Colorimetric method and colorimetric device

Abstract

The invention provides a colorimetric method and a colorimetric device which can carry out appropriate colorimetric even if there is a change in color density on a reference substance. A colorimetric device (1) implements: a reference information acquisition step (step S1) for acquiring colorimetric values of a plurality of reference points (A1 to Am) on a reference substance including a change in color shade; an object information acquisition step (step S2) for acquiring colorimetric values at a plurality of measurement points (B1 to Bm) on the object; a calculation step (step S4) for combining the reference point (An) and the measurement point (Bn) and calculating the Euclidean distance (L) on color space coordinates between the combined reference point (An) and measurement point (Bn); and a determination step (step S6) in which the Euclidean distance (L) calculated on the basis of at least one of the combinations of the reference point (An) and the measurement point (Bn) is compared with a predetermined threshold value (Lth) to determine whether or not the color of the reference substance is similar to the color of the object.

Description

Technical Field

[0001] The present invention relates to a colorimetric method and a colorimetric device. Background Art

[0002] There has been a technique for evaluating the color of an object by comparing it with the color of a reference object. For example, in Patent Document 1, color data (e.g., color difference, brightness) is extracted from a source image as a reference object and a copy image as an object, respectively, and the Mahalanobis distance of the color data is compared to obtain the similarity of the copy image with respect to the source image.

[0003] However, in the method described in Patent Document 1, when there are color density variations on the reference object, it may not be possible to correctly determine whether the colors are similar between the reference object and the object.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-292693 Summary of the Invention

[0005] The colorimetric method according to the present disclosure performs the following steps: a reference information acquisition step of acquiring colorimetric values of a plurality of reference points on a reference object including color density variations; an object information acquisition step of acquiring colorimetric values of a plurality of measurement points on an object; a calculation step of combining the reference points and the measurement points and calculating the Euclidean distance in the color space coordinates between the combined reference points and measurement points; and a determination step of determining whether the color of the reference object is similar to the color of the object by comparing the Euclidean distance calculated based on at least any one combination of the combination of the reference points and the measurement points with a predetermined threshold value.

[0006] The colorimetric device according to the present disclosure includes: a reference information acquisition unit that acquires colorimetric values of a plurality of reference points on a reference object including color density variations; an object information acquisition unit that acquires colorimetric values of a plurality of measurement points on an object; a calculation unit that combines the reference points and the measurement points and calculates the Euclidean distance in the color space coordinates between the combined reference points and measurement points; and a determination unit that determines whether the color of the reference object is similar to the color of the object by comparing the Euclidean distance calculated based on at least any one combination of the combination of the reference points and the measurement points with a predetermined threshold value. Brief Description of the Drawings

[0007] Figure 1 It is a block diagram showing a schematic configuration of a colorimetric device according to an embodiment of the present disclosure.

[0008] Figure 2A cross-sectional view schematically showing the structure of the spectroscope according to the present embodiment.

[0009] Figure 3 A flowchart for explaining the colorimetric method according to the present embodiment.

[0010] Figure 4 A diagram illustrating a plurality of reference points on a reference object.

[0011] Figure 5 A diagram illustrating a plurality of measurement points on an object. Detailed implementation mode

[0012] An embodiment of the present disclosure will be described.

[0013] Figure 1 A block diagram schematically showing the colorimetric device 1 according to the present embodiment. The colorimetric device 1 includes a spectroscope 10, a storage unit 20, a processor 30, a display unit 40, and an operation unit 50. The colorimetric device 1 measures the color of an object and performs colorimetry of the object relative to a reference object.

[0014] Figure 2 A diagram showing an example of the spectroscope 10 mounted on the colorimetric device 1.

[0015] The spectroscope 10 includes a light source unit 11, a light guide unit 12, a spectroscopic filter 13, and a light receiving unit 14.

[0016] The light source unit 11 includes a light source 11A and a condenser unit 11B, and the light emitted from the light source 11A is irradiated onto the object through the condenser unit 11B.

[0017] The light guide unit 12 includes a mirror 12A and a band-pass filter 12B. The band-pass filter 12B is a filter that allows light in a predetermined wavelength band to enter from the incident light. For example, it transmits light having a wavelength in the visible light band and blocks light having other wavelengths. The light reflected from the object is reflected by the mirror 12A and enters the spectroscopic filter 13 through the band-pass filter 12B.

[0018] The spectroscopic filter 13 is a filter that allows light of a predetermined wavelength to pass through from the incident light and can switch the transmission wavelength. For example, the spectroscopic filter 13 is a Fabry-Perot etalon, which includes a pair of opposed reflection films, and can switch the transmission wavelength by changing the distance between the pair of reflection films. In addition, the spectroscopic filter 13 may be other filters such as an AOTF (acousto-optic tunable filter) and an LCTF (liquid crystal tunable filter) in addition to the etalon element as described above.

[0019] The light-receiving unit 14 is, for example, a photodiode that receives the light transmitted through the spectral filter 13 and outputs a detection signal corresponding to the amount of received light. In addition, the detection signal output from the light-receiving unit 14 is input to the processor 30 via a signal processing unit (e.g., an I-V converter, an amplifier, and an AD converter), which is not shown.

[0020] Figure 1 The storage unit 20 in Figure 1 records various programs and various data for controlling the color comparison device 1. As the various programs recorded in the storage unit 20, for example, it includes a spectral measurement control program for controlling the spectroscope 10, a color comparison program for performing color comparison of the object based on the spectral measurement results, and the like.

[0021] In addition, as the various data stored in the storage unit 20, table data for driving the above-mentioned spectral filter 13, multiple reference object data, and the like can be listed.

[0022] The reference object data is a data set corresponding to the reference object, which includes multiple reference points A 1 to A m on the reference object, color measurement values, color measurement average values, the number of reference points A 1 to A m on the reference object, and a threshold value Lth. The threshold value Lth can be a value preset in advance through experiments or simulations based on the desired level of color comparison. The smaller the threshold value Lth, the higher the level of color comparison (e.g., color identity judgment) will be performed. The reference object is any object including color shade changes, and for example, natural objects such as plants, images of designs showing color shade changes, and the like can be listed.

[0023] In addition, the reference object data may also include any data indicating the positions of the reference points A 1 to A m on the reference object. For example, it may also include image data indicating the positions of the reference points A 1 to A m on the reference object.

[0024] The processor 30 is composed of an arithmetic circuit such as a CPU (Central Processing Unit), for example, and realizes various functions by reading and executing various programs stored in the storage unit 20. In the present embodiment, the processor 30 reads and executes the color comparison program stored in the storage unit 20, and thus functions as a reference information acquisition unit 31, an object information acquisition unit 32, a calculation unit 33, a combination determination unit 34, and a judgment unit 35 as Figure 1 shown. These respective functions will be described later.

[0025] The display unit 40 is, for example, a display, which displays measurement guidance for the user, color judgment results, and the like. The operation unit 50 is, for example, a button or a touch display, etc., which accepts input operations from the user.

[0026] Next, the colorimetric method in the colorimetric device 1 of the present embodiment will be described. Figure 3 FIG. is a flowchart showing the colorimetric method of the present embodiment.

[0027] First, the reference information acquisition unit 31 selects the reference object data in the storage unit 20 according to the input operation of the user, and acquires the colorimetric values of a plurality of reference points A 1 to A m at each of them (step S1).

[0028] Next, the spectroscope 10 is set on the object. When the user inputs an operation indicating the intention of performing spectroscopic measurement, the object information acquisition unit 32 controls the spectroscope 10 to acquire the colorimetric value of the measurement point B n on the object. Here, under the control of the object information acquisition unit 32, the spectroscope 10 changes the transmission wavelength of the spectral filter 13 at a preset wavelength interval, and measures the spectral data of the measurement point B n in the visible light band. Further, the object information acquisition unit 32 calculates the colorimetric value of the measurement point B n based on the spectral data of the measurement point B n As the colorimetric value, for example, any colorimetric system such as XYZ value, L*a*b* value, etc. can be used. The colorimetric value corresponding to the measurement point B n is stored in the data reference area for color judgment in the storage unit 20.

[0029] In addition, the method of calculating the colorimetric value from the spectral data can also use known techniques such as Japanese Patent Laid-Open No. 2017-49163. Further, calibration using a white reference plate or the like can also be performed before step S2.

[0030] Before performing the above step S2, the display unit 40 may also display the data indicating the positions of the reference points A 1 to A m on the reference object. In this case, the user refers to the data displayed on the display unit 40, and sets the spectroscope 10 on the object so that the positional relationship of the plurality of reference points A 1 to A m on the reference object is the same as the positional relationship of the plurality of measurement points B 1 to B m on the object, and determines the measurement point B nconfiguration. Here, "the same" means that the reference point A determined in step S5 described later n and the measurement point B n In the combination, for the purpose of avoiding a large color deviation, strict position correctness is not required.

[0031] Then, the object information acquisition unit 32 refers to the reference point A on the reference object acquired in step S1 1 to A m The number of and the color measurement points B of the measured object n are compared (step S3).

[0032] In the case where the number of the color measurement points B of the object n is less than the number of the reference points A 1 to A m Output a guide to urge measurement on the object to the display unit 40, etc., and return to step S2.

[0033] On the other hand, in the case where the number of the color measurement points B of the object n is equal to the number of the reference points A 1 to A m The object information acquisition unit 32 ends the measurement of the object and proceeds to step S4. Thus, the same number of measurement points B as the reference points A 1 to A m are obtained, and each color measurement value of B 1 to B m is obtained.

[0034] Next, the calculation unit 33 calculates the Euclidean distance L on the color space coordinates between each measurement point B 1 to B m and each reference point A 1 to A m in sequence, and combines the combined reference points A n and the measurement point B n to calculate the Euclidean distance L (step S4). That is, the calculation unit 33 forms combinations in a loop between the reference points A 1 to A m and the measurement points B 1 to B m and calculates the Euclidean distance L for each combination.

[0035] Next, the combination determination unit 34 determines the multiple reference points A n and the reference point A n in such a way that the sum of the Euclidean distances L of the combination of the measurement point B 1 to A m is minimized, and determines the multiple measurement points B1 to B m All combinations between, that is, m combinations (step S5).

[0036] Next, the determination unit 35 selects the reference point A determined in step S5 1 to A m and the measurement point B 1 to B m from among the m combinations, and calculates the maximum Euclidean distance Lmax. Then, it is determined whether the maximum Euclidean distance Lmax is less than or equal to a predetermined threshold Lth (step S6). This threshold Lth is, for example, a value included in the reference object data obtained in step S1.

[0037] In addition, as the process of step S6 is carried out, the determination unit 35 increments by one the determination count M stored in the storage unit 20.

[0038] When the maximum Euclidean distance Lmax is less than or equal to the threshold Lth (when step S6 is YES), the determination unit 35 determines that the color of the object is similar to the color of the reference object. Then, the determination unit 35 outputs the determination result to the display unit 40 or the like (step S7). Through the above steps, Figure 3 the flowchart ends.

[0039] On the other hand, when the maximum Euclidean distance Lmax is greater than the threshold Lth (when step S6 is NO), the determination unit 35 determines whether the determination count M stored in the storage unit 20 is less than or equal to a predetermined repetition threshold Mth (step S8). This repetition threshold Mth is not particularly limited and can be any number.

[0040] And when the determination count M is less than or equal to the repetition threshold Mth (when step S8 is YES), the determination unit 35 outputs a guidance for urging re-measurement to the display unit 40 or the like, and returns to step S2. At this time, the data of the measurement point B 1 to B m used in the previous color determination is removed from the data reference area for color determination.

[0041] When the determination count M is greater than the repetition threshold Mth (when step S8 is NO), the determination unit 35 determines that the color of the object is not similar to the color of the reference object. Then, the determination unit 35 outputs the determination result to the display unit 40 or the like (step S7). Through the above steps, Figure 3 the flowchart ends.

[0042] Hereinafter, for the three reference points A obtained through the above steps S1 to S3 1 , A 2 , A3 (Refer to Figure 4 ) and three measurement points B 1 , B 2 , B 3 (Refer to Figure 5 ) are exemplified for each color measurement value. In the above step S4, for example, when calculating the Euclidean distance L_(A 1 - B 1 ) between the reference point A 1 and the measurement point B 1 ), it can be calculated by the following formula (1).

[0043]

[0044] In addition, in the above step S5, when calculating the sum S of the Euclidean distances in the case of combining A 1 and B 1 , A 2 and B 2 , A 3 and B 3 , this sum S can be calculated by the following formula (2).

[0045] S = L_(A 1 - B 1 ) + L_(A 2 - B 2 ) + L_(A 3 - B 3 ) Formula (2)

[0046] When the three combinations of A 1 and B 1 , A 2 and B 2 , A 3 and B 3 are determined in the above step S5, in the above step S6, select the combination showing the maximum value among the Euclidean distances L_(A 1 - B 1 ), L_(A 2 - B 2 ), L_(A 3 - B 3 ). Assuming that the Euclidean distance L_(A 1 - B 1 ) shows the maximum value, compare this Euclidean distance L_(A 1 - B 1 ) with a predetermined threshold Lth.

[0047] Function and effect of this embodiment

[0048] The colorimetric device 1 of the present embodiment performs the following steps as described above, namely: a reference information acquisition step (step S1) that acquires colorimetric values of a plurality of reference points A 1 to A m on a reference object including color shade changes; an object information acquisition step (step S2) that acquires colorimetric values of a plurality of measurement points B 1 to B m on an object; a calculation step (step S4) that combines the reference points A n and the measurement points B n and calculates the Euclidean distance L on the color space coordinates between the combined reference points A n and the measurement points B n ; and a determination step (step S6) that determines whether the color of the reference object is similar to the color of the object by comparing the Euclidean distance L calculated based on at least any one combination in the combination of the reference points A n and the measurement points B n with a predetermined threshold value Lth.

[0049] According to the present embodiment, by setting positions of various color concentrations on a reference object including color shade changes as the reference points A n , setting a plurality of positions on the reference object as the measurement points B n , and using the colorimetric values of the reference points A n and the measurement points B n for determination, it is possible to perform a determination on whether the overall colors between the reference object and the object are similar. That is, in the present embodiment, even when there are color shade changes on the reference object, colorimetry can be appropriately performed.

[0050] In addition, in the present embodiment, since the respective position coordinates of the reference points A n on the reference object and the measurement points B n on the object are not required, colorimetry of the object with respect to the reference object can be simply performed.

[0051] In the present embodiment, preferably, the colorimetric value is represented by the L*a*b* colorimetric system. Thereby, colorimetry close to the user's perception can be performed.

[0052] The colorimetric device 1 of the present embodiment further performs a combination determination step (step S5) that determines the combination of the reference points A n and the measurement points B n in such a manner that the sum of the Euclidean distances L between the reference object and the object is minimized, and the determination step (step S6) is based on the reference points A determined in the combination determination step (step S5)n in combination with measurement point B n Compare the Euclidean distance L calculated from at least any one of the combinations in the combination with a predetermined threshold Lth.

[0053] Thus, in the case where not only the reference object but also the object has color shading changes, the reference point A n in combination with measurement point B n can be appropriately combined, and as a result, colorimetry can be appropriately performed.

[0054] In the present embodiment, the determination step (step S6) compares the maximum Euclidean distance Lmax calculated from any combination in the combination of the reference point and the measurement point determined in the combination determination step (step S5) with the threshold Lth.

[0055] Thus, by performing colorimetry using the data of the combination with the largest color deviation among the multiple combinations of the reference point A n in combination with measurement point B n it is possible to more appropriately determine whether the overall colors between the reference object and the object are similar.

[0056] In the present embodiment, the reference information acquisition step (step S1) acquires the colorimetric values, colorimetric average values, number of measurement points, and threshold Lth of multiple reference points A 1 to A m on the reference object in a set manner. Thus, colorimetry of the present embodiment can be simply performed. For example, the user can select the desired reference object data or use the threshold Lth suitable for the reference object.

[0057] Modification

[0058] The present invention is not limited to the above-described embodiment, and structures obtained by modifications and improvements within the scope that can achieve the object of the present invention are also included in the present invention.

[0059] Modification 1

[0060] In the above-described embodiment, the reference object data may not include the colorimetric average value and the threshold Lth. In addition, in the above-described embodiment, although the threshold Lth is set according to the reference object, it may also be fixed.

[0061] In the above-described embodiment, although the object information acquisition unit 32 calculates the colorimetric value of the measurement point B n based on the spectroscopic spectrum obtained from the spectroscope 10, the colorimetric value of the measurement point B n may also be obtained from an arbitrary database.

[0062] Modification 2

[0063] In step S6 of the above-described embodiment, the maximum Euclidean distance Lmax is compared with the threshold value Lth. However, the present invention is not limited thereto. For example, it is also possible to compare the average value of the Euclidean distance L calculated based on the combination of the reference points A 1 to A m and the measurement points B 1 to B m with the threshold value Lth, or to compare the minimum value of the Euclidean distance L calculated based on an arbitrary combination with the threshold value Lth.

[0064] Modification Example 3

[0065] In step S5 of the above-described embodiment, the reference points A 1 to A m and the measurement points B 1 to B m are determined in such a way that the sum of the Euclidean distances L is minimized. However, the present invention is not limited thereto. For example, in step S2 above, when the measurement order of the measurement points B n corresponding to the reference point A n is specified, etc., the combination may also be determined based on this measurement order.

[0066] Modification Example 4

[0067] In the above-described embodiment, the spectroscope 10 may also be a spectroscopic camera that captures a spectroscopic image. In this case, the object information acquisition unit 32 may also calculate the colorimetric value of the measurement point B n based on the average value of an arbitrary region (for example, 10 pixels × 10 pixels) in the spectroscopic image.

[0068] Alternatively, an RGB camera may be used instead of the spectroscope 10. In this case, the object information acquisition unit 32 may also acquire the colorimetric value of the measurement point B n based on the captured image.

[0069] Modification Example 5

[0070] In step S2 of the above-described embodiment, it was described that the positional relationship of the plurality of measurement points B 1 to B m on the object and the positional relationship of the plurality of reference points A 1 to A m on the reference object are set to be the same. However, the present invention is not limited thereto. For example, the validity of colorimetry may also be ensured by setting the number of repetitions of the measurement in step S5 to be large.

[0071] Modification Example 6

[0072] In step S1 of the above-described embodiment, the reference information acquisition unit 31 acquires reference object data such as colorimetric values from the storage unit 20. However, the present invention is not limited thereto. For example, the reference information acquisition unit 31 may also acquire reference object data from another database capable of communicating with the colorimetric device 1. In addition, the reference information acquisition unit 31 may control the spectroscope 10 and calculate the reference point A based on the spectroscopic measurement result of the reference object. n of the colorimetric value.

[0073] Summary of the present disclosure

[0074] The colorimetric method according to the present disclosure performs the following steps: a reference information acquisition step of acquiring colorimetric values of a plurality of reference points on a reference object including color shade changes; an object information acquisition step of acquiring colorimetric values of a plurality of measurement points on an object; a calculation step of combining the reference points and the measurement points and calculating the Euclidean distance on the color space coordinates between the combined reference points and measurement points; and a determination step of determining whether the color of the reference object and the color of the object are similar by comparing the Euclidean distance calculated based on at least any one combination of the combination of the reference points and the measurement points with a predetermined threshold value.

[0075] In the colorimetric method of this embodiment, preferably, the colorimetric value is represented by the L*a*b* colorimetric system.

[0076] The colorimetric method of this embodiment preferably further performs a combination determination step of determining all combinations between the reference points and the measurement points in such a manner that the total sum of the Euclidean distances between the reference object and the object becomes the minimum, and the determination step compares the Euclidean distance calculated based on at least any one combination of all combinations between the reference points and the measurement points determined in the combination determination step with a predetermined threshold value.

[0077] In the colorimetric method of this embodiment, preferably, the determination step compares the maximum Euclidean distance calculated based on any combination of all combinations between the reference points and the measurement points determined in the combination determination step with the threshold value.

[0078] In the colorimetric method of this embodiment, preferably, the reference information acquisition step acquires each colorimetric value, the colorimetric average value, the number of reference points, and the threshold value of the plurality of reference points on the reference object as a set.

[0079] The colorimetric device according to the present disclosure includes: a reference information acquisition unit that acquires colorimetric values of a plurality of reference points on a reference object including color shade changes; an object information acquisition unit that acquires colorimetric values of a plurality of measurement points on an object; a calculation unit that combines the reference points and the measurement points and calculates the Euclidean distance on the color space coordinates between the combined reference points and the measurement points; and a determination unit that determines whether the color of the reference object is similar to the color of the object by comparing the Euclidean distance calculated based on at least any one combination of the combination of the reference points and the measurement points with a predetermined threshold value.

[0080] The colorimetric device of this embodiment preferably further includes a display unit that displays data indicating the positions of the reference points on the reference object.

[0081] In addition, the colorimetric device of this embodiment preferably further includes a display unit that displays the determination result of the determination unit.

[0082] Symbol Explanation

[0083] 1... Colorimetric device; 10... Spectrophotometer; 11... Light source unit; 11A... Light source; 11B... Condensing unit; 12... Light guide unit; 12A... Reflecting mirror; 12B... Band-pass filter; 13... Spectral filter; 14... Light receiving unit; 20... Storage unit; 30... Processor; 31... Reference information acquisition unit; 32... Object information acquisition unit; 33... Calculation unit; 34... Combination determination unit; 35... Determination unit; 40... Display unit; 50... Operation unit.

Claims

1. A colorimetric method, which implements the following steps, namely: A reference information acquisition step of acquiring color measurement values ​​of a plurality of reference points on a reference object including color shading variations; an object information acquisition step of acquiring colorimetric values ​​of a plurality of measurement points on the object; a calculation step of combining the reference point with the measurement point and calculating the Euclidean distance between the combined reference point and the measurement point in the color space coordinates; A judging step of judging whether the color of the reference object is similar to the color of the target object by comparing the Euclidean distance calculated based on at least any one of the combinations of the reference point and the measurement point with a predetermined threshold value.

2. The colorimetric method according to claim 1, wherein The colorimetric values ​​are expressed by the L*a*b* colorimetric system.

3. The colorimetric method according to claim 1, wherein: further performing a combination determination step of determining all combinations of the reference points and the measurement points in such a manner that the sum of the Euclidean distances between the reference object and the object becomes minimum, The determination step compares the Euclidean distance calculated based on at least one of all the combinations between the reference point and the measurement point determined in the combination determination step with the threshold value.

4. The colorimetric method according to claim 3, wherein: The determination step compares the maximum Euclidean distance calculated based on any combination among all the combinations between the reference points and the measurement points determined in the combination determination step with the threshold value.

5. The colorimetric method according to claim 1, wherein: The reference information acquisition step acquires the colorimetric values ​​of the plurality of reference points on the reference object, the colorimetric average value, the number of the reference points, and the threshold value as one set.

6. A colorimetric device comprising: A reference information acquisition unit that acquires color measurement values ​​of a plurality of reference points on a reference object including changes in color shading; an object information acquisition unit that acquires colorimetric values ​​of a plurality of measurement points on the object; a calculation unit that combines the reference point with the measurement point and calculates a Euclidean distance in color space coordinates between the combined reference point and the measurement point; The determination unit determines whether the color of the reference object and the color of the target object are similar by comparing the Euclidean distance calculated based on at least any one of the combinations of the reference point and the measurement point with a predetermined threshold value.

7. The colorimetric device according to claim 6, wherein: A display unit is further provided for displaying data indicating the position of the reference point on the reference object.

8. The colorimetric device according to claim 6, wherein: A display unit is further provided for displaying a determination result of the determination unit.

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