JP2015177358A - Image reading device, image forming apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading device including color gamut correction means capable of implementing correction of a read color gamut without using a test chart, an image forming apparatus and a program.SOLUTION: The image reading device includes: illumination means for illuminating a plurality of reference color portions colored in different reference colors with lighting-control illumination light including a plurality of illumination light beams controlled to different quantities of light; and read means for reading each of the plurality of reference color portions illuminated with the lighting-control illumination light for each of the plurality of illumination light beams and outputting lighting-control image information for each reference color including a plurality of image information items corresponding to the plurality of illumination light beams. On the basis of the lighting-control image information for each reference color outputted from the read means, it is determined whether any abnormality is present in any image information within color gamuts including the plurality of image information items included in the lighting-control image information and, if any abnormality is present, correction information is generated for correcting the image information within a color gamut where the abnormality is present.

Description

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

Patent Document 1 discloses an image sensor that optically reads an image and converts it into an electrical signal, an output signal processing circuit that processes an electrical signal output from the image sensor, and a drive for driving the output signal processing circuit. An image reading apparatus comprising: a timing signal generating circuit that generates a timing signal; and a timing signal phase adjusting unit that adjusts a phase of the timing signal generated by the timing signal generating circuit. When reading the reference plate, incident light amount control means for changing the amount of reflected light from the gray reference plate incident on the image sensor in a plurality of stages, and an ideal value of the electric signal to be output from the image sensor. Ideal value storage means for storing for each gray density of a plurality of stages,
The timing signal phase adjusting means includes a value of the output electric signal of the image sensor at each stage changed by the incident light amount control means, and a gray density stored in the ideal value storage means corresponding to each stage. Compare the ideal value of the output electric signal of the image sensor in the stage to determine the sampling point where both values approximate, and generate the timing signal so that the output signal processing circuit is driven at this sampling point An image reading apparatus is disclosed that adjusts the phase of a timing signal generated by a circuit.

JP 2005-094165 A

  An object of the present invention is to provide an image reading apparatus, an image forming apparatus, and a program provided with a color gamut correction unit that can correct a read color gamut without using a test chart.

  In order to achieve the above object, an image reading apparatus according to claim 1, wherein a plurality of reference color portions colored with different reference colors are each provided with a plurality of illumination lights adjusted to different light amounts. Illuminating means for illuminating with the dimming illumination light, and each of the plurality of reference color portions illuminated with the dimming illumination light is read for each of the plurality of illumination lights, and a plurality of each corresponding to each of the plurality of illumination lights Reading means for outputting dimming image information for each reference color each including the image information, and a plurality of dimming image information included in the dimming image information based on the dimming image information for each reference color output from the reading means It is determined whether or not there is an abnormality in any of the image information in each color gamut including the image information, and when there is an abnormality, correction information for correcting the image information in the color gamut where the abnormality exists Generating means for generating.

  According to a second aspect of the present invention, in the first aspect of the present invention, the generating unit performs the interpolation by interpolating image information corresponding to illumination light in which the light amount of the dimming image information for each reference color is equal. Dimming image information for each color different from the reference color is calculated, and the correction information is generated based on the dimming image information for each reference color and the dimming image information for each color different from the reference color. .

  According to a third aspect of the present invention, in the second aspect of the present invention, the generation unit includes a first reference color included in the reference color and a second reference color included in the reference color. When calculating dimming image information for each color different from the existing reference color, the reference color is obtained by interpolation of image information corresponding to illumination light in which the light amounts of the first reference color and the second reference color are equal. The dimming image information for each color different from the above is calculated.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the color different from the reference color has an equal value of the color difference between the first reference color and the second reference color. Thus, the color corresponds to the dividing point when divided.

  According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects of the present invention, the generation means includes dimming image information for each reference color included in the correction information, and Reference image information predetermined for each of the dimming image information for each color different from the reference color, the dimming image information for each reference color, and the dimming image information for each color different from the reference color When the maximum value of the color differences, which are the differences from the above, is greater than or equal to a predetermined threshold value, it is determined that there is an abnormality in any of the image information in the color gamut.

  According to a sixth aspect of the invention, in the fifth aspect of the invention, each of the dimming image information for each reference color and the dimming image information for each color different from the reference color included in the correction information. Is converted into each of the corresponding reference image information, and the image information of the image read by the reading unit is color-converted with the calculated color conversion coefficient, and within the color gamut where the abnormality exists The image processing apparatus further includes correction means for correcting the image information.

  According to a seventh aspect of the invention, in the sixth aspect of the invention, when the color conversion coefficient is calculated by the storage means for storing the color conversion coefficient and the correction means, the storage means stores the color conversion coefficient. Updating means for updating the calculated color conversion coefficient to the calculated color conversion coefficient.

  The invention according to claim 8 is the invention according to claim 6 or 7, wherein the generation means has an abnormality by the correction means when a color conversion coefficient is calculated by the correction means. After the image information in the color gamut to be corrected is corrected, it is determined again whether there is an abnormality in any of the image information in the color gamut.

  The invention according to claim 9 further includes notification means for notifying the result of the determination again by the generation means in the invention according to claim 8.

The invention according to claim 10 is the invention according to any one of claims 6 to 9, wherein the correction means is dimming image information for each reference color included in the correction information. And each of the dimming image information for each color different from the reference color and each of the reference image information are arranged in an L ^* a ^* b ^* color space to calculate the color conversion coefficient, and within the color gamut where the abnormality exists Image information of the image with the corrected image information is used as image information in the L ^* a ^* b ^* color space, or image information obtained by converting the image information in the L ^* a ^* b ^* color space into image information in the RGB color space. It further includes output means for outputting.

  The invention described in claim 11 further includes display means for displaying the color difference for each of the reference colors obtained from the color difference in the invention described in any one of claims 5 to 10. It is a waste.

  The invention according to claim 12 is the invention according to any one of claims 1 to 11, wherein the different reference colors include a plurality of chromatic colors, and the plurality of chromatic colors are It is arranged so as to belong to each of hue regions obtained by dividing the hue of the color space in which the color indicated by the light control image information is evenly or substantially equally divided.

  Furthermore, in order to achieve the above object, an image forming apparatus according to a thirteenth aspect includes an image forming unit that forms an image, the image reading apparatus according to any one of the first to twelfth aspects, It is equipped with.

  On the other hand, in order to achieve the above object, the program according to claim 14 is configured to provide a plurality of reference light portions each of which is colored with a reference color different from each other with a plurality of illumination lights adjusted to different light amounts. Illuminating means for illuminating with the dimming illumination light, and each of the plurality of reference color portions illuminated with the dimming illumination light is read for each of the plurality of illumination lights, and a plurality of each corresponding to each of the plurality of illumination lights Reading means for outputting dimming image information for each reference color including each of the image information, and a program for controlling an image reading apparatus including the computer for each reference color output from the reading means Based on the dimming image information, it is determined whether or not there is an abnormality in any of the image information in each color gamut including the plurality of image information included in the dimming image information. In the color gamut where the anomaly exists It is intended to function as a generating means for generating correction information for correcting the image information.

  According to the invention described in claim 1 and claim 14, the color gamut correction capable of realizing the correction of the read color gamut without using the test chart as compared with the case where the generation unit of the present invention is not provided. An effect is provided that an image reading apparatus and a program including the means are provided.

  According to the second to fourth aspects of the present invention, the test chart is compared with a case where correction information is not generated by interpolation of image information corresponding to illumination light having the same amount of light control image information for each reference color. The effect that the corrected color gamut information of the image reading apparatus is generated without printing and reading the image is obtained.

According to the invention described in claim 5, when the maximum value of the color differences is equal to or greater than a predetermined threshold value, the test is performed in comparison with the case where it is not determined that any of the image information in the color gamut is abnormal. It is determined whether or not there is an abnormality in the color gamut of the image reading apparatus without printing and reading the chart,
The effect is obtained.

  According to the invention described in claims 6 and 7, the color of the image reading apparatus can be obtained without printing and reading the test chart as compared with the case where the correcting means, the storing means, and the updating means of the present invention are not provided. The effect that the conversion coefficient is created and updated is obtained.

  According to the eighth aspect of the present invention, it is inspected whether the effect of the correction by updating the color conversion coefficient for the machine difference of the image reading device or the change with time is compared with the case where the presence / absence of abnormality is not determined again. The effect that

  According to the ninth aspect of the present invention, whether or not the correction by updating the color conversion coefficient for the machine difference of the image reading apparatus and the change with time has exceeded the limit as compared with the case of not having the notification means of the present invention. It is possible to obtain an effect that the user is informed about this.

  According to the tenth aspect of the present invention, as compared with the case where the output means of the present invention is not provided, there is an effect that image information obtained by reading an image and image information regarding chromaticity can be obtained simultaneously.

  According to the eleventh aspect of the present invention, since the machine difference of the image reading apparatus and the degree of change with time are displayed as compared with the case where the display means of the present invention is not provided, the current state is understood by the user. An effect is obtained.

  According to the twelfth aspect of the present invention, compared to a case where a plurality of chromatic reference colors are not arranged so as to belong to each of hue regions obtained by dividing the hue of the color space equally or substantially equally, There is an effect that the accuracy of the taste correction is made constant without being biased to the hue.

According to the invention described in claim 13, compared with the case where the image reading apparatus of the present invention is not provided,
An advantage is provided in that an image forming apparatus including a color gamut correction unit capable of correcting a read color gamut without using a test chart is provided.

1 is a schematic configuration diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment. 1 is a schematic configuration diagram illustrating an example of a configuration of a built-in image sensor provided in an image forming apparatus according to an embodiment. It is a perspective view of the reference | standard roll which concerns on embodiment. 1 is a block diagram illustrating an example of a main configuration of an electric system in an image forming apparatus according to an embodiment. It is a block diagram which shows an example of a structure of the read signal processing part which concerns on embodiment. It is a figure which shows the change on a color space at the time of performing gradation reading with respect to each color reference plane which concerns on embodiment. It is a figure which shows distribution on the chromaticity diagram of each color reference surface which concerns on embodiment. It is a chromaticity diagram showing a method for generating inspection color gamut information according to an embodiment. It is a figure which shows the inspection color gamut information which concerns on embodiment. It is a chromaticity diagram showing a method for generating reference color gamut information according to an embodiment. It is a figure which shows the reference | standard color gamut information which concerns on embodiment It is a flowchart which shows an example of the flow of a process of the color gamut correction process program which concerns on embodiment.

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

  FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 10 according to an embodiment of the present invention, and FIG. 2 is a diagram of a built-in image sensor 200 provided in the image forming apparatus 10 according to the embodiment of the present invention. It is a figure which shows an example.

  The image forming apparatus 10 according to the present embodiment selectively forms a full-color image and a black-and-white image, and is connected to the first housing 10A and the first housing 10A as shown in FIG. A second housing 10B. An image signal processing unit 13 that performs image processing on image data supplied from an external device such as a computer is provided on the upper portion of the second housing 10B. On the other hand, the first special color (V), second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) toners are provided on the upper portion of the first housing 10A. Toner cartridges 14V, 14W, 14Y, 14M, 14C, and 14K are provided.

  Note that examples of the first special color and the second special color include colors other than yellow, magenta, cyan, and black (including transparency). In the following description, the first special color (V), the second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) are distinguished for each component. Will be described with a letter as a symbol followed by any letter of V, W, Y, M, C, or K. When the first special color (V), the second special color (W), yellow (Y), magenta (M), cyan (C), and black (K) are not distinguished, V, W, Y, M , C and K are omitted.

  Under the toner cartridge 14, six image forming units 16 corresponding to the toners of the respective colors are provided so as to correspond to the toner cartridges 14.

  An exposure device 40 (40V, 40W, 40Y, 40M, 40C, 40K) provided for each image forming unit 16 receives image data subjected to image processing by the image signal processing unit 13 from the image signal processing unit 13. receive. Then, the image carrier 18 (18V, 18W, 18Y, 18M, 18C, 18K), which will be described later, is irradiated with the light beam L modulated according to the image data.

  Each image forming unit 16 includes an image carrier 18 that is rotationally driven in one direction. By irradiating each image carrier 18 with the light beam L from each exposure device 40, an electrostatic latent image is formed on each image carrier 18.

Around each image carrier 18, a corona discharge (non-contact charging) scorotron charger that charges the image carrier 18 and an electrostatic latent image formed on the image carrier 18 by the exposure device 40 are developed. A developing device that develops with toner, which is an example of an agent, a blade that removes the developer remaining on the image carrier 18 after transfer, and a static eliminator that performs static elimination by irradiating the image carrier 18 after transfer with light. Is provided. The scorotron charger, developing device, blade, and static eliminator are
Opposite the surface of the image carrier 18, the image carrier 18 is arranged in this order from the upstream side to the downstream side in the rotation direction.

  A transfer unit 32 is provided below each image forming unit 16. The transfer unit 32 includes an annular intermediate transfer belt 34 that is in contact with each image carrier 18, and a primary transfer roll 36 that multi-transfers the toner image formed on each image carrier 18 to the intermediate transfer belt 34. Has been.

  The intermediate transfer belt 34 includes a drive roll 38 that is driven by a motor (not shown), a tension applying roll 41 that applies tension to the intermediate transfer belt 34, an opposing roll 42 that faces a secondary transfer roll 62 described below, It is wound around a plurality of winding rolls 44. And it is circularly moved in one direction (counterclockwise direction in FIG. 1) by the drive roll 38.

  Each primary transfer roll 36 is disposed opposite to the image carrier 18 of each image forming unit 16 with the intermediate transfer belt 34 interposed therebetween. The primary transfer roll 36 is applied with a transfer bias voltage having a polarity opposite to the toner polarity by a power supply unit (not shown). With this configuration, the toner image formed on the image carrier 18 is transferred to the intermediate transfer belt 34.

  On the opposite side of the drive roll 38 across the intermediate transfer belt 34, there is provided a removing device 46 that removes residual toner, paper dust and the like on the intermediate transfer belt 34 by bringing the blade into contact with the intermediate transfer belt 34. .

  Below the transfer unit 32, a plurality of recording medium storage units 48 that store a recording medium P as an example of a medium such as paper are provided. Each of the recording medium accommodating portions 48 can be pulled out from the first housing 10A. A delivery roll 52 that feeds the recording medium P from each recording medium container 48 to the transport path 60 is provided above one end side (right side in front view in FIG. 1) of each recording medium container 48.

  In each recording medium accommodating portion 48, a bottom plate 50 on which the recording medium P is placed is provided. The bottom plate 50 is lowered by an instruction from a control means (not shown) when the recording medium accommodating portion 48 is pulled out from the first housing 10A. When the bottom plate 50 is lowered, a space in which the user replenishes the recording medium P is formed in the recording medium accommodating portion 48.

When the recording medium accommodating portion 48 pulled out from the first housing 10A is attached to the first housing 10A,
The bottom plate 50 is raised by an instruction from the control means. As the bottom plate 50 moves up, the uppermost recording medium P placed on the bottom plate 50 and the delivery roll 52 come into contact with each other.

  On the downstream side in the recording medium conveyance direction of the delivery roll 52 (hereinafter sometimes simply referred to as “downstream side”), a separation roll 56 that separates the recording media P delivered from the recording medium accommodating portion 48 one by one. Is provided. A plurality of transport rolls 54 that transport the recording medium P downstream in the transport direction are provided on the downstream side of the separation roll 56.

  The conveyance path 60 provided between the recording medium storage unit 48 and the transfer unit 32 folds the recording medium P sent out from the recording medium storage unit 48 to the left side as viewed from the front in FIG. Further, the second folding portion 60B extends to the transfer position T between the secondary transfer roll 62 and the opposing roll 42 so as to be folded back to the right in the front view in FIG.

  The secondary transfer roll 62 is applied with a transfer bias voltage having a polarity opposite to the toner polarity by a power feeding unit (not shown). With this configuration, each color toner image transferred onto the intermediate transfer belt 34 is secondarily transferred by the secondary transfer roll 62 onto the recording medium P conveyed along the conveyance path 60.

  A preliminary path 66 extending from the side surface of the first housing 10 </ b> A is provided so as to join the second folding portion 60 </ b> B of the transport path 60. The recording medium P sent out from another recording medium accommodation unit (not shown) arranged adjacent to the first housing 10 </ b> A can enter the conveyance path 60 through the spare path 66.

  On the downstream side of the transfer position T, a plurality of conveyance belts 70 that convey the recording medium P onto which the toner image has been transferred toward the second casing 10B are provided in the first casing 10A, and are conveyed to the conveyance belt 70. A transport belt 80 that transports the recording medium P to the downstream side is provided in the second housing 10B.

  Each of the plurality of conveyor belts 70 and the conveyor belt 80 is formed in an annular shape and is wound around a pair of winding rolls 72. The pair of winding rolls 72 are respectively arranged on the upstream side and the downstream side in the conveyance direction of the recording medium P, and when one of them is driven to rotate, the conveyance belt 70 (conveyance belt 80) moves in one direction (in FIG. 1). Cycle in the clockwise direction.

  A fixing unit 82 for fixing the toner image transferred onto the surface of the recording medium P to the recording medium P with heat and pressure is provided on the downstream side of the conveyance belt 80.

  The fixing unit 82 includes a fixing belt 84 and a pressure roll 88 disposed so as to contact the fixing belt 84 from below. A fixing unit N is formed between the fixing belt 84 and the pressure roll 88 to fix the toner image by pressurizing and heating the recording medium P.

The fixing belt 84 is formed in an annular shape and is wound around the drive roll 89 and the driven roll 90. The drive roll 89 faces the pressure roll 88 from above,
The driven roll 90 is disposed above the drive roll 89.

  Each of the driving roll 89 and the driven roll 90 includes a heating unit such as a halogen heater. As a result, the fixing belt 84 is heated.

  As shown in FIG. 1, a conveyance belt 108 is provided on the downstream side of the fixing unit 82 to convey the recording medium P sent from the fixing unit 82 to the downstream side.

  A cooling unit 110 that cools the recording medium P heated by the fixing unit 82 is provided on the downstream side of the conveyance belt 108.

  The cooling unit 110 includes an absorption device 112 that absorbs the heat of the recording medium P, and a pressing device 114 that presses the recording medium P against the absorption device 112. The absorption device 112 is disposed on one side (upper side in FIG. 1) with respect to the conveyance path 60, and the pressing device 114 is disposed on the other side (lower side in FIG. 1).

  The absorption device 112 includes an annular absorption belt 116 that contacts the recording medium P and absorbs the heat of the recording medium P. The absorption belt 116 is wound around a driving roll 120 that transmits a driving force to the absorption belt 116 and a plurality of winding rolls 118.

  A heat sink 122 made of, for example, an aluminum material is provided on the inner peripheral side of the absorption belt 116 to dissipate the heat absorbed by the absorption belt 116 in contact with the absorption belt 116 in a planar shape.

  Further, a fan 128 for removing heat from the heat sink 122 and discharging hot air to the outside is disposed on the back side of the second housing 10B (the back side of the paper surface shown in FIG. 1).

  The pressing device 114 that presses the recording medium P against the absorbing device 112 includes an annular pressing belt 130 that conveys the recording medium P while pressing the recording medium P against the absorbing belt 116. The pressing belt 130 is wound around a plurality of winding rolls 132.

  On the downstream side of the cooling unit 110, there is provided a correction device 140 that conveys the recording medium P and corrects the curl of the recording medium P.

A built-in image sensor 200 that detects a toner density defect, an image defect, an image position defect, and the like of the toner image fixed on the recording medium P is provided on the downstream side of the correction device 140. In addition,
Details of the built-in image sensor 200 will be described later.

  On the downstream side of the built-in image sensor 200, a discharge roll 198 that discharges the recording medium P having an image formed on one side thereof to a discharge unit 196 attached to the side surface of the second housing 10B is provided.

  On the other hand, when images are formed on both sides, the recording medium P sent from the built-in image sensor 200 is conveyed to a reversing path 194 provided on the downstream side of the built-in image sensor 200.

  The reversing path 194 includes a branch path 194A that branches from the transport path 60, a paper transport path 194B that transports the recording medium P transported along the branch path 194A toward the first housing 10A, and a paper transport path. A reversing path 194 </ b> C is provided that turns the recording medium P conveyed along 194 </ b> B in the reverse direction to switch back and reverse the recording medium P.

  With this configuration, the recording medium P that is switched back and conveyed by the reverse path 194C is conveyed toward the first housing 10A, and further enters the conveyance path 60 provided above the recording medium container 48, and is transferred to the transfer position. It is sent to T again.

  Next, an image forming process of the image forming apparatus 10 will be described.

The image data that has been subjected to image processing by the image signal processing unit 13 is sent to each exposure device 40.
In each exposure device 40, each light beam L is emitted according to image data, and is exposed to each image carrier 18 charged by a scorotron charger, thereby forming an electrostatic latent image.

  The electrostatic latent image formed on the image carrier 18 is developed by the developing device, and the first special color (V), the second special color (W), yellow (Y), magenta (M), and cyan (C). A toner image of each color of black (K) is formed.

As shown in FIG. 1, each color toner image formed on the image carrier 18 of each of the image forming units 16V, 16W, 16Y, 16M, 16C, and 16K has six primary transfer rolls 36V,
Multiple transfer is sequentially performed on the intermediate transfer belt 34 by 36W, 36Y, 36M, 36C, and 36K.

  The color toner images transferred onto the intermediate transfer belt 34 are secondarily transferred onto the recording medium P conveyed from the recording medium container 48 by the secondary transfer roll 62. The recording medium P onto which the toner image has been transferred is transported toward the fixing unit 82 provided inside the second housing 10B by the transport belt 70.

  The toner images of the respective colors on the recording medium P are fixed on the recording medium P by being heated and pressurized by the fixing unit 82. Further, the recording medium P on which the toner image is fixed is cooled by passing through the cooling unit 110 and then sent to the correction device 140 to correct the curvature generated in the recording medium P.

  The recording medium P whose curvature is corrected is discharged to the discharge unit 196 by the discharge roll 198 after an image defect or the like is detected by the built-in image sensor 200.

  On the other hand, when an image is formed on a non-image surface where no image is formed (in the case of double-sided printing), the recording medium P is reversed by the reversing path 194 after passing through the built-in image sensor 200. Then, the toner is fed into a conveyance path 60 provided above the recording medium accommodating portion 48, and a toner image is formed on the back surface in the above-described procedure.

  In the image forming apparatus 10 according to the present embodiment, components for forming images of the first special color and the second special color (image forming units 16V and 16W, exposure devices 40V and 40W, toner cartridges 14V and 14W). The primary transfer rolls 36V and 36W) are configured to be attachable to the first housing 10A as additional parts according to the user's selection. Therefore, the image forming apparatus 10 does not have a component for forming the first special color and second special color images, and the image of any one of the first special color and the second special color. It is good also as a structure which has only the components for forming.

  Next, the built-in image sensor 200 will be described.

  In the following description, the length direction of the image forming apparatus 10 (sub-scanning direction that is the conveyance direction of the recording medium P) is the X direction, the height direction of the apparatus is the Y direction, and the depth direction of the apparatus (main scanning direction) is Z. The direction is assumed (see FIGS. 1 and 2).

  The built-in image sensor 200 according to the present embodiment is used, for example, for detecting whether or not there is an abnormality in the image formed on the recording medium P by the image forming unit 16. The built-in image sensor 200 in this case has a function as a means for measuring gradation reproducibility and color reproducibility of the image forming unit 16. In addition, in order to maintain the function as the measurement unit normally, the built-in image sensor 200 may be calibrated regularly or irregularly.

  As shown in FIG. 2, the built-in image sensor 200, which is an example of an image reading device, includes an illumination unit 202 that emits light toward a recording medium P on which an image is recorded, and a recording medium that is irradiated from the illumination unit 202. An imaging unit 208 having an imaging optical system 206 that forms an image of light reflected by P on a CCD sensor 204 as an example of a reading unit, and various standards and the like when using the built-in image sensor 200 or during calibration. And a setting unit 210 provided. The CCD sensor 204 according to the present embodiment includes a plurality of light receiving elements (for example, photodiodes) arranged along a direction corresponding to the main scanning direction, and a red image sensor and a green image sensor. An image sensor and a blue image sensor are provided. Each color image sensor is provided with a filter that transmits light of each color component on the light receiving surface of the light receiving element. Each color image sensor outputs, as a signal, the electric charge accumulated according to the amount of each color component of the light received by the light receiving element.

  The illumination unit 202 is disposed on the upper side of the conveyance path 60 of the recording medium P, and has a pair of a first lamp 212A and a second lamp 212B (hereinafter collectively referred to as “long” in the Z direction (main scanning direction)). , Sometimes referred to as “lamp 212”). As the lamp 212, for example, a fluorescent lamp, a xenon lamp, a plurality of white LEDs arranged along the main scanning direction, and the like are used. In the present embodiment, a plurality of white LEDs (not shown) are used. . In the present embodiment, the lamp 212 is configured by arranging a plurality of LED substrates (not shown) on which one or more white LEDs are mounted in the main scanning direction. Of course, the substrate on which the plurality of white LEDs are mounted may be a single substrate.

  Further, the length of the irradiation range of the lamp 212 is set larger than the width of the maximum recording medium P to be conveyed. The lamp 212 is arranged symmetrically with respect to the optical axis OA (designed optical axis) that is reflected by the recording medium P and travels toward the image forming unit 208. More specifically, the lamps 212 are arranged symmetrically with respect to the optical axis OA so that the irradiation angle to the recording medium P is, for example, not less than 45 ° and not more than 50 °.

Specifically, the pair of lamps 212 are arranged along the conveyance path 60 of the recording medium P, and are recorded on the first lamp 212A and the first lamp 212A arranged on the upstream side in the conveyance direction of the recording medium P. And a second lamp 212B disposed on the downstream side in the conveyance direction of the medium P.
Then, the light irradiated from the first lamp 212A and the second lamp 212B is irradiated to the irradiation position D of the transparent window glass 286 on the transport path 60 between the first lamp 212A and the second lamp 212B. It is configured. In the window glass 286, the irradiation area irradiated with light from the lamp 212 is an area that overlaps the area through which the image forming area of the recording medium P passes on the setting unit 210, and is formed on the recording medium P on the conveyance path 60. An area in which the obtained image is read by the CCD sensor 204 is configured to include a predetermined area (image reading area).

  The imaging optical system 206 also reflects the light guided along the optical axis OA in the X direction (in the present embodiment, downstream in the transport direction of the recording medium P), and the first mirror 214. The second mirror 216 that reflects the light reflected by the second mirror 216 upward, the third mirror 218 that reflects the light reflected by the second mirror 216 upstream in the transport direction of the recording medium P, and the light reflected by the third mirror 218 A lens 220 that focuses (images) the CCD sensor 204 is configured as a main part. The CCD sensor 204 is arranged on the upstream side in the transport direction of the recording medium P with respect to the optical axis OA.

  The length of the first mirror 214 in the Z direction is larger than the width of the maximum recording medium P. The first mirror 214, the second mirror 216, and the third mirror 218 squeeze (condensate) the reflected light of the recording medium P incident on the imaging optical system 206 in the Z direction (main scanning direction). It is designed to reflect. Thus, the reflected light from each part in the width direction of the recording medium P is incident on the substantially cylindrical lens 220.

  The built-in image sensor 200 is configured such that the CCD sensor 204 outputs (feeds back) the imaged light, that is, a signal corresponding to the image density, to the control device 20 (see FIGS. 1 and 4) of the image forming apparatus 10. Has been. The control device 20 performs processing for correcting an image formed in the image forming unit 16 based on a signal input from the built-in image sensor 200. As an example of the process of correcting the image, correction of the intensity of irradiation light by the exposure apparatus 40 based on a signal input from the built-in image sensor 200, the image formation position, and the like can be given.

  In addition, a light amount diaphragm unit 224 (224L, 224S, 224U)) is provided between the third mirror 218 and the lens 220 in the imaging optical system 206. The light amount diaphragm unit 224 narrows the light amount of light that forms an image on the CCD sensor 204 across the optical path in the Z direction in the Y direction (direction intersecting with the main scanning direction), and adjusts the amount of light diaphragm by operating from the outside. It is configured freely. The amount of light reduced by the light amount restrictor 224 is adjusted so that the amount of light imaged on the CCD sensor 204 is equal to or greater than a predetermined amount even if the light emission amount of the lamp 212 changes over time.

  The built-in image sensor 200 includes a control circuit 100 provided with a circuit board 262 for controlling a reference roll rotation motor 22 (see FIG. 4) which is a motor for rotating a reference roll 226 described later.

  The setting unit 210 includes a reference roll 226 that is long in the Z direction. The reference roll 226 is formed in a polygonal cylindrical shape in which a predetermined number of faces are formed in the circumferential direction. However, as shown in FIG. 3, the reference roll 226 according to the present embodiment has 10 faces. It is a polygonal cylinder.

  The reference roll 226 is directed toward the conveyance path 60 when the image detection of the recording medium P is not performed, and the detection reference surface 228 directed toward the conveyance path 60 when the image detection of the recording medium P is performed. And a retracting surface 230. In addition, the reference roll 226 is a reference surface (white reference surface 232, yellow reference surface 234, cyan reference surface 237, magenta color reference surface 239, red reference surface 231 and green reference surface) used for color gamut correction processing described later. A surface 233 and a blue reference surface 235) and a composite inspection surface 236 on which a plurality of inspection patterns are formed. In the following, when the reference plane of each color is not distinguished, it may be simply referred to as “color reference plane”.

  The reference roll 226 is configured to switch the surface to be directed to the conveyance path 60 side by rotating around the rotation shaft 226A. The surface of the reference roll 226 is switched by the control circuit 100 provided on the circuit board 262. Further, the reference roll 226 is formed in a decagonal cylindrical shape, so that a difference in distance from the rotation center between the center in the circumferential direction of each surface and the corner portion between the surfaces is suppressed. Thus, the corners between the surfaces of the reference roll 226 do not interfere with the illumination unit 202 while keeping the distance between each surface of the reference roll 226 and the irradiation position (window glass 286) of the lamp 212 small.

  The detection reference surface 228 has a circumferential width smaller than that of the other surfaces, and is a position reference surface that positions the detected (read) surface of the conveyed recording medium P at the irradiation position by the lamp 212. ing. In some cases, the circumferential surface of the reference roll 226 is 12 or more, and the circumferentially opposite sides of the detection reference surface 228 are guide surfaces that do not have the above-described functions as a reference.

The retracting surface 230 has a circumferential width larger than that of other surfaces. The retraction surface 230 is a guide surface that guides the recording medium P when the built-in image sensor 200 does not detect the image of the recording medium P, and the distance from the axis of the rotation shaft 226A is more than the detection reference surface 228. It is considered small. Thereby, when the image detection of the recording medium P by the built-in image sensor 200 is not performed, the image detection of the recording medium P by the built-in image sensor 200 is performed, compared with
A conveyance path having a wide interval with the illumination unit 202 (window glass 286) is formed.

  The composite inspection surface 236 is formed by arranging a position adjustment pattern for correcting the position in the rotation direction of the reference roll 226 (the conveyance direction of the recording medium P), a focus detection pattern, and a depth detection pattern on the same surface. ing.

  The white reference surface 232 is a reference surface for correcting lightness unevenness in the main scanning direction caused by the lamp 212 or the CCD sensor 204, that is, so-called shading correction, and is configured by adhering a white film, for example. . When the irradiation light from the lamp 212 is applied to the white reference surface 232, the reflected light reflected by the white reference surface 232 is input to the CCD sensor 204 via the imaging optical system 206 as a read signal. .

Each color reference plane including the white reference plane 232 in the present embodiment (white reference plane 232,
The yellow reference plane 234, the cyan reference plane 237, the magenta reference plane 239, the red reference plane 231, the green reference plane 233, and the blue reference plane 235) are the hue / main scanning direction attributed to the lamp 212 or the CCD sensor 204. Used as a reference plane (color sample) for correcting saturation unevenness. Each color reference surface is configured by attaching a film of each color, for example. When the irradiation light from the lamp 212 is applied to each color reference surface, the reflected light reflected by each color reference surface is input to the CCD sensor 204 via the imaging optical system 206 as a read signal.

  FIG. 4 is a block diagram showing a main configuration of the electrical system in the image forming apparatus 10 according to the embodiment of the present invention.

As described above, the control device 20 is based on the signal from the built-in image sensor 200.
A function of correcting an image formed in the image forming unit 16 is provided. The control device 20 also has a function of controlling calibration of the built-in image sensor 200 (for example, calibration of the CCD sensor 204 described above).

  More specifically, as shown in FIG. 4, the control device 20 includes a CPU (Central Processing Unit) 20A, a ROM (Read Only Memory) 20B, a RAM (Random Access Memory) 20C, an NVM (Non Volatile Memory) 20F, and An input / output port 20D is provided. Each is connected to each other via a bus 20E such as an address bus, a data bus, and a control bus.

  Various programs are stored in the ROM 20B, and various controls are performed by the CPU 20A reading the programs from the ROM 20B, developing them in the RAM 20C, and executing them.

  The NVM 20F is a nonvolatile storage medium that stores various types of information that must be retained even when the power switch of the apparatus is turned off.

  A user interface (UI) panel 30, a dimming circuit 370, a control circuit 100, and a read signal processing unit 350 are connected to the input / output port 20D. The UI panel 30 includes, for example, a touch panel display in which a transmissive touch panel is superimposed on a display. Various types of information are displayed on the display surface of the display, and information and instructions are received when the user touches the touch panel. In the present embodiment, an example in which the UI panel 30 is applied is described. However, the present invention is not limited to this, and a display unit such as a liquid crystal display and an operation unit provided with a numeric keypad, operation buttons, and the like are provided. It is good also as a form provided separately.

  The dimming circuit 370 is a circuit that continuously changes the brightness of the lamp 212 by controlling the current passed through the white LED constituting the lamp 212 when performing dimming reading of each color reference surface described later. In the present embodiment, “dimming reading” means that the current supplied to the white LED is changed at a predetermined stage to dim the lamp 212, and the reflected light from each color reference surface in the dimming state at each stage. Is read by the CCD sensor 204.

  Further, as described above, the control circuit 100 controls switching of each surface (the detection reference surface 228, the retreat surface 230, the composite inspection surface 236, and each color reference surface) of the reference roll 226. More specifically, the driving of the reference roll rotation motor 22 connected to the control circuit 100 is controlled based on an instruction from the control device 20.

  On the other hand, the read signal processing unit 350 performs various calibrations of the built-in image sensor 200 connected to the read signal processing unit 350, color gamut correction processing, which will be described later, and the like in accordance with instructions from the control device 20. Examples of the calibration of the built-in image sensor 200 include offset and gain correction for correcting the output upper and lower limit values of the CCD sensor 204. Further, shading correction that corrects the lightness distribution in the main scanning direction of the image data based on the profile of the image data obtained by reading the white reference surface 232 can be given. Furthermore, correction of hue / saturation unevenness in the main scanning direction for the image data, which is performed based on the profile of the image data obtained by reading each color reference plane, can be mentioned.

  Each of the above components constituting the read signal processing unit 350 according to the present embodiment is controlled by a control signal (not shown) from the CPU 20A input via the input / output port 20D.

  By the way, in the built-in image sensor 200, as one aspect of correction (calibration), color correction is performed on image data based on a read value obtained by reading an image formed on the recording medium P, that is, in addition to brightness. Hue / saturation correction may be performed. This is because even if the read value is obtained by reading the same image, a difference in hue / saturation is generated for each built-in image sensor 200 due to a machine difference of the illumination unit 202 or the CCD sensor 204 or a change with time. That is, for example, due to a difference in sensitivity caused by a manufacturing deviation of the filter of the CCD sensor 204 or a change in sensitivity due to a change in the filter over time, the reading value as image data for each built-in image sensor 200 may be different from each other or over time. This is because there is a possibility that a change occurs.

As one method of the above correction, there is a method using a test chart including gradation patch images of component colors with known color characteristics formed on photographic paper or the like. A method of measuring a color by reading the test chart with the built-in image sensor 200 or the like, and calculating a color conversion coefficient for converting image data obtained by the color measurement into target reference image data corresponding to the test chart It is. When the built-in image sensor 200 performs reading by the CCD sensor 204, the built-in image sensor 200 outputs image data obtained by correcting the read image data or the like with the calculated color conversion coefficient. However, in this method, there is an inconvenience that a test chart for a plurality of colors must be used for each correction. In addition, the test chart itself that needs to strictly manage the color difference is expensive, and the color difference of the test chart changes over time (for example,
(Discoloration).

  Therefore, in the image forming apparatus 10 according to the present embodiment, as one aspect of the calibration process, brightness, hue, and saturation (that is, color gamut) are corrected using each color reference plane. That is, a reading value obtained by irradiating each color reference surface while adjusting the irradiation light from the lamp 212 and reading the reflected light by the CCD sensor 204 (hereinafter, this reading value may be referred to as a “light adjustment reading value”). To get. Then, based on the light control read value, the machine gamut difference of each built-in image sensor 200 when an image formed by the image forming apparatus 10 or the like is read by the built-in image sensor 200 is corrected.

Hereinafter, in the color gamut correction processing according to the present embodiment, image data (R, G, B) in the RGB color space (device-dependent color space) that is a read value read by the CCD sensor 204 is used as an example of luminance color difference color. This is executed after being converted into image data (L ^* , a ^* , b ^* ) in a space L ^* a ^* b ^* color space (device-independent color space). Also, the conversion from the image data (R, G, B) to the image data (L ^* , a ^* , b ^* ) is executed using the color conversion coefficient M.

  Next, the function of the read signal processing unit 350 when the color gamut correction process is mainly executed will be described with reference to FIG.

As shown in FIG. 5, the read signal processing unit 350 includes an S & H (sample and hold) unit 352, an amplification unit 354, an A / D conversion unit 356, a shading correction unit 358, RGB1 / L ^* a ^* b ^* one color conversion. 360, inspection color gamut creation unit 361, reference color gamut storage unit 362, color gamut inspection unit 363, L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient creation unit 364, L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient update unit 365, L ^* a ^* b ^* 1 / L * a ^* b ^* 0 color conversion unit 366, L ^* a ^* b ^* 0 / RGB two-color conversion unit 367 It is comprised including.

The S & H unit 352 receives the red (R) analog read signal S _R1 , the green (G) analog read signal S _G1 , and the blue (B) analog read signal S _B1 transferred from the CCD sensor 204. Sampling and holding is performed by sampling (sampling) and holding (holding) for a certain period.

The amplifying unit 354 amplifies the read signals S _R1 , S _G1 , and S _B1 sampled and held by the S & H unit 352. Between the S & H unit 352 and the amplifying unit 354, the black output level of the read image (hereinafter, also referred to as “read image”) for the read signals S _R1 , S _G1 , S _B1 sampled and held. In some cases, a black level adjustment circuit for performing a correction process is provided so as to achieve a predetermined black level (zero level).

The A / D conversion unit 356 performs A / D (analog / digital) conversion on the read signals S _R1 , S _G1 , and S _B1 amplified by the amplification unit 354, and the image data (R, G, B) that is digital data. )

  The shading correction unit 358 corrects unevenness in brightness of the read output of the image caused by the lamp 212 and the CCD sensor 204 with respect to the image data (R, G, B) converted into a digital signal by the A / D conversion unit 356. To do. Then, correction is performed so that the white level of the read image matches the white level in image formation by the image forming unit 16.

^{RGB1 / L * a * b *} 1 color conversion unit 360, the image data after being shading correction by the shading correction section 358 (R, G, B) data RGB1 is, image by using a color conversion coefficient _{M 1} Data (L ^* , a ^* , b ^* ) is converted to data L ^* a ^* b ^* 1. M ₁ is a color conversion coefficient before update, which will be described later. The converted data L ^* a ^* b ^* 1 is output to the inspection color gamut creation unit 361 as signals (S _{L * 1} , S _{a * 1} , S _{b * 1} ). Note that the data RGB1 is image data indicating the result of dimming and reading each color reference surface of the built-in image sensor 200 (image forming apparatus 10) (hereinafter, also referred to as “inspection target”) that is the target of color gamut correction. R, G, B).

The inspection color gamut creation unit 361 performs interpolation processing between chromaticity points, which will be described later, using the data L ^* a ^* b ^* 1. Hereinafter, the data L ^* a ^* b ^* 1 after the interpolation processing may be referred to as “inspection color gamut information L ^* a ^* b ^* 1”.

The reference color gamut storage unit 362 is a storage unit that stores data L ^* a ^* b ^* 0 (hereinafter referred to as “reference color gamut information”) that is color gamut information that is a target of color reproduction. When the information is read out, it is output to the color gamut inspection unit 363 as signals (S _{L * 0} , S _{a * 0} , S _{b * 0} ). As the reference color gamut storage unit 362, a storage unit such as a ROM 20B or NVM 20F may be used.

The color gamut inspection unit 363 calculates and obtains a color difference from chromaticities corresponding to the reference color gamut information (data L ^* a ^* b ^* 0) and the inspection color gamut information (data L ^* a ^* b ^* 1). A maximum value (hereinafter, “maximum color difference”) of the obtained color differences is obtained. That is, the color difference is calculated for each reference color gamut information and inspection color gamut information with a combination of chromaticities having the same data number (described later), and the maximum value is obtained. When the maximum color difference is equal to or greater than a predetermined threshold, the reference color gamut information is used as a signal (S _{L * 0} , S _{a * 0} , S _{b * 0} ), and the inspection color gamut information is a signal (S _{L * 1} , S _{a * 1} , S _{b * 1} ) and output to the L ^* a ^* b ^* 1 / La ^* b ^* 0 color conversion coefficient creation unit 364.

The L ^* a ^* b ^* 1 / La ^* b ^* 0 color conversion coefficient creation unit 364 generates the reference color gamut information (data L ^* a ^* b ^* 0) from the inspection color gamut information (data L ^* a ^* b ^* 1). calculating a color conversion coefficient _{M 2} to, and outputs the calculated _{M 2} to ^{L * a * b * 1 /} L * a * b * 0 color conversion coefficient updating unit 365. The color conversion coefficient M ₂ may be calculated by, for example, calculating M ₂ satisfying the following formula (1) by multiple regression analysis such as the least square method or the maximum likelihood method.

^{L * a * b * 1 /} L * a * b * 0 color conversion coefficient updating unit 365 updates the color conversion coefficient _{M 2,} the updated _{^{M 2 L * a * b *}} 1 / L * a * b ^* Output to 0 color converter 366. The update is executed by updating M ₂ stored so far in the storage unit provided in the L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient update unit 365. May be. Further, the storage means such as NVM20F, it may be performed by updating the M ₂ stored so far.

^{L * a * b * 1 /} L * a * b * 0 color conversion section 366, using the color conversion coefficient _{M 2,} inspection color information (data ^L * ^a * ^b * 1) the reference color gamut information (data L ^* a ^* b ^* 0), and the conversion result is output as _a signal (S _{L * 0} , S _{a * 0} , S _{b * 0} ) to the L ^* a ^* b ^* 0 / RGB two-color converter 367. .

The L ^* a ^* b ^* 0 / RGB two-color conversion unit 367 uses the color conversion coefficient M ₃ (in this embodiment, updated M ₂ ) to generate reference color gamut information (data L ^* a ^* b ^* 0). The image data (R, G, B) is converted to data RGB2, and the conversion result is output as a signal (S _R2 , S _G2 , S _B2 ) to the input / output port 20D.

In the read signal processing unit 350, once M ₂ is calculated, the inspection color gamut information is obtained unless the maximum color difference becomes a predetermined threshold or more by the inspection in the color gamut inspection unit 363 and the color conversion coefficient M ₂ is updated. (data ^L * ^a * ^b * ^1), in the ^{L * a * b * 1 /} L * a * b * 0 color conversion section 366 is corrected by the color conversion coefficient _{M 2.} That is, the color conversion coefficient M ₂ has a closer examination gamut based color gamut predetermined allowable range (correction to) transform coefficients for.

  Further, as described above, each of the above-described units constituting the read signal processing unit 350 according to the present embodiment is controlled by a control signal (not shown) from the CPU 20A input via the input / output port 20D.

  Next, the color gamut correction processing according to the present embodiment will be described in more detail. First, the dimming reading according to the present embodiment will be described with reference to FIG. In the following description, the color gamut correction process is described by exemplifying a form executed by the read signal processing unit 350 shown in FIG. 5, but the present invention is not limited to this, and the process may be executed by the CPU 20A. .

In FIG. 6A, the white reference surface 232 is irradiated with the irradiation light while changing the value of the current passed through the white LED of the lamp 212 to control the light control, and the reflected light from the white reference surface 232 is read by the CCD sensor 204. Image data (R, G, B), which is a read value, is converted into image data (L ^* , a ^* , b ^* ), and the relationship between the lightness L ^* and the current value of the current flowing through the white LED is illustrated. It is. The dimming control is performed by the dimming circuit 370 shown in FIG. As indicated by the straight line W1 in FIG. 6A, the dimming read value of the white reference surface 232 shows a characteristic that the lightness L ^* changes substantially linearly with respect to the current flowing through the white LED. A shaded band shown in gray scale along the L ^* axis visually represents a change in lightness L ^* .

FIG. 6B is a diagram in which the reading value of the white reference surface 232 when the light control of the lamp 212 is controlled is plotted on the L ^* -b ^* plane. As shown by the straight line W2 in FIG. 6B, the read value shows a characteristic that changes from a position where the index b ^* is substantially 0 to a substantially straight line parallel to the lightness L ^* axis.

On the other hand, FIG. 6 (c) irradiates the yellow reference surface 234 with the irradiation light while changing the current value of the current flowing through the white LED of the lamp 212 and performing dimming control, and reflects the reflected light from the yellow reference surface 234 to the CCD sensor. The image data (R, G, B) that is the reading value read in 204 is converted into image data (L ^* , a ^* , b ^* ), and the image data (L ^* , a ^* , b ^* ) is converted to L ^*. -B ^* Plotted on a plane.

As indicated by the straight line Y in FIG. 6C, the dimming read value of the yellow reference surface 234 shows a characteristic that the L ^* -b ^* plane moves obliquely in a substantially straight line with respect to the current flowing through the white LED. . Note that a gray scale along the L ^* axis and a shaded band visually represents a change in lightness L ^* , and a gray scale along the b ^* axis and a shaded band visually represents a change in saturation in the b ^* direction. It represents. The same applies to the dimming reading with respect to the other color reference planes, and shows the characteristic that the L ^* a ^* b ^* color space moves substantially linearly corresponding to each color reference plane. That is, by performing dimming reading on each color reference surface, not only lightness but also information on hue and saturation can be obtained.

With reference to FIG. 7, the distribution on the chromaticity diagram (in this embodiment, the L ^* a ^* b ^* color space) of each color reference plane will be described. The L ^* a ^* b ^* color space is a three-dimensional space. However, in order to avoid complications in the illustration, the L ^* a ^* b ^* color space is illustrated below by projection onto a two-dimensional plane.

In the present embodiment, the colors of the chromatic color reference planes (yellow reference plane 234, magenta reference plane 239, cyan reference plane 237, red reference plane 231, green reference plane 233, and blue reference plane 235) The hue angles on the a ^* -b ^* plane are selected and arranged so as to be divided substantially evenly. That is, as shown in FIG. 7, each color of the yellow reference plane 234, the magenta reference plane 239, the cyan reference plane 237, the red reference plane 231, the green reference plane 233, and the blue reference plane 235 is a ^* -b ^*. On the plane, the hue angles are arranged so as to be divided substantially evenly.
Furthermore, in the present embodiment, in addition to the arrangement of each chromatic color reference plane, the color of the white reference plane 232, which is an achromatic reference plane, is arranged near the origin on the a ^* -b ^* plane. Here, the hue angle on the a ^* -b ^* plane refers to an angle θ formed by a straight line centered on the origin and the a ^* axis, as shown in FIG.

  In the present embodiment, after the dimming reading is performed for each color reference plane, interpolation processing is performed between each color reference plane and the white reference plane 232 which is an achromatic reference plane, and color gamut information (reference gamut information and Inspection color gamut information) is calculated. In the following, calculation of color gamut information will be described using the yellow reference plane 234 as an example, but the same applies to other color reference planes.

A method for calculating the inspection color gamut information will be described with reference to FIG. FIG. 8 illustrates the dimming read value of the white reference surface 232, the dimming read value of the yellow reference surface 234, and the interpolated value of both. That is, FIG. 8A shows the respective values on the L ^* -a ^* plane, and FIG. 8B shows the respective values on the L ^* -b ^* plane. Both figures show the same value with different plot planes.

In FIG. 8 (a), the optical reading tone of the white reference plane 232 S _W5 to no S _{W1 (point} indicated by ▲ in Fig. Hereinafter, the case of collectively "dimming readings S _W") shown in Has been. In addition, the dimming read value of the yellow reference surface 234 is indicated by S _Y1 to S _Y5 (points indicated by ● in the figure. Hereinafter, the dimming read value S _Y when collectively referred to). That is, in this embodiment, the case where the lamp 212 is dimmed in five stages is illustrated, and the order of S _W5 → S _W4 → S _W3 → S _W2 → S _W1 (that is, the subscript number decreases). In order) the current flowing through the white LED is increasing. Incidentally, dimming readings _{S W} and _{S Y} is the result obtained values of the processing in ^{RGB1 / L * a * b *} 1 color conversion section 360 of the read signal processing section 350 (see FIG. 5).

  Further, in the present embodiment, the current value of the white LED at each stage flowing by the dimming reading of the white reference surface 232 is equal to the current value of the white LED at each stage flowing by the dimming reading of the yellow reference surface 234. It is said. Equal currents flowing through the white LEDs mean that the illuminance on the white reference plane 232 and the illuminance on the yellow reference plane 234 are the same. Hereinafter, the illuminance due to the five levels of dimming may be referred to as illuminance L1 to illuminance L5 in descending order of the current value of the white LED.

  In the present embodiment, the case where the number of dimming steps is five will be described as an example. However, the number of dimming steps is not limited to five and may be any number of steps. Further, the current value for each stage of the white LED when performing dimming reading may be stored in advance in a storage unit such as the ROM 20B.

With reference to FIG. 8A again, the interpolation processing according to the present embodiment will be described. In the interpolation processing according to this embodiment, substantially equally divided between the dimming reading S _Y of the white reference plane optical reading tone 232 S _W and yellow reference surface 234 in the illuminance equal relationship. Then, chromaticities (L ^* , a ^* , b ^* ) in the color space corresponding to the points obtained by the division are obtained, and these are used as interpolation values.

Taking the dimming read values S _W1 and S _Y1 (illuminance L1) having the same current flowing through the white LED as an example, as shown in FIG. 8A, the distance between S _W1 and S _Y1 is approximately. By equally dividing into five, interpolation values S _WY11 , S _WY12 , S _WY13 , and S _W14 (points indicated by ◆ in the figure) are obtained. Hereinafter, when the interpolation value S _{WY11 and the} like are generically referred to, they may be referred to as “interpolation value S _WY ”.

Although illustration is omitted, similarly, the interpolation values S _WY21 to S _WY24 (illuminance L2) between the dimming read values S _W2 and S _Y2 are interpolated between the dimming read values S _W3 and S _Y3. The values S _WY31 to S _WY33 (illuminance L3), the interpolated values S _WY41 to S _WY43 (illuminance L4) between the dimming read values S _W4 and S _Y4, and the dimming read values S _W5 to S _Y5. Interpolation values S _WY51 and S _WY52 (illuminance L5) are respectively obtained.

  That is, in the interpolation process shown in FIG. 8A, the illuminance L1 and the illuminance L2 are divided into five, the illuminance L3 and the illuminance L4 are divided into four, and the illuminance L5 is divided into three. Of course, the number of divisions is not limited to this, and may be an appropriate number of divisions in consideration of the accuracy of the required inspection color gamut, calculation time, and the like. Further, it is not necessary to change the number of divisions depending on the illuminance, and the same number of divisions may be used, and further, it is not necessary to divide evenly.

8B, as described above, the dimming read values S _W and S _Y and the interpolation value S _WY represented on the L ^* −a ^* plane in FIG. 8A are set on the L ^* −b ^* plane. Each point shown in FIG. 8 (b) corresponds to each point given the same reference numeral in FIG. 8 (a).

Inspection color gamut information about the white reference surface 232 and the magenta color reference surface 239 (the dimming read value S _{W) is obtained} by a method similar to the calculation method of the inspection color gamut information performed for the white reference surface 232 and the yellow reference surface 234 described above. , S _M , interpolation value S _WM ), inspection color gamut information (dimming read values S _W , S _C , interpolation value S _WC ) for the white reference surface 232 and cyan reference surface 237, and white reference surface 232. examination gamut information about the red reference surface 231 (light readings _S W, _{S R,} the interpolation value _{S WR)} a test color gamut information (dimming readings _{S W} for the white reference plane 232 and the green reference plane 233 , S _G , interpolation value S _WG ), and inspection color gamut information (dimming read values S _W , S _B , interpolation value S _WB ) for the white reference surface 232 and the blue reference surface 235, respectively. Obviously, the optical reading S _W tone of the white reference plane 232 is determined once, the optical reading S _W tone measured the one may be used in common in the interpolation process of each color reference plane chromatic. The calculated inspection color gamut information may be temporarily stored in a storage unit such as the NVM 20F. Note that the interpolation values S _WY , S _WM , S _WC , S _WR , S _WG , and S _WB are values obtained as a result of processing in the inspection color gamut creation unit 361 of the read signal processing unit 350 (see FIG. 5).

FIG. 9 is a diagram illustrating the above-described method for calculating the inspection color gamut information using numerical examples. In FIG. 9, the “inspection data number” indicates the dimming read values S _W , S _Y , S _M , S _C , S _R , S _G , S _B , and the interpolated values S _WY , S _WM , S _WC , The numbers given to the values of S _WR , S _WG , and S _WB are shown. “Illuminance L1” to “Illuminance L5” in the “Method of creating inspection color gamut information” column indicates that the chromaticity is obtained by dimming and reading each color reference surface with the illuminance. Further, “Data interpolation 11” to “Data interpolation 52” in the “Method of creating inspection color gamut information” column indicates that the chromaticity is obtained as a result of the interpolation processing.

Specifically, data 01 to data 05 are chromaticities (L ^* , a ^* , b ^* ) obtained by dimming and reading the white reference surface 232 with illuminance L1 to illuminance L5, and data 06 to data 10 are illuminance L1. In addition, chromaticities (L ^* , a ^* , b ^* ) obtained by dimming and reading the yellow reference surface 234 with illuminance L5 are shown.

Data 11 to data 26 indicate chromaticities (L ^* , a ^* , b ^* ) obtained as a result of the interpolation processing. That is, data 11 to data 26 indicate the result of executing the above-described interpolation processing based on the dimming read values acquired from data 01 to data 10. For example, the chromaticities (L ^* , a ^* , b ^* ) shown corresponding to the data interpolation 11 to the data interpolation 14 indicate the interpolation values S _WY11 to S _WY14 calculated with the illuminance L1. The same applies to the remaining data interpolation 21 to data interpolation 24, data interpolation 31 to data interpolation 33, data interpolation 41 to data interpolation 43, data interpolation 51 and data interpolation 52.

The dimming read values S _W , S _Y , S _M , S _C , S _R , S _G , S _B , and the interpolation values S _WY , S _WM , S _WC , S _WR , S obtained by the above-described calculation. _{WG, S WB} may be previously temporarily stored in storage means such as NVM20F. The storage form when storing in the NVM 20F or the like may be, for example, the form shown in FIG.

  Next, creation of a reference color gamut will be described with reference to FIG.

The method of creating the reference color gamut is basically the same as the method of calculating the inspection color gamut described above.
FIG. 10 is basically the same diagram as FIG. The difference between the reference color gamut and the inspection color gamut is calculated, for example, by the inspection color gamut creation unit 361 (see FIG. 5) for each built-in image sensor 200 (image forming apparatus 10) whose inspection color gamut is to be corrected. The reference color gamut is a color gamut stored in advance in the reference color gamut storage unit 362 as a reference for correction. In other words, the reference color gamut is calculated in advance by using a standard machine of the built-in image sensor 200 (image forming apparatus 10) composed of parts having standard characteristics, and using the same method as that for calculating the inspection color gamut in advance. Color gamut. Alternatively, the initial value of the color gamut calculated in advance by the same method as the method of calculating the inspection color gamut for each built-in image sensor 200 (image forming apparatus 10) at the time of factory shipment may be used.

More specifically, in FIG. 10 (a), T _W1 to T _W5 (points indicated by Δ in FIG. 10 (a)) are dimmed in five levels and measured in advance in advance. This is a dimming read value. Further, T _Y1 to T _Y5 (points indicated by ◯ in FIG. 10A) are dimming reading values of the yellow reference surface 234 measured in advance in five steps. Then, similarly to the interpolation process in the calculation of the test color gamut, adjustment to _WY11 not interpolated value _T between the optical reading _{T W1} and _{T Y1 T WY14} the (illuminance L1), dimming readings _{T W2} and T It _WY21 no interpolation value _T between the _{Y2 T WY24} the (illuminance L2), to _WY31 no interpolation value _T between the dimming reading _{T W3} and _{T Y3 T WY33} the (illuminance L3), dimming readings _{T W4} It _WY41 no interpolation value _T between _{T Y4} and _{T WY43} the (illuminance L4), between the dimming reading _{T W5} and _{T Y5} obtaining each interpolated value _{T WY51} and _{T WY52} (illuminance L5). In FIG. 10A, the points indicated by ◇ indicate the respective interpolation values. Similar to the inspection color gamut, in the case of collectively dimming readings, T _W, is denoted like the T _Y, in the case of collectively interpolated value is denoted like the T _WY.

FIG. 10B shows the dimming read values T _W and T _Y and the interpolation value T _WY represented on the L ^* −a ^* plane in FIG. 10A on the L ^* −b ^* plane. Each point shown in FIG. 10 (b) corresponds to each point given the same reference numeral in FIG. 10 (a).

The reference color gamut information (the dimming read value T _{W) for the} white reference surface 232 and the magenta color reference surface 239 is obtained by the same method as the reference color gamut information calculation method executed for the white reference surface 232 and the yellow reference surface 234 described above. , T _M , interpolation value T _WM ), reference color gamut information (dimming read values T _W , T _C , interpolation value T _WC ) for the white reference plane 232 and the cyan reference plane 237, and the white reference plane 232. reference color gamut information about the red reference surface 231 (light readings _T W, _{T R,} the interpolation value _{T WR)} a reference color gamut information (dimming readings _{T W} for the white reference plane 232 and the green reference plane 233 , T _G , interpolation value T _WG ), and reference color gamut information (dimming read values T _W , T _B , interpolation value T _WB ) for the white reference surface 232 and the blue reference surface 235, respectively.

  Here, when the reference color gamut is created in advance, the current value that flows to the white LED at each step when performing the five-step dimming reading is the five-step current that flows to the white LED when the inspection color gamut is calculated. The value is the same as the value. That is, the illuminance L1 to illuminance L5 on each color reference surface when the reference color gamut is created in advance are the same as the illuminance on each color reference surface when the inspection color gamut is calculated.

FIG. 11 is a diagram for explaining calculation of each dimming read value and each interpolated value of the reference color gamut using numerical examples. As in FIG. 9, the reference data numbers 01 to 05 are used to adjust the white reference surface 232. light readings _{T W,} to the reference data 06 to 10 show a dimming readings _{T Y} yellow reference plane 234. Reference data numbers 11 to 26 indicate the interpolation values _TWY at the illuminances L1 to L5. Similarly to the inspection color gamut, the reference color gamut may be stored in the storage unit such as the reference color gamut storage unit 362 or the ROM 20B in the form shown in FIG.

  Next, a color gamut correction process executed by the image forming apparatus 10 according to the present embodiment will be described with reference to FIG. FIG. 12 is a flowchart showing a processing flow of the color gamut correction processing program according to the present embodiment.

  In the image forming apparatus 10 according to the present embodiment, the process shown in FIG. 12 is stored in the storage unit such as the ROM 20B by the CPU 20A when the user instructs the start of the color gamut correction process via the UI panel 30 or the like. This is done by reading and executing the color gamut correction processing program. Note that the processing shown in FIG. 12 is not limited to execution by a user instruction, and may be executed as part of correction (calibration) that is automatically performed regularly or irregularly, for example.

  In the present embodiment, the color gamut correction program is stored in advance in a storage unit such as the ROM 20B. However, the present invention is not limited to this. For example, the present invention may be applied to a form in which the color gamut correction processing program is provided in a state of being stored in a computer-readable portable storage medium. In addition, a form in which the color gamut correction processing program is distributed via a wired or wireless communication unit may be applied.

  Furthermore, in the present embodiment, the color gamut correction processing is realized by a software configuration using a computer by executing a program, but is not limited thereto. For example, you may implement | achieve by the hardware structure which employ | adopted ASIC (Application Specific Integrated Circuit), or the combination of a hardware structure and a software structure.

  As shown in FIG. 12, first, in step S100, the number of dimming steps N for dimming the lamp 212 is set. The number of dimming stages N (N = 5 in this embodiment) is set by reading the value stored in the storage means such as the ROM 20B in advance together with the current value to be supplied to the white LED set in each stage. May be.

In the next step S102, the read signal processing unit 350 (shading correction unit 358) is controlled so as to execute the above-described shading correction by reading the white reference plane 232.
In the next step S104, i, which is a counter of the number of dimming steps, is set to 1 and initialized.

  In the next step S106, the dimming circuit 370 is controlled so that the lamp 212 is lit at the illuminance L (i) corresponding to the dimming stage i.

  In the next step S108, the control circuit 100, the dimming circuit 370, and the read signal processing unit 350 are controlled so as to execute dimming reading of the white reference surface 232. The acquired reading value may be temporarily stored in a storage unit such as the RAM 20C or the NVM 20F.

In the next step S110, each chromatic color reference plane (in this embodiment, yellow reference plane 234, cyan reference plane 237, magenta reference plane 239, red reference plane 231, green reference plane 233, and blue reference plane). 235) to perform the dimming reading,
The light control circuit 370 and the read signal processing unit 350 are controlled. The acquired reading value of each color reference plane may be temporarily stored in a storage unit such as the RAM 20C or the NVM 20F.

In the next step S112, based on the dimming read value of the white reference surface 232 acquired in step S108 and the dimming read value of each color reference surface of the chromatic color acquired in step S110,
An inspection color gamut is created and added by the calculation method described above. The process of creating / adding the inspection color gamut is performed by executing the same process as the process in the inspection color gamut creating unit 361.

  In the next step S114, it is determined whether or not the value of the counter i is greater than N. If the determination is negative, the process proceeds to step S116, the counter i is incremented by 1, and the process returns to step S106.

On the other hand, if the determination in step S114 is affirmative, the process proceeds to step S118.
The maximum color difference described above is calculated.

As described above, the color difference is obtained by calculating the distance between the chromaticity of the inspection color gamut corresponding to the same illuminance L and the chromaticity of the reference color gamut. In other words, the chromaticity of light control readings _{S Y1} yellow reference surface 234 in the illuminance L1 inspection gamut ^{_{(L * SY1, a * SY1}} , b * SY1) and was a yellow reference surface 234 in the illuminance L1 of the reference color gamut dimming readings chromaticity of ^{_{T Y1 (L * TY1, a}} * TY1, b * TY1) and the _case, the color difference _{R Y1} between the _{S W1} and _{S Y1} is calculated by the following formula (2) The

Similarly, with respect to other dimming reading values and interpolation values in the inspection color gamut and the reference color gamut, the color differences in the same illuminance combination are calculated, and the maximum value of those color differences is obtained to obtain the maximum color difference. . More specifically, in the example of FIGS. 9 and 11, since 26 color differences are calculated, the maximum value among them is set as the maximum color difference.
When the color difference is calculated in step S118, for example, the calculated color difference may be displayed on the UI panel 30 together with the color gamut of each chromatic color reference plane to notify the user.

  In the next step S120, it is determined whether or not the maximum color difference calculated in step S118 is greater than or equal to a predetermined threshold value. The calculation of the maximum color difference in step S118 and the comparison with the maximum color difference threshold value in step S120 are performed by executing the same process as the process in the color gamut inspection unit 363.

  If a negative determination is made in step S120, the color gamut correction processing program is terminated. This is because when the maximum color difference is smaller than the threshold value, the change in the inspection color gamut or the machine difference is not a problem.

On the other hand, if an affirmative determination is made in step S120, the process proceeds to step S122, from inspection color gamut information (data L ^* a ^* b ^* 1) to reference color gamut information (data L ^* a ^* b ^* 0). to the calculated color conversion coefficient M _2. The calculation of the color conversion coefficient M ₂ is performed by executing a process similar to the process in the L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient creating unit 364.

In the next step S124, the updated color conversion coefficient _{M 2} calculated in step S122,
The color gamut correction processing program is terminated. The color conversion coefficient M ₂ is updated by executing the same process as the process in the L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient update unit 365.

Once M ₂ is calculated, the inspection color gamut information (data L ^* a ^* b ^* 1) is obtained as long as the maximum color difference becomes equal to or greater than a predetermined threshold by the inspection in the color gamut inspection unit 363 and the color conversion coefficient M ₂ is not updated. ) Is corrected by the color conversion coefficient M ₂ in the L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion unit 366. Further, the inspection color gamut information (data L ^* a ^* b ^* 1) corrected by the color conversion coefficient M ₂ is converted into image data (R, G, B) by the L ^* a ^* b ^* 0 / RGB two-color conversion unit 367. ) And output to the input / output port 20D.

In the present embodiment it has been described by way of example in the form of updating the color conversion coefficient M _2, but not limited thereto. For example, every time the color conversion coefficient M ₂ is calculated, the color conversion coefficient M ₂ may be stored in a storage unit such as the L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient update unit 365 or the NVM 20F in time series. Good. The form of storing the correction color conversion coefficient in the storage means such as the L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient updating unit 365 or the NVM 20F is not limited to the form of the matrix M, For example, it may be in the form of a LUT (Look Up Table) or a conversion formula.

When the color conversion coefficient M ₂ is updated, the color gamut correction processing program may be executed again to confirm the effect of the updated color conversion coefficient M ₂ . Furthermore, still by updating the color conversion coefficient M _2, if the maximum color difference is greater than or equal to the threshold value in step S120, that the correction of the color gamut can not be completed, for example, to view current UI panel 30 The user may be notified.

  As is apparent from the above description, according to the image reading apparatus, the image forming apparatus, and the program according to the present embodiment, the color gamut correcting means that can correct the read color gamut without using a test chart. An image reading apparatus, an image forming apparatus, and a program are provided.

  In the above-described embodiment, an example in which a white reference surface is used as an achromatic color reference surface has been described. However, the present invention is not limited to this. For example, a form using a black reference surface, a gray color reference surface, or the like may be used. In addition, although an example in which a yellow reference surface, a magenta reference surface, a cyan reference surface, a red reference surface, a green reference surface, and a blue reference surface are used as the chromatic color reference surface has been described, the present invention is not limited thereto. I can't. One or a plurality of other color reference planes may be added in consideration of required accuracy of color gamut correction.

  Further, in the above-described embodiment, the mode in which the color gamut interpolation processing is performed between the white reference plane and each chromatic color reference plane has been described as an example, but the present invention is not limited to this. For example, a color gamut obtained by performing an interpolation process between combinations of one or a plurality of chromatic color reference planes may be added.

  Moreover, although the said embodiment demonstrated and demonstrated the form which changes the electric current sent through white LED as a means to light-control the lamp 212, it is not restricted to this. For example, a lamp such as a xenon lamp may be used for the illumination unit 202, and the light may be adjusted by combining the lamp and a slit having a variable opening area.

  Further, in the above-described embodiment, a description has been given by exemplifying a form using a reflective color reference surface as each color reference surface. However, the present invention is not limited to this.

  Further, in the above-described embodiment, the embodiment using the built-in image sensor as the image reading device has been described as an example. However, the embodiment is not limited to this, and for example, a scanner may be used.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus, 10A 1st housing | casing, 10B 2nd housing | casing, 13 Image signal processing part, 14 Toner cartridge, 16 Image forming unit, 18 Image holding body, 20 Control apparatus,
20A CPU, 20B ROM, 20C RAM, 20D I / O port, 20E bus, 20F NVM, 22 reference roll rotation motor, 30 UI panel, 32 transfer section,
34 Intermediate transfer belt, 36 Primary transfer roll, 38 Drive roll, 40 Exposure device, 41 Tension applying roll, 42 Opposite roll, 44 Winding roll, 46 Removal device, 48 Recording medium container, 50 Bottom plate, 52 Delivery roll, 54 Transport roll, 56 separation roll,
60 conveying path, 60A first folding section, 60B second folding section, 62 secondary transfer roll, 66 preliminary path, 70, 80 conveying belt, 72 winding roll, 82 fixing unit, 84 fixing belt, 88 pressure roll, 89 Drive roll, 90 Drive roll, 100 Control circuit, 108 Conveyor belt, 110 Cooling unit, 112 Absorption device, 114 Pressing device, 116 Absorption belt, 118 Winding roll, 120 Drive roll, 122 Heat sink, 128 Fan, 130 Pressing belt 132 winding rolls, 140 straightening devices,
194 reverse path, 194A branch path, 194B paper transport path, 194C reverse path, 196 discharge unit, 198 discharge roll, 200 built-in image sensor, 202 illumination unit, 204 CCD sensor, 206 imaging optical system, 208 imaging unit, 210 Setting unit, 212 lamp, 212A first lamp, 212B second lamp, 214 first mirror, 216 second mirror, 218 third mirror, 220 lens, 224 light quantity diaphragm unit, 226 reference roll, 226A rotation axis, 228 detection reference Surface, 230 evacuation surface, 231 red reference surface, 232 white reference surface, 233 green reference surface, 234 yellow reference surface, 235 blue reference surface, 236 composite inspection surface, 237 cyan color reference surface, 239 magenta color reference surface, 262 circuit Substrate, 286 Window glass, 350 Read signal processing unit, 352 S H unit, 354 amplifier unit, 356 A / D conversion unit, 358 a shading correction ^{unit, 360 RGB1 / L * a *} b * 1 color conversion section 361 checking the color gamut creating unit, 362 a reference gamut storage unit, 363 color gamut Inspection unit, 364 L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient creation unit, 365 L ^* a ^* b ^* 1 / L ^* a ^* b ^* 0 color conversion coefficient update unit, 366 L ^* a ^* b ^* 1 / L * a ^* b ^* 0 color conversion unit, 367 L ^* a ^* b ^* 0 / RGB two-color conversion unit, 370 dimming circuit, D irradiation position, L light beam, N fixing unit, OA light Axis, P recording medium, T transfer position

Claims (14)

Illuminating means for illuminating each of a plurality of reference color portions colored with different reference colors with a dimming illumination light including a plurality of illumination lights adjusted to different light amounts;
Each of the plurality of reference color portions illuminated with the light control illumination light is read for each of the plurality of illumination lights, and light control for each reference color including a plurality of pieces of image information corresponding to each of the plurality of illumination lights. Reading means for outputting image information;
Whether there is an abnormality in any of the image information in each color gamut including a plurality of pieces of image information included in the dimming image information based on the dimming image information for each reference color output from the reading unit Generating means for generating correction information for correcting image information in a color gamut in which an abnormality exists, when determining whether or not an abnormality exists;
An image reading apparatus. The generating means calculates dimming image information for each color different from the reference color by interpolation of image information corresponding to illumination light having the same light intensity of the dimming image information for each reference color, and The image reading apparatus according to claim 1, wherein the correction information is generated based on dimming image information and dimming image information for each color different from the reference color. The generating means calculates the dimming image information for each color different from the reference color existing between the first reference color included in the reference color and the second reference color included in the reference color. The image reading according to claim 2, wherein dimming image information for each color different from the reference color is calculated by interpolation of image information corresponding to illumination light in which the light amounts of the first reference color and the second reference color are equal. apparatus. The color different from the reference color is a color corresponding to a dividing point when the color difference between the first reference color and the second reference color is divided so as to have an equal value. Image reading device. The generation means includes dimming image information for each reference color and dimming image information for each color different from the reference color included in the correction information, dimming image information for each reference color, and the reference color. If the maximum value of the color differences, which are the differences between each of the dimming image information for each color different from the reference image information determined in advance, is equal to or greater than a predetermined threshold, the image in the color gamut The image reading device according to claim 2, wherein it is determined that an abnormality exists in any of the information. Calculating a color conversion coefficient for converting each of the dimming image information for each reference color included in the correction information and the dimming image information for each color different from the reference color into the corresponding reference image information; The image reading apparatus according to claim 5, further comprising a correction unit that corrects image information in a color gamut in which an abnormality exists by color-converting image information of an image read by the reading unit using the calculated color conversion coefficient. Storage means for storing the color conversion coefficient;
7. The image according to claim 6, further comprising: an update unit that updates a color conversion coefficient stored in the storage unit to the calculated color conversion coefficient when a color conversion coefficient is calculated by the correction unit. Reader. When the color conversion coefficient is calculated by the correction unit, the generation unit corrects the image information in the color gamut in which the abnormality exists by the correction unit, and then again has an abnormality in any of the image information in the color gamut. The image reading apparatus according to claim 6, wherein whether or not to perform the determination is determined. The image reading apparatus according to claim 8, further comprising a notification unit that notifies a result of the determination again by the generation unit. The correction means converts the light control image information for each reference color and the light control image information for each color different from the reference color and the reference image information included in the correction information into L ^* a ^* b ^* colors Calculate the color conversion coefficient by placing it in space,
The image information of the image in which the image information in the color gamut where the abnormality exists is corrected is used as the image information of the L ^* a ^* b ^* color space, or the image information of the L ^* a ^* b ^* color space is the image of the RGB color space. The image reading apparatus according to any one of claims 6 to 9, further comprising output means for outputting the image information converted into information. 11. The image reading apparatus according to claim 5, further comprising display means for displaying the color difference for each of the reference colors for which the color difference has been obtained. The different reference colors include a plurality of chromatic colors, and the plurality of chromatic colors belong to each of hue regions obtained by dividing the hue of a color space in which the color indicated by the dimming image information is evenly or substantially equally divided. The image reading device according to claim 1, wherein the image reading device is disposed in the image reading device. An image forming means for forming an image;
An image reading apparatus according to any one of claims 1 to 12,
An image forming apparatus. Illuminating means for illuminating each of a plurality of reference color portions colored with different reference colors with a dimming illumination light including a plurality of illumination lights adjusted to different light amounts;
Each of the plurality of reference color portions illuminated with the light control illumination light is read for each of the plurality of illumination lights, and light control for each reference color including a plurality of pieces of image information corresponding to each of the plurality of illumination lights. Reading means for outputting image information;
A program for controlling an image reading apparatus including:
Computer
Whether there is an abnormality in any of the image information in each color gamut including a plurality of pieces of image information included in the dimming image information based on the dimming image information for each reference color output from the reading unit A program for functioning as a generation unit that determines whether or not an abnormality exists and generates correction information for correcting image information in a color gamut where the abnormality exists.