying step of recognizing the color information based on a digital image output by reading the color correction document in the output step, and specifying a colorimetric value based on the recognized color information;
A correction value for setting a correction value based on a gradation value of a pixel representing the color sample patch of the digital image output by reading the color correction document and a colorimetric value specified in the colorimetric value specifying step The setting stage,
A correction step of correcting the gradation value of the digital image output by reading an arbitrary document by the reading unit based on the correction value set in the correction value setting step;
A color correction method comprising: An image reading apparatus comprising reading means for reading a document and outputting a digital image,
A digital image output from the reading unit and read out from a color correction document in which a color sample patch and color information for specifying a colorimetric value of the color sample patch are read. A colorimetric value specifying means for recognizing the color information based on the color information and specifying a colorimetric value based on the recognized color information;
A correction value for setting a correction value based on a gradation value of a pixel representing the color sample patch of the digital image output by reading the color correction document and a colorimetric value specified by the colorimetric value specifying unit Setting means;
A color correction program for causing a gradation value of a digital image output by reading an arbitrary document by the reading means to function as a correction means for correcting the gradation value based on a correction value set by the correction value setting means.