Measuring apparatus, measuring method, and program

Abstract

To provide a measuring apparatus capable of imaging a surface of a living body at brightness suitable for acquiring biological information.SOLUTION: A measuring apparatus comprises: an imaging unit that images a living body to acquire a moving image; a pixel value calculation unit that calculates a representative value of pixel values of pixels in a region of interest containing an image of the living body from each image constituting the moving image; and an imaging control unit that sets an exposure time and sensitivity on the basis of an optimal frame rate and the representative value so that the representative value falls within a predetermined range. The imaging unit images the living body using the optimal frame rate, the exposure time, and the sensitivity.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a measurement device, a measurement method, and a program. [Background technology]

[0002] Patent Document 1 discloses a camera-equipped mobile communications terminal device that regards frequency information associated with a connected base station as frequency information for the location where the device itself is located, and controls flicker of the camera. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-094370 A Summary of the Invention [Problem to be solved by the invention]

[0004] When acquiring biometric information by imaging the surface of a living body, it is desirable to image the surface of the living body at the maximum frame rate that ensures stable operation of the terminal device performing the imaging process and at a brightness suitable for acquiring the biometric information. However, due to the frequency of the power source to which the light source is connected, the brightness of the light source may change periodically, resulting in observation of flicker, which is a periodic noise. Therefore, in order to image the surface of the living body at a brightness suitable for acquiring the biometric information, it is desirable to control the exposure time and adjust the sensitivity to reduce flicker. Therefore, an aspect of the present disclosure aims to provide a measuring device, a measuring method, and a program that can image the surface of a living body at a brightness suitable for acquiring the biometric information. [Means for solving the problem]

[0005] A measuring device according to one embodiment of the present disclosure includes an imaging unit that images a living body to obtain a moving image, a pixel value calculation unit that calculates a representative value of pixel values ​​of pixels in a region of interest including an image of the living body from each image that constitutes the moving image, and an imaging control unit that sets an optimal frame rate and an exposure time and sensitivity based on the representative value so that the representative value is within a predetermined range, and the imaging unit images the living body at the optimal frame rate, the exposure time, and the sensitivity.

[0006] A measurement method according to one embodiment of the present disclosure includes the steps of imaging a living body to obtain a moving image, calculating a representative value of pixel values ​​of pixels in a region of interest including an image of the living body from each image constituting the moving image, and setting an optimal frame rate and an exposure time and a sensitivity based on the representative value so that the representative value is within a predetermined range, and in the step of obtaining the moving image, the living body is imaged at the optimal frame rate, the exposure time, and the sensitivity.

[0007] A program according to one embodiment of the present disclosure causes a computer to execute the following functions: capturing an image of a living body to obtain a moving image; calculating a representative value of pixel values ​​of pixels in a region of interest including an image of the living body from each image constituting the moving image; setting an optimal frame rate and an exposure time and sensitivity based on the representative value so that the representative value is within a predetermined range; and calculating a pulse wave signal from the change in the representative value over time. In the function of obtaining the moving image, the living body is captured at the optimal frame rate, the exposure time, and the sensitivity. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of a usage mode of a measurement device. [Diagram 2] FIG. 2 is a block diagram showing an example of the configuration of a measurement device. [Diagram 3] FIG. 11 is a diagram illustrating an example of flicker-related information. [Figure 4] 4 is a flowchart showing an example of the operation of the measurement device according to the first embodiment. [Diagram 5]10 is a flowchart illustrating an example of a process for adjusting imaging parameters. [Figure 6] 6 is a flowchart showing an example of the process of adjusting imaging parameters subsequent to FIG. 5. [Figure 7] FIG. 11 is a block diagram showing an example of the configuration of a measurement device according to a second embodiment. [Figure 8] FIG. 11 is a diagram illustrating an example of a frame rate table. [Figure 9] 10 is a flowchart showing an example of the operation of the measurement device according to the second embodiment. [Figure 10] FIG. 13 is a block diagram showing an example of the configuration of a measurement device according to a third embodiment. [Figure 11] 13 is a flowchart showing an example of the operation of the measurement device according to the third embodiment. [Figure 12] 12 is a flowchart showing an example of the operation of the measuring device subsequent to that shown in FIG. [Figure 13] FIG. 13 is a block diagram showing an example of the configuration of a measurement device according to a modified example of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First embodiment A first embodiment will be described with reference to Figures 1 to 6. In the drawings, the same or equivalent elements are given the same reference numerals, and duplicated explanations will be omitted.

[0010] 1 is a diagram showing an example of a usage mode of the measuring device 100. As shown in the example of FIG.

[0011] The measuring device 100 calculates a pulse wave signal indicating a pulse wave from an image acquired by the imaging unit 101. For example, the measuring device 100 is a PC (Personal Computer), a smartphone, a tablet terminal, a terminal dedicated to pulse wave estimation, etc. In this specification, a pulse wave is a time-series signal indicating a change in the volume of blood vessels, calculated from a time-series signal indicating pixel values ​​of pixels included in an image, for the same position on the body surface. In this specification, a pixel value is information indicating the brightness of a pixel included in an image, and is, for example, a pixel value or a luminance value of a pixel for each of R (Red), G (Green), and B (Blue).

[0012] For example, the imaging unit 101 is configured with a CCD (Charged Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) image sensor. The imaging unit 101 may be configured with an image sensor for a camera including RGB (Red Green Blue) filters.

[0013] 2 is a block diagram showing an example of the configuration of the measuring device 100. The measuring device 100 includes an imaging section 101, a storage section 201, and a control section 202.

[0014] The imaging unit 101 captures an image of the living body 102 to obtain a moving image. Specifically, the imaging unit 101 captures an image of the living body 102 facing the imaging unit 101, and obtains a moving image composed of images including an image of the body surface of the living body 102. For example, the image of the body surface is an image of the forehead, cheek, fingertip, wrist, palm, etc. of the living body 102.

[0015] The storage unit 201 is a recording medium capable of recording various data, programs, etc., and is configured, for example, with a hard disk, an SSD (Solid State Drive), a semiconductor memory, etc. The storage unit 201 stores flicker-related information 211 (see FIG. 3) and an optimal frame rate 212.

[0016] The control unit 202 executes various processes according to the programs and data stored in the storage unit 201. The control unit 202 is realized by a processor such as a CPU (Central Processing Unit). The control unit 202 includes a pixel value calculation unit 203, an imaging control unit 204, a pulse wave calculation unit 205, a vital index calculation unit 206, and an output unit 207.

[0017] The pixel value calculation unit 203 calculates a representative value 215 of pixel values ​​of a region of interest including an image of the living body 102 from each image constituting the moving image 214 .

[0018] The imaging control unit 204 sets the exposure time and the sensitivity based on the optimal frame rate 212 and the representative value 215 so that the representative value 215 is within a predetermined range. The imaging control unit 204 sets the exposure time so that it is equal to or shorter than the shooting time interval determined from the optimal frame rate. Then, the imaging control unit 204 determines imaging parameters 213 including the set exposure time and the set sensitivity. The imaging control unit 204 controls the imaging unit 101 to capture an image of the living body 102 at the optimal frame rate 212 and the exposure time and sensitivity included in the imaging parameters 213, and acquires a moving image 214.

[0019] The pulse wave calculator 205 calculates a pulse wave signal 216 from the change over time of the representative value 215 .

[0020] The vital indicator calculation unit 206 calculates vital indicators of the living body 102 from the pulse wave signal 216. For example, the vital indicators of the living body 102 include an indicator related to blood pressure, an indicator related to pulse rate, and the like.

[0021] The output unit 207 outputs information to be notified to the living body 102. Specifically, the output unit 207 outputs the vital indicators calculated by the vital indicator calculation unit 206. Furthermore, when the imaging unit 101 cannot appropriately capture an image, the output unit 207 outputs a message notifying that the living body 102 cannot be appropriately captured.

[0022] 3 is a diagram showing an example of the flicker-related information 211. The flicker-related information 211 indicates the presence or absence of flicker and the frequency fq of the flicker. Flicker is a periodic change in brightness of a light source. When flicker occurs, the pixel values ​​of pixels included in an image acquired by the imaging unit 101 change periodically.

[0023] The flicker-related information 211 illustrated in Fig. 3 indicates that there is flicker. Furthermore, the flicker-related information 211 illustrated in Fig. 3 indicates that the flicker frequency fq is 120 Hz. For example, the flicker frequency fq indicated by the flicker-related information 211 is a value according to the lighting. For example, in the case of Japan, in western Japan where a 60 Hz power source is used, flicker with a frequency of 120 Hz may occur, and in eastern Japan where a 50 Hz power source is used, flicker with a frequency of 100 Hz may occur. Note that when the flicker-related information 211 indicates that there is no flicker, it is not necessary to indicate the flicker frequency fq.

[0024] Fig. 4 is a flowchart showing an example of the operation of the measuring device 100 according to this embodiment. In this example, when the measuring device 100 is started, the control unit 202 starts the process of step S401 illustrated in Fig. 4. It is assumed that the flicker-related information 211 is stored in the storage unit 201 at the time when the control unit 202 starts the process of step S401.

[0025] In step S401, the imaging control unit 204 determines whether or not flicker is present. Specifically, when the flicker-related information 211 indicates that there is flicker, the imaging control unit 204 determines that there is flicker. On the other hand, when the flicker-related information 211 indicates that there is no flicker, the imaging control unit 204 determines that there is no flicker.

[0026] If it is determined in step S401 that there is no flicker, in step S402, the imaging control unit 204 determines the predetermined frame rate as the optimum frame rate 212. For example, the predetermined frame rate is 60 fps (Frames per second). Then, the control unit 202 transitions the process to step S404.

[0027] On the other hand, if it is determined in step S401 that flicker exists, then in step S403 the imaging control unit 204 determines the optimum frame rate 212 based on the flicker frequency fq. Specifically, if it is determined in step S401 that flicker exists, the imaging control unit 204 determines the optimum frame rate 212 based on the flicker frequency fq indicated by the flicker-related information 211. Then, the control unit 202 transitions the process to step S404.

[0028] The imaging control unit 204 determines the exposure time included in the imaging parameters 213 based on the flicker frequency fq. Specifically, the imaging control unit 204 determines the exposure time included in the imaging parameters 213 to be N / fq seconds, where N is a positive integer. For example, when the flicker frequency fq is 120 Hz, the imaging control unit 204 changes the exposure time included in the imaging parameters 213 to 1 / 120 seconds. Also, for example, when the flicker frequency fq is 100 Hz, the imaging control unit 204 changes the exposure time included in the imaging parameters 213 to 1 / 100 seconds.

[0029] In step S404, the imaging control unit 204 controls the imaging unit 101 to capture an image of the living body 102 at the optimal frame rate 212, the exposure time included in the imaging parameters 213, and the sensitivity included in the imaging parameters 213, thereby acquiring a moving image 214. Then, the imaging unit 101 outputs each image constituting the moving image 214 to the pixel value calculation unit 203.

[0030] In step S405, pixel value calculation unit 203 determines a region of interest for each image constituting moving image 214. The region of interest is a part of a body surface region among the images constituting moving image 214, and is a region including a plurality of pixels. For example, when an image constituting moving image 214 includes a face region of living body 102, the region of interest includes a cheek part, a forehead part, or an area between the eyebrows. The number of regions of interest may be one or more. The shape of the region of interest may be a polygon surrounded by straight lines, or a shape surrounded by curved lines. Alternatively, the region of interest may be a closed region composed of straight lines and curved lines.

[0031] In step S406, pixel value calculation unit 203 calculates representative value 215 of pixel values ​​of the region of interest determined in step S405 for each image constituting moving image 214. For example, representative value 215 is an average value, a median value, or a mode value of pixel values ​​of each pixel in the region of interest. In addition, when imaging unit 101 is configured by an image sensor for a camera including RGB filters, pixel value calculation unit 203 may calculate a representative value of pixel values ​​for each of R, G, and B.

[0032] In step S407, the imaging control unit 204 executes a process of adjusting the imaging parameters 213 based on the optimum frame rate 212 and the representative value 215. Specifically, the imaging control unit 204 adjusts the exposure time included in the imaging parameters 213 and the sensitivity included in the imaging parameters 213 based on the optimum frame rate 212 and the representative value 215 so that the representative value 215 falls within a predetermined range. Details of the process of adjusting the imaging parameters 213 will be described later with reference to Figs. 5 to 6.

[0033] In step S408, the imaging control unit 204 determines whether or not the imaging unit 101 has captured an image of the living body 102 for a predetermined time. If the imaging unit 101 has not captured an image of the living body 102 for a predetermined time in step S409, the control unit 202 returns the process to step S404. As a result, the imaging control unit 204 repeats the process of adjusting the imaging parameters 213 in step S407 within the predetermined time, and controls the imaging unit 101 to acquire the moving image 214.

[0034] On the other hand, if the imaging section 101 images the living body 102 for a predetermined time in step S408, then in step S409 the pulse wave calculation section 205 calculates the pulse wave signal 216 from the change over time of the representative value 215. Specifically, the pulse wave calculation section 205 calculates the pulse wave signal 216 from the change over time of the representative value 215 corresponding to the same position in the body surface region. For example, the pulse wave calculation section 205 processes a signal indicating the change over time of the representative value 215 by multivariate analysis such as principal component analysis or independent component analysis, and calculates the processed result as the pulse wave signal 216. The change over time of the representative value includes information on the change in the volume of the blood vessels.

[0035] In step S410, vital index calculation unit 206 calculates the vital index of the measurement subject from pulse wave signal 216. For example, if the type of vital index of the measurement subject is blood pressure, vital index calculation unit 206 calculates the systolic blood pressure based on the rise angle of pulse wave signal 216. Also, for example, if the type of vital index of the measurement subject is pulse rate, vital index calculation unit 206 calculates the pulse rate based on the number of peaks of pulse wave signal 216.

[0036] Next, the process of adjusting the imaging parameters 213 will be described in detail with reference to Fig. 5 to Fig. 6. Fig. 5 to Fig. 6 are a flowchart showing an example of the process of adjusting the imaging parameters 213.

[0037] In step S501, the imaging control unit 204 determines whether or not the representative value 215 calculated in step S406 illustrated in Fig. 4 is within a predetermined range. For example, the imaging control unit 204 determines whether or not the representative value 215 for each of the images of the multiple frames constituting the moving image 214, calculated in step S406 illustrated in Fig. 4, is within a predetermined range.

[0038] Alternatively, the imaging control unit 204 may determine whether or not an average value of the representative values ​​215 for each of the images of the multiple frames constituting the moving image 214, calculated in step S406 illustrated in Fig. 4, is within a predetermined range. Alternatively, the imaging control unit 204 may determine whether or not the representative value 215 for an image of one selected frame, among the representative values ​​215 for each of the images of the multiple frames constituting the moving image 214, calculated in step S406, is within a predetermined range.

[0039] If the representative value 215 is within the predetermined range in step S401, the control unit 202 does not adjust the imaging parameters, and proceeds to step S408 illustrated in Fig. 4. On the other hand, if the representative value 215 is greater than the predetermined range in step S501, the control unit 202 proceeds to step S601 illustrated in Fig. 6.

[0040] If the representative value 215 is smaller than the predetermined range in step S501, the imaging control unit 204 determines in step S502 whether the exposure time included in the imaging parameters 213 can be extended. If the exposure time included in the imaging parameters 213 is shorter than the imaging time interval determined from the optimal frame rate 212, the imaging control unit 204 determines that the exposure time can be extended. For example, if the optimal frame rate 212 is 60 fps and the exposure time is shorter than 1 / 60 seconds, the imaging control unit 204 determines that the exposure time can be extended. On the other hand, if the exposure time included in the imaging parameters 213 is equal to or longer than the imaging time interval determined from the optimal frame rate 212, the imaging control unit 204 determines that the exposure time cannot be extended.

[0041] If the imaging control unit 204 is able to extend the exposure time in step S502, the imaging control unit 204 extends the exposure time based on the flicker frequency fq in step S503. That is, by the processes in steps S501 to S503, if the representative value 215 is smaller than a predetermined range and the exposure time included in the imaging parameters 213 is shorter than the shooting time interval determined from the optimal frame rate 212, the imaging control unit 204 adjusts the exposure time included in the imaging parameters 213.

[0042] Specifically, the imaging control unit 204 adjusts the exposure time included in the imaging parameters 213 by selecting one of a plurality of exposure time candidates calculated from the optimal frame rate 212 and setting the exposure time included in the imaging parameters 213. For example, the imaging control unit 204 adjusts the exposure time included in the imaging parameters 213 by changing the exposure time included in the imaging parameters 213 from N / fq to (N+1) / fq, thereby extending the exposure time included in the imaging parameters 213. N is a positive integer. For example, when the flicker frequency fq is 120 Hz and the exposure time included in the imaging parameters 213 is 1 / 120 seconds, the imaging control unit 204 changes the exposure time included in the imaging parameters 213 to 2 / 120. Also, for example, when the flicker frequency fq is 100 Hz and the exposure time included in the imaging parameters 213 is 1 / 100 seconds, the imaging control unit 204 changes the exposure time included in the imaging parameters 213 to 1 / 50 (=2 / 100) seconds. From the above, the imaging control unit 204 sets the exposure time so that it is equal to or shorter than the shooting time interval determined from the optimal frame rate 212 .

[0043] Then, after the imaging control unit 204 extends the exposure time based on the flicker frequency fq, the control unit 202 ends the process of adjusting the imaging parameters 213 and proceeds to step S408 illustrated in FIG.

[0044] If the imaging control unit 204 is not able to extend the exposure time in step S502, the imaging control unit 204 determines in step S504 whether the sensitivity included in the imaging parameters 213 is equal to or lower than the sensitivity upper limit value. The sensitivity upper limit value is set according to the measurement device 100 and is stored in the storage unit 201.

[0045] If the sensitivity included in the imaging parameters 213 is higher than the upper limit in step S504, the imaging control unit 204 stores a new sensitivity upper limit value higher than the sensitivity upper limit value stored in the storage unit 201 in step S505. Alternatively, in step S505, the imaging control unit 204 causes the output unit 207 to output a message notifying that the imaging environment is dark and therefore the imaging cannot be performed appropriately. The output unit 207 may cause a display (not shown) connected to the measurement device 100 to display text indicating a message notifying that the imaging environment is dark and therefore the imaging cannot be performed appropriately. Alternatively, the output unit 207 may cause a speaker (not shown) connected to the measurement device 100 to output audio indicating a message notifying that the imaging environment is dark and therefore the imaging cannot be performed appropriately. Then, the control unit 202 ends the process of adjusting the imaging parameters 213, and proceeds to step S408 illustrated in FIG. 4.

[0046] On the other hand, when the sensitivity included in the imaging parameters 213 is equal to or lower than the upper limit in step S504, the imaging control unit 204 adjusts the sensitivity included in the imaging parameters 213 by setting a new sensitivity higher than the sensitivity included in the imaging parameters 213 as the sensitivity included in the imaging parameters 213 in step S506. That is, adjusting the sensitivity included in the imaging parameters 213 by the imaging control unit 204 in step S506 means setting a new sensitivity higher than the sensitivity included in the imaging parameters 213 when the representative value 215 is smaller than the predetermined range, the exposure time included in the imaging parameters 213 is equal to or longer than the shooting time interval, and the sensitivity included in the imaging parameters 213 is smaller than the sensitivity upper limit. As described above, by the processes of steps S501 to S502, S504, and S506, the imaging control unit 204 adjusts the sensitivity included in the imaging parameters 213 when the representative value 215 is smaller than the predetermined range, and the exposure time included in the imaging parameters 213 is equal to or longer than the shooting time interval determined from the optimal frame rate 212. Then, the control unit 202 ends the process of adjusting the imaging parameters 213, and proceeds to step S408 illustrated in FIG.

[0047] Next, a process to be performed when the representative value 215 is greater than the predetermined range will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of the process for adjusting the imaging parameters 213, which follows Fig. 5.

[0048] 5, if the representative value 215 is greater than the predetermined range in step S501, it is determined in step S601 whether the sensitivity included in the imaging parameters 213 is greater than a sensitivity lower limit. The sensitivity lower limit is set according to the measurement device 100 and stored in the storage unit 201.

[0049] In step S601, if the sensitivity included in the imaging parameters 213 is greater than the sensitivity lower limit, the imaging control unit 204 determines a new sensitivity smaller than the sensitivity included in the imaging parameters 213 as the sensitivity included in the imaging parameters 213 in step S602, thereby adjusting the sensitivity included in the imaging parameters 213. In other words, the imaging control unit 204 adjusts the sensitivity included in the imaging parameters 213 by setting a new sensitivity smaller than the sensitivity when the representative value 215 is greater than the predetermined range and the sensitivity included in the imaging parameters 213 is greater than the sensitivity lower limit. As described above, by the processing of step S501 and steps S601 to S602 illustrated in FIG. 5, the imaging control unit 204 adjusts the sensitivity included in the imaging parameters when the representative value 215 is greater than the predetermined range and the sensitivity included in the imaging parameters 213 is greater than the sensitivity lower limit. Then, the control unit 202 ends the processing of adjusting the imaging parameters 213, and proceeds to step S408 illustrated in FIG. 4.

[0050] On the other hand, if the sensitivity included in the imaging parameters 213 is equal to or lower than the lower limit sensitivity in step S601, the imaging control unit 204 determines in step S603 whether the exposure time included in the imaging parameters 213 can be shortened.

[0051] When the exposure time included in the imaging parameters 213 is longer than a lower limit of the exposure time that can be set in the measurement device 100, the imaging control unit 204 determines that the exposure time can be shortened. The lower limit of the exposure time is set according to the measurement device 100 and stored in the storage unit 201. For example, when the lower limit of the exposure time is 80 milliseconds, when the exposure time included in the imaging parameters 213 is longer than 80 milliseconds, the imaging control unit 204 determines that the exposure time can be shortened. On the other hand, when the exposure time included in the imaging parameters 213 is shorter than the lower limit of the exposure time, the imaging control unit 204 determines that the exposure time cannot be shortened.

[0052] If the imaging control unit 204 is able to shorten the exposure time in step S603, the imaging control unit 204 shortens the exposure time based on the flicker frequency fq in step S604. That is, by the processes of steps S501, S601, and S603 to S604, the imaging control unit 204 adjusts the exposure time included in the imaging parameters 213 when the representative value 215 is greater than the predetermined range and the sensitivity included in the imaging parameters 213 is equal to or less than the sensitivity lower limit.

[0053] Specifically, the imaging control unit 204 adjusts the exposure time included in the imaging parameters 213 by selecting one of a plurality of exposure time candidates calculated from the optimal frame rate 212 and setting the exposure time included in the imaging parameters 213. For example, the imaging control unit 204 shortens the exposure time included in the imaging parameters 213 by changing the exposure time included in the imaging parameters 213 from N / fq to (N-1) / fq. N is a positive integer. For example, when the flicker frequency fq is 120 Hz and the exposure time included in the imaging parameters 213 is 1 / 60 (=2 / 120) seconds, the imaging control unit 204 changes the exposure time included in the imaging parameters 213 to 1 / 120. Also, for example, when the flicker frequency fq is 100 Hz and the exposure time included in the imaging parameters 213 is 1 / 50 (=2 / 100) seconds, the imaging control unit 204 changes the exposure time included in the imaging parameters 213 to 1 / 100 (=1 / 100) seconds. From the above, the imaging control unit 204 sets the exposure time so that it is equal to or shorter than the shooting time interval determined from the optimal frame rate 212 .

[0054] After the imaging control unit 204 shortens the exposure time based on the flicker frequency fq, the control unit 202 ends the process of adjusting the imaging parameters 213 and proceeds to step S408 illustrated in FIG.

[0055] On the other hand, if the imaging control unit 204 determines in step S603 that the exposure time cannot be shortened, the imaging control unit 204 causes the storage unit 201 to store a new sensitivity lower limit value that is lower than the sensitivity lower limit value stored in the storage unit 201 in step S604. Alternatively, in step S604, the imaging control unit 204 causes the output unit 207 to output a message to alert the living body 102 that the shooting environment is too bright to properly capture an image. The output unit 207 may cause a display (not shown) connected to the measurement device 100 to display text indicating a message to alert the living body 102. Alternatively, the output unit 207 may cause a speaker (not shown) connected to the measurement device 100 to output audio indicating a message to alert the living body 102. Then, the control unit 202 ends the process of adjusting the imaging parameters 213, and proceeds to step S408 illustrated in FIG. 4.

[0056] As described above, the measuring device 100 according to this embodiment can control the exposure time and adjust the sensitivity so as to reduce flicker in order to image the surface of a living body with brightness suitable for acquiring biological information.

[0057] Second Embodiment The second embodiment will be described with reference to Figures 7 to 9. In the drawings, the same or similar elements are given the same reference numerals, and duplicated explanations will be omitted. Configurations and processes having substantially the same functions as other embodiments will be referred to by the same reference numerals, and explanations will be omitted, and differences from other embodiments will be described.

[0058] Fig. 7 is a block diagram showing an example of the configuration of the measurement device 100 according to this embodiment. The measurement device 100 shown in Fig. 7 differs from the measurement device 100 shown in Fig. 2 in that the measurement device 100 shown in Fig. 7 includes a flicker detection unit 701 and stores a frame rate table 711 in the storage unit 201.

[0059] The flicker detection unit 701 detects at least one type selected from the group consisting of the presence or absence of flicker and the frequency of flicker.

[0060] 8 is a diagram showing an example of the frame rate table 711. The registered frame rates are associated with registered frequencies in the frame rate table 711. Specifically, the frame rate table 711 registers, as the registered frame rates, frame rates for which the absolute value of the difference between the registered frequency and an integer multiple of the registered frame rate is equal to or greater than a threshold value.

[0061] For example, if the registered frequency is 120Hz, the registered frame rate is 50fps. Also, if the registered frequency is 100Hz, the registered frame rate is 60fps. Note that the registered frequency and registered frame rate illustrated in FIG. 6 are merely examples, and the registered frequency and registered frame rate are not limited to the values ​​illustrated in FIG. 6.

[0062] For example, a registered frequency and a registered frame rate may be associated with each other and registered in the frame rate table 711 for each manufacturer or model of the measuring device 100. Alternatively, the registered frequency and the registered frame rate may be associated with each other and registered in the frame rate table 711 by a user inputting the registered frequency and the registered frame rate using an operation unit (not shown) included in the measuring device 100.

[0063] Fig. 9 is a flowchart showing an example of the operation of the measuring device 100 according to this embodiment. In this example, when the measuring device 100 is started, the control unit 202 starts the process of step S901 shown in Fig. 9. It is assumed that the frame rate table 711 is stored in the storage unit 201 at the time when the control unit 202 starts the process of step S901 shown in Fig. 9.

[0064] In step S901, the imaging control unit 204 starts the imaging unit 101. When started, the imaging unit 101 starts a process of capturing an image of the imaging range and acquiring an image. The image acquired in step S901 is an image acquired in order to detect the presence or absence of flicker. When the imaging unit 101 captures an image in order to detect the presence or absence of flicker, the living body 102 does not need to be present in the imaging range.

[0065] In step S902, the flicker detection unit 701 determines whether or not a flicker has been detected. For example, the flicker detection unit 701 calculates a luminance value from the pixel values ​​of pixels in a predetermined area included in an image captured to detect the presence or absence of a flicker. The predetermined area is an area different from the body surface. In this case, the flicker detection unit 701 detects the timing of a peak of the time change of the luminance value from a time series signal indicating the time change of the calculated luminance value. If the timing of the peak of the time change of the luminance value is periodic, the flicker detection unit 701 determines that a flicker has been detected. For example, if the timing of the peak of the time change of the luminance value is a period caused by a preset flicker, the flicker detection unit 701 determines that a flicker has been detected. On the other hand, if the timing of the peak of the time change of the luminance value is not periodic, the flicker detection unit 701 determines that a flicker cannot be detected. The flicker detection unit 701 may capture an image of the imaging range at a plurality of frame rates, and determine that a flicker has been detected if the cycle of the peak timing of the time change in luminance value differs among the different frame rates.

[0066] If no flicker is detected in step S902, in step S903, the imaging control unit 204 determines the predetermined frame rate as the optimal frame rate 212. The process of step S903 is similar to the process of step S402 illustrated in Fig. 4, and therefore a detailed description thereof will be omitted. Then, the control unit 202 proceeds to the process of step S404 illustrated in Fig. 4.

[0067] On the other hand, if a flicker is detected in step S902, the flicker detection unit 701 detects the flicker frequency fq in step S904. For example, when the flicker detection unit 701 detects the timing of a peak in the time change of the luminance value, it detects the flicker frequency fq from the time interval of the detected timing. Alternatively, the flicker detection unit 701 may calculate a frequency spectrum related to a time-series signal indicating the time change of the luminance value. Then, the flicker detection unit 701 may detect a peak frequency within a predetermined frequency band in the calculated frequency spectrum as the flicker frequency fq.

[0068] In step S905, the imaging control unit 204 selects, in the frame rate table 711, a registered frequency that is the closest value to the frequency fq of the flicker detected in step S904.

[0069] In step S906, the imaging control unit 204 determines the registered frame rate associated with the selected registered frequency in the frame rate table 711 as the optimum frame rate 212. Then, the control unit 202 transitions the process to step S404 illustrated in FIG.

[0070] As described above, the measuring device 100 according to this embodiment detects the presence or absence of flicker and captures the living body 102 at a frame rate registered in advance according to the frequency fq of the flicker. This allows the measuring device 100 according to this embodiment to suppress the influence of noise due to flicker and capture the living body 102 at the highest possible frame rate.

[0071] Third embodiment The third embodiment will be described with reference to Figures 10 to 12. In the drawings, the same or similar elements are given the same reference numerals, and duplicated explanations are omitted. Configurations and processes having substantially the same functions as the other embodiments are referred to by the same reference numerals, and explanations are omitted, and differences from the other embodiments are described.

[0072] Fig. 10 is a block diagram showing an example of the configuration of the measuring device 100 according to this embodiment. The measuring device 100 shown in Fig. 10 is different from the measuring device 100 shown in Fig. 7 in that the measuring device 100 shown in Fig. 10 includes an imaging interval calculation unit 1001 and an imaging control unit 1002 instead of the imaging control unit 204.

[0073] The image capture interval calculation unit 1001 calculates the actual frame rate fr from the time difference between when each image constituting the moving image 214 was acquired.

[0074] The imaging control unit 1002 controls the settings of the imaging unit 101 according to the difference between the actual frame rate fr and the optimal frame rate 212. Specifically, the imaging control unit 1002 controls the settings of the imaging unit 101 so that the difference between the actual frame rate fr and the optimal frame rate 212 falls within a predetermined range.

[0075] Fig. 11 is a flowchart showing an example of the operation of the measuring device 100 according to this embodiment. The processing of steps S1101 to S1106 illustrated in Fig. 11 is similar to the processing of steps S901 to S906 illustrated in Fig. 9, and therefore detailed description thereof will be omitted.

[0076] In step S1107, the imaging control unit 1002 controls the imaging unit 101 to capture an image of the living body 102 using the exposure time and sensitivity included in the imaging parameters 213. The imaging unit 101 then outputs each image constituting the acquired moving image to the pixel value calculation unit 203.

[0077] In step S1108, the imaging control unit 1002 acquires the time at which each image constituting the moving image in step S1107 was acquired. For example, when the imaging control unit 1002 acquires the time at which an image was acquired, the imaging control unit 1002 stores in the storage unit 201 time information in which the time at which the image was acquired is associated with the frame number assigned to the image.

[0078] In step S1109, pixel value calculation unit 203 determines a region of interest for each image constituting the acquired moving image. In step S1110, pixel value calculation unit 203 calculates representative value 215 of pixel values ​​of the region of interest for each image constituting the acquired moving image. The processes in steps S1109 to S1110 are similar to the processes in steps S405 to S406 illustrated in FIG. 4, and therefore detailed description thereof will be omitted.

[0079] In step S1111, the imaging control unit 204 executes a process of adjusting the imaging parameters 213 based on the optimal frame rate 212 determined in step S1103 or step S1106 and the representative value 215 calculated in step S1110. The details of the process of adjusting the imaging parameters 213 are as shown in Fig. 5 and Fig. 6, and a detailed description will be omitted. Then, the control unit 202 proceeds to the process of step S1201 shown in Fig. 12.

[0080] FIG. 12 is a flowchart showing an example of the operation of the measuring apparatus 100 following FIG.

[0081] In step S1201, the imaging interval calculation unit 1001 calculates an actual frame rate fr for a predetermined number of frame images from the time difference between the times acquired in step S1108 illustrated in Fig. 11. For example, the imaging interval calculation unit 1001 acquires time information from the storage unit 201 to calculate the time difference between the times when the predetermined number of frame images are acquired.

[0082] For example, when the predetermined number of frames is two frames, the imaging interval calculation unit 1001 calculates the absolute value of the difference between the time t1 and the time t0 at which the images of the two consecutive frames are acquired as the time difference. The time t0 is the time at which the image of the frame that is the earlier of the two consecutive frames is acquired. The time t1 is the time at which the image of the frame that is the later of the two consecutive frames is acquired after the time t0. Then, the imaging interval calculation unit 1001 calculates the reciprocal of the calculated time difference as the actual frame rate fr. That is, the imaging interval calculation unit 1001 calculates the actual frame rate fr by the calculation formula fr=1 / (t1-t0).

[0083] Alternatively, for example, when the predetermined number of frames is three or more frames, the actual frame rate fr may be calculated from the time difference between when images of two consecutive frames among the three or more frames are acquired.

[0084] For example, when the predetermined number of frames is N frames, the time when the image of each frame is acquired is represented as time t i Here, N is an integer equal to or greater than 3, and i is an integer equal to or greater than 0 and equal to or less than N-1. In this case, the frame rates of two consecutive frames among the N frames are each 1 / (t k -t k-1 ), where k is an integer equal to or greater than 1 and equal to or less than N-1. The imaging interval calculation unit 1001 calculates a representative value of the frame rates for two consecutive frames out of the N frames as the actual frame rate fr. For example, the imaging interval calculation unit 1001 calculates fr=(Σ N-1 k=1 (1 / (t k -t k-1 The actual frame rate fr is calculated by the formula: fr=(1 / (t3-t2)+1 / (t2-t1)+1 / (t1-t0)) / 3. For example, when N=4, the imaging interval calculation unit 1001 calculates the actual frame rate fr by the formula: fr=(1 / (t3-t2)+1 / (t2-t1)+1 / (t1-t0)) / 3.

[0085] Alternatively, the imaging interval calculation unit 1001 calculates fr=(N-1) / (t N-1 For example, if the predetermined number of frames is 30 frames, the image capture interval calculation unit 1001 may calculate the actual frame rate fr using the formula fr=29 / (t 29 The actual frame rate fr is calculated using the formula:

[0086] In step S1202, the imaging control unit 1002 determines whether the actual frame rate fr is lower than the optimal frame rate 212. If the actual frame rate fr is lower than the optimal frame rate 212 in step S1202, in step S1203, the imaging control unit 1002 determines a new exposure time that is shorter than the exposure time when each image constituting the moving image acquired in step S1107 illustrated in FIG. 11 was acquired. By the imaging control unit 1002 making the new exposure time ET2 shorter than the exposure time when each image constituting the acquired moving image was acquired, the actual frame rate fr2 thereafter becomes higher than the actual frame rate fr1 when the image was acquired in step S1107. Then, the control unit 202 returns the process to step S1107 illustrated in FIG. 11.

[0087] On the other hand, if the actual frame rate fr is equal to or higher than the optimum frame rate 212 in step S1202, the imaging control unit 1002 determines in step S1204 whether the difference between the actual frame rate fr and the optimum frame rate 212 is within a predetermined range.

[0088] If the difference between the actual frame rate fr and the optimal frame rate 212 is not within the predetermined range in step S1204, the control unit 202 returns the process to step S1107 illustrated in Fig. 11. On the other hand, if the difference between the actual frame rate fr and the optimal frame rate 212 is within the predetermined range in step S1204, the imaging control unit 1002 controls the imaging unit 101 in step S1205 to capture the living body 102 at the optimal frame rate determined in step S1103 or step S1106 illustrated in Fig. 11, the exposure time included in the imaging parameters 213 adjusted in step S1111 illustrated in Fig. 11, and the sensitivity included in the imaging parameters 213 adjusted in step S1111, to acquire the moving image 214. The imaging unit 101 outputs each image constituting the acquired moving image 214 to the pixel value calculation unit 203.

[0089] In step S1206, the imaging control unit 204 determines whether or not the imaging unit 101 has captured an image of the living body 102 for a predetermined time. If the imaging unit 101 has not captured an image of the living body 102 for the predetermined time in step S1206, the control unit 202 returns the process to step S1205. On the other hand, if the imaging unit 101 has captured an image of the living body 102 for the predetermined time in step S1206, the control unit 202 proceeds to step S409 illustrated in FIG.

[0090] As described above, the measuring device 100 according to this embodiment adjusts the imaging parameters 213 according to the actual frame rate fr so as to approach the optimal frame rate 212. As a result, even if the actual frame rate fr is lower than the optimal frame rate 212 due to the processing time required by the imaging unit 101 and the processing time required by the pixel value calculation unit 203, the measuring device 100 according to this embodiment can control the exposure time and adjust the sensitivity so as to reduce flicker in order to image the surface of the living body with brightness suitable for acquiring biological information.

[0091] (Modification 1 of the third embodiment) As a first modified example of the measuring device 100 according to this embodiment, the imaging control unit 1002 may determine the optimum frame rate 212 by a predetermined calculation formula according to the flicker frequency fq. For example, the imaging control unit 1002 may determine a value obtained by dividing the flicker frequency fq by an integer N as the optimum frame rate 212. For example, when the flicker frequency fq is 120 Hz, the imaging control unit 1002 may determine 60 fps (=120 / 2) as the optimum frame rate 212. Or, for example, when the flicker frequency fq is 100 Hz, the imaging control unit 1002 may determine 50 fps (=100 / 2) as the optimum frame rate 212.

[0092] (Modification 2 of the third embodiment) As a second modification of the measuring device 100 according to this embodiment, when the upper limit of the frame rate can be set, the imaging control unit 1002 may determine the upper limit of the frame rate to be the optimum frame rate 212 determined in step S1103 or step S1106. This allows the imaging control unit 1002 to prevent the actual frame rate fr from exceeding the optimum frame rate 212. As a result, the imaging control unit 1002 can easily keep the difference between the actual frame rate fr and the optimum frame rate 212 within a predetermined range.

[0093] (Modification 3 of the third embodiment) As a third modification of the measuring device 100 according to the present embodiment, the imaging control unit 1002 may adjust the exposure time at intervals of a predetermined time or more. After the imaging control unit 1002 adjusts the imaging parameters 213 in step S1111 illustrated in Fig. 11, if the difference between the actual frame rate fr and the optimal frame rate 212 is not within a predetermined range after the shortest switching time has elapsed, the control unit 202 may return the process to step S1107 illustrated in Fig. 11. This allows the imaging control unit 1002 to prevent frequent changes in the exposure time when the difference between the actual frame rate fr and the optimal frame rate 212 is not within a predetermined range.

[0094] (Modification 4 of the third embodiment) As a fourth modification of the measuring device 100 according to the present embodiment, the flicker-related information 211 may be stored in the storage unit 201 .

[0095] Fig. 13 is a block diagram showing an example of the configuration of measurement device 100 according to this modification. The difference between measurement device 100 shown in Fig. 13 and measurement device 100 shown in Fig. 10 is that measurement device 100 shown in Fig. 13 does not include flicker detection unit 701.

[0096] The imaging control unit 1002 according to this modification determines the optimum frame rate 212 based on the presence or absence of flicker indicated by the flicker-related information 211, or the flicker frequency fq indicated by the flicker-related information 211. This allows the measuring device 100 according to this modification to bring the actual frame rate fr closer to the optimum frame rate based on the flicker frequency fq set according to the illumination.

[0097] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Furthermore, new technical features can be formed by combining the technical means disclosed in the respective embodiments. [Explanation of symbols]

[0098] 100 Measuring device, 101 Imaging unit, 102 Living body, 201 Memory unit, 202 Control unit, 203 Pixel value calculation unit, 204 Imaging control unit, 205 Pulse wave calculation unit, 206 Vital index calculation unit, 207 Output unit, 211 Flicker related information, 212 Optimal frame rate, 213 Imaging parameters, 214 Moving image, 215 Representative value, 216 Pulse wave signal, 701 Flicker detection unit, 711 Frame rate table, 1001 Imaging interval calculation unit, 1002 Imaging control unit

Claims

1. an imaging unit that captures an image of a living body and acquires a moving image; a pixel value calculation unit that calculates a representative value of pixel values ​​of pixels in a region of interest including an image of the living body from each image constituting the moving image; an imaging control unit that sets an optimal frame rate and an exposure time and a sensitivity based on the representative value so that the representative value falls within a predetermined range; Equipped with The imaging unit images the living body at the optimal frame rate, the exposure time, and the sensitivity. Measuring equipment.

2. The imaging control unit is adjusting the sensitivity when the representative value is smaller than the predetermined range and the exposure time is equal to or greater than the photographing time interval determined from the optimal frame rate; When the representative value is smaller than the predetermined range and the exposure time is shorter than the photographing time interval, the exposure time is adjusted.

2. The measuring device of claim 1.

3. The imaging control unit is adjusting the exposure time when the representative value is greater than the predetermined range and the sensitivity is equal to or less than a lower sensitivity limit value; When the representative value is greater than the predetermined range and the sensitivity is greater than the lower sensitivity limit, the sensitivity is adjusted.

2. The measuring device of claim 1.

4. Adjusting the exposure time involves selecting one of a plurality of exposure time candidates calculated from the optimal frame rate and setting the exposure time.

4. The measuring device according to claim 2 or 3.

5. The imaging control unit sets the exposure time to be equal to or less than the photographing time interval determined from the optimal frame rate.

2. The measuring device of claim 1.

6. Adjusting the sensitivity includes setting a new sensitivity higher than the sensitivity when the representative value is smaller than the predetermined range, the exposure time is equal to or longer than the photographing time interval, and the sensitivity is smaller than a sensitivity upper limit value.

3. The measuring device according to claim 2.

7. Adjusting the sensitivity includes setting a new sensitivity lower than the sensitivity when the representative value is greater than the predetermined range and the sensitivity is greater than the sensitivity lower limit value.

4. The measuring device according to claim 3.

8. A step of capturing an image of a living body to obtain a moving image; calculating a representative value of pixel values ​​of pixels in a region of interest including an image of the living body from each image constituting the moving image; setting an exposure time and a sensitivity based on an optimal frame rate and the representative value so that the representative value falls within a predetermined range; Equipped with In the step of acquiring the moving image, the living body is imaged at the optimal frame rate, the exposure time, and the sensitivity. Measurement method.

9. On the computer, A function of capturing an image of a living body and acquiring a moving image; a function of calculating a representative value of pixel values ​​of pixels in a region of interest including an image of the living body from each image constituting the moving image; a function of setting an exposure time and a sensitivity based on an optimum frame rate and the representative value so that the representative value falls within a predetermined range; a function of calculating a pulse wave signal from the change over time of the representative value; Run the command, In the function of acquiring the moving image, the living body is imaged at the optimal frame rate, the exposure time, and the sensitivity. program.

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