JP2017049030A - Device, system, program and method for measuring deterioration level of edible oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a general-purpose device to measure the chromaticity value and acid value of measuring object edible oil with accuracy sufficient for practical use.SOLUTION: A device (1) for measuring the degree of deterioration in edible oil includes: an imaging unit (11) for photographing a test piece to obtain image data; a storage unit (13) for storing correspondence relation (50-52) between the chromaticity value and acid value of the edible oil and the color value of the image data on the test piece; a chromaticity value acquisition unit (144) for acquiring the chromaticity value of the edible oil by referring to the correspondence relation on the basis of the color value of the image data on the test piece soaked in the edible oil; an acid value acquisition unit (145) for acquiring the acid value of the edible oil by referring to the correspondence relation on the basis of the color value of the image data on the test piece soaked in the edible oil and the acquired chromaticity value; and an output unit (16) for outputting the acquired chromaticity value and acid value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an apparatus, a system, a program, and a method for measuring the degree of deterioration of edible oil.

  In edible oils such as frying oil, free fatty acids are produced with deterioration. As a test paper for determining the degree of deterioration of edible oil by simply measuring the content (acid value) of this free fatty acid, a test piece with a reagent that causes a color reaction to the free fatty acid is used. Yes.

  In Patent Document 1, light is irradiated to a colored body (test paper) that reacts with fats and oils and produces different color depending on the degree of deterioration of the fats and oils, light reflected by the colored bodies is received, and the intensity of the reflected light A fat and oil deterioration degree measuring device that determines the degree of deterioration of fats and oils based on the information and the comparison information and displays the degree of deterioration is described.

  In Patent Document 2, when the mark is viewed from above through the opening of the container main body on the inner surface of the container main body provided with a mark colored in green, blue or purple different from the color of the inner surface, the mark is displayed. A method for evaluating the degree of deterioration of frying oil is described, which includes a step of pouring frying oil until it cannot be identified, and a step of measuring the depth from the liquid level of the frying oil to the mark.

  Patent Document 3 discloses a sample dispensing mechanism that sucks a sample housed in a sample container and discharges it to a reaction container, a reagent dispensing mechanism that sucks a reagent housed in a reagent container and discharges it to a reaction container, and a reaction Controls the operation of multiple photometers that detect the light irradiated to the container, the sample dispensing mechanism and the reagent dispensing mechanism, and sets the allowable concentration range of the calibration curve for each photometer, and sets the allowable concentration range Select one of a plurality of photometers according to the sample concentration calculated based on the light detected by each photometer, and set the concentration based on the light detected by the selected photometer as the sample concentration. An automatic analyzer comprising a controller for determining is described.

JP 2010-281610 A JP 2009-025194 A JP 2014-006160 A

  In the measurement of the degree of deterioration of edible oil using a test piece, the acid value of the edible oil is determined by comparing the color of the test piece immersed in the edible oil to be measured with the color of the reference table (color chart). Determined. However, when such a color comparison is performed by a human, the determination result depends on the subjectivity, and there is a problem that the measurement value varies depending on the measurer.

  If the color of the test piece is automatically read out and compared, and the result is displayed as a numerical value, as in the measurement apparatus of Patent Document 1, it is possible to objectively measure the degree of deterioration of edible oil. However, in the measuring apparatus of Patent Document 1, it is necessary to install a test paper soaked in edible oil inside the apparatus. For this reason, it is difficult to obtain sufficient measurement accuracy because the installation portion of the test paper is easily contaminated with oil and cannot be calibrated.

  In addition, when controlling the quality of edible oils such as frying oil, the color of the oil is an important factor, so it is desirable that not only the acid value but also the chromaticity value such as the Robibond value can be measured simultaneously. However, in order to objectively measure the chromaticity value, acid value, etc., an expensive dedicated measuring device must be used, and maintenance work thereof is also required. For this reason, it is preferable that both chromaticity value and acid value of edible oil can be easily measured using an inexpensive general-purpose apparatus.

  Therefore, an object of the present invention is to make it possible to measure the chromaticity value and the acid value of an edible oil to be measured with a general-purpose apparatus with a practically sufficient accuracy.

  An apparatus according to the present invention includes an imaging unit that captures an image of a test piece to acquire image data, and a storage unit that stores a correspondence relationship between the chromaticity value and acid value of edible oil, and the color value of image data of the test piece A chromaticity value acquisition unit that acquires the chromaticity value of the edible oil based on the color value of the image data of the test piece immersed in the edible oil, and a correspondence relationship, and a test piece immersed in the edible oil. Based on the color value of the image data and the acquired chromaticity value, an acid value acquisition unit that acquires the acid value of the edible oil with reference to the correspondence relationship, and an output unit that outputs the acquired chromaticity value and acid value It is characterized by having.

  In the above apparatus, the storage unit stores a plurality of calibration curves indicating the relationship between the acid value of the edible oil and the color value of the image data of the test piece as the correspondence relationship according to the chromaticity value of the edible oil. The acid value acquisition unit preferably acquires the acid value with reference to a calibration curve corresponding to the acquired chromaticity value.

  In the above-described apparatus, the chromaticity value acquisition unit refers to the correspondence relationship based on the color value of the portion corresponding to the blank portion that does not include the reagent that changes color by reacting with the edible oil in the image data of the test piece. It is preferable to obtain the degree value.

  The above apparatus includes a deterioration determination unit that determines whether or not the reagent is deteriorated based on the color value of the portion corresponding to the reagent portion including the reagent in the image data of the test piece before being immersed in the edible oil. In addition, the output unit preferably outputs the determination result by the deterioration determination unit.

  The above apparatus uses the color value of the portion corresponding to the reagent portion of the image data of the test piece before being immersed in edible oil, and corresponds to the reagent portion of the image data of the test piece immersed in edible oil. It is preferable to further include a deterioration correction unit that corrects the color value of the portion to be used, and the acid value acquisition unit uses the color value corrected by the deterioration correction unit as the color value.

  The above apparatus calculates the color temperature of the light source and the exposure condition based on the whole or a part of the image data captured by the imaging unit, and performs correction according to the calculated color temperature and the exposure condition. It is preferable that a photographing condition correction unit for performing the value is further included, and the chromaticity value acquisition unit and the acid value acquisition unit use the color value corrected by the photographing condition correction unit as the color value.

  The above apparatus further includes a receiving unit that receives an input of the type of edible oil to be measured, and the storage unit has a correspondence relationship between the acid value of the edible oil and the color value of the image data of the test piece. Is stored for each type of edible oil, and the acid value acquisition unit preferably acquires the acid value with reference to a calibration curve corresponding to the input type of edible oil.

  A system according to the present invention includes a terminal device and a server device that can communicate with each other, and the terminal device images an image of a test piece immersed in edible oil to obtain image data, and the test piece A terminal communication unit that transmits chromaticity value and acid value data of edible oil from the server device, and a display unit that displays the received chromaticity value and acid value. The server device is based on the color value of the edible oil and the acid value and the color value of the image data received from the terminal device, the storage unit storing the correspondence relationship between the color value of the image data of the test piece The chromaticity value acquisition unit that acquires the chromaticity value of the edible oil with reference to the relationship, and the edible oil with reference to the correspondence relationship based on the color value of the image data received from the terminal device and the acquired chromaticity value The acid value acquisition unit that acquires the acid value of the Receiving data from the terminal device, characterized in that the obtained chromaticity values and acid values and a server communication unit that transmits to the terminal device.

  The program according to the present invention includes an image of a test piece immersed in edible oil in a computer having a storage unit that stores the correspondence between the chromaticity value and acid value of edible oil and the color value of image data of the test piece. Acquire data, acquire the chromaticity value of edible oil by referring to the correspondence based on the color value of the image data, and refer to the correspondence based on the color value of the image data and the acquired chromaticity value It is characterized by acquiring the acid value of the edible oil and realizing the function of outputting the acquired chromaticity value and acid value.

  The method according to the present invention includes a step of immersing a test piece in edible oil, a step of imaging a test piece immersed in edible oil, a chromaticity value and an acid value of the edible oil, and a color value of image data of the test piece. A computer having a storage unit for storing a correspondence relationship between the edible oil, and measuring the chromaticity value of the edible oil with reference to the correspondence relationship based on the color value of the image data of the imaged test piece; And measuring the acid value of the edible oil with reference to the correspondence based on the color value of the data and the acquired chromaticity value.

  In the dipping step of the above method, it is preferable to immerse a test piece made of an edible oil-absorbing material in edible oil.

  According to the present invention, the chromaticity value and acid value of the edible oil to be measured can be measured with a general-purpose apparatus with sufficient practical accuracy.

1 is a schematic configuration diagram of a terminal device 1. FIG. It is a figure for demonstrating the measurement by the terminal device 1 using a test piece. It is a graph which shows the example of the calibration curve of chromaticity value. It is a graph which shows the example of the calibration curve of an acid value. 3 is a functional block diagram of a control unit 14. FIG. It is the figure which showed the attention area | region on the image 23 of a test piece. It is a graph for demonstrating light source correction and exposure correction. 5 is a graph showing the accuracy of chromaticity value measurement of the terminal device 1. It is a graph which shows the precision of the acid value measurement of the terminal device. It is a graph which shows the relationship between the exposure time of a test piece, and the color value of image data. 4 is a flowchart illustrating an operation example of the terminal device 1. 1 is a schematic configuration diagram of a communication system 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof. In this specification, the RGB color system and the L * a * b * color system are taken as examples. However, the present invention is not limited to these color systems, and any color system can be adopted. is there. In addition, the description of the RGB format in this specification means the RGB format in a broad sense, and includes the sRGB format and other RGB formats.

  FIG. 1 is a schematic configuration diagram of the terminal device 1. The terminal device 1 includes an imaging unit 11, a light emitting unit 12, a storage unit 13, a control unit 14, an operation unit 15, and a display unit 16.

  The terminal device 1 is an example of a device that measures the degree of deterioration of edible oil, and is, for example, a mobile terminal such as a smartphone with a built-in camera. The terminal device 1 takes an image of a test piece immersed in the edible oil to be measured, and measures a chromaticity value and an acid value as the degree of deterioration of the edible oil based on the color indicated by the test piece. And display them numerically. In the terminal device 1, for example, a Robibond value is used as the chromaticity value. Hereinafter, the Robibond value and the acid value are also referred to as “LB value” and “AV value”, respectively.

  The imaging unit 11 captures an image of a test piece and acquires image data in a format such as RAW (DNG) data, JPEG (JFIF) data, or RGB data. The light emitting unit 12 is disposed adjacent to the lens constituting the imaging unit 11 and emits light when the imaging unit 11 performs imaging as necessary.

  The storage unit 13 is, for example, a semiconductor memory, and stores image data acquired by the imaging unit 11, data necessary for the operation of the terminal device 1, and the like. Moreover, the memory | storage part 13 memorize | stores the color information (color value) of the measuring object according to the deterioration degree of the edible oil of a measuring object as reference information. This reference information is a correspondence relationship between the chromaticity value and acid value of the edible oil to be measured, and the color value of the image data of the test piece. For example, the storage unit 13 includes a calibration curve indicating the relationship between the color value of the image data of the test piece immersed in edible oil and the chromaticity value of the edible oil, and the image of the test piece immersed in the edible oil. A calibration curve indicating the relationship between the color value of the data and the acid value of the edible oil is stored. Note that the color information (color value) and chromaticity value are not limited to a specific color space, and may be in any color space, and based on eigenvectors by multivariate analysis, the specific information that is most easily determined. It may be a color space.

  The control unit 14 includes a CPU, RAM, ROM, and the like, and controls the operation of the terminal device 1. The control unit 14 corresponds to an arithmetic function that operates a program for analyzing image data of a test piece taken by the imaging unit 11. The operation unit 15 includes, for example, a touch panel and key buttons, and accepts user operations. The display unit 16 is, for example, a liquid crystal display, and may be integrated with the operation unit 15 as a touch panel display. The display unit 16 is an example of an output unit, and displays the chromaticity value and acid value of the measurement result by the control unit 14.

  FIG. 2 is a diagram for explaining measurement by the terminal device 1 using a test piece. In FIG. 2, the terminal device 1 which displayed the test piece 21 of the unused state, the test piece 22 immersed in the cooking oil of measurement object, and the image 23 of the test piece 22 is shown.

  The test piece 21 has a mark 25 that serves as a measure of the upper end position when immersed in edible oil, a reagent part 26 that contains a reagent that changes color by reacting with the edible oil, and a blank part 27 that does not contain a reagent. One mark 25 is provided on the upper part of the test piece 21. Although it does not specifically limit as a base material of the test piece 21, From a viewpoint of acquisition of the chromaticity value of the edible oil mentioned later, edible oil absorptive materials, such as a filter paper, are suitable. The reagent part 26 is an area coated with an acid-base indicator that reacts with color when exposed to free fatty acids caused by deterioration of edible oil. In the test piece 21, for example, the A band, the B band, and the C band And four regions of the D band. The A band to the D band are, for example, the same blue color in a state where they do not react with the measurement object. The margin part 27 is a white region between the A band and the D band on the test piece 21.

  When the test piece 21 is immersed in the edible oil to be measured, the color of the A band to the D band changes from blue to yellow, for example, according to the degree of deterioration. At that time, when the degree of deterioration is low, only the D band changes color. However, as the degree of deterioration increases, more areas change color in the order of D band, C band, B band, and A band, and the degree of deterioration is the highest. If it is high, all areas of the reagent section 26 are discolored. FIG. 2 shows the test piece 22 in which the colors of the C band and the D band are changed.

  The terminal device 1 captures the image 23 of the test piece 22 immersed in the edible oil to be measured by the imaging unit 11 and acquires the color information of the test piece from the image data without contact. At that time, the terminal apparatus 1 converts the RGB color system data of the test piece image into L * a * b * color system data. The reagent part 26 of the test piece 21 reacts with the free fatty acid in the edible oil and changes its color from blue to yellow, and the edible oil itself changes from light yellow to dark brown due to deterioration. Is most accurately represented by the value of the b * axis among the three axes of the L * a * b * color system. Therefore, the terminal device 1 uses the b * value as the color value of the image data of the test piece, and refers to the calibration curve data stored in the storage unit 13 based on the b * value. A Robibond value and an AV value corresponding to the color of the test piece are obtained. Then, the terminal device 1 displays the obtained Robibond value and AV value as the measurement value 24 on the display unit 16.

  Thus, the deterioration of the edible oil is obtained by the test piece 21 and the terminal device 1 that photographs the test piece 22 immersed in the edible oil, analyzes the image data, and displays the degree of deterioration of the edible oil numerically. A system to measure the degree is configured. The display unit 16 may display information indicating whether or not the measured value 24 is within the reference range together with the measured value 24. Further, the output of the chromaticity value and the acid value from the terminal device 1 is not limited to the display output, and may be other forms such as a print output and a data output to an external device.

  FIG. 3 is a graph showing an example of a calibration curve of chromaticity values. The calibration curve 50 shown in FIG. 3 is obtained from the Robibond values of a plurality of frying oils (vegetable oils) measured by the Robibond colorimeter and the image data of the blank portion 27 of the test piece 22 immersed in these frying oils. It was created by plotting the obtained b * values. The vertical axis of the graph of FIG. 3 is the Robi bond value (LB value), and the horizontal axis is the b * value (referred to as cb * value) of the corrected margin 27. For the cb * value, the image of the test piece 22 is taken for each frying oil together with the gray color chip, and the conditions of the light source at the time of shooting and the automatic exposure conditions of the imaging unit 11 are the same based on the gray color. This is a value obtained by correcting the b * value of each image data.

  When the test piece 21 is soaked in the frying oil, the blank portion 27 of the test piece 21 turns brown according to the color of the frying oil by the filter paper that is the base material of the test piece 21 absorbing the frying oil. However, it can be seen from the graph of FIG. 3 that there is a high correlation between the cb * value at that time and the Robibond value of the frying oil. From the calibration curve 50 in FIG. 3, the Robibond value (LB value) of the edible oil to be measured is obtained from the cb * value of the blank portion 27 in the image data of the test piece 21. The storage unit 13 stores data of the calibration curve 50 as a correspondence between the color value of the image data of the test piece immersed in the edible oil and the chromaticity value of the edible oil.

  FIG. 4 is a graph showing an example of a calibration curve of acid value. The calibration curves 51 and 52 shown in FIG. 4 are the acid values of a plurality of frying oils measured by the official method and the b * values obtained from the C-band image data of the test piece 22 immersed in the frying oils. It is created by plotting and. The vertical axis of the graph of FIG. 4 is the acid value (AV value), and the horizontal axis is the corrected b * value (cb * value) of the C band. For the cb * value, the image of the test piece 22 is taken for each frying oil together with the gray color chip, and the conditions of the light source at the time of shooting and the automatic exposure conditions of the imaging unit 11 are the same based on the gray color. This is a value obtained by correcting the b * value of each image data.

  Since the color of the reagent part 26 changes from the D band, a calibration curve may be created for the cb * value of the D band, or a plurality of reagent parts 26 such as the D band and the C band or the D band to B band. You may create about. However, in many practical cases, among the four regions of the reagent part 26, the Cb cb * value is in the range of 0 to 5 including an acid value of 2.5 which serves as a guide for edible oil replacement. Is the highest correlation with the acid value of the edible oil to be measured. Therefore, the storage unit 13 stores the correspondence between the Cb cb * value and the AV value as the correspondence between the color value of the image data of the test piece immersed in the edible oil and the acid value of the edible oil. To do.

  When the acid value of the edible oil is obtained from the color of the test piece 22, the color of the edible oil affects the color of the test piece 22. Therefore, in order to improve the accuracy of the measurement value of the acid value, the storage unit 13 uses a calibration curve indicating the relationship between the acid value of the edible oil and the color value of the image data of the test piece as the chromaticity of the edible oil. A plurality of data are stored according to the value, and the terminal device 1 uses different calibration curves depending on the color of the edible oil to be measured. FIG. 4 shows an example in which two types of calibration curves 51 and 52 are selectively used according to chromaticity values (LB values). Among these, the calibration curve 51 is a calibration curve for edible oils having an LB value of less than 70 and a light color, and the calibration curve 52 is a calibration curve for edible oils having an LB value of 70 or more and a dark color. . Three or more calibration curves may be prepared according to the chromaticity value, and they may be used properly. However, as a result of the experiment, it has been confirmed that the two calibration curves 51 and 52 have sufficient accuracy in practice. Yes.

  The inventor created a calibration curve 51 for edible oil with a light color as follows. First, using canola oil (Nisshin Oilio) and oleic acid, create multiple oils with different acid values between 0.1 and 5.0, and use the official method to accurately determine the acid value of these oils. Measured. And these oils were heated at 160 to 170 degreeC, the test piece 21 was immersed in it, and the obtained test piece 22 was image | photographed with the imaging part 11 of the terminal device 1 with the gray color chip. When the cb * value in the C band of the obtained image data and the acid value obtained by the official method were plotted, the results indicated by circles in FIG. 4 were obtained. For light oils with an LB value of less than 70, these results fit well with the straight line equation denoted 51. Therefore, for the oil having an LB value of less than 70, the equation is adopted as the calibration curve 51.

  In addition, the inventor created a calibration curve 52 for dark cooking oil as follows. First, a plurality of frying oils (vegetable oils) actually used in family restaurants were collected, and the acid value of these oils was accurately measured using an official method. And these oils were heated at 160 to 170 degreeC, the test piece 21 was immersed in it, and the obtained test piece 22 was image | photographed with the imaging part 11 of the terminal device 1 with the gray color chip. When the cb * value of the C band of the obtained image data and the acid value obtained by the official method were plotted, the results indicated by triangles in FIG. 4 were obtained. For dark oils with an LB value of 70 or more, these results fit well with the curve equation represented by reference numeral 52. Therefore, for oils having an LB value of 70 or more, the equation is adopted as the calibration curve 52.

  In the measurement of the acid value of edible oil, the accuracy of the measured value can be improved by using different calibration curves depending on the chromaticity value of the edible oil as described above. In the terminal device 1, the data of the calibration curves 51 and 52 are stored in the storage unit 13 as a correspondence relationship between the color value of the image data of the test piece immersed in the edible oil and the acid value of the edible oil.

  Next, each function of the control unit 14 for measuring the chromaticity value and the acid value will be described.

  FIG. 5 is a functional block diagram of the control unit 14. The control unit 14 includes, as functional blocks, a pixel selection unit 141, a conversion unit 142, an imaging condition correction unit 143, a chromaticity value acquisition unit 144, an acid value acquisition unit 145, a deterioration determination unit 146, and a deterioration correction. Part 147.

  The pixel selection unit 141 selects a pixel for calculating color information from the test piece image acquired by the imaging unit 11.

  FIG. 6 is a diagram showing a region of interest on the image 23 of the test piece. In FIG. 6, a set of pixels in each region of interest selected by the pixel selection unit 141 is indicated by a square. The image 23 is, for example, an image obtained by placing the test piece 22 on a gray (achromatic) sheet having a reflectance of about 18%. The x-axis is taken in the horizontal direction of the image 23 and the y-axis is taken in the vertical direction.

  For example, the pixel selection unit 141 detects a rectangular region including the A band to the D band in response to an operation in which the user designates the test piece 22 via the operation unit 15. Specifically, the user touches the C band on the touch panel on which the image 23 is displayed, or the user moves the image 23 within the screen and superimposes the target mark displayed on the screen on the C band. The pixel selection unit 141 recognizes the position of the C band, identifies a similar color range by detecting the position of the C band, and detects other areas based on the coordinates of the C band. (A band, B band, and D band) are detected. Alternatively, the pixel selection unit 141 may detect a rectangular region including the A-band to the D-band from the density difference between the white color of the region other than the A-band to the D-band of the test piece 22 and the gray background. Alternatively, the pixel selection unit 141 detects only the rectangular region or a portion to be used based on a user instruction, for example, only the C band by extracting the features of the test piece 22 including the A band to the D band and recognizing the image. May be.

  When the rectangular area is detected, the pixel selection unit 141 selects the center point (Cx, Cy) of the C band as the central pixel of the target area for obtaining the acid value of the edible oil from the relative positional relationship on the test piece. To do. In addition, the pixel selection unit 141 selects the point (Yx, Yy) of the margin part 27 between the B band and the C band as the central pixel of the region of interest for obtaining the chromaticity value of the edible oil. In addition, the pixel selection unit 141 includes a point (Wx, Wy) in the white portion that is not soaked in cooking oil, and a point (Gx, Gy) on the gray sheet of the background that is further above the mark 25 on the upper side of the test piece. ) Is selected as the center pixel of the region of interest for correcting the color temperature of the light source and the exposure conditions during shooting. In order to reduce the measurement error, the pixel selection unit 141 has ± 2 pixels of 5 × 5 pixels, ± 3 pixels of 7 × 7 pixels, or ± 4 pixels of 9 in the x and y directions centered on each of the above points. A plurality of pixels such as × 9 pixels may be selected.

  The conversion unit 142 converts the color value of the image data captured by the imaging unit 11 into a color value of the L * a * b * color system. Since the color value of the image data photographed by the imaging unit 11 is usually RGB color system data, the conversion unit 142 converts, for example, RGB color system data into L * a * b * color system data. Convert to data. When the image data acquired by the imaging unit 11 is RAW data, the conversion unit 142 converts the RAW data into RGB values using, for example, a conversion table provided by the manufacturer that manufactured the imaging unit 11. Further, it is converted into an L * a * b * value.

  The imaging condition correction unit 143 calculates the color temperature of the light source (difference from D65 (color temperature: 6504k) as a reference light source) based on the whole or a part of the image data of the image captured by the imaging unit 11, Correction corresponding to the color temperature is performed on the color value of the image data. Further, the photographing condition correction unit 143 calculates the exposure condition of the light source based on the whole or part of the image data captured by the imaging unit 11, and performs correction according to the exposure condition on the color value of the image data. Do it.

  FIG. 7 is a graph for explaining light source correction and exposure correction. In FIG. 7, sR values, sG values, and sB values are plotted when the same test piece is photographed on five achromatic (gray) sheets of uniform and different densities. The horizontal axis is a sample number N for identifying a test piece, and a larger value corresponds to a brighter sheet. The vertical axis represents the sR value, sG value, or sB value. Graphs Dr, Dg, and Db respectively correspond to changes in the sR value, sG value, and sB value of the D band, and graphs aveR, aveG, and aveB respectively represent changes in the average sR value, sG value, and sB value of the entire image. It corresponds to.

  For example, when an image of a test piece is taken under an illumination light source of an incandescent lamp instead of a fluorescent lamp equivalent to D65, the RGB value of the A band to D band or the average RGB of the entire image is affected by the light source. The value changes. Further, the values shown in the graph of FIG. 7 are obtained when the same test piece is photographed against a background of uniform and different dark colors, but if there is no test piece, the automatic exposure mechanism works, All images should have the same brightness (reflectance about 18%). However, if a substantially white test piece is placed on a gray background, the corresponding amount gives an error, and the brightness of the test piece in the image changes, which affects the brightness of the test piece.

  Therefore, for example, the relationship shown in FIG. 7 is stored in the storage unit 13 in advance, and the imaging condition correction unit 143 uses the relationship shown in FIG. 7 to correct the RGB value due to the light source and the automatic exposure mechanism. Do. In that case, the imaging condition correction unit 143 is configured to calculate the average RGB value of the entire image captured by placing the test piece on the gray sheet, and the RGB value of the point (Gx, Gy) in FIG. At least one of a value indicating a color) and an RGB value (a value indicating the white color of the test piece) of the portion (Wx, Wy) in FIG. 6 is acquired. Then, the imaging condition correction unit 143 calculates a deviation from the graph of FIG. 7 for at least one of the average RGB value of the entire acquired image, the RGB value of the sheet, and the RGB value indicating the white color of the test piece. The RGB values of the image data are corrected by an amount that cancels the deviation.

  Even when the background is not uniform, the photographing condition correction unit 143 may correct the so-called subject based on the assumption that the total average reflectance of the subject is an achromatic color of around 18%. If the background color and the light source are known, correction can be made based on the background color and the light source. Moreover, if the color temperature of the illumination at the time of imaging is recorded as imaging information, the imaging condition correction unit 143 may extract and use it. It is possible to improve the measurement accuracy of the chromaticity value and the acid value by using the standard background when shooting the test piece and further correcting the automatic exposure of the light source and the imaging unit 11 by the imaging condition correction unit 143. .

  Note that the imaging condition correction unit 143 may perform correction processing on the L * a * b * values converted by the conversion unit 142. Since RGB values and L * a * b * values have a one-to-one correspondence, correcting RGB values is synonymous with correcting L * a * b * values.

  The chromaticity value acquisition unit 144 acquires the chromaticity value of the edible oil with reference to the correspondence relationship stored in the storage unit 13 based on the color value of the image data of the test piece 22 immersed in the edible oil. . At that time, the chromaticity value acquisition unit 144 acquires the chromaticity value with reference to the calibration curve 50 shown in FIG. 3 based on the b * value of the portion corresponding to the blank portion 27 in the image data of the test piece 22. To do. The chromaticity value acquisition unit 144 may use the value (cb * value) corrected by the imaging condition correction unit 143 as the b * value. The chromaticity value (LB value) acquired by the chromaticity value acquisition unit 144 is displayed on the display unit 16.

  The acid value acquisition unit 145 is a correspondence relationship stored in the storage unit 13 based on the color value of the image data of the test piece 22 immersed in cooking oil and the chromaticity value acquired by the chromaticity value acquisition unit 144. To obtain the acid value of the edible oil. At that time, the acid value acquisition unit 145 is based on the b * value of the portion corresponding to the C band in the image data of the test piece 22, and according to the acquired chromaticity value, the calibration curve 51, shown in FIG. The acid value is acquired with reference to any of 52. For example, the acid value acquisition unit 145 uses the calibration curve 51 if the chromaticity value (LB value) is less than 70, and uses the calibration curve 52 if the chromaticity value (LB value) is 70 or more. The acid value acquisition unit 145 may use the value (cb * value) corrected by the imaging condition correction unit 143 as the b * value. The acid value (AV value) acquired by the acid value acquisition unit 145 is displayed on the display unit 16.

  FIG. 8 is a graph showing the accuracy of the chromaticity value measurement of the terminal device 1. This graph plots the difference (ΔLB) between a plurality of frying oils by measuring the chromaticity value (LB value) by the terminal device 1 and measuring the actual LB value by the Robibond colorimeter. It is. The horizontal axis in FIG. 8 represents the actual LB value of the frying oil, and the vertical axis represents the value obtained by subtracting the actual LB value from the LB value measured by the terminal device 1. The practically acceptable error of the LB value is about ± 20, and the measured value of 95.1% is within this range. Therefore, the chromaticity value measurement by the terminal device 1 is sufficiently accurate for practical use. It was confirmed that there was.

  FIG. 9 is a graph showing the accuracy of acid value measurement of the terminal device 1. In this graph, the acid value (AV value) of a plurality of frying oils is measured by the terminal device 1 and the actual AV value is measured by an official method, and the difference (ΔAV) between them is plotted. The horizontal axis in FIG. 9 represents the actual AV value of the frying oil, and the vertical axis represents the value obtained by subtracting the actual AV value from the AV value measured by the terminal device 1. The practically acceptable error of the AV value is about ± 0.5, and the measured value of 88.1% is within this range. Therefore, the acid value measurement by the terminal device 1 has a practically sufficient accuracy. It was confirmed that.

  The deterioration determination unit 146 determines whether or not the reagent is deteriorated based on the color value of the portion corresponding to the reagent unit 26 in the image data of the test piece before being immersed in the edible oil.

  Since the reagent part 26 of the test piece 21 reacts gradually with carbon dioxide and moisture in the air, the reagent part 26 deteriorates (oxidizes) over time unless it is stored in a sealed state. When frying oil is measured with the deteriorated test piece 21, the color changes by an amount corresponding to the deterioration, and the measured value may deviate from the correct acid value. According to the guidelines of the Ministry of Health, Labor and Welfare (“Health Code for Lunch Boxes and Salmon” June 29, 1979, Circular Food No. 161, Notification of the Director of Food Sanitation, Ministry of Health and Welfare) If the deteriorated test piece 21 is used, for example, an incorrect AV value of 2.5 or more is output even though the oil has not yet been replaced. There may be cases where it is replaced in vain. For this reason, it is important to confirm whether the test piece 21 can be measured correctly.

  FIG. 10 is a graph showing the relationship between the exposure time of the test piece and the color value of the image data. The color of the A band to the D band of the reagent unit 26 changes from blue to yellow depending on the degree of deterioration. Therefore, by using, for example, the C band color value in the image data of the reagent unit 26, deterioration of the test piece (oxidation) ) Can check the degree. The degree of deterioration depends on the temperature, humidity, and exposure time, but in FIG. 10, when the temperature is fixed at 25.8 ° C. and the humidity is fixed at 44.0%, the exposure of the test piece 21 before being immersed in cooking oil. The relationship between time and the b * value of the image data of C band is shown. The horizontal axis of the graph of FIG. 10 is the exposure time t (unit: time), and the vertical axis is the b * value (cb * value) of the C band after correction by the imaging condition correction unit 143. From the graph of FIG. 10, it can be seen that there is a high correlation between the exposure time t and the color value (cb * value) of the C band.

  Since the allowable range of the acid value is “actual acid value ± 0.5”, it is considered that the test piece 21 that has deteriorated by 0.5 or more in terms of the acid value is not suitable for use. The time required for the test piece to deteriorate due to exposure to an extent corresponding to an acid value of 0.5 is 10.8 hours under conditions of a temperature of 25.8 ° C. and a humidity of 44.0%. From the graph of FIG. 10, the Cb cb * value rises by about 10 in 10.8 hours. Therefore, in the test piece 21 in which the Cb cb * value has risen by about 10 or more before use, the correct acidity is obtained. It turns out that value (AV value) cannot be measured. Therefore, the terminal device 1 uses the cb * value (about −17) when the test piece 21 is exposed for 10.8 hours as the threshold value Th in the graph of FIG. .

  Based on the above consideration, the deterioration determination unit 146 acquires, for example, the b * value of the C band from the image data of the test piece before use taken by the imaging unit 11, and the value and the threshold Th Judge the size. At that time, the image of the test piece before use is taken together with the reference color chip in the same manner as the test piece after use, and the b * value of the image data is the cb * value after correction by the shooting condition correction unit 143. Is preferably used. If the C-band cb * value is less than the threshold Th, the deterioration determining unit 146 determines that the target test piece 21 is usable (Good), and the C-band cb * value is the threshold. When the value is equal to or greater than Th, it is determined that the target test piece 21 is unusable (NG). The determination result (Good or NG) by the deterioration determination unit 146 is displayed on the display unit 16.

  In this way, the test piece before being soaked in edible oil is photographed by the imaging unit 11, and the degradation determination unit 146 analyzes the C-band image data in the image to determine how much the test piece is deteriorated. And whether the specimen can be measured correctly. If the test piece 21 determined to be usable by the deterioration determining unit 146 is used, the correct acid value can be measured, and the quality control of the edible oil can be performed correctly.

  The deterioration correcting unit 147 uses the color value of the portion corresponding to the reagent unit 26 in the image data of the test piece 21 before being soaked in edible oil, among the image data of the test piece 22 soaked in edible oil. The color value of the part corresponding to the reagent part 26 is corrected. Since the difference between the cb * value of the C band included in the image data of the test piece before use and the Y intercept cb0 in the graph of FIG. 10 indicates the degree of deterioration (oxidation), the deterioration correction unit 147 An amount corresponding to this difference is corrected for the cb * value of the C band of the test piece. Specifically, the deterioration correction unit 147 acquires the cb * value of the C band of the test piece before use, which is imaged together with the reference color chip by the imaging unit 11 and corrected by the imaging condition correction unit 143. And the difference between the Y intercept cb0 in the graph of FIG. Then, the deterioration correction unit 147 corrects the influence of the deterioration degree of the test piece by subtracting the same value as this difference from the cb * value of the C band included in the data of the image of the test piece 22 immersed in cooking oil. To do. In this case, the acid value acquisition unit 145 uses the value corrected by the deterioration correction unit 147 as the cb * value.

  In order to confirm the effect of the correction by the deterioration correction unit 147, the inventor added oleic acid to a new oil, canola oil (Nisshin Oilio), and the acid value was 1.88, 2.44, 2.88. Created frying oil. And about each frying oil, while obtaining the actual acid value by the official method, AV value was measured 54 times by the terminal device 1. The error between the AV value by the official method and the AV value by the terminal device 1 is ΔAV, and the AV value is within ± 0.5 of the allowable range using a statistical method under the assumption that the error follows a normal distribution. As a result, the results shown in Table 1 were obtained.

  As can be seen from the results in Table 1, when the acid value is calculated using the image data of the test piece before being immersed in the edible oil, after adding correction according to the degree of deterioration of the test piece to the image data, Although it takes time to photograph the test piece twice, it is possible to improve the measurement accuracy of the AV value.

  FIG. 11 is a flowchart illustrating an operation example of the terminal device 1. The processing of each step in FIG. 11 is executed by the control unit 14 in cooperation with each element of the terminal device 1 based on a program stored in the storage unit 13.

  First, the control unit 14 acquires image data of a test piece before use by causing the imaging unit 11 to image the test piece before being immersed in edible oil (before use) (step S1). Then, the conversion unit 142 converts the RGB values of the image data obtained in step S1 and selected by the pixel selection unit 141 into L * a * b * values (step S2). Then, the imaging condition correction unit 143 corrects the light source and the automatic exposure for the b * value obtained in step S2, and acquires the cb * value (step S3).

  Here, the deterioration determination unit 146 determines whether or not the cb * value obtained in step S3 is less than a threshold value Th for determining deterioration of the test piece (step S4). If the cb * value is equal to or greater than the threshold Th (No in step S4), the deterioration determining unit 146 determines that the photographed test piece is unusable, and the process returns to step S1. At that time, the deterioration determination unit 146 causes the display unit 16 to display the determination result.

  On the other hand, when the cb * value is less than the threshold value Th (Yes in step S4), the deterioration determination unit 146 determines that the photographed test piece is usable, and the process proceeds to step S4. At that time, the deterioration determination unit 146 causes the display unit 16 to display the determination result.

  Next, the control unit 14 obtains image data of the used test piece when the user images the test piece after being immersed in edible oil (after use) by the imaging unit 11 (step S5). Then, the conversion unit 142 converts the RGB value of the image data obtained in Step S5 and selected by the pixel selection unit 141 into an L * a * b * value (Step S6). Then, the imaging condition correction unit 143 corrects the light source and the automatic exposure for the b * value obtained in step S6, and acquires the cb * value (step S7).

  Here, the deterioration correction unit 147 performs deterioration correction by subtracting the cb * value obtained in step S3 from the cb * value obtained in step S7 (step S8). Further, the chromaticity value acquisition unit 144 refers to the calibration curve 50 data stored in the storage unit 13 and acquires the LB value of the edible oil to be measured from the cb * value obtained in step S8. (Step S9). Then, the acid value acquisition unit 145 determines whether or not the LB value obtained in step S9 is less than 70 (step S10).

  If the LB value is less than 70 (Yes in Step S10), the acid value acquisition unit 145 refers to the data of the calibration curve 51 for light color stored in the storage unit 13, and is obtained in Step S8. The AV value of the edible oil to be measured is acquired from the cb * value (step S11). On the other hand, when the LB value is 70 or more (No in step S10), the acid value acquisition unit 145 refers to the data of the dark color calibration curve 52 stored in the storage unit 13 and performs step S8. The AV value of the edible oil to be measured is acquired from the cb * value obtained in (Step S12). Then, the control unit 14 causes the display unit 16 to display the LB value obtained in step S9 and the AV value obtained in step S11 or S12 (step S13). Thus, the operation of the terminal device 1 ends.

  In the above description, the acid value acquisition unit 145 uses the two calibration curves 51 and 52. However, since the color of the oil may differ depending on the type of edible oil, ultimately, for each type of oil. A calibration curve may be prepared. In this case, the memory | storage part 13 memorize | stores the calibration curve which shows the relationship between the acid value of edible oil, and the color value of the image data of a test piece for every kind of edible oil. And the operation part 15 functions as a reception part which receives the input of the kind of edible oil of measurement object, and the acid value acquisition part 145 refers to the calibration curve corresponding to the input kind of edible oil, and determines acid value. get.

  As described above, according to the terminal device 1, the degree of deterioration of edible oil can be measured using a general-purpose portable terminal, not a dedicated analyzer, and is objective from visual determination using a color table. High results are obtained. There are a wide variety of edible oils used as frying oils, but the generation of free fatty acids due to oil degradation is common to all oils. Therefore, for any frying oil, the degree of generation of free fatty acids (degradation degree = oxidation degree) is obtained as a color value, various corrections are made, and the chromaticity value (LB value) and acid are obtained using calibration curves 50 to 52 By obtaining the value (AV value), the degree of deterioration can be objectively grasped with high accuracy. Further, since the terminal device 1 obtains the image data of the test piece in contact with the oil in a non-contact manner by the camera, the device is not soiled by the oil content of the test piece, and the correct acid value can be measured. If it is a handheld device in which all necessary hardware is incorporated, the terminal device 1 can be realized simply by installing a program that realizes the function of the control unit 14, so no investment for manufacturing a dedicated device is required. It is possible to measure the degree of deterioration of edible oil at low cost.

  In addition, in the terminal device 1, in addition to the chromaticity value and the acid value, for example, pH measurement and determination of a specific inorganic substance or organic substance can be performed by the same method as described above.

  FIG. 12 is a schematic configuration diagram of the communication system 2. The communication system 2 is a system for measuring the degree of deterioration of edible oil, and includes a terminal device 3 and a server device 4 that can communicate with each other. Each of these devices is connected to each other via a wired or wireless communication network 6. The communication network 6 includes the Internet, for example.

  The terminal device 3 includes an imaging unit 31, a light emitting unit 32, a storage unit 33, a control unit 34, a terminal communication unit 35, and a display unit 36. The imaging unit 31 captures an image of an object to be measured, and acquires test piece image data in a format such as RAW (DNG) data, JPEG (JFIF) data, or RGB data. The light emitting unit 32 emits light during imaging by the imaging unit 31 as necessary. The storage unit 33 stores image data acquired by the imaging unit 31, data necessary for the operation of the terminal device 3, and the like. The control unit 34 includes a CPU, a RAM, a ROM, and the like, and controls the operation of the terminal device 3. The terminal communication unit 35 transmits the image data captured by the imaging unit 31 to the server device 4 and receives the measurement result of the image data from the server device 4. The display unit 36 displays the measurement result received from the server device 4.

  The server device 4 includes a server communication unit 41, a storage unit 42, and a control unit 43. The server communication unit 41 receives image data from the terminal device 3 and transmits a measurement result of the image data to the terminal device 3. The storage unit 42 stores image data received from the terminal device 3, imaging information, data necessary for the operation of the server device 4, and the like. In particular, the storage unit 42 stores a correspondence relationship between the chromaticity value and acid value of the edible oil to be measured and the color value of the image data of the test piece. The control unit 43 is configured by a CPU, a RAM, a ROM, and the like, and has the same function as the control unit 14 of the terminal device 1. That is, the control unit 43 acquires the chromaticity value of the edible oil based on the color value of the image data of the test piece received from the terminal device 3 with reference to the correspondence relationship in the storage unit 42, and the color of the image data Based on the value and the acquired chromaticity value, the acid value of the edible oil is acquired with reference to the correspondence relationship in the storage unit 42. And the control part 43 transmits the acquired chromaticity value and acid value to the terminal device 3 via the server communication part 41 as a measurement result.

  As described above, the imaging of the test piece, the display of the measurement result, and the measurement of the chromaticity value and the acid value may be performed by different apparatuses. If a higher-speed and high-capacity server device 4 is used, a highly accurate analysis can be performed by complex image processing, and collaboration with another database is facilitated. The determination result by the server device 4 may be displayed by a device different from the terminal device 3 including a separate display device in the communication system 2.

  The communication system 2 can be used, for example, when it is desired to collect measurement results at a headquarters such as a chain restaurant that operates a plurality of stores. In this case, if each store owns the terminal device 3 and the server device 4 is installed in the headquarters, the image data of the test piece photographed in each store is transferred to the headquarters, and image analysis is performed by the server device 4 in the headquarters. Thus, it is possible to easily grasp and manage the management status of the frying oil in each store.

  A computer program for causing a computer to realize the functions of the control units 14, 34, and 43 of the terminal devices 1 and 3 and the server device 4 is recorded on a computer-readable recording medium such as a magnetic recording medium or an optical recording medium. It may be provided in the form.

DESCRIPTION OF SYMBOLS 1 Terminal device 11 Imaging part 12 Light emission part 13 Storage part 14 Control part 141 Pixel selection part 142 Conversion part 143 Shooting condition correction part 144 Chromaticity value acquisition part 145 Acid value acquisition part 146 Degradation determination part 147 Degradation correction part 15 Operation part 16 Display unit 2 Communication system 3 Terminal device 4 Server device

Claims (11)

An imaging unit for imaging a test piece and acquiring image data;
A storage unit for storing a correspondence relationship between the chromaticity value and acid value of the edible oil and the color value of the image data of the test piece;
A chromaticity value acquisition unit that acquires the chromaticity value of the edible oil with reference to the correspondence relationship based on the color value of the image data of the test piece immersed in the edible oil,
Based on the color value of the image data of the test piece immersed in edible oil and the acquired chromaticity value, an acid value acquisition unit that acquires the acid value of the edible oil with reference to the correspondence relationship;
An output unit for outputting the acquired chromaticity value and the acid value;
A device characterized by comprising: The storage unit stores a plurality of calibration curves indicating the relationship between the acid value of the edible oil and the color value of the image data of the test piece as the correspondence relationship according to the chromaticity value of the edible oil,
The apparatus according to claim 1, wherein the acid value acquisition unit acquires the acid value with reference to a calibration curve corresponding to the acquired chromaticity value.   The chromaticity value acquisition unit is configured to refer to the correspondence relationship based on a color value of a portion corresponding to a blank portion that does not include a reagent that changes color by reacting with edible oil in image data of a test piece, and the chromaticity value The device according to claim 1, wherein the device is obtained. A deterioration determination unit that determines whether or not the reagent is deteriorated based on a color value of a portion corresponding to the reagent portion including the reagent in the image data of the test piece before being immersed in edible oil ,
The apparatus according to claim 3, wherein the output unit outputs a determination result by the deterioration determination unit. Using the color value of the portion corresponding to the reagent portion in the image data of the test piece before being immersed in edible oil, the portion corresponding to the reagent portion in the image data of the test piece immersed in edible oil A deterioration correction unit for correcting the color value;
The apparatus according to claim 4, wherein the acid value acquisition unit uses the color value corrected by the deterioration correction unit as the color value. The color temperature of the light source and the exposure condition are calculated based on the whole or part of the image data captured by the imaging unit, and the correction according to the calculated color temperature and the exposure condition is performed on the color value of the image data. And a shooting condition correction unit
The apparatus according to any one of claims 1 to 5, wherein the chromaticity value acquisition unit and the acid value acquisition unit use the color value corrected by the imaging condition correction unit as the color value. It further has a reception unit that accepts input of the type of edible oil to be measured,
The storage unit stores, as the correspondence relationship, a calibration curve indicating the relationship between the acid value of the edible oil and the color value of the image data of the test piece for each type of edible oil,
The said acid value acquisition part is an apparatus of Claim 1 which acquires the said acid value with reference to the calibration curve corresponding to the input kind of edible oil. A system including a terminal device and a server device that can communicate with each other,
The terminal device
An imaging unit that captures image data by imaging a specimen immersed in cooking oil; and
A terminal communication unit that transmits image data of a test piece to the server device, and receives chromaticity value and acid value data of edible oil from the server device;
A display unit for displaying the received chromaticity value and the acid value;
The server device
A storage unit for storing a correspondence relationship between the chromaticity value and acid value of the edible oil and the color value of the image data of the test piece;
Based on the color value of the image data received from the terminal device, a chromaticity value acquisition unit that acquires the chromaticity value of the edible oil with reference to the correspondence relationship;
Based on the color value of the image data received from the terminal device and the acquired chromaticity value, an acid value acquisition unit that acquires the acid value of edible oil with reference to the correspondence relationship;
A server communication unit that receives the image data from the terminal device and transmits the acquired chromaticity value and the acid value to the terminal device,
A system characterized by that. A computer having a storage unit for storing a correspondence relationship between the chromaticity value and acid value of edible oil and the color value of image data of a test piece;
Acquire image data of test specimens immersed in cooking oil,
Based on the color value of the image data to obtain the chromaticity value of edible oil with reference to the correspondence relationship,
Based on the color value of the image data and the acquired chromaticity value, the acid value of the edible oil is acquired with reference to the correspondence relationship,
Outputting the acquired chromaticity value and the acid value;
A program characterized by realizing a function. Soaking the specimen in cooking oil;
Imaging a specimen immersed in cooking oil;
The computer having a storage unit for storing the correspondence between the chromaticity value and acid value of the edible oil and the color value of the image data of the test piece is based on the color value of the image data of the taken test piece. Measuring the chromaticity value of the edible oil with reference to
The computer measures the acid value of the edible oil based on the color value of the image data and the acquired chromaticity value with reference to the correspondence relationship;
A method characterized by comprising:   The method according to claim 10, wherein in the step of immersing, a test piece at least partially made of an edible oil-absorbing material is immersed in edible oil.

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