WO2019054016A1

WO2019054016A1 - Characteristic value measurement device, method, and program using color image

Info

Publication number: WO2019054016A1
Application number: PCT/JP2018/025080
Authority: WO
Inventors: 忠久當山
Original assignee: 株式会社オルタステクノロジー
Priority date: 2017-09-13
Filing date: 2018-07-02
Publication date: 2019-03-21
Also published as: JP2019052887A

Abstract

This characteristic value measurement device is for measuring characteristic values of a detected substance in a sample, wherein the device comprises: an imaging means that captures a color image on a test paper onto which the sample has been dripped; and a computation means that executes prescribed computation on the basis of the captured color image and calculates the characteristic values of the detected substance in the sample on the basis of the results of the computation. The test paper retains a color-reaction reagent with wavelength characteristics such that the reflectance at a first wavelength represents a maximum value and the reflectance at a second wavelength that differs from the first wavelength represents a minimum value.

Description

Device, method, and program for measuring characteristic value using a colored image

The present invention is an apparatus and method for measuring a characteristic value such as concentration or acid value of a detection substance in a sample based on an image obtained as a result of a color reaction on a test paper to which the sample is dropped. And the program.

Conventionally, when analyzing characteristic values such as concentration and acid value of a detection substance in a sample, the carrier mainly composed of paper or resin is used as a method to easily replace the analysis device. An analytical method that uses a color tone judgment that visually compares a colored test strip with a standard color chart using a test strip on which a reaction reagent whose coloration state changes according to characteristic values such as concentration and acid value is fixed There is.

However, it is difficult to obtain objective and accurate results because visual color judgment is affected by ambient light, specimen coloring, individual subjectivity, and the like.

Therefore, as a simple method that can obtain objective and more accurate results, the optical element is used to calculate the sum, difference or ratio of various spectral intensities, or time difference to reduce the variation of the test paper Method of performing coloration of colored matter by color analysis of information captured using a method (first method) or a CCD light receiving element etc. based on various tristimulus values such as RGB color system Method has been proposed.

Patent 1228630 specification JP-A-3-220445 JP-A-7-35744 Japanese Patent Laid-Open No. 2000-121561 JP 2001-349834 A JP 10-73534 A Patent No. 3880057 Patent No. 5330106 WO 2016/031267

However, the calculation performed by the above-described first method does not necessarily carry out the optimum calculation processing according to each color reaction system, and there is a problem that sufficient measurement accuracy can not be obtained.

On the other hand, in the second method described above, the visual judgment is replaced with the device measurement, and the color tone judgment result depending on the subjectivity, the individual difference in the judgment timing, the color tone change due to external light etc. Is planned.

However, sufficient measures have not been taken with regard to measurement paper errors, coloration due to specimen history, and measurement errors resulting from the amount of specimen collection.

Also, since color analysis is simply based on comparison of the calculated value of the light quantity of the reflected light and transmitted light of the test paper color product with the reference value, the optimum arithmetic processing according to the individual color reaction system is not necessarily required. However, there is still a problem that sufficient measurement accuracy can not be obtained.

The present invention has been made in view of such circumstances, and provides a characteristic value measuring apparatus, method, and program for measuring characteristic values of a detection substance in a sample simply and with sufficient accuracy. With the goal.

A characteristic value measuring apparatus according to an aspect of the present invention is an apparatus for measuring a characteristic value of a detection substance in a sample, the imaging means for capturing a color image on a test paper on which the sample is dropped, and imaging And calculating means for performing a predetermined calculation based on the color-changed image and calculating a characteristic value of the detected substance in the sample based on the result of the calculation. Here, the test paper has a color reaction reagent having a wavelength characteristic in which the light reflectance exhibits a maximum value at a first wavelength and the light reflectance exhibits a minimum value at a second wavelength different from the first wavelength. Hold.

The characteristic value measuring method according to one aspect of the present invention is a method for measuring a characteristic value of a detection substance in a sample, and the light reflectance exhibits a maximum value at the first wavelength, and the first wavelength And a step of dropping a sample on a test sheet holding a color reaction reagent having a wavelength characteristic in which the light reflectance shows a local minimum value at a second wavelength different from the above, and a presentation generated on the test sheet according to the drop of the sample The steps of capturing a color image, and performing a predetermined calculation based on the captured color image, and calculating a characteristic value of the detected substance in the sample based on the result of the calculation.

A program according to an aspect of the present invention is a program according to one embodiment of the present invention, in which a light reflectance exhibits a maximum value at a first wavelength to measure a characteristic value of a detection substance in a sample, and a second wavelength different from the first wavelength A test paper holding a color reaction reagent having a wavelength characteristic in which the light reflectance shows a local minimum value, a function to cause the imaging means to image a color image generated by dropping the sample, and the imaged color image It is a program for causing a computer to realize a function of executing a predetermined calculation based on the calculation result and calculating a characteristic value of a detection substance in a sample based on the calculation result.

According to the present invention, it is possible to measure characteristic values of a detection substance in a sample simply and with sufficient accuracy.

FIG. 1 is a block diagram showing a configuration example of a characteristic value measuring device to which the characteristic value measuring method according to the embodiment is applied. FIG. 2A is a figure (in the case of acid value = 1.5) which shows an example of a time-dependent change of a test paper spectral reflectance factor. FIG. 2B is a diagram (in the case of acid value = 2.5) showing an example of the time-dependent change of the test paper spectral reflectance. FIG. 2C is a diagram (in the case of acid value = 3.5) showing an example of the temporal change of the test paper spectral reflectance. FIG. 3 is a view showing an example of a calibration curve consisting of second-order fitting of the magenta component and the acid value of fat and oil. FIG. 4 is a diagram showing an example of a calibration curve consisting of secondary fitting of magenta component / yellow component and acid value of fat and oil. FIG. 5 is a view showing an example of a calibration curve consisting of second-order fitting of an RG (red-green) difference tone value and an acid value of fat and oil. FIG. 6A is a diagram showing an example of the correlation between R (red) pixel tone values and the acid value of fats and oils. FIG. 6B is a diagram showing an example of the correlation between G (green) pixel tone values and the acid value of fats and oils. FIG. 7 is a flowchart showing an operation example of the characteristic value measuring device according to the embodiment. FIG. 8 is a schematic view showing an example of the imaging screen.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a characteristic value measuring apparatus 10 to which a characteristic value measuring method according to an embodiment of the present invention is applied.

The characteristic value measuring apparatus 10 is an apparatus for measuring a characteristic value such as concentration, acid value, etc., of a detection substance in a sample, and is an imaging unit 12, an operation unit 14, a storage unit 16, and an output unit 18. , The display unit 20, and the display 21.

In order to obtain the characteristic value, it is necessary to drop the sample on the test paper 22, cause a color reaction on the test paper 22, and capture the color image of the color reaction by the imaging unit 12. Therefore, the test paper 22 has a wavelength at which the light reflectance exhibits a maximum value at the first wavelength and the light reflectance exhibits a minimum value at a second wavelength different from the first wavelength such that a color reaction occurs. It holds a color reaction reagent having characteristics.

As a specific example of the test paper 22 which hold | maintains such a color reaction reagent, although it is not limited, there exists AV test paper by Shibata science. The Shibata Scientific AV Test Paper is suitable for measuring the acid value of fryer oil, and when fryer oil is dropped, light is emitted at a first wavelength (530 nm), as illustrated in FIG. 2A. The color reaction reagent having a wavelength characteristic in which the reflectance shows the maximum value and the light reflectance shows the minimum value at the second wavelength (620 nm) is held.

According to this color reaction, it is possible to determine the acid value (AV) value of fats and oils by visual colorimetry after a predetermined time has elapsed. In addition, as shown in FIGS. 2A, 2B, and 2C, as the acid value increases (1.5 → 2.5 → 3.5), the first wavelength showing a maximum value goes from 530 nm to the long wavelength side The shift results in the disappearance of the blue component and the change of the reaction color from yellowish green to yellow. On the other hand, the second wavelength showing a minimal value does not shift from 620 nm even if the acid value increases (1.5 → 2.5 → 3.5), but the light reflectance increases and the red component increases. To go.

When the imaging unit 12 captures a color image, the imaging unit 12 outputs an imaging result to the calculation unit 14. As the imaging unit 12, for example, a color imaging device such as a built-in CCD light receiving device can be used, but an external device such as a smartphone or a digital camera can also be used. When using these external devices, the imaging unit 12 is provided outside the characteristic value measuring device 10.

The calculation unit 14 executes a predetermined calculation based on the imaging result of the color image output from the imaging unit 12 and calculates the characteristic value of the detection substance in the sample based on the calculation result. When calculating the characteristic value, the result of the calculation is performed by collating with a previously prepared calibration curve. Alternatively, it is performed by substituting the result of the operation into a mathematical expression representing a calibration curve. The calibration curve is stored in advance in the storage unit 16.

The storage device 16 is realized by a program memory (for example, a non-volatile memory such as a solid state drive (SSD) or a hard disk drive (HDD) that can be written and read as needed) and stores one or more calibration curves. There is. When calculating the characteristic value, the calculation unit 14 selects an appropriate calibration curve from among the calibration curves stored in the storage device 16 for comparison. FIGS. 3, 5 and 4 are examples of calibration curves stored in the storage device 16.

The calibration curve 1 shown in FIG. 3 shows the correlation between the strength of the magenta component (M component) obtained from the color image and the acid value of the oil. The calibration curve 2 shown in FIG. 4 shows the correlation between the ratio of the intensity of the magenta component to the intensity of the yellow component (M component / Y component) obtained from the color image and the acid value of the oil. The calibration curve 3 shown in FIG. 5 shows the correlation between the difference between the intensity of the red component and the intensity of the green component (RG difference tone value) obtained from the color image and the acid value of the oil and fat. .

In each of the calibration curves 1, 2 and 3, a fat or oil having a known acid value is dropped on the test paper 22, a color image on the test paper 22 is captured, and the Y axis value is calculated based on the color image. A process of calculating and plotting the calculation result is performed at a plurality of acid values, and finally, obtained by performing second-order fitting on a plurality of plots.

As shown in FIG. 3, in the calibration curve 1, the unit of the Y axis is the intensity of the magenta component. Hereinafter, the unit of the Y axis in the calibration curve is referred to as "index". The reason why the index of the calibration curve 1 is the strength of the magenta component will be described. In this index, it is said that the first wavelength (530 nm) at which the color reaction reagent exhibits a maximum value changes as shown in FIG. 2A, according to the amount of acid value, as shown in FIG. 2B and FIG. 2C. It is determined focusing on having wavelength characteristics. In this case, the intensity of the complementary color component (magenta component) of the color component (green component) including the first wavelength (530 nm) and the acid value have a good correlation of determination coefficient R ² = 0.963 of ^second -order fitting Have a relationship.

As shown in FIG. 4, in the calibration curve 2, the index is M component / Y component. This index is shown in FIG. 2A as the color reaction reagent shows the first wavelength (530 nm) at which the maximum value is shown, and as the acid value increases as shown in FIG. 2B and FIG. It is determined focusing on the wavelength characteristic of shifting to the side. In this case, the intensity of the complementary color component (magenta component) of the color component (green component) including the first wavelength (530 nm) before the shift and the color component (yellow component) including the first wavelength (530 nm <) after the shift The ratio of M) to the intensity (M component / Y component) and the acid value have a good correlation with the ^second -order fitting determination coefficient R ² = 0.978.

As shown in FIG. 5, in the calibration curve 3, the index is an RG difference tone value. This index has a wavelength characteristic that the color reaction reagent has a first wavelength (530 nm) showing a maximum value and a second wavelength (620 nm) showing a minimum value, as shown in FIG. 2A. The decision was made focusing on the In this case, the difference (RG difference tone value) between the intensity of the color component (green component) including the first wavelength (530 nm) and the intensity of the color component (red component) including the second wavelength (620 nm) ) And acid value have a good correlation of determination coefficient of ^second -order fitting R ² = 0.958. The reason for having such a good correlation is that, by subtracting the G tone value from the R tone value, the bias component that does not contribute to the color reaction is subtracted from the reflected light reflected by the test paper 22, This is because the correlation is enhanced.

As described above, in each of the calibration curves 1, 2 and 3, an appropriate index having a good correlation with the acid value is used, but for reference, the correlation in the case of using other indices is introduce.

For example, FIG. 6A shows the relationship between the red component (R component) tone value and the acid value. The determination coefficient R ^{2 is} 0.265, and no high correlation is observed. Also, FIG. 6B shows the relationship between the green component (G component) tone value and the acid value. The coefficient of determination R ^{2 is} 0.504, and again no high correlation is seen. These indices can not be used as a calibration curve because they have a low correlation with acid value.

Therefore, the operation unit 14 uses the imaging results output from the imaging unit 12 and calibration curves such as calibration curves 1, ² and 3 having a good determination coefficient R ² to detect the acid of the detection substance in the sample. Calculate the value.

For example, when the calculation unit 14 calculates the acid value using the calibration curve 1, the calculation unit 14 calculates the intensity of the magenta component which is the index of the calibration curve 1 from the imaging result output from the imaging unit 12 . Then, the acid value is calculated from the calculated strength of the magenta component and the calibration curve 1. Specifically, the acid value is calculated by comparing the calculated intensity of the magenta component with the calibration curve 1. Alternatively, the acid value is calculated by substituting the calculated intensity of the magenta component into the equation representing the calibration curve 1.

When the calculation unit 14 calculates the acid value using the calibration curve 2, the calculation unit 14 calculates the M component / Y component that is the index of the calibration curve 2 from the imaging result output from the imaging unit 12. Do. Then, the acid value is calculated from the calculated M component / Y component and the calibration curve 2. Specifically, the acid value is calculated by comparing the calculated intensity of the M component / Y component with the calibration curve 2. Alternatively, the acid value is calculated by substituting the calculated intensity of the M component / Y component into the equation representing the calibration curve 2.

In addition, when the calculation unit 14 calculates the acid value using the calibration curve 3, the calculation unit 14 determines from the imaging result output from the imaging unit 12 an RG difference tone value that is an index of the calibration curve 3. Calculate Then, the acid value is calculated from the calculated RG difference tone value and the calibration curve 3. Specifically, the acid value is calculated by comparing the calculated RG difference tone value with the calibration curve 3. Alternatively, the acid value is calculated by substituting the calculated intensity of the RG difference tone value into the equation representing the calibration curve 3.

Generally, since RGB color filters are used for the pixels of the color imaging element, the output value of the imaging result is the RGB tone value. Therefore, when calculating the index of the calibration curve 3, the calculation unit 14 can use the output value of the imaging result as it is, but in order to calculate the index of the calibration curve 1 or the calibration curve 2, imaging is performed. The RGB tone values of each sub-pixel in the result need to be converted to CMYK values.

When RGB tone values are output as 8-bit 255 tone, conversion of RGB tone values to CMYK values is performed using the following equations (1) to (7).

R% = R / 255 (1)
G% = G / 255 (2)
B% = B / 255 (3)
K = min (1-R%, 1-G%, 1-B%) ... (4)
C% = (1-R% -K) / (1-K) (5)
M% = (1-G% -K) / (1-K) (6)
Y% = (1-B% -K) / (1-K) (7)
The output unit 18 outputs the index, the acid value, and the like calculated by the calculation unit 14 as electronic data.

The display unit 20 causes the display 21 to display the index, the acid value, and the like calculated by the calculation unit 14. The display unit 20 may further display the calibration curve used by the calculation unit 14 from the display 21 or may display the calculated index on the displayed calibration curve.

Arithmetic unit 14, output unit 18, and display unit 20 are, for example, a field-programmable gate array (FPGA) or a central processing unit (CPU) or a combination thereof and a program memory (for example, a solid state drive (SSD) or a hard disk (HDD)). The present invention is realized by a computer having a non-volatile memory capable of writing and reading at any time such as Drive), and realizes control functions necessary to implement the present embodiment. These control functions are all realized by causing the FPGA or CPU to execute the measurement program stored in the program memory.

For example, the characteristic value measuring device 10 can be realized by a smartphone in which the measurement program is installed. The specific example which measures an acid value by the measurement program installed in the smart phone is demonstrated using the flowchart shown in FIG.

First, the measurer activates the measurement program installed in the smartphone (S1). As a result, the camera imaging mode of the smartphone is activated, and an imaging target mark 24 such as a □ (square) mark or an X mark as shown in FIG. 8 is displayed at the center of the screen. It is in the state of waiting for the start of measurement of acid value.

Next, the measurer drops the fat as the sample onto the reagent portion 23 of the test paper 22 (S2) and simultaneously presses the measurement start button displayed from the smartphone (S3).

When the measurement start button is pressed, the measurement program starts counting time (S4), and after a predetermined time has elapsed (S5: Yes), issues an alarm sound or voice guidance prompting imaging (S6). The predetermined time is preferably several seconds to several minutes, for example, 30 seconds to 2 minutes. It is desirable that the predetermined time be a time zone in which most of the color reaction is completed and the color change is stable, and the reaction speed is controlled to be completed within a predetermined time by the component configuration of the reagent. Is preferred.

Next, the measurer displays an imaging target mark 24 as represented by a square (□) as an example in FIG. 8 from the screen of the smartphone (S7), and matches it with the reagent portion 23 of the test paper 22. (S8), imaging is performed (S9). In addition, it is desirable that the imaging target mark 24 be displayed so as to match the size of the reagent portion 23, so that the imaging distances between the test paper 22 and the camera (smartphone) are kept substantially the same. An image with less of

Thereafter, an operation for calculating the acid value is performed using the imaging result and the calibration curve. Here, the case where the calibration curve 1 is installed in the smartphone and the acid value is calculated by using the calibration curve 1 will be described as an example.

That is, the measurement program reads the imaging result obtained in step S9, selects one or more pixels in the vicinity of the center of the reagent portion 23, and corresponds to each pixel according to the equations (1) to (3) described above. R, G, B gradation values (%) are calculated (S10). When a plurality of pixels are selected, an average value of a plurality of pixels may be used, or a median or mode of a plurality of pixels may be used. In addition, in accordance with the change shape of the color emission spectrum or in consideration of the sensitivity characteristic of the image pickup element, for example, for each of R, G, B components like a * R, b * G, c * B. An appropriate correction coefficient a, b, c may be multiplied.

Next, the minimum value K among 1-R%, 1-G%, and 1-B% is calculated according to the above-mentioned equation (4) (S11).

Further, the strength of the magenta component (M component) is determined according to the above (6) (S12).

And the acid value of fats and oils is calculated by collating the intensity | strength of M component with the calibration curve 1, or substituting in the formula showing the calibration curve 1 (S13), The calculated acid value is displayed from the display 21 Display (S14).

As described above, in the calibration curve 1, since the strength of the M component and the acid value have a good correlation of determination coefficient R ² = 0.963 of the ^second fitting, the M component using the calibration curve 1 The acid value calculated from the strength of has a high accuracy.

In this example, although an example using a smartphone has been described, a color reaction may be imaged using a digital camera, or a dedicated measuring device using an imaging element such as a CCD light receiving element is used. May be

In the case of using a digital camera, it is performed by sending the imaged imaging result to a device such as a personal computer installed with a measurement program via a recording medium, communication means, and the like.

As described above, according to the characteristic value measuring apparatus 10 to which the characteristic value measuring method according to the present embodiment is applied, the color reaction caused by the dropping of the sample on the test paper 22 is started by the action as described above. An acid value can be calculated with high accuracy by imaging a color-developed image, calculating an index based on the imaging result, and collating the index with a calibration curve.

As an example in the above, highest determination coefficient R ² of the calibration curve 2, then high determination coefficient R ² of the calibration curve 1, followed been described determination coefficient R ² of the calibration curve 3 is high. However, depending on the color reaction, the order of the determination coefficient R ² may not follow this order. It is important to use an appropriate calibration curve for the response waveform including the characteristics of the optical system. Similarly, it is important not only to check the acid value of fats and oils, but to grasp and apply an appropriate calibration curve according to the application such as concentration.

As described above, according to the characteristic value measuring apparatus 10 to which the characteristic value measuring method according to the present embodiment is applied, the characteristic value of the detection substance in the sample can be simply and highly accurately, though it is a simple method. It becomes possible to measure by

By this, especially when measuring an acid value as a characteristic value, the following applications are attained. That is, when the refined fryer oil (the acid value of the edible oil is 0.5 or less) is used for frying, the fats and oils react with water at high temperature to cause hydrolysis and increase the acid value. In addition, when fats and oils are auto-oxidized, carbon chains of fatty acids are cut to generate aldehydes, and further, the portions are oxidized to become carboxylic acids, resulting in an increase in acid value. Thus, the acid value is an indicator of the deterioration of the fryer oil. According to the present invention, since the acid value can be measured simply and with sufficient accuracy, it can be used, for example, to measure the acid value of fryer oil used for frying in a convenience store. For example, it becomes possible to easily grasp the appropriate timing for changing the fryer oil.

The present invention is not limited to the above embodiment, and can be variously modified in the implementation stage without departing from the scope of the invention. In addition, the embodiments may be implemented in combination as appropriate as possible, in which case the combined effect is obtained. Furthermore, the above embodiments include inventions of various stages, and various inventions can be extracted by an appropriate combination of a plurality of disclosed configuration requirements.

For example, in the above embodiment, the measurement method in the case of the acid value was described as the characteristic value, but those skilled in the art can also apply to measurement of the concentration by the characteristic value measurement method according to the present embodiment. You will easily think of what is possible.

Claims

An apparatus for measuring a characteristic value of a detection substance in a sample, the apparatus comprising:
An imaging unit configured to capture a color image on a test paper on which the sample is dropped;
Arithmetic means for executing a predetermined calculation based on the captured color image and calculating a characteristic value of the detection substance in the sample based on the result of the calculation
The test paper has a color reaction reagent having a wavelength characteristic in which the light reflectance exhibits a maximum value at a first wavelength and the light reflectance exhibits a minimum value at a second wavelength different from the first wavelength. Characteristic value measuring device to hold.
When the first wavelength changes according to the amount of the characteristic value, a calibration curve indicating the correlation between the intensity of the complementary color component of the color component including the first wavelength and the characteristic value is stored in advance Further comprising a storage device,
The calculation unit according to claim 1, wherein the calculation unit calculates the intensity of the complementary color component from the captured color image, and calculates the characteristic value based on the intensity of the complementary color component and the calibration curve. Characteristic value measuring device.
When the first wavelength shifts according to the amount of the characteristic value, the intensity of the complementary color component of the color component including the first wavelength before the shift and the color component including the first wavelength after the shift A storage device storing in advance a calibration curve indicating a correlation between the ratio to the intensity of the light emission and the characteristic value;
The characteristic value measuring device according to claim 1, wherein the calculating means calculates the ratio from the captured color image, and calculates the characteristic value based on the ratio and the calibration curve.
It further comprises a storage device storing in advance a calibration curve showing a correlation between the characteristic value and the difference between the intensity of the color component including the first wavelength, the intensity of the color component including the second wavelength,
The characteristic value measuring device according to claim 1, wherein the calculation means calculates the difference from the captured color image, and calculates the characteristic value based on the difference and the calibration curve.
The characteristic value measuring device according to claim 1, wherein the imaging means is a camera function of a smartphone or a digital camera.
A method for measuring a characteristic value of a detection substance in a sample, comprising
Test paper holding a color reaction reagent having a wavelength characteristic in which the light reflectance exhibits a maximum value at a first wavelength and the light reflectance exhibits a minimum value at a second wavelength different from the first wavelength And dropping the sample.
Imaging a color image generated on the test paper in response to the dropping of the sample;
And D. performing a predetermined calculation based on the captured color image, and calculating a characteristic value of the detection substance in the sample based on a result of the calculation.
When the first wavelength changes according to the amount of the characteristic value, a calibration curve indicating the correlation between the intensity of the complementary color component of the color component including the first wavelength and the characteristic value is stored in advance Remember to
In the calculating step, an intensity of the complementary color component is calculated from the captured color image, and the characteristic value is calculated based on the intensity of the complementary color component and the calibration curve. Characteristic value measurement method described.
When the first wavelength shifts according to the amount of the characteristic value, the intensity of the complementary color component of the color component including the first wavelength before the shift and the color component including the first wavelength after the shift A calibration curve indicating the correlation between the ratio of the intensity of the light and the characteristic value is stored in advance in the storage device,
The characteristic value measuring method according to claim 6, wherein in the calculating step, the ratio is calculated from the captured color image, and the characteristic value is calculated based on the ratio and the calibration curve. .
A calibration curve indicating a correlation between the characteristic value and the difference between the intensity of the color component including the first wavelength and the intensity of the color component including the second wavelength is stored in the storage device in advance
The characteristic value measuring method according to claim 6, wherein in the calculating step, the difference is calculated from the captured color image, and the characteristic value is calculated based on the difference and the calibration curve. .
The characteristic value measuring method according to claim 6, wherein the characteristic value is an acid value of the detection substance in the sample.
The characteristic value measurement method according to claim 6, wherein the imaging step is performed using a camera function of a smartphone or a digital camera.
In order to measure the characteristic value of the detection substance in the sample, the light reflectance exhibits a maximum value at a first wavelength, and the light reflectance exhibits a minimum value at a second wavelength different from the first wavelength. A function of causing an imaging unit to capture a color image generated by dropping the sample on test paper holding a color reaction reagent having a wavelength characteristic to be shown;
A program for causing a computer to realize a function of executing a predetermined calculation based on the captured color image and calculating a characteristic value of a detection substance in the sample based on a result of the calculation.