JP2017018152A - Color measuring device, color measuring method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device that recognizes each of multiple teeth and measures color individually.SOLUTION: A color measuring device that sets tooth areas to an image 55 with horizontal teeth captured and measures color of each tooth area comprises: a recognition unit 33 that recognizes the tooth area from the captured image; a setting unit 35 that sets a detection range of an interdental part in the captured image on the basis of the number of longitudinal pixels in the tooth area; and a detection unit 36 that detects the interdental part on the basis of luminosity of each pixel in the tooth area in the detection range of the interdental part. The recognition unit 33 again recognizes a new tooth area from the tooth area with the interdental part excluded.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a color measurement device, a color measurement method, and a program for measuring the color of a patient's teeth in a dental clinic or the like.

  In dental clinics, color samples called shade guides are used when teeth are whitened or when fillings are prosthetic. During the above-mentioned treatment, the progress of whitening and selection of fillings are performed while visually comparing the patient's teeth and the shade guide. In addition, instead of visual comparison, color measurement of a patient's teeth may be performed using a color measurement device. This type of colorimetric device captures a tooth and recognizes the tooth from the captured image, but there is a problem that a plurality of teeth are recognized as one tooth. Conventionally, as a method for individually recognizing a plurality of teeth, there is known a method of irradiating a tooth with laser light and identifying an interdental portion between teeth from a discontinuous change in luminance value of reflected light ( For example, see Patent Document 1).

JP 2012-217762 A

  However, in the method described in Patent Document 1, the luminance value of reflected light sometimes becomes discontinuous due to the surface shape of the tooth other than the interdental part. Thus, a part of the teeth is recognized as an interproximal part, causing a problem that the recognition of the teeth fails. As described above, even if the conventional interdental identification method is used, the interproximal part cannot be properly recognized, and it is difficult to measure the color by recognizing the teeth one by one.

  The present invention has been made in view of such a point, and an object thereof is to provide a color measuring device, a color measuring method, and a program capable of individually measuring a plurality of teeth.

  The color measurement device of the present invention is a color measurement device that sets a tooth region for a captured image obtained by imaging side-by-side teeth and performs color measurement for each tooth region, and recognizes a tooth region from the captured image. A setting unit that sets a detection range of the interdental portion in the captured image based on the number of pixels in the column of the tooth portion and the tooth region, and based on the brightness of each pixel of the tooth region in the detection range of the interdental portion And a detection unit for detecting the interdental portion, wherein the recognition unit re-recognizes a new tooth region from the tooth region excluding the interdental portion.

  The color measurement method of the present invention is a color measurement method by a color measurement device that sets a tooth region for a captured image obtained by imaging side-by-side teeth and performs color measurement for each tooth region, and includes a tooth region from the captured image. The step of recognizing, the step of setting a detection range of the interdental portion in the captured image based on the number of pixels in the column of the tooth region, and the brightness of each pixel of the tooth region in the detection range of the interdental portion And detecting the interproximal portion and re-recognizing a new tooth region from the tooth region excluding the interproximal portion.

  According to these configurations, since teeth generally tend to narrow in the longitudinal direction in the interdental portion, the interdental portion can be roughly specified from the number of pixels in the column of the tooth region. Since the detection range of the interdental part is set based on the rough position of the interdental part, when detecting the interdental part using the brightness of each pixel of the tooth area, the pixel that is actually the tooth area is the interdental area. It is possible to suppress erroneous detection as a part. By re-recognizing a new tooth region from the tooth region excluding the interdental portion, a tooth region composed of a plurality of teeth can be appropriately separated at the interproximal portion, and color measurement can be performed for each tooth region.

  In the color measurement device, the setting unit generates a histogram indicating the number of pixels in the column of the tooth region for each horizontal coordinate of the captured image, and the interdental spacing is based on the coordinates that are valleys in the histogram. Set the detection range of the part. According to this configuration, the interdental portion can be roughly specified from the coordinates that become the valleys of the histogram, and the detection range of the interdental portion can be appropriately set.

  In the color measurement device, the detection unit detects, as the interdental portion, a pixel whose brightness changes from a dark pixel to a bright pixel in the detection range of the interdental portion. According to this configuration, since the interdental pixels tend to have low brightness, the interdental part can be detected from the change in the brightness of each pixel within the detection range of the interdental part.

  In the color measurement device, the recognition unit attaches the same label to a connected pixel in which a color difference of each pixel of the captured image with respect to a reference value is smaller than a threshold value, and based on the label, uses the connected pixel as the tooth region. After the recognition and detection of the interdental part, the same label is attached to the connected pixels excluding the interdental pixel, and the connected pixel is re-recognized as the new tooth region based on the label. According to this configuration, a portion that cannot be separated with a threshold value in the tooth region can be separated by removing the interdental portion and re-recognized as a new tooth region.

  In the above colorimetric device, the device includes a paint unit that tracks the contour of the tooth region and paints the inside of the contour with a label attached to a connected pixel of the tooth region. According to this configuration, even if a label loss partially occurs in the tooth region, the label loss can be filled and recognized as a tooth region.

  The colorimetric apparatus includes an opening processing unit that performs an opening process on the tooth region after the detection of the interdental part. According to this configuration, although it is not a tooth region, noise recognized as a part of the tooth region can be reduced by the opening process.

  A program according to the present invention causes a colorimetric apparatus to execute the above colorimetric method. According to this configuration, by installing a program in the color measurement device, it is possible to appropriately separate individual tooth regions from the color measurement device and perform color measurement for each tooth region.

  According to the present invention, it is possible to set the detection range of the interdental portion from the number of pixels in the column of the tooth region, and detect the interproximal portion based on the brightness of the pixel within the detection range of the interdental portion. By recognizing a new tooth region from the tooth region excluding the interdental portion, a tooth region composed of a plurality of teeth can be appropriately separated at the interproximal portion, and color measurement can be performed for each tooth region.

It is a schematic diagram of the color measuring device according to the present embodiment. It is a figure which shows an example of the color system conversion process which concerns on this Embodiment. It is a block diagram of the detailed structure of the process part which concerns on this Embodiment. It is a flowchart of the automatic recognition process of the tooth area | region which concerns on this Embodiment. It is a figure which shows an example of the color difference calculation process which concerns on this Embodiment. It is a figure which shows an example of the first labeling process which concerns on this Embodiment. It is a figure which shows an example of the painting process which concerns on this Embodiment. It is a figure which shows an example of the histogram process which concerns on this Embodiment. It is a figure which shows an example of the interdental part detection process which concerns on this Embodiment. It is a figure which shows an example of the labeling process after the 2nd which concerns on this Embodiment. It is a figure which shows an example of the histogram process after the 2nd time which concerns on this Embodiment, and an interdental part detection process. It is a figure which shows an example of the opening process which concerns on this Embodiment. It is a figure which shows an example of the labeling process result which concerns on this Embodiment. It is a figure which shows an example of the image drawing process which concerns on this Embodiment. It is a figure which shows an example of the determination process of the shade guide grade which concerns on this Embodiment.

  Hereinafter, a color measuring device according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram of a colorimetric apparatus according to the present embodiment. FIG. 2 is a diagram showing an example of the color system conversion process according to the present embodiment. The color measurement device according to the present embodiment is merely an example, and can be changed as appropriate. In addition, the schematic diagram of the color measurement device shown in FIG. 1 is simplified for explaining the present invention, and it is assumed that the color measurement device normally includes a configuration.

  As shown in FIG. 1, the colorimetric device 1 measures the color of a patient's teeth 51 by a spectral colorimetric method using an interference filter 18 and determines a shade guide grade. The color measuring device 1 is configured so that the reflection surface of the integrating hemisphere 12 with the illumination light source 11 faces the tooth 51 and the reflected light from the tooth 51 is captured by the image sensor 15. The illumination light source 11 is an LED (Light Emitting Diode) and is installed so as to irradiate the integrating hemisphere 12. The illumination light source 11 may be a light source that emits light over the entire visible range and has a sufficient amount of light, and may be either a halogen lamp or a xenon lamp.

  The integrating hemisphere 12 scatters light from the illumination light source 11 on the reflecting surface, so that light is applied to the tooth 51 from all directions to reduce the influence of the unevenness on the surface of the tooth 51. Behind the integrating hemisphere 12, a lens 13 that forms an image of the reflected light from the tooth 51 on the optical axis of the image sensor 15 is provided. Behind the lens 13 is a filter device 14 that splits the reflected light into a plurality of wavelengths. The filter device 14 is configured by rotatably supporting a filter disk 17 on a filter switching mechanism 16 such as a revolver. The filter disk 17 is provided with 16 interference filters 18 capable of switching the transmission wavelength every 20 nm in the range of 400 nm to 700 nm.

  An image sensor 15 that receives reflected light transmitted through the interference filter 18 is provided behind the lens 13 with the interference filter 18 interposed therebetween. The image sensor 15 is a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) camera, picks up an image while switching the interference filter 18, and outputs a sensor value for each reflected reflected light to the control unit 21. Yes. Further, the integrating hemisphere 12 is provided with a monitoring sensor 19 that constantly monitors deterioration of the illumination light source 11 over time and fluctuation due to ambient conditions. The monitoring sensor 19 outputs a sensor value obtained from illumination by the illumination light source 11 to the control unit 21.

  The control unit 21 measures the color of the tooth 51 from the captured image 55 of the image sensor 15 and displays a shade guide grade for each tooth 51. The processing unit 22, the storage unit 23, the determination unit 24, and the display unit 25. It has. The processing unit 22 performs various processes such as a spectral reflectance calculation process and a color system conversion process on the captured image 55 of the tooth 51. The storage unit 23 stores color system values for each shade guide grade. The determination unit 24 compares the color system values of the tooth 51 and the shade guide to determine the shade guide grade of the tooth 51. The display unit 25 displays the real-time image of the tooth 51 and the captured image 55 and also displays the shade guide grade on the captured image 55 in an overlapping manner.

  Note that the control unit 21 of the color measurement device 1 is configured by a processor, a memory, and the like that execute various processes. The memory is composed of one or more storage media such as ROM (Read Only Memory) and RAM (Random Access Memory) depending on the application. A recognition program or the like is stored. Further, the colorimetric device 1 may be provided with a distance sensor (not shown) for correcting a change in the amount of light in the integrating hemisphere 12. The color difference based on the light amount may be corrected in consideration of a change in the light amount depending on the distance between the tooth 51 and the integrating hemisphere 12.

In the color measuring device 1 configured as described above, when the tooth 51 is imaged by the image sensor 15, for example, a captured image 55 of 256 × 256 pixels is output to the processing unit 22. As shown in FIG. 2A, the processing unit 22 (see FIG. 1) uses three values: a sensor value from the image sensor 15, a calibration value that has been held in advance by a calibration process, and a sensor value from the monitoring sensor 19. A spectral reflectance is calculated for each pixel for each interference filter 18. Further, as shown in FIG. 2B, the XYZ tristimulus value of the XYZ color system is calculated from the spectral reflectance, and the XYZ tristimulus value is converted to the value of the L ^* a ^* b ^* color system by multiplying the weight coefficient. The object color is expressed. In addition, L ^* indicates lightness, a ^* indicates a red-green axis color, and b ^* indicates a yellow-blue axis color.

The determination unit 24 (see FIG. 1), the measurement range 57 set in the captured image 55 (see FIG. 2C), the tooth 51 L ^* a ^* b ^* color system value and the shade guide grade L ^* a ^* B ^* The color difference ΔE of the color system value is calculated. The grade with the smallest color difference ΔE is determined as the shade guide grade in the measurement range. Then, as shown in FIG. 2C, the shade guide grade is displayed so as to be superimposed on the tooth 51 of the captured image 55 on the display unit 25 (see FIG. 1). Various processes such as the above spectral reflectance calculation process, conversion process to XYZ color system, conversion process to L ^* a ^* b ^* color system, calculation process of color difference ΔE, etc. are performed based on JIS standards. Is done.

  By the way, the measurement mode of the color measurement device 1 (see FIG. 1) is set to two types, a manual mode and an auto mode, and the mode can be switched by operating the color measurement device 1. In the manual mode, the measurement range of the shade guide grade can be adjusted according to the patient and imaging conditions. On the other hand, in the auto mode, the tooth area is automatically recognized using the color difference in the captured image 55, and the measurement range of the shade guide grade is automatically set from the tooth area. However, when the tooth area is automatically recognized, the plurality of teeth 51 are recognized as the integrated tooth area 61, and it is difficult to recognize the teeth 51 as individual tooth areas 61 (see FIG. 6C).

  This is considered because the interdental portion 62 between the tooth 51 and the tooth 51 cannot be recognized in the tooth region 61. When the present inventor carefully examined the characteristics of the interdental part 62, the interdental part 62 tends to have a lower brightness than the tooth 51, and the interdental part 62 allows the number of pixels in the column of the tooth region 61 to be reduced. I found it to be less. Therefore, in the automatic recognition processing of the tooth region 61 according to the present embodiment, a pixel that satisfies the condition that the lightness of the interdental portion 62 is low and the condition that the number of pixels in the column of the tooth region 61 is small is defined as the interdental portion 62. By detecting, the teeth 51 are separated and recognized one by one.

  Hereinafter, the automatic recognition processing of the tooth region will be described in detail with reference to FIGS. FIG. 3 is a block diagram of a detailed configuration of the processing unit according to the present embodiment. FIG. 4 is a flowchart of the automatic recognition process of the tooth area according to the present embodiment. FIG. 5 is a diagram showing an example of color difference calculation processing according to the present embodiment. FIG. 6 is a diagram illustrating an example of an initial labeling process according to the present embodiment. FIG. 7 is a diagram illustrating an example of a painting process according to the present embodiment. FIG. 8 is a diagram showing an example of histogram processing according to the present embodiment.

  Moreover, FIG. 9 is a figure which shows an example of the interdental part detection process which concerns on this Embodiment. FIG. 10 is a diagram illustrating an example of the second and subsequent labeling processes according to the present embodiment. FIG. 11 is a diagram illustrating an example of the second and subsequent histogram processing and interdental portion detection processing according to the present embodiment. FIG. 12 is a diagram illustrating an example of the opening process according to the present embodiment. FIG. 13 is a diagram illustrating an example of a labeling process result according to the present embodiment. FIG. 14 is a diagram illustrating an example of an image drawing process according to the present embodiment. In the description of FIG. 4, the description will be made using the reference numerals of FIG. 3 as appropriate.

  As shown in FIG. 3, the processing unit 22 performs a color system conversion process, a color difference calculation process, a labeling process, a painting process, a histogram process, an interdental part detection process, an opening process, and an image drawing process, which will be described later. A conversion unit 31, a calculation unit 32, a recognition unit 33, a painting unit 34, a setting unit 35, a detection unit 36, an opening unit 37, and a drawing unit 38 are provided. In the following description, a labeling process including a process of recognizing a tooth region from the captured image 55 in addition to a process of labeling pixels is referred to. In addition to the generation of the histogram, the process including setting the detection range of the interdental part from the histogram is referred to as a histogram process.

As shown in FIG. 4, the conversion unit 31 performs a color system conversion process (step S01). In the color system conversion process, as described above, the spectral reflectance is obtained for each pixel of the captured image 55, the XYZ tristimulus values are obtained from the spectral reflectances, and the XYZ tristimulus values are multiplied by the weight coefficient. It is converted into a value of L ^* a ^* b ^* color system (see FIGS. 2A and 2B). Next, a color difference calculation process is performed by the calculation unit 32 (step S02). As shown in FIG. 5, in the color difference calculation process, the reference pixel 65 is selected from the captured image 55, and the reference value of the L ^* a ^* b ^* color system of the reference pixel 65 is set. As the reference value, an average value of L ^* a ^* b ^* color system values around the reference pixel 65 may be used. Then, at each pixel of the captured image 55, the color difference between the reference value of the L ^* a ^* b ^* color system of L ^* a ^* b ^* color system value and the reference pixels 65 of each pixel is calculated.

  Next, a labeling process is performed in the recognition unit 33 (step S03). As shown in FIG. 6A, in the first labeling process, a color difference histogram indicating the number of pixels for each color difference is created for the captured image 55, and a color difference threshold is set from the color difference histogram by a discriminant analysis method. As shown in FIG. 6B, the same label is attached to the connected pixels in which the color difference between the pixels of the captured image 55 is smaller than the threshold value. The recognition unit 33 recognizes the connected pixels with the same label as the tooth region 61. In this embodiment, the connected pixels are numbered as labels, but other labels such as alphabets may be attached.

  As shown in FIG. 6C, in the tooth region 61 after the labeling process, the tooth 51 and the portion other than the tooth 51 are recognized separately, but the tooth 51 cannot be recognized one by one. That is, a plurality of teeth 51 are recognized as one tooth region 61. This is considered to occur because the color difference of the interdental portion 62 becomes smaller than the above threshold value. In this case, it has been considered to simply lower the threshold value, but the influence on the tooth region 61 other than the interdental portion 62 is great, and the tooth region 61 may be partially lost. Therefore, instead of detecting the interdental portion 62 using the color difference threshold, the interdental portion 62 is detected by a combination of histogram processing and interdental portion detection processing.

  Next, a painting process is performed in the painting unit 34 (step S04). As shown in FIG. 7, in the filling process, the outline of the tooth region 61 is traced, and the inside of the outline is filled with a label attached to a connected pixel of the tooth region 61. In this case, the captured image 55 is scanned for each line in the X direction (lateral direction), and a defective portion 67 inside the tooth region is detected from the contour of the tooth region 61. The label of each pixel in the missing portion 67 of the tooth region 61 is changed to the label of the tooth region 61. As a result, even if a label loss partially occurs in the tooth region 61 after the labeling process, the label defect can be filled and recognized as the tooth region 61.

  Next, histogram processing is performed in the setting unit 35 (step S05). As shown in FIG. 8A, in the histogram processing, a histogram indicating the number of pixels in the column of the tooth region 61 is generated for each X coordinate of the captured image 55, and the interdental portion 62 is detected based on the coordinates 68 that are valleys in the histogram. A range is set. In this case, as shown in FIG. 8B, the captured image 55 is scanned for each line in the Y direction, and the number of pixels in the column of the tooth region 61 is detected. At this time, since the missing portion 67 (see FIG. 7) inside the tooth region 61 is painted by the previous painting process, the detection accuracy of the number of pixels in the column of the tooth region 61 is improved. Then, in the captured image 55, ± 5 pixels centering on each pixel that becomes a valley in the histogram is set in the detection range 69 of the interdental portion 62.

  Next, an interdental part detection process is implemented in the detection part 36 (step S06). As shown in FIG. 9, in the interdental part detection process, the interdental part 62 is detected based on the brightness of each pixel of the tooth region 61 in the detection range 69 of the interdental part 62. In this case, a pixel whose brightness changes from a dark pixel to a bright pixel in the detection range 69 of the interdental portion 62 is detected as the interdental portion 62. For example, in a lightness waveform at a certain Y coordinate, the lightness waveform is first-order differentiated to calculate the slope of each pixel by utilizing the fact that a coordinate having a slope of 0 is the peak of the lightness waveform. A pixel whose polarity changes to a positive value in the detection range 69 is detected as the interdental portion 62. Note that the SG method (Savitzky-Golay method) may be used to calculate the primary differential value.

  In this interdental part detection process, since the detection range 69 of the interdental part 62 is set by the previous histogram process, the detection accuracy of the interdental part 62 is improved. That is, since the tooth 51 generally tends to narrow in the interdental portion 62 in the vertical direction, the approximate position of the interdental portion 62 is specified from the number of pixels in the column of the tooth region 61 by histogram processing. Since the detection range 69 of the interdental part 62 is set so as to include the rough position of the interdental part 62, it is prevented from being detected as the interdental part 62 outside the detection range 69 in the interdental part detection processing. it can. For example, the coordinate 66 in FIG. 9 indicates the peak of the lightness waveform, but is outside the detection range 69, so that the pixel at this coordinate 66 is not detected as the interdental portion 62.

  Next, the labeling process is performed again by the recognition unit 33 (step S07). In this process, as shown in FIG. 10, from the tooth region 61 recognized by the previous labeling process, the connected pixels excluding the interdental part 62 pixels are given the same label, and the connected pixels are given the same label. Is re-recognized as a new tooth region 61.

  By the way, even if the labeling process is performed except for the pixels of the interdental portion 62, the plurality of teeth 51 may not be completely separated. For example, as shown in FIG. 11A, when the interdental portion 62 extends obliquely, the portion surrounded by the broken line is outside the detection range 69 of the interdental portion 62 in the histogram processing, and the tooth in the interdental portion detection processing It is not recognized as the intermediate part 62. For this reason, in the present embodiment, the histogram process, the interdental part detection process, and the labeling process are repeated a predetermined number of times (for example, three times or more) (step S08) to detect the interdental part 62 extending obliquely. I am doing so.

  As shown in FIG. 11B, when the histogram processing is repeated, the interdental portion 62 is removed from the tooth region 61, and the number of pixels in the column of the tooth region 61 is decreased, whereby the coordinates 68 that are the valleys of the histogram change. The detection range 69 of the interdental portion 62 is slightly shifted. Thereby, it is possible to detect the interdental portion 62 that extends obliquely by the interdental portion detection processing while shifting the detection range 69 by repeating the histogram processing. When the histogram process is repeated a predetermined number of times (Yes in step S08), the painting process is performed again in the painting unit 34 (step S09). In the filling process, as described above, the outline of the tooth region 61 is traced, and the defective portion 67 (see FIG. 7) generated in the tooth region 61 is filled.

  Next, an opening process is performed in the opening part 37 (step S10). Here, an image of the opening process will be described with reference to FIG. 12A. As shown in FIG. 12A, in order from the left, a state before the opening process, a state where the contraction process is performed, and a state where the expansion process is performed are shown. More specifically, when the tooth region 61 is contracted several times, the state shown in the center of FIG. 12A is reached, and the labeling process is performed in this state. Further, when the tooth region 61 is expanded the same number of times as the contraction, the rightmost diagram of FIG. 12A is obtained. FIG. 12B is obtained by performing an opening process on the process performed up to step S09. By the opening process, it is possible to separate a fine connection part that could not be separated by the process up to step S09. Furthermore, as shown in FIG. 12B, noise 71 recognized as a part of the tooth region 61 can be reduced although it is not the tooth region 61. In the opening process, if the defect portion 67 (see FIG. 7) remains in the tooth region 61, the defect portion 67 is emphasized. However, the defect portion 67 in the tooth region 61 is applied in the previous painting process. Since it is crushed, the defect part 67 does not remain in the tooth region 61.

  Next, a final labeling process is performed in the recognition unit 33 (step S11). As described above, in the labeling process, a new tooth region 61 is re-recognized from the current tooth region 61. As a result, as shown in FIG. 13, each of the plurality of teeth 51 is recognized as a tooth region 61. As described above, the tooth region 61 composed of the plurality of teeth 51 can be appropriately separated by the interdental portion 62 while reducing the defect in the tooth region 61. Next, an image drawing process is performed in the drawing unit 38 (step S12). As shown in FIG. 14, in the image drawing process, pixels with the same label in the labeling process are colored with the same color, and a colored image of the tooth region 61 is drawn. In this way, the tooth region 61 is automatically recognized by separating the plurality of teeth 51.

  With reference to FIG. 15, the determination process of the shade guide grade by the color measuring device will be described. FIG. 15 is a diagram showing an example of a shade guide grade determination process according to the present embodiment. In the following description, it is assumed that the color measurement device is set to the auto mode and the tooth region is automatically recognized.

  As shown in FIG. 15, when the measurement button of the color measuring device 1 is pressed, the patient's tooth 51 is imaged (see step S21, FIG. 1). Next, the tooth region 61 is automatically recognized from the captured image 55 of the tooth 51 by the above-described automatic recognition processing of the tooth region 61 (step S22, see FIG. 14). Thereby, the tooth area | region 61 is recognized in the state which isolate | separated the several tooth 51 separately. Next, a shade guide grade measurement range 57 is set for each tooth region 61 (see step S23, FIG. 14).

Next, in the measurement range 57 set in the captured image 55, the color difference between the L ^* a ^* b ^* color system value of the tooth region 61 and the L ^* a ^* b ^* color system value of each shade guide grade is Calculated (step S24). The grade with the smallest color difference is determined as the shade guide grade for the tooth 51 in the measurement range 57 (step S25). Then, the shade guide grade is displayed so as to be superimposed on the tooth 51 of the captured image 55 (see step S26, FIG. 2C). Thus, shade guide grades are individually displayed for the patient's teeth 51.

  As described above, the colorimetric device 1 according to the present embodiment roughly specifies the interdental part 62 from the number of pixels in the column of the tooth region 61, and determines the interdental part based on the rough position of the interdental part 62. 62 detection ranges 69 are set. For this reason, when the interdental part 62 is detected using the brightness of each pixel in the tooth region 61, it is possible to prevent the pixels that are actually the tooth area 61 from being erroneously detected as the interdental part 62. Further, by re-recognizing a new tooth region 61 from the tooth region 61 excluding the interdental portion 62, the tooth region 61 composed of a plurality of teeth 51 is appropriately separated by the interdental portion 62, and each tooth region 61 is separated. The color can be measured.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the present embodiment, the recognition unit 33 is configured to recognize the tooth region 61 by the labeling process, but is not limited to this configuration. The recognition unit 33 only needs to recognize the tooth region 61 and may recognize the tooth region 61 by a process other than the labeling process.

  Further, in the present embodiment, the setting unit 35 generates a histogram indicating the number of pixels in the column of the tooth region 61 for each X coordinate of the captured image 55, and the interdental portion 62 of the interdental portion 62 is based on the coordinates that become the valley of the histogram. Although the detection range 69 is set, the present invention is not limited to this configuration. The setting unit 35 only needs to be able to set the detection range 69 of the interdental part 62 based on the number of pixels in the column of the tooth region 61, and does not need to generate a histogram.

  In the present embodiment, the detection unit 36 detects, as the interdental portion 62, a pixel whose lightness changes from a dark pixel to a bright pixel using the first-order differential value of the lightness waveform in the detection range 69 of the interdental portion 62. However, the present invention is not limited to this configuration. The detection unit 36 only needs to be able to detect the interdental portion 62 based on the brightness of each pixel of the tooth region 61 in the detection range 69 of the interdental portion 62, and does not need to use the primary differential value of the lightness waveform. Good.

  In the present embodiment, the labeling process uses a threshold value calculated by the discriminant analysis method from the color difference histogram. However, the present invention is not limited to this configuration. In the labeling process, a predetermined fixed threshold value may be used.

  In the present embodiment, the color difference calculation process is configured to obtain the reference value from the reference pixel 65 of the captured image 55, but is not limited to this configuration. In the color difference calculation process, a reference value stored in advance may be used instead of obtaining the reference value from the reference pixel 65.

  In the present embodiment, the painting process and the opening process are performed, but the present invention is not limited to this configuration. If the tooth region 61 can be accurately recognized without performing the painting process and the opening process, the painting process and the opening process can be omitted.

  In the present embodiment, the histogram process, the interdental part detection process, and the labeling process are repeated a predetermined number of times in the automatic recognition process of the tooth region 61. However, the present invention is not limited to this configuration. When the interdental part 62 is appropriately detected in the first interdental part detection process, the histogram process, the interdental part detection process, and the labeling process may not be repeated.

  In the present embodiment, the colorimetric device 1 may be integrated with an optical system that captures the reflected light from the tooth 51 and a control system such as an automatic recognition process for the tooth region, or separately. It may be. For example, the color measuring device 1 may be composed of an optical device and a computer connected to the device.

  As described above, the present invention has an effect that it is possible to individually measure a plurality of teeth, and in particular, a color measuring device that measures a patient's teeth in a dental clinic or the like and compares it with a shade guide. Useful for colorimetric methods and programs.

DESCRIPTION OF SYMBOLS 1 Color measuring device 22 Processing part 33 Recognition part 34 Filling part 35 Setting part 36 Detection part 37 Opening part 51 Tooth 55 Captured image 61 Tooth area | region 62 Interdental part 68 Histogram coordinate 69 Detection range

Claims (8)

A color measurement device that sets a tooth region for a captured image obtained by imaging teeth arranged side by side and performs color measurement for each tooth region,
A recognition unit for recognizing a tooth region from the captured image;
Based on the number of pixels in the column of the tooth region, a setting unit that sets a detection range of the interdental portion in the captured image;
A detection unit that detects the interdental part based on the brightness of each pixel of the tooth region in the detection range of the interdental part,
The color measuring apparatus, wherein the recognition unit re-recognizes a new tooth region from the tooth region excluding the interdental portion.   The setting unit generates a histogram indicating the number of pixels in the column of the tooth region for each horizontal coordinate of the captured image, and sets the detection range of the interdental portion based on coordinates that become valleys in the histogram. The colorimetric apparatus according to claim 1, wherein:   The colorimetric apparatus according to claim 1, wherein the detection unit detects, as the interdental portion, a pixel whose brightness changes from a dark pixel to a bright pixel in the detection range of the interdental portion. . The recognition unit attaches the same label to connected pixels in which the color difference of each pixel of the captured image with respect to a reference value is smaller than a threshold, and recognizes the connected pixel as the tooth region based on the label,
After detecting the interdental portion, the same label is attached to the connected pixels excluding the interdental pixels, and the connected pixel is re-recognized as the new tooth region based on the label. The colorimetric apparatus according to claim 1.   The colorimetric apparatus according to claim 4, further comprising a painting unit that tracks a contour of the tooth region and paints an inside of the contour with a label attached to a connected pixel of the tooth region.   The colorimetric apparatus according to claim 1, further comprising an opening processing unit that performs an opening process on the tooth region after the detection of the interdental part. It is a color measurement method by a color measurement device that sets a tooth region for a captured image obtained by imaging side-by-side teeth and performs color measurement for each tooth region,
Recognizing a tooth region from the captured image;
Setting a detection range of an interdental portion in the captured image based on the number of pixels in a column of the tooth region;
Detecting the interdental part based on the brightness of each pixel of the tooth region in the detection range of the interdental part;
And re-recognizing a new tooth region from the tooth region except for the interdental portion.   A program for causing a colorimetric apparatus to execute the colorimetric method according to claim 7.

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