JP2019118105A - Imaging apparatus, mage forming apparatus and colorimetry method - Google Patents

Abstract

To image a subject without being affected by irregular reflection around the subject.SOLUTION: An imaging unit 30 comprises a housing 32 in which openings 32b and 32c are formed in its bottom face part 32a and a reference chart plate 38 having a reference chart KC formed therein. The reference chart plate 38 is fitted in the housing 32 at the side of the bottom face part 32a. In the reference chart plate 38, a slit 38a is formed at a position facing the opening 32c. In the reference chart plate 38, a black reflection suppression part 40 is formed in the periphery of the slit 38a. The imaging unit 30 causes an illumination light source to irradiate the reference chart KC and the slit 38a with illumination light, receives, with an image sensor part, reflection light from a subject and the reference chart KC located below the slit 38a, and images the subject together with the reference chart KC.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an imaging apparatus, an image forming apparatus, and a color measurement method.

  Image forming apparatuses such as color ink jet image forming apparatuses and color electrophotographic image forming apparatuses have offsets for advertisement media, brochures, etc. for which a high image is required although the number of printings is relatively small as the image quality improves. It is also being used for printing.

  In offset printing that requires high image quality, the color of the printed matter requested by the customer may be different from the color of the print output result actually printed out by the image forming apparatus.

  Usually, the customer confirms the color of the printed matter on the display and orders printing, but the image forming apparatus has color reproduction characteristics unique to the model and is different from the color confirmed on the display It may result in printing.

  Therefore, conventionally, a technology for performing color reproduction using a color space independent of a device such as a display or an image forming apparatus, for example, L * a * b * color space or xyz color space has come to be used. .

  Then, the image forming apparatus controls the amount of coloring material and the like in order to output a designated color. For example, in the ink jet type image forming apparatus, output color is controlled by controlling the discharge amount of the ink from the ink head by arithmetically controlling the discharge amount of the ink, the printing pattern, etc. In the image forming apparatus, output color is controlled by controlling the amount of adhesion of toner to the photosensitive member, the amount of light of the laser beam, and the like.

  However, the amount of coloring material, for example, the amount of ink ejected from the ink jet image forming apparatus, varies due to the state of the nozzle of the head, the viscosity variation of the ink, the variation of the ejection drive element (piezo element etc.), Variations in color reproducibility occur. In addition, the discharge amount of the ink of the ink jet type image forming apparatus may change with time in one image forming apparatus or may be different for each image forming apparatus, and temporally, for each image forming apparatus. Dispersion in the color reproduction of the image.

  Therefore, conventionally, in the image forming apparatus, color adjustment processing is performed to suppress output variation due to the characteristic unique to the device and to improve the reproducibility of the output with respect to the input. In this color adjustment process, for example, an image of a color patch of a reference color (reference color patch image) is actually output by the image forming apparatus, and the reference color patch image is measured by a color measurement device. Then, a color conversion parameter is generated based on the difference between the colorimetric value of the standard color patch image measured by the color measurement device and the color specification value in the standard color space of the corresponding standard color, and this color conversion parameter is calculated. Set in the image forming apparatus. Thereafter, when outputting an image according to the input image data, the image forming apparatus performs color conversion on the input image data based on the set color conversion parameter, and performs color conversion. By recording and outputting the image based on the image data, it is possible to suppress the variation of the output due to the characteristic unique to the device, and to output the image with high color reproducibility.

  In this conventional color adjustment process, a spectral colorimeter is widely used as a colorimetry device for measuring a reference color patch image, and the spectral colorimeter can obtain spectral reflectance for each wavelength. Therefore, highly accurate color measurement can be performed. However, since the spectrocolorimeter is an expensive device equipped with a large number of sensors, there is a demand for performing high-accuracy colorimetry using a cheaper device.

  Then, conventionally, the case is taken, the reference pattern used for color measurement disposed in the case, and the reference pattern imaged in a partial region of the imaging region, and the color measurement object is imaged in the other region. A two-dimensional sensor, the two-dimensional sensor, an imaging element disposed on the optical path of the reference pattern and the color measurement target, and forming an image of the reference pattern on a sensor surface of the two-dimensional sensor; An imaging device comprising: a transmitting member disposed in an optical path between a sensor and the color measurement target, and having a refractive index for setting an image forming position of the color measurement target by the image forming element as the two-dimensional sensor surface; Has been proposed (see Patent Document 1). And in this prior art, a housing | casing is moved on the color measurement object recorded on the paper etc., and the reference pattern in a housing | casing and the color measurement object are imaged.

  However, in the prior art described in the above-mentioned publication, there is a problem that the imaging quality is lowered.

  Therefore, an object of the present invention is to improve the imaging quality of a subject.

  In order to solve the problems described above and achieve the object, an imaging apparatus according to the present invention is a two-dimensional image sensor, and data of an image obtained by imaging a predetermined area in an imaging area of the two-dimensional image sensor. Among them, a correction data generation unit that generates correction data based on image data of a predetermined color, and at least an image captured by the two-dimensional image sensor, which is included in the predetermined area and is more than the predetermined area And a correction unit that corrects, with the correction data, data of a color measurement target obtained from a narrow area, and the correction data is data corresponding to a range wider than the narrow area.

  According to the present invention, the imaging quality of a subject can be improved.

FIG. 1 is a schematic perspective view of an image forming apparatus to which an embodiment of the present invention is applied. The top view of a carriage part. FIG. The top view of an imaging unit. FIG. 6 is a cross-sectional view of the imaging unit of FIG. FIG. 6 is a cross-sectional view of the imaging unit of FIG. The top view of a reference | standard chart board. FIG. 2 is a block diagram of an essential part of the image forming apparatus. FIG. 2 is a block diagram of an imaging unit and a colorimetry control unit. FIG. 6 is a view showing an example of three-dimensional image data when an image of a white reference plate is taken as a subject. The figure which shows an example of shading correction data. Explanatory drawing of the acquisition process of the reference colorimetric value and imaging | photography reference | standard RGB value from a reference | standard sheet | seat, and reference value linear transformation matrix acquisition process. The figure which shows an example of an initial stage reference | standard RGB value. The figure which shows an example of the image data which imaged the reference | standard chart and the imaging object together. Explanatory drawing of a colorimetric process. Explanatory drawing of a reference | standard RGB inter-linear transformation matrix production | generation process. The figure which shows the relationship of an initial reference | standard RGB value and the color measurement reference | standard RGB value. Explanatory drawing of a basic color measurement process. FIG. 19 is a diagram showing a basic color measurement process continued from FIG. 18; Front sectional drawing of the imaging unit which is not provided with the optical path length change member. 20 is a cross-sectional view of the imaging unit of FIG. FIG. 1 is a system configuration diagram of an image forming system to which a color measurement system is applied.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added, but the scope of the present invention is unduly limited by the following description. Also, not all of the configurations described in the present embodiment are essential components of the present invention.

  FIGS. 1 to 22 are views showing an embodiment of an imaging unit, a color measurement apparatus, an image forming apparatus, a color measurement system and a color measurement method according to the present invention, and FIG. FIG. 1 is a schematic perspective view of an image forming apparatus 1 to which an embodiment of an apparatus, an image forming apparatus, a color measurement system, and a color measurement method is applied.

  In FIG. 1, in the image forming apparatus 1, a main body case 2 is disposed on a main body frame 3, and in the main body case 2, a main guide rod in a main scanning direction indicated by a double arrow A in FIG. 4 and the auxiliary guide rod 5 are stretched. The main guide rod 4 movably supports the carriage 6, and the carriage 6 is provided with a connection piece 6 a that engages with the sub guide rod 5 to stabilize the posture of the carriage 6.

  In the image forming apparatus 1, an endless belt-shaped timing belt 7 is disposed along the main guide rod 4, and the timing belt 7 is stretched between a driving pulley 8 and a driven pulley 9. The driving pulley 8 is rotationally driven by the main scanning motor 10, and the driven pulley 9 is disposed in a state of giving a predetermined tension to the timing belt 7. The driving pulley 8 is rotationally driven by the main scanning motor 10 to rotationally move the timing belt 7 in the main scanning direction according to the rotation direction.

  The carriage 6 is connected to the timing belt 7, and the timing belt 7 is rotationally moved in the main scanning direction by the driving pulley 8 to reciprocate in the main scanning direction along the main guide rod 4.

  In the image forming apparatus 1, the cartridge unit 11 and the maintenance mechanism unit 12 are accommodated at both end positions in the main scanning direction in the main body case 2, and the cartridge unit 11 is yellow (Y), magenta (M), cyan Cartridges for storing the respective inks of (C) and black (K) are stored replaceably. The cartridges of the cartridge unit 11 are connected to the recording heads 20 y, 20 m, 20 c, and 20 k (see FIG. 2) of the corresponding colors of the recording head 20 mounted on the carriage 6 by pipes not shown. The cartridge supplies the ink to the recording heads 20y, 20m, 20c and 20k through the pipes. In the following description, the recording heads 20 y, 20 m, 20 c, and 20 k are collectively referred to as the recording head 20.

  As described later, while moving the carriage 6 in the main scanning direction, the image forming apparatus 1 moves on the platen 14 (see FIG. 2) in the sub scanning direction (arrow B direction in FIG. 1) orthogonal to the main scanning direction. By discharging the ink onto the recording medium P which is intermittently transported, the image is recorded and output on the recording medium P.

  That is, the image forming apparatus 1 of the present embodiment intermittently conveys the recording medium P in the sub scanning direction, and while the conveyance of the recording medium P is stopped in the sub scanning direction, the carriage 6 in the main scanning direction. While being moved, ink is discharged from the nozzle array of the recording head 20 mounted on the carriage 6 onto the recording medium P on the platen 14 to form an image on the recording medium P.

  The maintenance mechanism unit 12 cleans the ejection surface of the recording head 20, performs capping, discharges unnecessary ink, and the like to discharge unnecessary ink from the recording head 20 and maintain the reliability of the recording head 20. There is.

  The image forming apparatus 1 is provided with a cover 13 so as to be able to open and close the conveyance portion of the recording medium P, and the cover 13 is opened by opening the cover 13 at the time of maintenance of the image forming apparatus 1 or jamming. It is possible to perform operations such as maintenance and removal of the jam recording medium P.

  As shown in FIG. 2, the carriage 6 carries the recording heads 20y, 20m, 20c, and 20k. The recording heads 20y, 20m, 20c, and 20k are connected to the corresponding color cartridges of the cartridge unit 11 by pipes, respectively, and discharge the corresponding color inks onto the opposing recording medium P. That is, the recording head 20 y has a yellow (Y) ink, the recording head 20 m has a magenta (M) ink, the recording head 20 c has a cyan (C) ink, and the recording head 20 k has a black (K) ink Each discharge.

  The recording head 20 is mounted on the carriage 6 so that its discharge surface (nozzle surface) faces downward (the recording medium P side) in FIG. 1 and discharges the ink onto the recording medium P.

  In the image forming apparatus 1, an encoder sheet 15 is disposed parallel to the timing belt 7, that is, the main guide rod 4, at least over the movement range of the carriage 6. On the other hand, an encoder sensor 21 for reading an encoder sheet 15 is attached to the carriage 6. The image forming apparatus 1 controls the movement of the carriage 6 in the main scanning direction by controlling the driving of the main scanning motor 10 based on the reading result of the encoder sheet 15 by the encoder sensor 21.

  As shown in FIG. 3, in the recording head 20 mounted on the carriage 6, each of the recording heads 20y, 20m, 20c, and 20k is configured by a plurality of nozzle arrays. The recording head 20 forms an image on the recording medium P by discharging ink from the nozzle array onto the recording medium P conveyed on the platen 14. In the image forming apparatus 1, the upstream recording head 20 and the downstream recording head 20 are mounted on the carriage 6 in order to secure a wide width of an image that can be formed on the recording medium P by one scan of the carriage 6. ing. The recording head 20k for ejecting the black ink is mounted on the carriage 6 twice as many as the recording heads 20y, 6m, and 6c for ejecting the color ink in order to improve the printing speed of the black. Further, the recording heads 20y and 6m are arranged in a state of being divided in the main scanning direction and adjacent to each other in order to match the overlapping order of colors by the reciprocating operation of the carriage 6 and prevent color change between the forward pass and the return pass. It is done. The arrangement of the recording heads 20 y, 20 m, 20 c and 20 k of the recording head 20 is not limited to the arrangement shown in FIG.

  As shown in FIG. 2, the imaging unit 30 is attached to the carriage 6, and the imaging unit 30 captures an image of the subject in order to measure the subject (color measurement target) at the time of color adjustment processing described later. Do.

  The imaging unit 30 is mounted on the substrate 31 as shown in FIG. 4 which is a plan view, FIG. 5 which is a sectional view taken along the line AA of FIG. 4 and FIG. A rectangular box-shaped casing 32 whose surface on the side of the substrate 31 is open is fixed by a fastening member 33.

  The substrate 31 is fixed to the carriage 6 shown in FIG. The housing 32 is not limited to a square box shape, and may be, for example, a cylindrical shape or an elliptical cylinder shape having a bottom portion 32a in which the openings 32b and 32c are formed.

  The image sensor unit 34 is disposed on the surface of the substrate 31 on the housing 32 side of the substrate 31 and at the center thereof. The image sensor unit (sensor means) 34 is a CCD (Charge Coupled Device) sensor. And a two-dimensional image sensor 35 such as a CMOS (Complementary Metal Oxide Semiconductor) sensor or the like and a lens 36.

  In the imaging unit 30, the lower surface of a surface portion (hereinafter referred to as a bottom surface portion) 32a of the casing 32 opposite to the substrate 31 faces the recording medium P on the platen 14 with a predetermined distance d. In the state, it is attached to the carriage 6. In the bottom surface portion (facing surface) 32a, substantially rectangular openings 32b and 32c are formed side by side across the bottom surface portion 32a of a predetermined width in the main scanning direction with the center line Lo at the center. . The gap d is preferably as small as possible in consideration of the focal length with respect to the two-dimensional image sensor 35 as described later, but the lower surface of the housing 32 and the recording medium P For example, the size is set to about 1 mm to 2 mm. The bottom surface portion 32a between the opening 32b and the opening 32c may be subjected to a predetermined surface treatment or the like that absorbs specularly reflected light from the illumination light source 37 described later.

  The housing 32 is formed with a recess 32d on the outer surface on the side of the bottom surface 32a in a state including both the opening 32b and the opening 32c, and on the outer surface side of the housing 32 further than the recess 32d. A recess 32e larger than the recess 32d is formed.

  A reference chart plate (plate-like member) 38 is detachably fitted in the recess 32b so as to cover both the opening 32b and the opening 32c, and in a state of covering and holding the reference chart 38, a holding plate A reference numeral 39 is removably fitted in the recess 32e.

  The opening 32 b and the opening 32 c are closed by the reference chart plate 38 and the holding plate 39. At a position facing the opening 32c of the reference chart plate 38, as shown in FIGS. 5 and 6, the imaging unit 30 has a predetermined width in the movement direction, and a predetermined length in the direction orthogonal to the movement direction. Slit (opening) 38a is formed. Further, in the holding plate 39, an opening 39a larger than the slit 38a is formed at a position corresponding to the slit 38a.

  The slits 38a are, as described later, reference color patches KP (see FIG. 12) and a colorimetry adjustment sheet CS (see FIG. 12) of a reference sheet KS (see FIG. 12) which is an imaging target (subject) formed on the recording medium P. 5 (see FIG. 15) is used to image the colorimetry adjustment color patch CP (see FIG. 5 and FIG. 15). The slit 38a may have at least a size capable of capturing all patch images of imaging targets, but since there is a gap d between the housing 32 and the imaging target, the shadow generated around the slits 38a is taken into consideration Then, the size is slightly larger than the size of the imaging area of the imaging target.

  A reflection suppressing portion (reflection suppressing means) 40 is provided around the slit 38a on the surface on the side of the housing 32 of the reference chart plate 38, as shown in FIG. In the image forming apparatus 1 of the present embodiment, reflection is suppressed by being applied in black of a predetermined width. The reference chart plate 38 is a portion facing the opening 32c, and a portion other than the reflection suppressing portion 40 applied in black has a color with a small reflectance, for example, gray (gray). It may be applied. Also, this gray data value may be a color data value that exceeds the maximum value of the color data of the color of the reference chart KC.

  The reference chart plate 38 is a surface on the inner side of the housing 32, and a reference chart KC is formed at a position facing the opening 32b.

  The reference chart KC is compared with the reference color patch KP of the reference sheet KS and the colorimetry adjustment value of the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS to be imaged in the color adjustment processing by the imaging unit 30. Photographed together with the reference color patch KP and the colorimetry adjustment color patch CP. That is, the imaging unit 30 measures the color of the reference color patch KP of the reference sheet KS and the colorimetry adjustment sheet CS located outside the housing 32 through the slits 38 a of the opening 32 c provided in the bottom surface 32 a of the housing 32. The adjustment color patch CP is imaged. Then, the imaging unit 30 compares the color patch on the reference chart KC located in the opening 32 b of the bottom 32 a of the housing 32 with the imaging of the reference color patch KP and the colorimetry adjustment color patch CP. Take an image.

  In the imaging unit 30, the two-dimensional image sensor 35 sequentially scans pixels to read an image. Therefore, strictly speaking, the reference color patch KP of the reference sheet KS and the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS and the reference chart KC are not read together, but the reference color patch KP and colorimetry are within one frame. Since the images of the adjustment color patch CP and the reference chart KC can be acquired, they are expressed as “acquired together” or “acquired together” as appropriate.

  The reference chart KC has a plurality of reference color patch rows Pa to Pd for color measurement, a pattern row Pe for dot diameter measurement, a distance measurement on the surface (upper surface) on the inner side of the casing 32 as shown in FIG. For the line lk and the chart position specifying marker mk are formed.

  The patch arrays Pa to Pd for color measurement include a patch array Pa in which primary color patches of YMC are arranged in gradation order, a patch array Pa in which color patches of secondary colors of RGB are arranged in gradation order, and gray There are a patch row (tone pattern of achromatic color) Pc in which patches of the scale are arranged in the tone order, and a patch row Pd in which patches of the third color are arranged. The dot diameter measurement pattern row Pe is a pattern row for geometric shape measurement in which circular patterns of different sizes are arranged in order of size.

  The distance measurement lines lk are formed as rectangular frame lines surrounding the patch arrays Pa to Pd for color measurement and the dot diameter measurement pattern array Pe. The chart position specifying markers mk are provided at four corner positions of the distance measurement line lk, and are markers for specifying each patch position.

  The colorimetric control unit 106 (see FIGS. 8 and 9) described later identifies the distance measurement line lk and the chart position specifying markers mk at the four corners from the image data of the reference chart KC acquired from the imaging unit 30. , The position of the reference chart KC and the position of each pattern are specified.

  The patches constituting the reference color patch row Pa to Pd for color measurement are L *, which is a standard color space, using a spectroscope BS (see FIG. 10), similarly to a reference patch KP of a reference chart KC described later. The color values (L * a * b * values) in the a * b * color space are measured in advance. Each of these patches serves as a reference value when the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS described later is measured.

  The configuration of the patch rows Pa to Pd for color measurement arranged on the reference chart KC is not limited to the arrangement example shown in FIG. 7, and any patch row can be used. For example, patch rows Pa to Pd may use patches capable of specifying the color range as wide as possible, or patch rows Pa of YMCK primary colors and patch rows Pc of gray scale may be used for image formation. It may be composed of patches of colorimetric values of ink used in the device 1. Further, the RGB secondary color patch array Pa of the reference chart KC may be configured by patches of colorimetric values that can be developed with the ink used in the image forming apparatus 1, and further, colorimetric values such as JapanColor etc. You may use the reference | standard color chip which was defined.

  The reference chart plate 38 on which the reference chart KC is formed is a recess 32d formed on the outer periphery of the surface on the recording medium P side of the opening 32b and the opening 32c formed on the bottom 32a of the housing 32. Are located in Therefore, the reference chart KC is imaged by the two-dimensional image sensor 35 of the image sensor unit 34 at the same focal length as the imaging target such as the recording medium P.

  The reference chart KC is detachably set in the recess 32d formed on the outer periphery of the surface on the recording medium P side of the opening 32b and the opening 32c formed on the bottom 32a of the housing 32. There is. The reference chart KC is detachably held by a holding plate 39 which is detachably fitted to the recess 32e outside the recess 32d. Therefore, even if dust or the like invading the inside of the housing 32 adheres to the surface of the reference chart KC, the holding plate 32e and the reference chart plate 38 are removed to clean the surface of the reference chart plate 38 on the reference chart KC side. be able to. Then, the reference chart plate 38 can be attached again after cleaning, and the measurement accuracy of the reference chart KC can be improved.

  Referring back to FIG. 4 to FIG. As shown in FIG. 4, the imaging unit 30 is on the center line Lo in the sub scanning direction passing the center of the image sensor unit 34, and is equally spaced from the center of the image sensor unit 34 by a predetermined amount in the sub scanning direction. A pair of illumination light sources 37 is disposed on the substrate 31 at a distant position. As the illumination light source 37, an LED (Light Emitting Diode) or the like is used.

  Furthermore, in the imaging unit 30, the arrangement conditions of the opening 32c in the imaging area and the reference chart KC are arranged substantially symmetrically with respect to a center line Lo connecting the center of the lens 36 and the illumination light source 37. Therefore, the imaging unit 30 can make the imaging conditions of the two-dimensional image sensor 35 identical in line symmetry, and improve the accuracy of the color adjustment process and the color measurement process of the two-dimensional image sensor 35 using the reference chart KC. be able to.

  The lens 36 is disposed in the optical path of the subject and the reflected light from the reference chart KC to the two-dimensional image sensor 35, and focuses the reflected light on the two-dimensional image sensor 35. As the lens 36, one imaging lens may be used, or a plurality of lenses may be used in combination.

  In the case 32, the light path length changing member 50 is disposed on the bottom surface portion 32 a in a state of closing the opening 32 c in the case 32, and the light path length changing member 50 is provided around the opening 32 c. Fixed or held on the housing 32 of the

  The light path length changing member 50 has a refractive index n, and a light transmitting member having a length Lp in the light transmission direction (hereinafter referred to as the length of the light path length changing member) Lp is used. And the length Lp of the light transmission direction has an optical path length change amount (an amount of floating of an image) C determined by the following equation (1).

C = Lp (1-1 / n) (1)
The optical path length (focal length) L from the imaging surface of the recording medium P to the two-dimensional image sensor 35 of the image sensor unit 34 is given by the following equation (2).

L = Lt + Lp (1-1 / n) (2)
Here, Lt is the distance between the apex on the imaging target side of the lens 36 and the imaging surface of the recording medium P.

  Then, in the imaging unit 30, the optical path length (focal length) L from the imaging surface of the recording medium P to the two-dimensional image sensor 35 and the optical path length (focal length) from the reference chart KC to the two-dimensional image sensor 35 match. In the above, the refractive index n and the length Lp of the optical path length changing member 50 are set. By setting in this manner, the focal position of the reference chart KC with respect to the two-dimensional image sensor 35 of the image sensor unit 34 and the focal position of the subject (imaging plane) can be made to coincide.

  In addition, the imaging unit 30 emits illumination light irradiated to the imaging surface of the recording medium P through the optical path length changing member 50 and the slit 38a of the opening 32c and illumination light irradiating the reference chart KC from the same illumination light source 37 Illumination light. Therefore, the imaging unit 30 can image the reference chart KC and the imaging surface of the recording medium P together under the same illumination condition. Further, the illumination light sources 37 are disposed on the center line Lo, which is a substantially intermediate position between the reference chart KC and the recording medium P, and two are disposed symmetrically with respect to the lens 36 on the center line Lo. Therefore, the imaging unit 30 can uniformly illuminate the reference chart KC and the imaging area of the recording medium P under substantially the same illumination condition.

  Furthermore, in the imaging unit 30, the arrangement conditions of the slit 38a of the opening 32c in the imaging area and the reference chart KC are arranged substantially symmetrically with respect to a center line Lo connecting the center of the lens 36 and the illumination light source 37. Therefore, the imaging unit 30 can make the imaging conditions of the two-dimensional image sensor 35 identical in line symmetry, and improve the accuracy of the color adjustment process and the color measurement process of the two-dimensional image sensor 35 using the reference chart KC. be able to.

  The image forming apparatus 1 of this embodiment is configured as a block as shown in FIG. 8 and includes a central processing unit (CPU) 101, a read only memory (ROM) 102, a random access memory (RAM) 103, and a main scan. The driver 104, the recording head driver 105, the colorimetry control unit 106, the paper conveyance unit 107, the sub scanning driver 108, and the like, and the recording head 20 mounted on the carriage 6 as described above, the encoder sensor 21, and imaging A unit 30 and the like are provided.

  The ROM 102 stores programs such as a basic program and a color adjustment processing program as the image forming apparatus 1 and necessary system data.

  The CPU 101 controls each part of the image forming apparatus 1 to execute basic processing as the image forming apparatus 1 while using the RAM 103 as a work memory based on a program in the ROM 102. The CPU 101 also executes color adjustment processing at the time of image formation based on the colorimetric values obtained by the colorimetric processing in the colorimetric control unit 106 based on the RGB values captured by the imaging unit 30.

  In the control of the carriage 6 and the paper conveyance unit 107, the CPU 101 controls the drive of the main scanning driver 104 based on the encoder value from the encoder sensor 21 to control the movement of the carriage 6 in the main scanning direction. Further, the CPU 101 controls the driving of the paper conveyance unit 107 such as a sub-scanning motor and a conveyance roller (not shown) via the sub-scanning driver 108. Further, the CPU 101 controls the discharge timing and the ink discharge amount of the ink by the recording head 20 via the recording head driver 105.

  As described above, the imaging unit 30 generates a colorimetric value for color adjustment that accurately reproduces the color of image data when recording and outputting an image into a color intended by the user, as described later. At the time of colorimetry, the colorimetry adjustment color patch CP formed on the recording medium P by the recording head 20 is imaged, and the imaged RGB values are output to the CPU 101.

  The imaging unit 30 and the colorimetry control unit 106 are configured as a block as shown in FIG. The imaging unit 30 includes the illumination light source 37 and the image sensor unit 34, and also includes an image processing unit 110, an interface unit 120, and the like. The image processing unit 110 includes a black level correction circuit 111, an A / D conversion unit 112, a shading correction unit 113, a white balance correction unit 114, a γ correction unit 115, and an image format conversion unit 116. The imaging unit 30 and the colorimetry control unit 106 function as a colorimetry device as a whole.

  The imaging unit 30 outputs, to the image processing unit 110, analog RGB image data in which the image sensor unit 34 images the subject and the reference chart KC together. The image processing unit 110 performs necessary image processing on the analog RGB image data sent from the image sensor unit 34 and outputs the image processing to the colorimetry control unit 106.

  The black level correction circuit 111 receives an analog image signal output from the image sensor unit 34 via an AC coupling capacitor (not shown). The black level correction circuit 111 clamps the image signal when the image sensor unit 34 reads the black color of the reflection suppressing unit 40 formed around the slit 38a at a predetermined potential as a black offset level, and an appropriate offset is generated. Apply a voltage and sample and hold. The black level correction circuit 111 converts the image signal into a continuous analog signal by sampling and holding the image signal by the sample pulse, and then outputs the pixels of each color signal to a certain level, in particular, the A / D converter 112 It is amplified to the level of the reference voltage and output to the A / D converter 112.

  That is, the black level correction circuit 111 line-clamps the black color of the reflection suppression unit 40 to clamp the black offset level to a predetermined potential, and the reflection suppression unit 40 after digital conversion in the A / D conversion unit 112. The output of is approximately the target black offset level.

  The A / D conversion unit 112 compares an analog image signal input from the black level correction circuit 111 with a reference voltage, converts the analog image signal into, for example, 8-bit digital data, and outputs the digital data to the shading correction unit 113.

  The shading correction unit 113 corrects, for the RGB image data from the A / D conversion unit 112, an error in image data caused by uneven illuminance of the illumination light from the illumination light source 37 with respect to the imaging range of the image sensor unit 34. And outputs it to the white balance correction unit 114.

  The white balance correction unit 114 corrects the white balance of the RGB image data after the shading correction and outputs the corrected white balance to the γ correction unit 115.

  The γ correction unit 115 corrects the image data input from the white balance correction unit 114 so as to compensate for the linearity of the sensitivity of the image sensor unit 34, and outputs the corrected data to the image format conversion unit 116.

  The image format conversion unit 116 converts the γ-corrected image data into an arbitrary format, and outputs the image data to the colorimetry control unit 106 via the interface unit 120.

  The interface unit 120 causes the imaging unit 30 to acquire various setting signals, timing signals, and light source drive signals sent from the colorimetry control unit 106, and to send image data from the imaging unit 30 to the colorimetry control unit 106. It is an interface.

  Then, the shading correction unit 113 may arrange a white reference plate in the imaging region of the slit 38a, and the imaging unit 30 may read the white reference plate together with the reference sheet KS to perform shading correction. In this case, the image data of the white reference plate imaged by the imaging unit 30 can be three-dimensionally represented as shown in FIG. The image data output by the imaging unit 30 is RGB image data, but in FIG. 10, only one color is shown. Further, in FIG. 10, for the sake of simplicity, image data in the case where only four patches are formed on the reference chart KC is illustrated.

  The shading correction unit 113 extracts, from the image data output from the image sensor unit 34, image data of a peripheral area of a predetermined color which is a base of correction data. Specifically, the shading correction unit 113 first removes, from the image data output from the shading correction unit 113, the image data of a previously stored area (a predetermined area of the imaging range of the image sensor unit 34). . In FIG. 10, the bottom surface area is the bottom surface 32a of the housing 32 located between the opening 32b and the opening 32c. Although FIG. 10 shows the case where the bottom surface 32a is subjected to the diffusion process for diffusing the illumination light from the illumination light source 37, the diffusion process may not be performed.

  Then, the shading correction unit 113 uses the chart position specifying marker mk of the reference chart KC and the like to provide each patch (including the dot diameter measurement pattern row Pe and the distance measurement line lk) provided on the reference chart KC. Identify the location of The shading correction unit 113 removes the image data of the area of each patch from the image data output from the image sensor unit 34. The shading correction unit 113 detects the black reflection suppression unit 40 provided around the slit 38 a of the reference chart plate 38. From the image data output from the image sensor unit 34, the image data of the black reflection suppressing unit 40 and the region outside the black region are removed, and the image data of the white reference plate is acquired. Further, the shading correction unit 113 extracts image data of the peripheral area consisting of only the area of the predetermined color of the reference chart KC, as shown in FIG. The shading correction unit 113 compares the image data of all areas of the imaging range output from the image sensor unit 34 with a predetermined threshold, and removes the area whose image data is equal to or less than the threshold to obtain image data of the peripheral area. May be extracted.

  The shading correction unit 113 generates shading correction data by interpolating the image data of each patch area of the reference chart KC, the reflection suppressing unit 40 and the white reference board inside the area based on the extracted image data of the peripheral area. . Specifically, for example, the shading correction unit 113 obtains an approximate expression that approximates the extracted image data of the peripheral region with a low order (about 2 to 3 order) polynomial, and this approximate expression is used for each patch of the reference chart KC. The image data of these areas are interpolated by applying to the black area, the black reflection suppressing portion 40 and the area (white reference plate) inside the black area. Further, the shading correction unit 113 interpolates the image data of the area of each patch of the reference chart KC, the reflection suppression unit 40, and the white reference plate area inside thereof using, for example, two-dimensional spline interpolation or the like. It is also good.

  Then, the shading correction unit 113 generates shading correction data as shown in FIG. 11 by interpolation of the image data, and stores the shading correction data in the internal storage unit. The shading correction unit 113 performs shading correction of the image data output from the image sensor unit 34 using the shading correction data of the internal storage unit at the time of imaging of the reference color patch KP, at the time of imaging of the colorimetric sheet CS, and at the time of imaging of the object. I do.

  In the above description, the image data of the peripheral area is extracted by removing the image data of the area of each patch provided in the reference chart KC from the image data output from the image sensor unit 34. However, when the intervals between the patches provided in the reference chart KC are narrow and image data of the area between the patches can not be properly extracted, a line for distance measurement is obtained from the image data output from the image sensor unit 34. The image data of the area of the entire reference chart KC surrounded by lk may be removed to extract the image data of the peripheral area.

  As described above, by imaging the white reference plate as a subject, shading correction can be performed accurately and easily.

  Further, by providing the black reflection suppressing portion 40 around the slit 38 a and reading the black reflection suppressing portion 40, black reference correction by the black level correction circuit 111 can be easily and appropriately performed.

  Furthermore, the shading correction unit 113 generates correction data to be used for shading correction using image data of only the white reference plate excluding image data around the white reference plate among the image data output from the image sensor unit 34. ing. Therefore, highly accurate correction data can be obtained, and the correction accuracy of shading correction can be improved.

  The colorimetric control unit (calculation unit) 106 includes a frame memory 121, a timing signal generation unit 122, a light source drive control unit 123, an operation unit 124, and a non-volatile memory 125. The operation unit 124 is a colorimetric value calculation unit It has 126.

  The frame memory 121 is a memory for temporarily storing the image data sent from the imaging unit 30, and outputs the stored image data to the operation unit 124.

  As shown in FIG. 12, the non-volatile memory 125 is L * which is the colorimetric value of the colorimetric result of the plurality of reference color patches KP arrayed on the reference sheet KS by the spectroscope (colorimetry device) BS. At least one of the a * b * value and the XYZ value (in FIG. 12, both the L * a * b * value and the XYZ value) is patched to the memory table Tb1 of the non-volatile memory 125 as a reference colorimetric value. It is stored corresponding to the number.

  Furthermore, in the state where the reference colorimetric value is stored in the non-volatile memory 125 in the memory table Tb 1 and in the initial state of the image forming device 1, the image forming device 1 Set on the platen 14. The image forming apparatus 1 controls the movement of the carriage 6 to control the imaging reference RGB values of the non-volatile memory 125 by reading the same reference patch KP as that read by the spectroscope BS in the reference sheet KS by the imaging unit 30. The memory table Tb1 is stored in correspondence with the patch number, that is, in correspondence with the reference colorimetric value. Furthermore, the image forming apparatus 1 captures each patch of the reference chart KC of the imaging unit 30 together with the reference sheet KS to acquire RGB values. The image forming apparatus 1 stores the RGB value of each patch of the reference chart KC as the initial reference RGB value RdGdBd in the memory table Tb1 of the non-volatile memory 125 under the control of the calculation unit 124.

  When the image forming apparatus 1 stores the reference colorimetric value, the imaging reference RGB value, and the initial reference RGB value RdGdBd in the non-volatile memory 125, the colorimetric value calculation unit 126 calculates the reference colorimetry stored in the non-volatile memory 125. A calculated reference value linear transformation matrix is calculated by converting a pair of XYZ values of values and imaging reference RGB values, that is, pairs of XYZ values of the same patch number and imaging reference RGB values. The transformation matrix is stored in non-volatile memory 125.

  In the image forming apparatus 1, the above process is executed in the initial state of the image forming apparatus 1, and the reference colorimetric value, the imaging reference RGB value and the initial reference RGB value RdGdBd which are the execution result are stored in the memory table Tb1 of the non-volatile memory 125. Then, the reference value linear transformation matrix is calculated and stored in the non-volatile memory 125.

  Furthermore, as described later, the image forming apparatus 1 according to the present embodiment has a colorimetry adjustment color patch CP and a case as a subject formed on the recording medium P by the recording head 20 changing with time during color adjustment processing. The image sensor unit 34 simultaneously images the reference chart KC disposed inside the body 32 and outputs image data including the colorimetry adjustment color patch CP and the reference chart KC to the colorimetry control unit 106. The colorimetry control unit 106 measures the colorimetry adjustment color patch CP captured by the image sensor unit 34 at the time of color adjustment processing acquired from the imaging unit 30 as a reference color patch of the reference sheet KS (hereinafter referred to as an initial reference color patch). The colorimetry adjustment color patch CP is converted to the initial reference RGB value RdGdBd of the initial reference RGB value RdGdBd of the patches Pa to Pe of the reference chart KC read and stored together when read by the imaging unit 30. Among them, a portion having linearity is taken out and subjected to linear conversion to perform colorimetric processing for obtaining a colorimetric value.

  That is, the operation unit 124 controls the operation of the colorimetry control unit 106, and the colorimetry value calculation unit 126 executes the colorimetry process and outputs the colorimetry value that is the processing result of the colorimetry process to the CPU 101 Do. The CPU 101 performs color adjustment processing on image data using the colorimetric values, and controls the recording head 20 based on the image data subjected to color adjustment processing, thereby forming an image in a state in which color reproducibility is improved.

  The timing signal generation unit 122 generates a timing signal for controlling the timing of imaging by the image sensor unit 34 of the imaging unit 30 and supplies the timing signal to the imaging unit 30.

  The light source drive control unit 123 generates a light source drive signal for driving the illumination light source 37 of the imaging unit 30 and supplies the signal to the imaging unit 30.

  The imaging unit 30 and the colorimetry control unit 106 function as a colorimetry device as a whole.

  The image forming apparatus 1 of this embodiment includes a ROM, an electrically erasable and programmable read only memory (EEPROM) (registered trademark), an EPROM, a flash memory, a flexible disk, a compact disc read only memory (CD-ROM), and a CD-RW (CD-RW). The colorimetry method according to the present embodiment recorded on a computer-readable recording medium such as Compact Disc Rewritable, DVD (Digital Versatile Disk), SD (Secure Digital) card, MO (Magneto-Optical Disc), etc. is executed. By reading the color measurement program and introducing it into the ROM 102 or the non-volatile memory 125 etc., the influence of the reflection of the illumination light on the subject of the illumination light source 37 is prevented, and the subject and the reference chart always have stable positional relationship and high accuracy Image forming apparatus equipped with a color measurement device provided with a color measurement unit for executing a color measurement method for imaging It has been built as 1. This color measurement program is a computer executable program described in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark) or an object-oriented blogging language, and is stored in the above recording medium. Can be distributed.

  Next, the operation of this embodiment will be described. The image forming apparatus 1 of the present embodiment improves the imaging quality of the subject without being affected by the diffuse reflection around the subject.

  The image forming apparatus 1 of this embodiment, as shown in FIG. 12, measures the colorimetry results by the spectroscope BS of a plurality of reference color patches arrayed on the reference sheet KS as L * a * b * values. At least one of the XYZ values is stored in the memory table Tb1 of the non-volatile memory 125 as a reference colorimetric value corresponding to the patch number.

  Further, the image forming apparatus 1 is in a state in which the reference colorimetric value is stored in the non-volatile memory 125 in the memory table Tb1, and the reference sheet is in the initial state due to the manufacturing or overfall. The KS is set on the platen 14 of the image forming apparatus 1. The image forming apparatus 1 controls the movement of the carriage 6 to image the same reference patch as that read by the spectroscope BS of the reference sheet KS by the imaging unit 30. Further, as shown in FIG. 12, the image forming apparatus 1 captures each patch (initial reference color patch) of the reference chart KC disposed inside the housing 32 together with the reference patch of the reference sheet KS.

  The image forming apparatus 1 measures an imaging reference RGB value which is an RGB value obtained by processing the image data obtained by imaging the reference patch of the reference sheet KS by the image processing unit 110, that is, a device dependent signal dependent on the device As shown in FIG. 12, the operation unit 124 of the 106 stores the memory table Tb1 of the non-volatile memory 125 in correspondence with the patch number, that is, in correspondence with the reference colorimetric value. The operation unit 124 further reads the initial reference color patch of the reference chart KC and processes the image data by the image processing unit 110 as the initial reference RGB value RdGdBd, as shown in FIG. Store in

  In the image data of the initial reference color batch of the reference chart KC read by the imaging unit 30, the calculation unit 124 measures a predetermined area of the imaging area imaged through the slit 38a, for example, an area shown by a dashed line in FIG. An average value is calculated for each color target area), and is used as an initial reference RGB value RdGdBd. When the initial reference RGB value RdGdBd is calculated by averaging a large number of pixels in the area to be measured in this way, the influence of noise can be reduced and the bit resolution can be improved. FIG. 13B is a scatter diagram in which the initial reference RGB values RdGdBd are plotted. In FIG. 13A, a reference L * a * b * value Ldaddd obtained by converting the initial reference RGB value RdGdBd into an L * a * b * value and a reference XYZ value xdydzd converted into an XYZ value are also registered in the non-volatile memory 125 Showing the status.

  When the image forming apparatus 1 stores the reference colorimetric value, the imaging reference RGB value, and the initial reference RGB value RdGdBd in the non-volatile memory 125, the colorimetric value calculation unit 126 of the calculation unit 124 calculates the reference value linear transformation matrix. Are stored in the non-volatile memory 125. That is, the colorimetric value calculation unit 126 pairs the XYZ value of the reference colorimetric value and the imaging reference RGB value stored in the non-volatile memory 125, that is, the pair of the XYZ value of the same patch number and the imaging reference RGB value. On the other hand, a reference value linear transformation matrix to be converted mutually is calculated and stored in the non-volatile memory 125.

  In this state, in the image forming apparatus 1, the CPU 101 controls the main scanning movement of the carriage 6, the conveyance control of the recording medium P by the paper conveyance unit 107, and the recording head based on image data and print settings input from the outside. The drive control of 20 is performed to control the ink discharge from each of the recording heads 20 y, 20 m, 20 c, 20 k of the recording head 20 while intermittently conveying the recording medium P, and print the image on the recording medium P Do.

  At this time, the discharge amount of the ink from the recording heads 20 y, 20 m, 20 c, and 20 k may change due to the characteristic unique to the device, the temporal change, and the like. When the discharge amount of the ink changes, the image forming apparatus 1 forms an image in a color different from the color of the image intended by the user, and the color reproducibility deteriorates.

  Therefore, the image forming apparatus 1 obtains a colorimetric value at a predetermined color adjustment processing timing, and executes a color adjustment process that performs color adjustment based on the colorimetric value.

  That is, at the color adjustment processing timing, the image forming apparatus 1 forms a plurality of color patches (colorimetry adjustment color patches) CP on the recording medium P by the recording head 20 as shown in FIG. Record and output as a sheet CS. In this colorimetry adjustment sheet CS, colorimetry adjustment color patches CP which are a plurality of color patches for colorimetry adjustment are formed and output by the recording head 20. On the colorimetry adjustment sheet CS, a colorimetry adjustment color patch CP reflecting the output characteristics at the color adjustment processing timing of the image forming apparatus 1, in particular, the output characteristics of the recording head 20, is formed. The color patch data of the colorimetry adjustment color patch CP is stored in advance in the non-volatile memory 125 or the like.

  Then, as described later, the image forming apparatus 1 measures the RGB values obtained by imaging the plurality of colorimetry adjustment color patches CP of the colorimetry adjustment sheet CS as the colorimetry target RGB values (colorimetry RGB values). The color target RGB values are converted to initial reference RGB values RdG dBd. Among the reference colorimetric values registered in the memory table Tb1 of the non-volatile memory 125, the image forming apparatus 1 obtains a reference colorimetric value close to the colorimetric value obtained by converting the initial reference RGB value RdGdBd (in Neighborhood reference colorimetric value) is selected. The image forming apparatus 1 obtains a colorimetric value for converting the color measurement target RGB value into the selected vicinity reference colorimetric value, and performs recording based on image data after color conversion based on the colorimetric value. The head 20 outputs an image. The image forming apparatus 1 thus improves the color reproducibility of the formed image.

  Therefore, the image forming apparatus 1 performs color measurement processing as shown in FIG. That is, the image processing apparatus 1 sets the colorimetry adjustment sheet CS on the platen 14 or holds the colorimetry adjustment sheet CS on the platen 14 without discharging the sheet at the stage of recording. The image forming apparatus 1 controls the movement of the carriage 6 and images the plurality of colorimetry adjustment color patches CP on the colorimetry adjustment sheet CS on the platen 14 with the image pickup unit 30, and at the same time, generates a reference chart by the image pickup unit 30. Take an image of the KC patch. When the image forming apparatus 1 captures together the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS and the patch of the reference chart KC by the imaging unit 30, the image processing unit 110 of the imaging unit 30 Necessary image processing is performed on the image data of the colorimetric adjustment color patch CP and the image data of the patch of the reference chart KC. The image processing unit 110 sends the image data (RGB values) of the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS to the colorimetry control unit 106 as a colorimetry object RGB value, that is, a device dependent signal dependent on a device. In addition, the image processing unit 110 sends the image data (RGB values) of the patch of the reference chart KC to the colorimetry control unit 106 as a reference RGB value RdsGdsBds at the time of colorimetry. As shown in FIG. 15, the colorimetry control unit 106 temporarily stores the colorimetry object RGB values and the colorimetry reference RGB values RdsGdsBds in the frame memory 121 (step S11).

  In the colorimetry control unit 106, the colorimetry value calculation unit 126 of the operation unit 124 initializes the colorimetry object RGB values stored in the frame memory 121, using a later-described inter-RGB linear conversion matrix to be described later. It converts into RGB value RsGsBs (steps S12 and S13).

  The calculation unit 124 of the colorimetry control unit 106 executes the basic colorimetry process described later as the colorimetry target RGB value (step S14) as the converted colorimetry target RGB value RsGsBs that has been converted, to obtain L * a * b *. * Acquire the colorimetric value (step S15).

  Then, in the image forming apparatus 1 of the present embodiment, the colorimetric value calculation unit 126 of the operation unit 124 obtains the above-mentioned reference RGB linear conversion matrix as shown in FIG. 16 and FIG. 17.

  That is, as shown in FIG. 16, when the reference color patch KP of the reference sheet KS is imaged by the imaging unit 30 at the initial stage, the colorimetric value calculation unit 126 of the arithmetic unit 124 images the patch of the reference chart KC together. Patch of the reference chart KC together with the initial reference RGB value RdGdBd stored in the nonvolatile memory 125 and the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS by the imaging unit 30 at the time of colorimetry. The color measurement reference RGB value RdsGdsBds stored in the non-volatile memory 125 is read out from the non-volatile memory 125. The colorimetric value calculation unit 126 obtains a linear conversion matrix between reference RGB which converts the colorimetric reference RGB value RdsGdsBds into the initial reference RGB value RdGdBd, and stores the obtained reference RGB linear conversion matrix in the non-volatile memory 125.

  That is, in FIG. 17, the point indicated by the white point in FIG. 17A is a point where the initial reference RGB value RdGdBd is plotted in the rgb space, and the filled point is the colorimetric reference RGB value RdsGdsBds as the rgb. It is a point plotted in space. As can be seen from FIG. 17A, the value of the colorimetric reference RGB value RdsGdsBds fluctuates from the value of the initial reference RGB value RdGdBd. The directions of fluctuation on these rgb spaces are generally the same as indicated by the arrows in FIG. 17B, but the directions of deviation differ depending on the hue. As described above, even if the patch of the same reference chart KC is imaged, the RGB value fluctuates due to temporal change of the illumination light source 37, temporal change of the two-dimensional image sensor 35, and the like.

  As described above, the colorimetric value is measured using the RGB color values to be measured when the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS is imaged in the state of fluctuating when the patches of the same reference chart KC are imaged. If there is a problem, an error may occur in the colorimetric value by the amount of fluctuation.

  Therefore, the image forming apparatus 1 according to the present embodiment uses the estimation method such as the least squares method between the initial reference RGB value RdGdBd and the colorimetric reference RGB value RdsGdsBds to initialize the colorimetric reference RGB value RdsGdsBds. An inter-reference RGB linear conversion matrix to be converted to the reference RGB value RdGdBd is determined. The image forming apparatus 1 picks up the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS with the imaging unit 30 using the reference RGB linear conversion matrix, and stores the colorimetry target RGB stored in the non-volatile memory 125 The values are converted into initialized colorimetric target RGB values RsGsBs. The image forming apparatus 1 performs basic colorimetric processing, which will be described later, using the converted initial colorimetry target RGB values RsGsBs as the colorimetry target RGB values to acquire L * a * b * colorimetric values.

  This reference RGB-to-RGB linear transformation matrix may be not only the first-order one but also a higher-order non-linear matrix, and if the non-linearity is high between rgb space and XYZ space, it may be a high-order matrix. , Conversion accuracy can be improved.

  Then, the imaging unit 30 images the reference color patch KP of the reference sheet KS as a subject and the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS through the opening 32 c formed in the bottom surface portion 32 a. At this time, the imaging unit 30 simultaneously images the patch of the reference sheet KS disposed in the opening 32 b of the bottom portion 32 a of the housing 32. Therefore, the imaging unit 30 can always capture the reference color patch KP of the reference sheet KS as a subject and the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS with the patch of the reference sheet KS in the same positional relationship. , Can be imaged in a stable state.

  Furthermore, the imaging unit 30 measures the optical path length in the optical path between the two-dimensional image sensor 35 and the reference color patch KP of the reference sheet KS as the subject through the opening 32c and the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS. A change member 50 is provided. The optical path length changing member 50 has an optical path length (focal length) L from the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS as a subject to the image sensor unit 34 and an optical path length from the reference chart KC to the image sensor unit 34 The refractive index n and the length Lp are set such that the (focal length) Lc matches. Therefore, the focal position of the reference chart KC with respect to the image sensor unit 34 and the focal position of the subject (the reference color patch KP of the reference sheet KS and the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS) can be matched. As a result, the reference color patch KP of the reference sheet KS, the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS, and the reference chart KC to be compared with these are always captured stably with high accuracy and the same accuracy. be able to.

  Further, the imaging unit 30 is configured such that the illumination light irradiated to the imaging surface of the recording medium P through the optical path length changing member 50 and the slit 38a and the illumination light irradiating the reference chart KC are illumination light from the same illumination light source 37. is there. Therefore, the imaging unit 30 can image the reference chart KC and the imaging surface of the recording medium P together under the same illumination condition. Further, the illumination light sources 37 are disposed on the center line Lo, which is a substantially intermediate position between the reference chart KC and the recording medium P, and two are disposed symmetrically with respect to the lens 36 on the center line Lo. Therefore, the imaging unit 30 can uniformly illuminate the reference chart KC and the imaging area of the recording medium P under substantially the same illumination condition.

  Furthermore, in the imaging unit 30, the arrangement conditions of the slit 38a in the imaging area and the reference chart KC are arranged substantially symmetrically with respect to a center line Lo connecting the center of the lens 36 and the illumination light source 37. Therefore, the imaging unit 30 can make the imaging conditions of the two-dimensional image sensor 35 identical in line symmetry, and improve the accuracy of the color adjustment process and the color measurement process of the two-dimensional image sensor 35 using the reference chart KC. be able to.

  In addition, in the imaging unit 30, the reflection suppressing portion 40 is formed around the slit 38a. Therefore, the imaging unit 30 can perform imaging while suppressing the influence of diffuse reflection of the illumination light emitted from the illumination light source 37 to the colorimetric object, and the imaging quality is improved to improve the accuracy of the color adjustment process and the colorimetric process. It can be further improved.

  Furthermore, as described above, in the imaging unit 30, the reflection suppressing portion 40 is provided in black. Therefore, the imaging unit 30 can further suppress the influence of the diffuse reflection of the illumination light, and can perform the black reference correction easily and inexpensively by using the black color of the reflection suppressing portion 40.

  Then, the image forming apparatus 1 obtains the initial colorimetric target RGB values RsGsBs as described above, and executes the basic colorimetric processing as shown in FIG. 18 and FIG. That is, among the reference colorimetric values registered in the memory table Tb1 of the non-volatile memory 125, the image forming apparatus 1 generates a reference near the distance close to the colorimetric value converted to the colorimetric object RGB value. A colorimetric value (neighboring reference colorimetric value) is selected, and basic colorimetric processing is performed to obtain a colorimetric value for converting the color measurement target RGB value into the selected proximity reference colorimetric value. The image forming apparatus 1 improves the color reproducibility of the formed image by the image forming apparatus 1 by outputting the image by the recording head 20 based on the image data after color conversion based on the colorimetric value. Let

  That is, as shown in FIG. 18, the image forming apparatus 1 picks up the colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS and obtains the initial colorimetry target RGB values RsGsBs as described above, and measures the colorimetry target RGB. The value is stored in the non-volatile memory 125 as a value (step S21). Next, the image forming apparatus 1 uses the reference value linear transformation matrix (step S22), converts it into a first XYZ value (step S23), and stores it in the non-volatile memory 125 (step S24). For example, in FIG. 18, the colorimetric value calculation unit 126 sets the colorimetric object RGB values (3, 200, 5) of the imaging unit 30 to the first XYZ values (first colorimetric values) of (20, 80, 10). And stored in the non-volatile memory 125.

  The colorimetric value calculation unit 126 refers to the first XYZ values with reference to the memory table Tb1 of the non-volatile memory 125 or uses a known conversion formula to obtain the first L * a * b * values (first colorimetric values). ) (Step S25), and stored in the non-volatile memory 125 (step S26). For example, in FIG. 16, the colorimetric value calculation unit 126 converts the first XYZ values (20, 80, 10) into first L * a * b * values (75, -60, 8) which are imaging colorimetric values. doing.

  Next, as shown by the L * a * b * space in FIG. 18, the colorimetric value calculation unit 126 sets the reference of color patches of a plurality of colors registered in the memory table Tb1 stored in the non-volatile memory 125. Search for colorimetric values (L * a * b * values). The colorimetric value calculation unit 126 is configured to extract a color patch having a distance closer to the first L * a * b * value on the L * a * b * space among the reference colorimetric values (L * a * b * values). A set of (nearby color patches) is selected (step S27). For example, in the diagram of the L * a * b * space of FIG. 18, a diagram in which 60 color patches are selected and plotted on the L * a * b * space is shown. The colorimetric value calculation unit 126 may select, for example, a first L * a * b * value and reference colorimetric values (L * a * b * values) of a plurality of color patches as a method of selecting a patch having a short distance. Calculate the distance to all points. When the colorimetric value calculation unit 126 calculates the distance, the reference L * a * b * value of the color patch having a distance closer to the first L * a * b * value, which is the first colorimetric value (in FIG. 18, Select the hatched reference L * a * b * value).

  Next, as shown in FIG. 19, the colorimetric value calculation unit 126 refers to the memory table Tb1, and picks up an imaging reference RGB value that is paired with the first L * a * b * value of the selected set, ie, A combination of imaging reference RGB values (selected RGB values) and reference XYZ values of the same patch number as the first L * a * b * of the selected set is selected (step S28). The colorimetric value calculation unit 126 obtains a selected RGB value linear conversion matrix for converting between the set of the imaging reference RGB and the reference XYZ of the selected combination (selected set) using the least square method. The colorimetric value calculation unit 126 stores the obtained selected RGB value linear conversion matrix in the non-volatile memory 125 (step S29).

  The colorimetric value calculation unit 126 picks up each colorimetric adjustment color patch CP of the colorimetric adjustment sheet CS to be measured by the imaging unit 30 and digitally converts the colorimetric object RGB value into the selected RGB value linear. The conversion matrix is used to determine second XYZ values which are second colorimetric values (step S30). The colorimetric value calculation unit 126 converts the obtained second XYZ values into second L * a * b * values using a known conversion formula (step S31), and obtains the final colorimetric values (step S32). ).

  The colorimetric value calculation unit 126 performs image adjustment based on the image data subjected to color conversion using the obtained colorimetric value, and drives the recording head 20 based on the image data subjected to image adjustment to form an image.

  That is, the image forming apparatus 1 according to the present embodiment captures and acquires a plurality of colorimetry adjustment color patches CP of the colorimetry adjustment sheet CS reflecting the output characteristics of the recording head 20 at the color adjustment processing timing. The first L * a * b * values obtained when the reference sheet KS is imaged in the initial state using the reference value linear transformation matrix are obtained for the RGB values to be measured. The image forming apparatus 1 is a distance to the first L * a * b * value in the L * a * b * space among the reference L * a * b * of the patches of the plurality of colors registered in the memory table Tb1. Choose a patch set with the near reference L * a * b * value of. The image forming apparatus 1 converts the color measurement target RGB values corresponding to the selected reference L * a * b * values into L * a * b * values by using the selected RGB value linear conversion matrix. The a * b * colorimetric values are determined. Then, the colorimetric value calculation unit 126 performs image adjustment based on the image data subjected to color conversion using the obtained colorimetric value, and drives the recording head 20 based on the image data subjected to image adjustment to form an image. Do.

  As described above, the imaging unit 30 of the image forming apparatus 1 according to the present embodiment includes the housing 32 having the slit (opening) 38a, and the image sensor unit (sensor means for imaging an object outside the housing 32 through the slit 38a. 34, a reference chart KC of a plurality of colors which is disposed in the housing 32 and is imaged by the image sensor unit 34 with the subject, and a surface around the slit 38a of the housing 32 and on the image sensor unit 34 side. And a reflection suppressing portion (reflection suppressing means) 40 provided on the

  Therefore, the influence of diffuse reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be suppressed, and the imaging quality of the subject can be improved by imaging the subject with high accuracy.

  Further, the image forming apparatus 1 of the present embodiment is based on the imaging means for imaging an arbitrary subject together with the reference chart KC composed of a plurality of colors, the imaging subject of the imaging means and the imaging data of the reference chart KC. The color measurement apparatus includes a color measurement control unit (calculation unit) 106 that calculates a color measurement value of a subject, and the image pickup unit 30 is provided as the image pickup unit.

  Therefore, the influence of the diffuse reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be suppressed, and the subject can be imaged with high precision, and the imaging quality of the subject is improved, with high precision. It can measure color.

  Furthermore, the image forming apparatus 1 of the present embodiment is an image forming apparatus that forms an image using image data color-adjusted based on the colorimetric value measured by the color measuring device, and as the color measuring device, The color measurement device is provided.

  Therefore, it is possible to image the subject with high accuracy by suppressing the influence of diffuse reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject, and color measuring with high accuracy to obtain a high quality image. Can be formed.

  Further, the color measurement device of the image forming apparatus 1 of the present embodiment is formed on the reference chart plate (predetermined plate member) 38 together with the reference chart KC composed of a plurality of colors and the reflection suppressing portion 40 An imaging process step of imaging an arbitrary subject through the slit (opening) 38a provided and acquiring the RGB value of the reference chart KC and the RGB value of the subject, and each color of the reference color patch consisting of a plurality of colors A reference colorimetric value which is a colorimetric value in a predetermined color space independent of the device and the RGB value of each color of the reference color patch acquired by capturing in the imaging processing step with the reference color patch as the subject Relate an initial reference RGB value which is an RGB value of the reference chart KC acquired and acquired in the imaging processing step together with a certain imaging reference RGB value and the reference color patch A reference value storage processing step to be stored in the non-volatile memory (reference value storage means) 125, a colorimetry RGB value acquired by imaging a predetermined colorimetry subject in the imaging processing step, and the colorimetry Colorimetry RGB value storage processing step of storing a colorimetry reference RGB value, which is an RGB value of the reference chart KC picked up with the image pickup subject, in the non-volatile memory (colorimetry RGB value storage means) 125; Using the inter-reference RGB linear conversion matrix generation processing step of generating an inter-reference RGB linear conversion matrix for converting the color measurement reference RGB values into the initial reference RGB values; and using the reference RGB inter-linear conversion matrix RGB value conversion processing step of converting RGB values into initialized RGB values for color measurement, and criteria of converting the imaging reference RGB values into the reference colorimetric values The reference value linear conversion matrix calculation processing step for calculating a linear conversion matrix, and the RGB value for initialization colorimetric conversion converted in the RGB value conversion processing step is converted to a colorimetric value using the reference value linear conversion matrix Image pickup colorimetric value calculation processing step of taking an image pickup colorimetric value, and patch selection processing of selecting a predetermined number of the reference color patches having a short distance in the predetermined color space from the reference color patch A step, an RGB selection processing step of selecting the colorimetric RGB values corresponding to the predetermined number of selected reference color patches as a selected RGB value, a selection RGB of converting the selected RGB values into the reference colorimetric values Using a selected RGB value linear conversion matrix calculation step of calculating a value linear conversion matrix, and the selected RGB value linear conversion matrix And a colorimetric value conversion processing step of converting the RGB values of the subject for color measurement acquired in the imaging processing step into colorimetric values.

  Therefore, the influence of the diffuse reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be suppressed, and the subject can be imaged with high precision, and the imaging quality of the subject is improved, with high precision. It can measure color.

  Furthermore, in the imaging unit 30 of the image forming apparatus 1 of the present embodiment, the reflection suppressing portion 40 is a black surface provided on the surface on the image sensor portion 34 side around the slit 38 a.

  Therefore, the influence of diffuse reflection of the illumination light emitted from the illumination light source 37 of the image sensor unit 34 to the subject can be easily and inexpensively suppressed, and the subject can be imaged at low cost with high accuracy. By using for reference correction, black reference correction can be performed easily and appropriately.

  Further, in the imaging unit 30 of the image forming apparatus 1 of the present embodiment, the outer periphery of the reflection suppressing portion 40 of the housing 32 is grayed over a predetermined range.

  Therefore, the reflected light from around the slit 38a can be further reduced, and the subject can be imaged with higher accuracy.

  Further, in the imaging unit 30 of the image forming apparatus 1 of the present embodiment, the gray color of the outer periphery of the reflection suppressing portion 40 is a color data value exceeding the maximum value of the color data of the color of the reference chart KC.

  Therefore, the gray area and the black area around the reference chart KC and the slit 38a can be divided by the threshold value of color data, and the shading correction in the gray area can be performed. As a result, when performing color measurement using this imaging unit 30, color measurement accuracy can be further improved.

  Further, in the imaging unit 30 of the image forming apparatus 1 of the present embodiment, the slits 38a and the reference chart KC are provided side by side at a predetermined interval on a reference chart plate (plate-like member) 38 detachably attached to the housing 32. It is done.

  Therefore, the reference chart KC and the area around the slit 38a can always be maintained in a normal state, and the subject can be imaged with higher accuracy.

  In this case, the imaging unit 30 changes the optical path length as shown in FIGS. 20 and 21 when the focal distance to the image sensor unit 34 of the subject such as the reference chart KC and the recording medium P can be ignored for accuracy. The member 50 may not be provided. Also in this case, as shown in FIG. 21, a reflection suppressing portion 40 such as black is provided around the slit 38 a formed in the reference chart plate 38. In FIGS. 20 and 21, the same components as those in FIGS. 4 to 6 are denoted by the same reference numerals, and the description thereof will be omitted.

  In this way, the influence of the reflected light around the slit 38a on the captured image can be prevented even more inexpensively and reliably.

  Further, the optical path changing member is not limited to one provided only on the opening 32 c (slit 38 a) side, and may be provided on the opening 32 b side.

  Furthermore, in the above embodiment, the slit 38a which is an opening is formed in the reference chart plate 38 to which the reference chart KC is applied, but the slit 38a needs to be formed in the reference chart plate 38 Absent. For example, the slits 38a may be formed directly on the bottom surface 32a of the housing 32 independently of the reference chart plate 38, or may be formed on a plate provided in the opening 32c.

  In the above description, the colorimetry process is performed by the colorimetry control unit 106 of the image forming apparatus 1. However, the colorimetry process does not have to be performed inside the image forming apparatus 1, for example, as shown in FIG. As shown, as the image forming system (color measurement system) 200, the image forming apparatus 210 is connected to the external apparatus 220, and outputs the image data captured by the image forming apparatus 210 to the external apparatus 220, The external device 220 performs color adjustment processing including color measurement processing, and outputs the image data after color adjustment to the image forming apparatus 210, and the image forming apparatus 210 forms an image based on the image data from the external device 220. You may

  That is, the image forming apparatus 210 includes an engine 211, an operation display unit 212, an I / F unit 213, and other I / F units 214, and the respective units are connected by a bus 215. In addition, the external device 220 can use, for example, a computer having a normal hardware configuration and software configuration, and a color adjustment program including a color measurement program that executes color adjustment processing accompanied by color measurement processing of the present invention as software. Is introduced to execute color adjustment processing accompanied by colorimetric processing. The external device 220 includes a CPU 221, a memory unit 222, an image processing unit 223, a communication I / F unit 224, an I / F unit 225, and the like, and the units are connected by a bus 226. The memory unit 222 includes a ROM 227, a RAM 228, a hard disk (HDD) 229, and the like.

  The image forming apparatus 210 is connected to an external device 220 by a line 230 by an I / F unit 213. The line 230 is a dedicated line, a network such as a LAN (Local Area Network), the Internet, etc. Alternatively, it may be wireless.

  The image forming apparatus 210 forms and outputs an image on a recording medium by the engine 211 based on image data sent from the external device 220 under the control of the external device 220. The engine 211 forms an image on a recording medium by an ink jet method or the like, and the operation display unit 212 includes various operation keys and a display such as an LCD (Liquid Crystal Display), and is necessary for the operation of the image forming apparatus 210 Various operations are performed by the operation keys, and various information notified from the image forming apparatus 210 to the user is displayed and output on the display. The other I / F unit 214 is used for connection of the expansion unit and the like.

  The engine 211 includes a carriage that moves in the main scanning direction similar to that described in the above embodiment, and the imaging unit 30 is attached to the carriage. The image forming apparatus 210 forms the colorimetry adjustment color patch CP on the recording medium based on the color patch data of the colorimetry adjustment color patch CP sent from the external device 220 under the control of the CPU 221 of the external device 220. Then, the colorimetry adjustment sheet CS is generated. The image forming apparatus 210 reads the generated colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS by the imaging unit 30, and transmits the colorimetry adjustment color patch CP to the external device 220 via the I / F unit 213.

  The external device (calculation unit) 220 stores an image formation control program for controlling the operation of the image forming apparatus 210, a color adjustment program for performing color adjustment processing with colorimetric processing of the present invention, and necessary data in the hard disk 229 or ROM 227 It is done. The external device 220 causes the CPU 221 to control the image forming apparatus 210 based on a program in the ROM 227 or the hard disk 229 to execute basic processing as the image forming apparatus 210 and to perform color adjustment involving the color measurement process of the present invention. Execute the process

  The hard disk 229 stores the program and also stores various data necessary to execute the color adjustment process. In particular, the hard disk 229 is at least one of L * a * b * values and XYZ values of the measurement results of the plurality of reference color patches KP arrayed in the reference sheet KS described in the above embodiment. Together with imaging reference RGB values, reference value linear transformation matrix, table of neighboring points and selected RGB value linear transformation matrix, reference sheet KS when the reference patch KP of the reference sheet KS is read by the imaging unit 30 of the image forming apparatus 210 Initial reference RGB value RdGdBd of each color patch of the read reference chart KC, and colorimetry adjustment color patch CP of the colorimetry adjustment sheet CS The color reference RGB value RdsGdsBds of the reference patch of the reference chart KC read together And colorimetric standard RGB values RdsGdsBds to initial reference RGB values RdGdBd Reference RGB between linear transformation matrix is stored.

  A communication I / F unit 224 is connected to an image processing apparatus such as a scanner apparatus, a multifunction peripheral, or another external apparatus via a line such as a network, and receives image data to be output to the image forming apparatus 210. The I / F unit 213, the I / F unit 224, and the line 230 function as communication means as a whole.

  The image processing unit 223 performs various image processing necessary for forming and outputting the image data by the engine 211 of the image forming apparatus 210.

  As described above, the CPU 221 controls the operation of the image forming apparatus 210 and executes the color measurement process executed by the calculation unit 124 of the color measurement control unit 106, in particular, the color measurement value calculation unit 126 to measure the color values. Ask for The CPU 221 performs color adjustment on the image data based on the obtained colorimetric value, and outputs the image data to the image forming apparatus 210.

  In the image forming system 200 of FIG. 22, the external apparatus 220 controls the operation of the image forming apparatus 210, but the form of the image forming system 200 is not limited to this. For example, in the image forming system 200, the image forming apparatus 210 itself is provided with a controller such as a CPU, and the image forming operation itself is controlled by the controller to obtain colorimetric values only, or colorimetry The external device 220 may execute only the color adjustment process including the process.

  As described above, when color adjustment processing including color measurement processing or color measurement processing is performed at least by an external device of the image forming apparatus 210, color reproducibility is appropriately and inexpensively improved in the inexpensive image forming apparatus 210. it can.

  Although the invention made by the inventor has been specifically described based on the preferred embodiments, the present invention is not limited to those described in the above embodiments, and various modifications may be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 image forming apparatus 2 main body housing 3 main frame 4 main guide rod 5 secondary guide rod 6 carriage 6 a connection piece 7 timing belt 8 drive pulley 9 driven pulley 10 main scanning motor 11 cartridge portion 12 maintenance mechanism portion 13 cover 14 platen 15 encoder Sheet 20, 20y, 20m, 20c, 20k Recording head 21 Encoder sensor 30 Imaging unit 31 Top cover 32 Casing 32a Bottom 32b Opening 32c Opening 32c Opening 32d Recess 32e Recess 32f Communication port 33 Fastening member 34 Image sensor 35 2D Image sensor 36 Lens 37 Illumination light source 38 Reference chart plate 38a Slit 39 Holding plate 39a Opening 40 Reflection suppressing portion 50 Optical path length changing member 101 CPU
102 ROM
103 RAM
104 main scanning driver 105 recording head driver 106 colorimetric control unit 107 paper conveyance unit 108 sub scanning driver 110 image processing unit 111 interface unit 112 A / D conversion unit 113 shading correction unit 114 white balance correction unit 115 γ correction unit 116 image format Conversion unit 121 Frame memory 122 Timing signal generation unit 123 Light source drive control unit 124 Operation unit 125 Non-volatile memory 126 Colorimetry value calculation unit 200 Image forming system 210 Image forming apparatus 211 Engine 212 Operation display unit 213 I / F unit 214 Other I / F section 215 Bus 220 External device 221 CPU
222 Memory section 223 Image processing section 224 Communication I / F section 225 I / F section 226 Bus 227 ROM
228 RAM
229 hard disk 230 line P recording medium Lo center line KS reference sheet KP reference color patch CS colorimetry adjustment sheet CP colorimetry adjustment patch KC reference chart Pa to Pd reference color patch row Pe dot diameter measurement pattern row lk distance measurement line mk Chart position specification marker Tb1 memory table

JP, 2012-063270, A

Claims (15)

Two-dimensional image sensor,
A correction data generation unit that generates correction data based on image data of a predetermined color among data obtained by imaging a predetermined region in an imaging region of the two-dimensional image sensor;
A correction unit that corrects, with the correction data, data of an object to be measured that is included in the predetermined area and is obtained from an area narrower than the predetermined area in an image captured by the two-dimensional image sensor;
Equipped with
The correction data is data corresponding to a wider range than the narrow area.
An imaging device characterized by The imaging device comprises an illumination light source for illuminating an imaging area of the two-dimensional image sensor.
The imaging device according to claim 1, The correction data is correction data for correcting uneven illuminance in the imaging region of the two-dimensional image sensor.
The imaging device according to claim 1 or 2, characterized in that: The imaging device captures an image of the color measurement target through an opening,
The narrow area is an area inside the opening.
The imaging device according to any one of claims 1 to 3, characterized in that: The periphery of the opening is black,
The imaging device according to claim 4, An area outside the black area with respect to the opening is included in the predetermined area.
The imaging device according to claim 5, The outer area adjacent to the black area with respect to the opening is gray,
The imaging device according to claim 5 or 6, characterized in that: The correction unit corrects the data obtained from the black area as a black level.
The imaging device according to any one of claims 5 to 7. The imaging device includes a reference chart imaged by the two-dimensional image sensor.
An area around the reference chart is included in the predetermined area,
The imaging device according to any one of claims 1 to 8, characterized in that. The correction unit corrects at least data of the reference chart in an image captured by the two-dimensional image sensor.
The imaging device according to claim 9, characterized in that: The two-dimensional image sensor captures a white plate through the opening,
The correction data generation unit generates correction data based on data of the predetermined area including data obtained by imaging the white plate.
The imaging device according to any one of claims 4 to 8, characterized in that. An imaging device according to any one of claims 1 to 11,
An image forming unit for forming the color measurement target on an object;
A moving unit for relatively moving the imaging device and the color measurement target;
An image forming apparatus comprising: An imaging device according to any one of claims 1 to 11,
An image forming unit for forming the color measurement target on an object;
An image forming apparatus comprising: An imaging device according to any one of claims 1 to 11,
A recording head for forming the color measurement target on an object;
A carriage on which the recording head is mounted;
Equipped with
The imaging device is attached to the carriage.
An image forming apparatus characterized by Creating correction data based on image data of a predetermined color among data obtained by imaging a predetermined region in an imaging region of the two-dimensional image sensor;
Correcting, with the correction data, data of an object to be measured which is at least included in the predetermined area in an image captured by the two-dimensional image sensor and obtained from an area narrower than the predetermined area;
Including
The correction data is data corresponding to a wider range than the narrow area.
A colorimetric method characterized by