Inspection method and inspection device

Abstract

To provide an inspection method and an inspection device that can perform accurate inspection.SOLUTION: A method includes: a first acquisition step of acquiring information in which information on a difference in color from a reference color is allocated to each of a plurality of first division areas obtained by dividing a reference image; a second acquisition step of acquiring information in which information on a difference in color from the reference color is allocated to each of a plurality of second division areas obtained by dividing a picked-up image; a first comparison step of comparing the information on the difference in color in each first division area with the information on the difference in color in each second division area; and a second comparison step of comparing the information on the difference in color in each first division area with the information on the difference in color in each second division area in a combination different from the combination compared in the first comparison step. The method determines whether reference image data and picked-up image data match each other based on a first comparison result obtained in the first comparison step and a second comparison result obtained in the second comparison step.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an inspection method and an inspection apparatus. [Background technology]

[0002] For example, there is known a recognition device that judges whether a reference image serving as a standard for authenticity judgment of a printed matter matches a comparison image to be compared. For example, the print image recognition device described in Patent Document 1 sequentially executes an overall integration process, a block integration process, a block differentiation process, and a judgment stage.

[0003] The overall integration process is a process for calculating an overall integration value by adding up the pixel values ​​of all pixels in the entire image to be compared for each color component. The block integration process is a process for calculating a block integration value by dividing the entire image into a plurality of blocks and adding up the pixel values ​​of each pixel in each divided block for each color component. The block differentiation process is a process for calculating a block differentiation value by calculating the difference between adjacent pixels in each divided block and calculating the average value of the differences. The determination step is a process for determining whether the reference image and the comparison image match by comparing the overall integration value, block integration value, and block differentiation value of the reference image and the test image, respectively. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-183471 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the identification device described in Patent Document 1 assumes that the position of the measurement target is fixed when capturing the comparison image. Therefore, if the orientation of the measurement target differs from the orientation of the measurement target in the reference image, there is a risk that the device may determine that the two do not match when they would normally be determined to match. [Means for solving the problem]

[0006] The inspection method of the present invention is a method for inspecting whether or not reference image data of a reference image and captured image data of a captured image match, comprising the steps of: a first acquisition step of acquiring information in which information on color difference with respect to a reference color is assigned to each of a plurality of first divided regions obtained by dividing the reference image; a second acquisition step of acquiring information in which information on color difference with respect to the reference color is assigned to each of a plurality of second divided regions obtained by dividing the captured image; a first comparison step of comparing color difference information of each of the first divided regions with color difference information of the corresponding second divided regions; a second comparison step of comparing the color difference information of each of the first divided regions and the color difference information of each of the second divided regions in a combination different from the combination compared in the first comparison step, The method is characterized in that it is determined whether or not the reference image data and the captured image data match based on a first comparison result obtained in the first comparison step and a second comparison result obtained in the second comparison step.

[0007] The inspection device of the present invention is an inspection device including a control unit that inspects whether or not reference image data of a reference image and captured image data of a captured image match, The control unit is a first acquisition step of acquiring information in which information on color difference with respect to a reference color is assigned to each of a plurality of first divided regions obtained by dividing the reference image; a second acquisition step of acquiring information in which information on color difference with respect to the reference color is assigned to each of a plurality of second divided regions obtained by dividing the captured image; a first comparison step of comparing color difference information of each of the first divided regions with color difference information of the corresponding second divided regions; a second comparison step of comparing the color difference information of each of the first divided regions with the color difference information of each of the second divided regions in a combination different from the combination compared in the first comparison step; The method is characterized in that it is determined whether or not the reference image data and the captured image data match based on a first comparison result obtained in the first comparison step and a second comparison result obtained in the second comparison step. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a functional block diagram of a first embodiment of an inspection device according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the spectroscopic unit shown in FIG. [Diagram 3] FIG. 3 is a flowchart for explaining an example of the first embodiment of the inspection method of the present invention. [Figure 4] FIG. 4 is a flowchart for explaining an example of the first embodiment of the inspection method of the present invention. [Diagram 5] FIG. 5 is a diagram showing a state in which the first divided region is set in the reference image. [Figure 6] FIG. 6 is a diagram showing a state in which each of the first divided regions is compared with a reference color. [Figure 7] FIG. 7 is a graph showing waveforms indicating color differences in the first divided regions. [Figure 8] FIG. 8 is a diagram showing a state in which the second divided region is set in the captured image. [Figure 9] FIG. 9 is a diagram showing a state in which each second divided area is compared with a reference color. [Figure 10] FIG. 10 is a graph showing waveforms indicating color differences in the second divided regions. [Figure 11] FIG. 11 is a diagram showing a state in which the second divided region is set in a captured image in a rotated state. [Figure 12]FIG. 12 is a diagram showing a state in which each second divided area is compared with a reference color. [Figure 13] FIG. 13 is a graph showing waveforms indicating color differences in the second divided regions. [Figure 14] FIG. 14 is a graph showing waveforms indicating color differences of each first divided region with respect to each first divided region in the second embodiment of the inspection method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment FIG. 1 is a functional block diagram of a first embodiment of the inspection device of the present invention. FIG. 2 is a cross-sectional view of the spectroscopic unit shown in FIG. 1. FIG. 3 is a flowchart for explaining an example of a first embodiment of the inspection method of the present invention. FIG. 4 is a flowchart for explaining an example of a first embodiment of the inspection method of the present invention. FIG. 5 is a diagram showing a state in which a first divided region is set in a reference image. FIG. 6 is a diagram showing a state in which each first divided region is compared with a reference color. FIG. 7 is a graph showing a waveform showing a color difference of each first divided region. FIG. 8 is a diagram showing a state in which a second divided region is set in a captured image. FIG. 9 is a diagram showing a state in which each second divided region is compared with a reference color. FIG. 10 is a graph showing a waveform showing a color difference of each second divided region. FIG. 11 is a diagram showing a state in which a second divided region is set in a captured image in a rotated state. FIG. 12 is a diagram showing a state in which each second divided region is compared with a reference color. FIG. 13 is a graph showing a waveform showing a color difference of each second divided region.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An inspection method and an inspection apparatus according to the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0011] 1. Inspection equipment The inspection device 1 shown in Fig. 1 is a device that executes the inspection method of the present invention, and is a device that inspects whether or not a captured image Px, which is an image of an object X, matches a reference image Ps. Specifically, the device disperses light reflected by the object X, generates a spectroscopic image based on light of multiple wavelengths, and a spectrum obtained from the spectroscopic image, and performs the above inspection based on this information. The object X is not particularly limited, and examples thereof include a pattern printed on paper, patterned fabric, tiles, etc.

[0012] The inspection device 1 includes a spectroscopic measurement unit 10, a control unit 60, a display unit 15, an input unit 16, and a storage unit 17. Each unit will be described below in order.

[0013] 1.1.Spectroscopic measurement section The spectroscopic measurement section 10 includes a light source 31 , an image sensor 21 , and a spectroscopic section 41 .

[0014] The light source 31 is an element that irradiates light onto the imaging target X. The light that is irradiated onto the imaging target X and reflected therefrom is incident as reflected light onto the imaging element 21 via a spectroscopic unit 41, which will be described later. Note that the light source 31 may be provided separately from the inspection device 1.

[0015] Examples of the light source 31 include an LED (Light Emitting Diode) element, an organic EL (Electro Luminescence) element, a xenon lamp, and a halogen lamp. A light source having a light intensity over the entire wavelength range that can be separated by the spectroscopic section 41 described later is preferably used as the light source 31, and specifically, a light source capable of emitting white light having a light intensity over the entire visible light range is preferably used. The light source 31 may also be an element capable of emitting light in a wavelength range other than white light, for example, light other than visible light such as infrared light.

[0016] The imaging element 21 is an element that captures an image of light reflected by an imaging target X. Examples of the imaging element 21 include a charge coupled device (CCD) and a complementary metal oxide semiconductor (CMOS).

[0017] The spectroscopic section 41 is an optical element having a function of selectively emitting (transmitting) light in a specific wavelength region from the incident light. The light emitted from the spectroscopic section 41 is incident on the image sensor 21. The spectroscopic section 41 shown in Fig. 2 is a wavelength-tunable interference filter that can change the wavelength region of the emitted light, that is, the specific wavelength region.

[0018] Examples of tunable interference filters include tunable Fabry-Perot etalon filters, acousto-optical tunable filters (AOTF), linear variable filters (LVF), and liquid crystal tunable filters (LCTF). Of these, tunable Fabry-Perot etalon filters are preferably used as tunable interference filters. In tunable Fabry-Perot etalon filters, the size of the gap between two filters (mirrors) can be adjusted by an electrostatic actuator 45 (described later) or the like. This allows the specific wavelength region to be changed.

[0019] Moreover, the Fabry-Perot etalon filter extracts light in a specific wavelength region by utilizing multiple interference caused by two filters. Since each filter can be made thin, the spectroscopic section 41 to which the Fabry-Perot etalon filter is applied can be made sufficiently thin. Specifically, the thickness of the spectroscopic section 41 can be set to 2.0 mm or less. Therefore, the spectroscopic section 41, and in turn the inspection device 1, can be made smaller.

[0020] FIG. 2 shows a spectroscopic section 41 in which a tunable Fabry-Perot etalon filter is applied as a tunable interference filter.

[0021] The spectroscopic unit 41 shown in Fig. 2 has an optical axis OA extending vertically in Fig. 2, and is a plate-shaped member extending in a direction intersecting the optical axis OA. Such spectroscopic unit 41 includes a fixed substrate 410, a movable substrate 420, a fixed reflective film 411, a movable reflective film 421, a fixed electrode 412, a movable electrode 422, and a bonding film 414. The fixed substrate 410 and the movable substrate 420 are laminated on each other and bonded together via the bonding film 414.

[0022] The fixed substrate 410 has a reflective film mounting portion 415 located at the center when viewed from a position on the optical axis OA, and a groove 413 surrounding the reflective film mounting portion 415. The length along the optical axis OA of the portion of the fixed substrate 410 corresponding to the reflective film mounting portion 415, i.e., the thickness, is greater than that of the portion corresponding to the groove 413. A fixed reflective film 411 is provided on the surface of the reflective film mounting portion 415 facing the movable substrate 420. The fixed reflective film 411 functions as a fixed optical mirror, which is one of the optical elements of the Fabry-Perot etalon filter.

[0023] The movable substrate 420 has a reflective film installation portion 425 located at the center in a plan view from a position on the optical axis OA, and a groove 423 surrounding the reflective film installation portion 425. The length along the optical axis OA of the portion of the movable substrate 420 corresponding to the reflective film installation portion 425, i.e., the thickness, is greater than that of the portion corresponding to the groove 423. A movable reflective film 421 is provided on the surface of the reflective film installation portion 425 facing the fixed substrate 410. The movable reflective film 421 also functions as a movable optical mirror, which is one of the optical elements of the Fabry-Perot etalon filter.

[0024] A fixed electrode 412 is provided on the surface of the groove 413 of the fixed substrate 410 facing the movable substrate 420. A movable electrode 422 is provided on the surface of the groove 423 of the movable substrate 420 facing the fixed substrate 410. When a voltage is applied between the fixed electrode 412 and the movable electrode 422, an electrostatic attraction is generated and the size of the gap between the fixed reflective film 411 and the movable reflective film 421 is adjusted. In this way, the fixed electrode 412 and the movable electrode 422 constitute an electrostatic actuator 45. In addition, since the movable electrode 422 is provided at a position corresponding to the groove 423, the amount of displacement of the movable reflective film 421 when an electrostatic attraction is generated can be increased.

[0025] The thickness of the fixed substrate 410 and the movable substrate 420 is preferably about 0.1 mm or more and 1.0 mm or less. With such thickness, it is possible to keep the thickness of the entire spectroscopic unit 41 to 2.0 mm or less. This allows the spectroscopic measurement unit 10 to be miniaturized.

[0026] Here, the fixed reflection film 411 and the movable reflection film 421 are disposed opposite to each other with a gap therebetween. The fixed electrode 412 and the movable electrode 422 are also disposed opposite to each other with a gap therebetween. As described above, the fixed electrode 412 and the movable electrode 422 constitute an electrostatic actuator 45 that adjusts the size of the gap between the fixed reflection film 411 and the movable reflection film 421. Specifically, when a voltage is applied between the fixed electrode 412 and the movable electrode 422, an electrostatic attraction is generated, and the movable substrate 420 is deflected. As a result, the size of the gap between the fixed reflection film 411 and the movable reflection film 421, that is, the distance, can be changed. Then, by appropriately setting the size of this gap, the wavelength region of the light that passes through the spectroscopic unit 41 along the optical axis OA can be selected. That is, the specific wavelength region can be changed. Also, by changing the configuration of the fixed reflection film 411 and the movable reflection film 421, the half-width of the transmitted light, that is, the resolution of the Fabry-Perot etalon filter can be controlled.

[0027] Examples of materials constituting the fixed substrate 410 and the movable substrate 420 include various types of glass such as soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and non-alkali glass, and quartz.

[0028] The bonding film 414 bonds the fixed substrate 410 and the movable substrate 420. The bonding film 414 is not particularly limited, but an example thereof is a plasma polymerized film whose main material is siloxane.

[0029] The fixed reflective film 411 and the movable reflective film 421 may each be, for example, a metal film such as Ag or an Ag alloy, or a dielectric multilayer film having a high refractive index layer and a low refractive index layer.

[0030] Examples of materials constituting the fixed electrode 412 and the movable electrode 422 include various conductive materials.

[0031] The spectroscopic measurement section 10 shown in FIG. 1 further includes a spectroscopic section side optical system 81 and an image sensor side optical system 83 .

[0032] The spectroscopic unit-side optical system 81 is disposed between the imaging target X and the spectroscopic unit 41. The spectroscopic unit-side optical system 81 shown in FIG. 1 includes an incident lens 811 as an incident optical system, and a projection lens 812. The spectroscopic unit-side optical system 81 as described above guides light reflected by the imaging target X to the spectroscopic unit 41.

[0033] The imaging element side optical system 83 is disposed between the spectroscopic section 41 and the imaging element 21. The imaging element side optical system 83 shown in Fig. 1 includes an input / output lens 831. The imaging element side optical system 83 guides the output light emitted from the spectroscopic section 41 to the imaging element 21.

[0034] By providing at least one of the spectroscopic unit side optical system 81 and the image sensor side optical system 83 in the spectroscopic measurement unit 10, the light collection efficiency of the light reflected by the image pickup target X by the image sensor 21 can be increased.

[0035] At least one of the spectroscopic unit side optical system 81 and the image sensor side optical system 83 may be omitted depending on the light collection efficiency of the image sensor 21 .

[0036] 1. The spectroscopic unit side optical system 81 may be disposed between the spectroscopic unit 41 and the image sensor side optical system 83, in addition to the position shown in FIG.

[0037] Although the spectroscopic measurement unit 10 has been described above, the position of the spectroscopic unit 41 is not limited to the position shown in Fig. 1. Specifically, in the spectroscopic measurement unit 10 shown in Fig. 1, the spectroscopic unit 41 is disposed between the image pickup target X and the image pickup element 21, but the spectroscopic unit 41 may be disposed between the image pickup target X and the light source 31.

[0038] 1.2.Display section The display unit 15 displays an image obtained by visualizing the spectral image captured by the imaging element 21, and any other information. As the display unit 15, for example, a liquid crystal display element, an organic EL display element, or the like is used.

[0039] 1.3. Input section The input unit 16 accepts input of data required for the operation of the control unit 60 by a user of the inspection device 1 .

[0040] For example, a touch panel, a slide pad, a keyboard, a mouse, etc. are used as the input unit 16. The input unit 16 may be combined with the display unit 15 and integrated with the display unit 15.

[0041] 1.4.Storage section The memory unit 17 stores various information such as programs and data necessary for the operation of each functional unit of the control unit 60, data acquired by the spectroscopic measurement unit 10, data necessary for display on the display unit 15, and data inputted through the input unit 16.

[0042] The storage unit 17 may be a memory such as a random access memory (RAM) or a read only memory (ROM).

[0043] 1.5.Control Unit 1 includes a light source control unit 601, a spectral control unit 602, an image generation unit 603, a display control unit 605, and a determination unit 610. The operation of each of these functional units is realized by a combination of hardware such as a processor, such as a CPU (Central Processing Unit), a memory, and an external interface. For example, the control unit 60 reads out and executes a program stored in the storage unit 17 to operate each functional unit and realize its function.

[0044] The light source control unit 601 controls the turning on and off of the light source 31 and the wavelength, intensity, etc. of the emitted light based on information input to the input unit 16, information stored in the storage unit 17, and the like.

[0045] The spectroscopic control unit 602 acquires a drive voltage corresponding to a specific wavelength region of the light emitted from the spectroscopic unit 41, based on the information stored in the storage unit 17. Then, it outputs a control signal for applying the acquired drive voltage to the electrostatic actuator 45 of the spectroscopic unit 41. In this way, the spectroscopic control unit 602 can control the operation of the spectroscopic unit 41 to control the specific wavelength region of the light emitted from the spectroscopic unit 41.

[0046] The image generating unit 603 controls the operation of the spectroscopic measurement unit 10, and causes the light incident on the imaging element 21 via the spectroscopic unit 41 to be captured. Then, a spectroscopic image is generated based on the imaging data obtained from the imaging element 21. The image generating unit 603 also causes the memory unit 17 to store the generated spectroscopic image. A plurality of wavelengths are selected from the light reflected by the imaging target X, and the spectroscopic image includes captured images at each wavelength. When the image generating unit 603 stores the spectroscopic image in the memory unit 17, the image generating unit 603 also stores in the memory unit 17 the specific wavelength region at which the spectroscopic image was generated.

[0047] The image generating unit 603 may store a visualized image obtained by visualizing the spectroscopic image in the storage unit 17 together with the spectroscopic image, or may display the visualized image on the display unit 15 as it is.

[0048] The display control unit 605 causes the display unit 15 to display the spectroscopic images, various information, and the like as visualized images.

[0049] The determination unit 610 includes a division unit 611 , a reference value determination unit 612 , a spectrum generation unit 613 , a color value calculation unit 614 , a color difference calculation unit 615 , and a determination unit 616 .

[0050] As will be described in detail later, the division unit 611 divides the reference image Ps to generate a plurality of first divided regions, and divides the captured image Px, which is an image of the imaging target X, to generate a plurality of second divided regions.

[0051] Such a division unit 611 executes steps S102 and S202, which will be described later.

[0052] The reference value determination unit 612 determines a reference value for obtaining color differences between the first and second divided regions in a second embodiment described later.

[0053] The spectrum generating unit 613 generates a spectrum for each pixel from the spectral image of the imaging target X and the specific wavelength region stored in the storage unit 17. The spectrum is a distribution of light intensity for each wavelength, and it is possible to generate a spectrum for each pixel from the spectral image. Therefore, the spectrum generating unit 613 can also calculate an "overall spectrum" which is an average spectrum for the entire measurement target area, and "region spectra" which are average spectra for each region generated by the dividing unit 611.

[0054] In this embodiment, the optical spectrum is a spectrum obtained by measuring light intensity in four or more wavelength bands. Furthermore, the optical spectrum according to this embodiment is preferably a spectrum obtained by measuring light intensity in 16 or more wavelength bands.

[0055] The spectrum generating unit 613 may be configured to generate spectroscopic information based on information obtained directly from the image generating unit 603 without going through the storage unit 17. The generated spectroscopic information is stored in the storage unit 17.

[0056] Such a spectrum generating unit 613 executes steps S103 and S203 described later.

[0057] The color value calculation unit 614, for example, calculates tristimulus values ​​for each region from the spectrum, and further calculates color values ​​from the calculated tristimulus values. These color values ​​are values ​​that represent the color of the entire measurement target area and the color of each region. The calculated color values ​​are stored in the storage unit 17 together with information that identifies the entire measurement target area and information that identifies each region.

[0058] Such a color value calculation unit 614 executes steps S104 and S204, which will be described later.

[0059] The color difference calculation unit 615 calculates the color difference from a reference value based on the color value of each region calculated by the color value calculation unit 614. The color difference calculation unit 615 executes steps S105 and S205, which will be described later.

[0060] The determination unit 616 compares the color difference calculated by the color difference calculation unit 615 with a threshold value and determines whether the color difference is within an allowable range. The determination result is stored in the storage unit 17 and, if necessary, is displayed on the display unit 15. The determination unit 616 executes step S106 and steps S206 to S212, which will be described later.

[0061] 2. Testing Method Next, an example of the inspection method of the present invention will be described with reference to the flow charts shown in FIGS. The inspection method includes a first step S1 of acquiring reference image data DPs of a reference image Ps and making various preparations as shown in FIG. 3, and a second step S2 of performing an inspection as shown in FIG.

[0062] 2.1. First step S1 First, in step S101, reference image data DPs of a reference image Ps is obtained. In this step, the spectroscopic measurement unit 10 may be used to capture an image of a reference object and acquire reference image data DPs of the reference image Ps, or the reference image data DPs of the reference image Ps input from the input unit 16 may be acquired, or the reference image data DPs of the reference image Ps that has been previously stored in the memory unit 17 may be read out and acquired.

[0063] Next, in step S102, the number of vertical and horizontal divisions is specified. That is, it is determined how to divide the reference image Ps to set the first divided images. In this embodiment, as shown in FIG. 5, a total of eight first divided regions are set in two rows and four columns. In the following description, the four divided regions in the upper part of the figure are referred to as the first divided region Ps1, the first divided region Ps2, the first divided region Ps3, and the first divided region Ps4 from the left in the figure, and the four divided regions in the lower part of the figure are referred to as the first divided region Ps5, the first divided region Ps6, the first divided region Ps7, and the first divided region Ps8 from the left in the figure.

[0064] Next, in step S103, the spectral images of the first divided regions Ps1 to Ps8 are measured, that is, the spectral spectrum is obtained. The sweep wavelength range of the spectral spectrum can be any wavelength range in the visible light range, for example, a wavelength range of 400 nm to 700 nm or a wavelength range of 380 nm to 780 nm. Moreover, these wavelength ranges may be configured to be set using the input unit 16, or may be set in advance. Moreover, the measurement interval is not particularly limited, and can be, for example, 5 nm, 10 nm, or 20 nm. These measurement intervals may be configured to be set using the input unit 16, or may be set in advance.

[0065] Next, in step S104, color values ​​of the first divided region Ps1 to the first divided region Ps8 are calculated. The color values ​​referred to here refer to the average color values ​​of the first divided region Ps1 to the first divided region Ps8. The color values ​​can be calculated from the overall XYZ values ​​according to the definition of a predetermined color space. Examples of the predetermined color space include the L*a*b* color system, the LCH color system, the Munsell color system, and the Yxy color system. When a non-luminous object such as a printed matter or fabric is to be inspected, it is preferable that the color values ​​are calculated according to the color space definition of the L*a*b* color system.

[0066] Next, in step S105, the color difference ΔE of the first divided region Ps1 to the first divided region Ps8 is calculated, and the calculation result is stored. In this embodiment, the color difference ΔE refers to the difference from the color value of the reference color Cs. That is, the color difference ΔE of the first divided region Ps1 can be obtained by calculating the difference between the average color value of the first divided region Ps1 and the color value of the reference color Cs. Similarly, the color difference ΔE of the first divided region Ps2 can be obtained by calculating the difference between the average color value of the first divided region Ps2 and the color value of the reference color Cs. Similarly, the color difference ΔE of the first divided region Ps3 can be obtained by calculating the difference between the average color value of the first divided region Ps3 and the color value of the reference color Cs. Similarly, the color difference ΔE of the first divided region Ps4 can be obtained by calculating the difference between the average color value of the first divided region Ps4 and the color value of the reference color Cs. Similarly, the color difference ΔE of the first divided region Ps5 can be found by calculating the difference between the average color value of the first divided region Ps5 and the color value of the reference color Cs. Similarly, the color difference ΔE of the first divided region Ps6 can be found by calculating the difference between the average color value of the first divided region Ps6 and the color value of the reference color Cs.

[0067] A specific method for calculating the color difference is not particularly limited, but may be a method using a known color difference formula, such as the CIE76 color difference formula (ΔE76), the CIE94 color difference formula (ΔE94), the CMC color difference formula (ΔEcmc), the CIEDE2000 color difference formula (ΔE00), etc.

[0068] Next, in step S106, waveform information of the color difference ΔE of the first divided region Ps1 to the first divided region Ps8, i.e., the ΔE waveform, is calculated and stored. The ΔE waveform can be represented by a graph plotting the color difference ΔE of the first divided region Ps1 to the first divided region Ps8, as shown in FIG.

[0069] Through the above-described first step S1, preparation of reference image data DPs of the reference image Ps is completed prior to inspection. That is, the first step S1 is a first acquisition step for acquiring information in which color difference information for the reference color Cs is assigned to each of the multiple first division regions Ps1 to Ps8 into which the reference image Ps is divided.

[0070] 2.2. Second step S2 First, in step S201, captured image data DPx of the captured image Px is acquired. In this step, the spectroscopic measurement unit 10 is used to capture an image of the imaging target X to acquire the captured image data DPx of the captured image Px. However, the present invention is not limited to this configuration, and may be configured to acquire captured image data DPx of the captured image Px input from the input unit 16, or may be configured to read and acquire captured image data DPx of the captured image Px stored in advance in the storage unit 17.

[0071] In addition, in this step, if the position of the measurement target X in the captured image Px is shifted from the position of the measurement target X in the reference image Ps, processing such as trimming may be performed to place the measurement target X in the same position. Also, this processing may be performed in advance.

[0072] Next, in step S202, the number of vertical and horizontal divisions is specified. That is, it is determined how to divide the captured image Px to set the second divided image. In this step, the number of divisions is set to be the same as the number of divisions set in step S102 of the first step S1. Therefore, as shown in FIG. 8, a total of eight first divided regions with two rows and four columns are set. In the following description, the four divided regions in the upper part of the figure are referred to as the second divided region Px1, the second divided region Px2, the second divided region Px3, and the second divided region Px4 from the left in the figure, and the four divided regions in the lower part of the figure are referred to as the second divided region Px5, the second divided region Px6, the second divided region Px7, and the second divided region Px8 from the left in the figure.

[0073] Next, in step S203, the spectral images of the second divided regions Px1 to Px8 are measured, that is, the spectral spectra are obtained. In this step, the spectral spectra are obtained in the same manner as in step S103 of the first step S1.

[0074] Next, in step S204, the color values ​​of the second divided regions Px1 to Px8 are calculated. The color values ​​referred to here refer to the average color values ​​of the second divided regions Px1 to Px8. The calculation method is the same as that in step S103 of the first step S1.

[0075] Next, in step S205, the color difference ΔE of the second divided region Px1 to the second divided region Px8 is calculated, and the calculation results are stored. As shown in FIG. 9, the color difference ΔE of the second divided region Px1 can be obtained by calculating the difference between the average color value of the second divided region Px1 and the color value of the reference color Cs. Similarly, the color difference ΔE of the second divided region Px2 can be obtained by calculating the difference between the average color value of the second divided region Px2 and the color value of the reference color Cs. Similarly, the color difference ΔE of the second divided region Px3 can be obtained by calculating the difference between the average color value of the second divided region Px3 and the color value of the reference color Cs. Similarly, the color difference ΔE of the second divided region Px4 can be obtained by calculating the difference between the average color value of the second divided region Px4 and the color value of the reference color Cs. Similarly, the color difference ΔE of the second divided region Px5 can be found by calculating the difference between the average color value of the second divided region Px5 and the color value of the reference color Cs. Similarly, the color difference ΔE of the second divided region Px6 can be found by calculating the difference between the average color value of the second divided region Px6 and the color value of the reference color Cs. A specific method for calculating the color difference is as described in step S105.

[0076] Next, in step S206, waveform information of the color difference ΔE of the second divided regions Px1 to Px8, i.e., the ΔE waveform, is calculated and stored. The ΔE waveform can be represented by a graph plotting the color differences ΔE of the second divided regions Px1 to Px8, as shown in FIG.

[0077] In this step, captured image data DPx' of captured image Px' obtained by rotating captured image Px by 180 degrees is generated as shown in Fig. 11. That is, the four divided regions in the upper part of the figure are, from the left in the figure, second divided region Px8, second divided region Px2, second divided region Px6, and second divided region Px5, and the four divided regions in the lower part of the figure are, from the left in the figure, second divided region Px4, second divided region Px3, second divided region Px2, and second divided region Px1.

[0078] Then, the color difference ΔE between the second divided regions Px1 to Px8 is calculated, and the ΔE waveform is calculated and stored, as shown in Fig. 12. The ΔE waveform can be represented by a graph in which the color differences ΔE between the second divided regions Px8 to Px2 are plotted in order from the left, as shown in Fig. 13.

[0079] Such steps S201 to S205 constitute a second acquisition step of acquiring information in which information on color difference with respect to the reference color Cs is assigned to each of the plurality of second divided regions Px1 to Px8 into which the captured image Px is divided.

[0080] Next, in step S207, the ΔE waveform shown in Fig. 7 is compared with the ΔE waveform shown in Fig. 10 calculated in step S206, and it is determined whether they match. The determination in this step is made, for example, using Mahalanobis distance determination based on a preset threshold. That is, the color differences ΔE of the first divided regions Ps1 to Ps8 and the color differences ΔE of the second divided regions Px1 to Px8 are compared in predetermined combinations, and it is determined whether the deviation is equal to or smaller than a predetermined value.

[0081] In addition, the comparison in this step can be said to be performed using combination 1 as follows. Collocation 1: (Color difference information of the first divided region Ps1 and color difference information of the second divided region Px1) (Color difference information of the first divided region Ps2 and color difference information of the second divided region Px2) (Color difference information of the first divided region Ps3 and color difference information of the second divided region Px3) (Color difference information of the first divided region Ps4 and color difference information of the second divided region Px4) (Color difference information of the first divided region Ps5 and color difference information of the second divided region Px5) (Color difference information of the first divided region Ps6 and color difference information of the second divided region Px6) (Color difference information of the first divided region Ps7 and color difference information of the second divided region Px7) (Color difference information of the first divided region Ps8 and color difference information of the second divided region Px8)

[0082] Such step S207 is a first comparison step in which the color difference information of the first division regions Ps1 to Ps8 is compared with the color difference information of the corresponding second division regions Px1 to Px8. The comparison result in this step is the first comparison result.

[0083] If it is determined in step S207 that they match, the process proceeds to step S209. On the other hand, if it is determined in step S207 that they do not match, in step S207, the ΔE waveform shown in Fig. 7 is compared with the ΔE waveform shown in Fig. 13 calculated in step S206, and it is determined whether they match. The determination in this step is made in the same manner as in step S207 above. That is, the color differences ΔE of the first divided regions Ps1 to Ps8 and the color differences ΔE of the second divided regions Px1 to Px8 are compared in predetermined combinations, and it is determined whether the deviation is equal to or smaller than a predetermined value.

[0084] In addition, the comparison in this step can be said to be made using combination 2 as follows. Collocation 2: (Color difference information of the first divided region Ps1 and color difference information of the second divided region Px8) (Color difference information of the first divided region Ps2 and color difference information of the second divided region Px7) (Color difference information of the first divided region Ps3 and color difference information of the second divided region Px6) (Color difference information of the first divided region Ps4 and color difference information of the second divided region Px5) (Color difference information of the first divided region Ps5 and color difference information of the second divided region Px4) (Color difference information of the first divided region Ps6 and color difference information of the second divided region Px3) (Color difference information of the first divided region Ps7 and color difference information of the second divided region Px2) (Color difference information of the first divided region Ps8 and color difference information of the second divided region Px1)

[0085] Such step S208 is a second comparison step in which the color difference information of the first divided region Ps1 to Ps8 is compared with the color difference information of the second divided region Px1 to Px8 in a combination different from the combination compared in the first comparison step, step S207. The comparison result in this step is the second comparison result.

[0086] If it is determined in step S208 that they do not match, then in step S212, it is assumed that the reference image data DPs and the captured image data DPx do not match. This determination result may be displayed on the display unit 15 as necessary. On the other hand, if it is determined in step S208 that they do match, the process proceeds to step S209.

[0087] By going through steps S207 and S208, the following advantages can be obtained. For example, when the captured image Px is acquired in a state rotated 180° and the captured image Px in the 180° rotated state is compared with the reference image Ps, it may be determined that they do not match, even though they should be determined to match. This is a drawback of performing only one comparison, as in the conventional method, that is, performing only one comparison, assuming that the captured image Px and the reference image Ps are in the same orientation. In contrast, in the present invention, it is possible to prevent erroneous determination as in the conventional method, in which it is determined whether the reference image data DPs and the captured image data DPx match based on the comparison results in the first comparison step and the second comparison step described above, and it is possible to perform a more accurate inspection.

[0088] Next, in step S209, a color inspection is performed, that is, the color values ​​of the reference image Ps and the captured image Px are compared, and it is determined whether the degree of deviation is within an allowable range.

[0089] This step may be configured to determine whether or not the difference between the average color value of the entire reference image Ps and the color value of the entire captured image Px is equal to or less than a threshold value, or to determine whether or not the difference in color value between each of the regions is equal to or less than a threshold value by comparing the color values ​​of each of the first divided regions Ps1 to Ps8 with the color values ​​of each of the second divided regions Px1 to Px8 in the above combination 1 or combination 2. In the latter case, the comparison is performed using the combinations determined to match in step S207 or step S208 out of combination 1 and combination 2.

[0090] If it is determined in step S209 that the difference between the color values ​​of the reference image Ps and the captured image Px is equal to or smaller than the threshold value, it is determined in step S211 that the reference image data DPs and the captured image data DPx match. The result of this determination may be displayed on the display unit 15 as necessary.

[0091] If it is determined in step S209 that the difference between the color values ​​of the reference image Ps and the captured image Px exceeds the threshold value, it is determined in step S212 that the reference image data DPs and the captured image data DPx do not match.

[0092] Note that steps S209 and S210 may be omitted. Even if it is determined in step S209 that the difference between the color values ​​of the reference image Ps and the captured image Px exceeds the threshold, the process may proceed to step S211 and determine that they match. In this case, however, it is preferable to store information that the reference image data DPs and the captured image data DPx match but do not match in color.

[0093] By going through step S209, if even the color values ​​match, it can be regarded as a match, and a more accurate inspection can be performed.

[0094] As described above, the inspection method of the present invention is an inspection method for inspecting whether or not reference image data DPs of a reference image Ps and captured image data DPx of a captured image Px match, and includes a first acquisition step of acquiring information in which color difference information with respect to a reference color Cs is assigned to each of a plurality of first divided regions Ps1 to Ps8 into which the reference image Ps is divided, a second acquisition step of acquiring information in which color difference information with respect to the reference color Cs is assigned to each of a plurality of second divided regions Px1 to Px8 into which the captured image is divided, and The method includes a first comparison step of comparing the color difference information of the first division region Ps8 with the color difference information of the corresponding second division region Px1 to Px8, and a second comparison step of comparing the color difference information of the first division region Ps1 to Ps8 with the color difference information of the second division region Px1 to Px8 in a combination different from the combination compared in the first comparison step, and judges whether the reference image data DPs and the captured image data DPx match based on the first comparison result obtained in the first comparison step and the second comparison result obtained in the second comparison step. According to the present invention, the following advantages can be obtained. For example, when the captured image Px is acquired in a state rotated 180° and the captured image Px in the 180° rotated state is compared with the reference image Ps, it may be judged that they do not match, even though it should be judged that they match. This is a drawback of performing only one comparison, as in the conventional method, on the assumption that the captured image Px and the reference image Ps are in the same orientation. In contrast, in the present invention, whether or not the reference image data DPs and the captured image data DPx match is determined based on the comparison results in the first comparison step and the second comparison step described above, so that erroneous determinations as in the conventional method can be prevented and more accurate inspection can be performed.

[0095] The inspection method of the present invention includes a control unit 60 that inspects whether or not reference image data DPs of a reference image Ps and captured image data DPx of a captured image Px match. The control unit 60 includes a first acquisition step of acquiring information in which color difference information with respect to a reference color Cs is assigned to each of a plurality of first division regions Ps1 to Ps8 into which the reference image Ps is divided, a second acquisition step of acquiring information in which color difference information with respect to the reference color Cs is assigned to each of a plurality of second division regions Px1 to Px8 into which the captured image is divided, and The method includes a first comparison step of comparing the color difference information of the first division region Ps8 with the color difference information of the corresponding second division region Px1 to Px8, and a second comparison step of comparing the color difference information of the first division region Ps1 to Ps8 with the color difference information of the second division region Px1 to Px8 in a combination different from the combination compared in the first comparison step, and judges whether the reference image data DPs and the captured image data DPx match based on the first comparison result obtained in the first comparison step and the second comparison result obtained in the second comparison step. According to the present invention, as described above, it is possible to prevent erroneous judgments as in the conventional method, and to perform more accurate inspection.

[0096] In addition, in the inspection method of the present invention, if the degree of deviation between the color difference information of each of the first division regions Ps1 to Ps8 and the color difference information of each of the second division regions Px1 to Px8 in one of the first comparison result and the second comparison result is equal to or less than a threshold value, it is determined that the reference image data DPs and the captured image data DPx match, and if the degree of deviation between the color difference information of each of the first division regions Ps1 to Ps8 and the color difference information of each of the second division regions Px1 to Px8 in both the first comparison result and the second comparison result is greater than a threshold value, it is determined that the reference image data DPs and the captured image data DPx do not match. This makes it possible to more effectively prevent erroneous judgments as in the past, and to perform more accurate inspections.

[0097] In the second comparison step, when the reference image Ps and the captured image Px are rotated relatively to each other and superimposed on each other, the color difference information of the overlapping first and second divided regions is compared. This makes it possible to more effectively prevent erroneous determinations as in the past, even if the captured image Px is acquired in a 180° rotated state.

[0098] Moreover, the color difference information to be compared is waveform information indicating the relationship between the color difference and the positions of the first divided region Ps1 to Ps8 and the second divided region Px1 to Px8, as shown in Fig. 7, Fig. 10, and Fig. 13. This makes it possible to execute the first comparison step and the second comparison step by the simple method of comparing the waveform information.

[0099] In this embodiment, the reference color Cs is a predetermined color. This makes it possible to calculate color difference information for the first divided region Ps1 to the first divided region Ps8 and the second divided region Px1 to the second divided region Px8 through simple control.

[0100] Also, as described in steps S209 and S210, the color values ​​of the first division region Ps1 to Ps8 and the second division region Px1 to Px8 are taken into consideration to determine whether the reference image data DPs and the captured image data DPx match. This makes it possible to determine that the color values ​​of the first division region Ps1 to Ps8 and the second division region Px1 to Px8 match, thereby enabling more accurate inspection.

[0101] <Second embodiment> FIG. 14 is a graph for explaining a method of determining a reference color in the second embodiment of the inspection method of the present invention.

[0102] The second embodiment will be described below, but in the following description, the differences from the first embodiment will be mainly described, and a description of similar points will be omitted.

[0103] In this embodiment, the method of determining the reference color Cs when calculating the color difference in step S105 is different from that in the first embodiment, so only the method of determining the reference color Cs will be described.

[0104] First, the average color value of the first divided region Ps1 is set as a provisional reference color, and the color difference between the first divided region Ps1 and the first divided region Ps8 is calculated. The method of calculating the color difference is as described in the first embodiment. Then, by plotting the color difference ΔE between the first divided region Ps1 and the first divided region Ps8, a waveform ΔE1 can be obtained as shown in FIG.

[0105] Next, the average color value of the second divided region Px3 is used as a provisional reference color, and the color differences between the first divided regions Ps1 to Ps8 are calculated. Then, by plotting the color differences ΔE between the first divided regions Ps1 to Ps8, a waveform ΔE3 can be obtained as shown in FIG.

[0106] Next, the average color value of the second divided region Px4 is used as a provisional reference color, and the color differences between the first divided regions Ps1 to Ps8 are calculated. Then, by plotting the color differences ΔE between the first divided regions Ps1 to Ps8, a waveform ΔE4 can be obtained as shown in FIG.

[0107] Next, the average color value of the second divided region Px5 is used as a provisional reference color, and the color differences between the first divided regions Ps1 to Ps8 are calculated. Then, by plotting the color differences ΔE between the first divided regions Ps1 to Ps8, a waveform ΔE5 can be obtained as shown in FIG.

[0108] Next, the average color value of the second divided region Px6 is used as a provisional reference color, and the color differences between the first divided regions Ps1 to Ps8 are calculated. Then, by plotting the color differences ΔE between the first divided regions Ps1 to Ps8, a waveform ΔE6 can be obtained as shown in FIG.

[0109] Next, the average color value of the second divided region Px7 is used as a provisional reference color, and the color differences between the first divided regions Ps1 to Ps8 are calculated. Then, by plotting the color differences ΔE between the first divided regions Ps1 to Ps8, a waveform ΔE7 can be obtained as shown in FIG.

[0110] Next, the average color value of the second divided region Px8 is used as a provisional reference color, and the color differences between the first divided regions Ps1 to Ps8 are calculated. Then, by plotting the color difference ΔE between the first divided regions Ps1 to Ps8, a waveform ΔE8 can be obtained as shown in FIG.

[0111] Then, among the waveforms ΔE1 to ΔE8, the waveform with the largest difference between the maximum color difference and the minimum color difference is selected. In the illustrated configuration, the waveform ΔE1 is selected because the difference between the color difference of the first divided region Ps1 and the color difference of the first divided region Ps2 is the largest in the waveform ΔE1, and the provisional reference color at that time, that is, the average color value of the first divided region Ps1, is set as the reference color Cs, and the waveform ΔE1 is used in the subsequent steps.

[0112] According to this method, when comparing waveforms, the waveform in which the characteristics of the waveform are most clearly expressed is used, so that more accurate testing can be performed.

[0113] In this manner, in this embodiment, the reference color Cs is the average color, i.e., the average color value, within one of the first divided regions Ps1 to Ps8, which eliminates the need to set a separate reference color Cs in advance, simplifying control.

[0114] In this embodiment, the first divided regions Ps1 to Ps8 are selected one by one in order, and the degree of deviation between the average color in the selected first divided region and the average color in the first divided regions other than the selected first divided region is calculated in order, that is, the color difference is calculated in order, and the color of the first divided region with the largest difference between the largest color difference and the smallest color difference is set as the reference color Cs. With this configuration, the optimal reference color Cs can be set each time, and therefore more accurate inspection can be performed.

[0115] It is also possible to store the reference color Cs in advance and perform control as in this embodiment. That is, the color that maximizes the difference between the largest color difference and the smallest color difference may be selected from the waveform shown in Fig. 7 and the eight waveforms shown in Fig. 14.

[0116] Although the inspection method and inspection device of the present invention have been described above with reference to the illustrated embodiments, the present invention is not limited thereto. Furthermore, each step and each structure of the inspection method and inspection device can be replaced with any step or structure that can perform a similar function. Furthermore, any step or structure may be added. Furthermore, the present invention may be a combination of the features of each embodiment.

[0117] Furthermore, the first comparison step and the second comparison step may be performed in this order, in the reverse order, or simultaneously.

[0118] In the above embodiments, the configuration for comparing the waveforms of color differences has been described, but the present invention is not limited to this, and for example, the configuration may further include comparing optical spectra with each other. In this case, the comparison can be made using a correlation coefficient between the waveforms or a squared sum of the errors between the waveforms.

[0119] In addition, in each of the above-described embodiments, the captured image is rotated for comparison, but the present invention is not limited to this, and the reference image may be rotated for comparison. In this case, it is preferable to generate reference image data by rotating the reference image in advance.

[0120] In the above embodiments, the reference image and the captured image are rectangular, and the divided regions are set to 8 regions of 2 rows and 4 columns, but the number of divisions and the division pattern are not limited to this in the present invention. In addition, when the reference image and the captured image are square, and the vertical and horizontal division ratios are the same, such as 2 rows and 2 columns, it is preferable to generate four images rotated by 90 degrees each and compare them.

[0121] In each of the above embodiments, a configuration has been described in which an image is acquired using a spectroscopic section, but the present invention is not limited to this, and a configuration in which an image is acquired using an imaging section that omits the spectroscopic section may also be used. [Explanation of symbols]

[0122] 1...inspection device, 10...spectroscopic measurement section, 15...display section, 16...input section, 17...storage section, 21...imaging element, 31...light source, 41...spectroscopic section, 45...electrostatic actuator, 60...control section, 81...spectroscopic section side optical system, 83...imaging element side optical system, 410...fixed substrate, 411...fixed reflective film, 412...fixed electrode, 413...groove, 414...bonding film, 415...reflective film installation section, 420...movable substrate , 421... movable reflective film, 422... movable electrode, 423... groove, 425... reflective film installation section, 601... light source control section, 602... spectral control section, 603... image generation section, 605... display control section, 610... judgment section, 611... division section, 612... reference value determination section, 613... spectrum generation section, 614... color value calculation section, 615... color difference calculation section, 616... judgment section, 811... entrance lens, 812... projection lens 831...input / output lens, Cs...reference color, DPs...reference image data, DPx...captured image data, DPx'...captured image data, OA...optical axis, Ps...reference image, Ps1...first divided region, Ps2...first divided region, Ps3...first divided region, Ps4...first divided region, Ps5...first divided region, Ps6...first divided region, Ps7...first divided region, Ps8...first divided region, Px... Captured image, Px'...captured image, Px1...second divided area, Px2...second divided area, Px3...second divided area, Px4...second divided area, Px5...second divided area, Px6...second divided area, Px7...second divided area, Px8...second divided area, X...imaged object, ΔE1...waveform, ΔE2...waveform, ΔE3...waveform, ΔE4...waveform, ΔE5...waveform, ΔE6...waveform, ΔE7...waveform, ΔE8...waveform

Claims

1. 1. A method for inspecting whether reference image data of a reference image and captured image data of a captured image match, comprising the steps of: a first acquisition step of acquiring information in which information on color difference with respect to a reference color is assigned to each of a plurality of first divided regions obtained by dividing the reference image; a second acquisition step of acquiring information in which information on color difference with respect to the reference color is assigned to each of a plurality of second divided regions obtained by dividing the captured image; a first comparison step of comparing color difference information of each of the first divided regions with color difference information of the corresponding second divided regions; a second comparison step of comparing the color difference information of each of the first divided regions and the color difference information of each of the second divided regions in a combination different from the combination compared in the first comparison step, determining whether or not the reference image data and the captured image data match based on a first comparison result obtained in the first comparison step and a second comparison result obtained in the second comparison step; The inspection method is characterized in that in the second comparison step, when the reference image and the captured image are rotated relatively to each other and superimposed, color difference information between the overlapping first and second divided areas is compared.

2. determining that the reference image data and the captured image data match when a degree of deviation between the color difference information of each of the first divided regions and the color difference information of each of the second divided regions in one of the first comparison result and the second comparison result is equal to or less than a threshold value; The inspection method described in claim 1, wherein if the degree of deviation between the color difference information of each of the first divided regions and the color difference information of each of the second divided regions in both the first comparison result and the second comparison result exceeds a threshold value, it is determined that the reference image data and the captured image data do not match.

3. 3. The inspection method according to claim 1, wherein the information on the color difference is waveform information indicating a relationship between the color difference and the positions of the first divided region and the second divided region.

4. 4. The inspection method according to claim 1, wherein the reference color is a predetermined color.

5. 4. The inspection method according to claim 1, wherein the reference color is an average color within one of the first divided regions.

6. 6. The inspection method according to claim 5, further comprising the steps of: selecting each of the first divided regions one by one in sequence; calculating the degree of deviation between the average color within the selected first divided region and the average color within the first divided regions other than the selected first divided region in sequence; and determining the color of the first divided region for which the difference between the color with the greatest degree of deviation and the color with the smallest degree of deviation is the largest as the reference color.

7. 7. The inspection method according to claim 1, wherein the judgment is made taking into account color values ​​of the first divided region and the second divided region.

8. The inspection method according to claim 1 , wherein the captured image is a spectroscopic image captured by a spectroscopic camera.

9. An inspection device including a control unit that inspects whether or not reference image data of a reference image and captured image data of a captured image match, The control unit is a first acquisition step of acquiring information in which information on color difference with respect to a reference color is assigned to each of a plurality of first divided regions obtained by dividing the reference image; a second acquisition step of acquiring information in which information on color difference with respect to the reference color is assigned to each of a plurality of second divided regions obtained by dividing the captured image; a first comparison step of comparing color difference information of each of the first divided regions with color difference information of the corresponding second divided regions; a second comparison step of comparing the color difference information of each of the first divided regions with the color difference information of each of the second divided regions in a combination different from the combination compared in the first comparison step; determining whether or not the reference image data and the captured image data match based on a first comparison result obtained in the first comparison step and a second comparison result obtained in the second comparison step; An inspection device characterized in that in the second comparison step, when the reference image and the captured image are rotated relatively to each other and superimposed, color difference information between the overlapping first and second divided areas is compared.

Images