Measurement device, measurement method, and recording medium

Abstract

Provided is a measurement device capable of imaging the surface of a living body at a brightness suitable for acquiring biological information. This measurement device is provided with: an imaging unit that captures an image of a living body and acquires a moving image; a pixel value calculation unit that calculates, from each image constituting the moving image, a representative value of a pixel value of a pixel in a region of interest including the image of the living body; 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 prescribed range, the imaging unit imaging the living body at the optimal frame rate, the exposure time, and the sensitivity.

Description

Technical Field

[0001] The present disclosure relates to a measuring device, a measuring method, and a recording medium. Background Art

[0002] Japanese Patent Application Laid-Open No. 2006-094370 discloses a mobile communication terminal device with a camera, which regards frequency information corresponding to a base station of a connection target as frequency information of a location where the device exists and performs camera blinking control. Summary of the invention

[0003] In the case of acquiring biological information by photographing the surface of a biological body, it is desirable to photograph the surface of the biological body at a maximum frame rate that ensures that the terminal device performing the image processing operates stably and at a brightness suitable for acquiring biological information. However, sometimes the brightness of the light source changes periodically due to the frequency of the power source to which the light source is connected, resulting in the observation of periodic noise, i.e., flicker. Therefore, in order to photograph the surface of the biological body at a brightness suitable for acquiring biological information, it is preferable to control the exposure time to reduce flicker and adjust the sensitivity.

[0004] Therefore, one aspect of the present disclosure is to provide a measuring device, a measuring method, and a recording medium capable of capturing an image of a surface of a living body at a brightness suitable for acquiring information about the living body. Solutions for solving problems

[0005] A measuring device according to one embodiment of the present invention comprises: an imaging unit for photographing a living body to obtain a dynamic image; a pixel value calculation unit for calculating a representative value of pixel values ​​of pixels in a region of interest of an image of the living body based on images constituting the dynamic image; and an imaging control unit for setting an exposure time and a sensitivity based on an optimal frame rate and the representative value so that the representative value is within a prescribed range, the imaging unit photographing 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 invention comprises: a process of photographing a living body to obtain a dynamic image; a process of calculating a representative value of pixel values ​​of pixels in a region of interest of an image of the living body based on each image constituting the dynamic image; and a process of setting exposure time and sensitivity based on an optimal frame rate and the representative value so that the representative value is within a prescribed range, wherein in the process of obtaining the dynamic image, the living body is photographed at the optimal frame rate, the exposure time and the sensitivity.

[0007] A computer-readable recording medium according to one embodiment of the present invention enables a computer to execute the following functions: a function of acquiring a dynamic image by photographing a living body; a function of calculating a representative value of pixel values ​​of pixels in a region of interest of an image of the living body based on the images constituting the dynamic image; a function of setting exposure time and sensitivity based on an optimal frame rate and the representative value so that the representative value is within a predetermined range; and a function of calculating a pulse wave signal based on a temporal variation of the representative value, wherein in the function of acquiring the dynamic image, the living body is photographed at the optimal frame rate, the exposure time, and the sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a diagram showing an example of how the measuring device is used. Figure 2 This is a block diagram showing an example of the configuration of a measuring device. Figure 3 This is a diagram showing an example of flicker-related information. Figure 4 This is a flowchart showing an example of the operation of the measuring device according to the first embodiment. Figure 5 This is a flowchart showing an example of a process of adjusting imaging parameters. Figure 6 It shows that Figure 5 A flowchart of an example of a process for adjusting imaging parameters. Figure 7 This is a block diagram showing an example of the configuration of a measuring device according to the second embodiment. Figure 8 is a diagram showing an example of a frame rate table. Fig. 9 This is a flowchart showing an example of the operation of the measuring device according to the second embodiment. Fig.10 This is a block diagram showing an example of the configuration of a measuring device according to the third embodiment. Fig.11 This is a flowchart showing an example of the operation of the measuring device according to the third embodiment. Fig.12 It shows that Fig.11 A flowchart of an example of the operation of the measuring device. Fig.13 This is a block diagram showing an example of the configuration of a measuring device according to a modified example of the third embodiment. DETAILED DESCRIPTION

[0009] (First Embodiment) Reference Figure 1 to Figure 6In the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0010] Figure 1 FIG. 1 is a diagram showing an example of how the measuring device 100 is used. Figure 1 As shown in the example, the measuring device 100 includes an imaging unit 101 .

[0011] The measuring device 100 calculates a pulse wave signal representing a pulse wave based on 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 pulse wave estimation dedicated terminal, etc. In this specification, a pulse wave refers to a time series signal representing a volume change of a blood vessel calculated from a time series signal representing a pixel value of a pixel included in an image at the same position on the body surface. In this specification, a pixel value is information representing the brightness of a pixel included in an image, for example, a pixel value or a brightness value of each R (Red), G (Green), or B (Blue) pixel.

[0012] For example, the imaging unit 101 is composed of a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) image sensor. Alternatively, the imaging unit 101 may be composed of an image sensor for a camera including an RGB (Red Green Blue) filter.

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

[0014] The imaging unit 101 captures a living body 102 and obtains a dynamic image. Specifically, the imaging unit 101 captures the living body 102 facing the imaging unit 101 and obtains a dynamic image composed of images including an image of the body surface of the living body 102. For example, the image of the body surface includes 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 composed of, for example, a hard disk, an SSD (Solid State Drive), a semiconductor memory, etc. The storage unit 201 stores flicker-related information 211 (see Figure 3 ) and optimal frame rate 212.

[0016] The control unit 202 performs various processes according to the programs and data stored in the storage unit 201. The control unit 202 is implemented 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 in an image including the living body 102 , based on each image constituting the moving image 214 .

[0018] The imaging control unit 204 sets the exposure time and sensitivity based on the optimal frame rate 212 and the representative value 215 so that the representative value 215 falls within a predetermined range. The imaging control unit 204 sets the exposure time so that it becomes less than the imaging time interval determined by the optimal frame rate. Furthermore, the imaging control unit 204 determines the imaging parameter 213 including the set exposure time and the set sensitivity. The imaging control unit 204 controls the imaging unit 101 to acquire a dynamic image 214 so that the biological body 102 is imaged according to the optimal frame rate 212, the exposure time and the sensitivity included in the imaging parameter 213.

[0019] The pulse wave calculation unit 205 calculates a pulse wave signal 216 based on the temporal change of the representative value 215 .

[0020] The vital index calculation unit 206 calculates the vital index of the living body 102 based on the pulse wave signal 216. For example, the vital index of the living body 102 includes an index related to blood pressure and an index related to pulse rate.

[0021] The output unit 207 outputs information notified to the living body 102. Specifically, the output unit 207 outputs the vital body index calculated by the vital body index calculation unit 206. Furthermore, when the imaging unit 101 cannot properly photograph, the output unit 207 outputs a message notifying that the living body 102 cannot be properly photographed.

[0022] Figure 3 2 is a diagram showing an example of flicker-related information 211. The flicker-related information 211 shows the presence or absence of flicker and the frequency fq of flicker. Flicker is a periodic change in brightness of a light source. When flicker occurs, the pixel values ​​of pixels included in the image acquired by the imaging unit 101 change periodically.

[0023] Figure 3 The flicker-related information 211 illustrated in FIG. 2 indicates that flicker exists. Further, Figure 3The flicker-related information 211 illustrated in the example indicates that the frequency fq of the flicker is 120 Hz. For example, the frequency fq of the flicker indicated by the flicker-related information 211 is a value corresponding to the lighting. For example, in the case of Japan, in western Japan where a 60 Hz power supply is used, a flicker with a frequency of 120 Hz is generated, and in eastern Japan where a 50 Hz power supply is used, a flicker with a frequency of 100 Hz may be generated. It should be noted that when indicating that there is no flicker, the flicker-related information 211 may not indicate the frequency fq of the flicker.

[0024] Figure 4 FIG. 2 is a flowchart showing an example of the operation of the measuring device 100 according to the present embodiment. In this example, when the measuring device 100 is started, the control unit 202 starts Figure 4 Exemplary Processing of Step S401 It is assumed that the flicker-related information 211 is stored in the storage unit 201 when the control unit 202 starts the processing of Step S401 .

[0025] In step S401, the camera control unit 204 determines whether there is flicker. Specifically, when the flicker-related information 211 indicates that there is flicker, the camera 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 camera 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 image capture control unit 204 determines a predetermined frame rate as the optimal frame rate 212. For example, the predetermined frame rate is 60 fps (Frames per second). Then, the control unit 202 transfers the process to step S404.

[0027] On the other hand, when it is determined in step S401 that flicker exists, in step S403, the image capture control unit 204 determines the optimal frame rate 212 based on the frequency fq of the flicker. Specifically, when it is determined in step S401 that flicker exists, the image capture control unit 204 determines the optimal frame rate 212 based on the frequency fq of the flicker indicated by the flicker-related information 211. Then, the control unit 202 transfers the process to step S404.

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

[0029] In step S404, the imaging control unit 204 controls the imaging unit 101 to acquire the dynamic image 214, so that the imaging unit 101 images the biological body 102 according to the optimal frame rate 212, the exposure time included in the imaging parameter 213, and the sensitivity included in the imaging parameter 213. Then, the imaging unit 101 outputs each image constituting the dynamic image 214 to the pixel value calculation unit 203.

[0030] In step S405, the pixel value calculation unit 203 determines a region of interest for each image constituting the dynamic image 214. The region of interest is a part of the region of the body surface in the image constituting the dynamic image 214, and is a region including a plurality of pixels. For example, when the image constituting the dynamic image 214 includes the face region of the biological body 102, the region of interest includes the cheek portion, the forehead portion, or the glabella portion. 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 curves. Alternatively, the region of interest may be a closed region consisting of straight lines and curves.

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

[0032] In step S407, the imaging control unit 204 performs a process of adjusting the imaging parameter 213 based on the optimal frame rate 212 and the representative value 215. Specifically, the imaging control unit 204 adjusts the exposure time included in the imaging parameter 213 and the sensitivity included in the imaging parameter 213 based on the optimal frame rate 212 and the representative value 215 so that the representative value 215 falls within a predetermined range. For details of the process of adjusting the imaging parameter 213, refer to To be described later.

[0033] In step S408, the imaging control unit 204 determines whether the imaging unit 101 has captured the biological body 102 for a predetermined time. In step S409, if the imaging unit 101 has not captured the biological body 102 for a predetermined time, the control unit 202 returns the process to step S404. Thus, the imaging control unit 204 repeatedly performs the process of adjusting the imaging parameter 213 in step S407 within a predetermined time, and controls the imaging unit 101 to acquire the dynamic image 214.

[0034] On the other hand, when the imaging unit 101 captures the biological body 102 for a predetermined time in step S408, the pulse wave calculation unit 205 calculates the pulse wave signal 216 based on the temporal change of the representative value 215 in step S409. Specifically, the pulse wave calculation unit 205 calculates the pulse wave signal 216 based on the temporal change of the representative value 215 corresponding to the same position in the area of ​​the body surface. For example, the pulse wave calculation unit 205 processes the signal indicating the temporal change of the representative value 215 by multivariate analysis such as principal component analysis and independent component analysis, and calculates the processed result as the pulse wave signal 216. The temporal change of the representative value includes information on the change in the volume of the blood vessel.

[0035] In step S410, the vital index calculation unit 206 calculates the vital index of the measurement object based on the pulse wave signal 216. For example, when the type of the vital index of the measurement object is blood pressure, the vital index calculation unit 206 calculates the maximum blood pressure based on the rising angle of the pulse wave signal 216. In addition, for example, when the type of the vital index of the measurement object is pulse rate, the vital index calculation unit 206 calculates the pulse rate based on the number of peaks of the pulse wave signal 216.

[0036] Next, refer to The process of adjusting the imaging parameters 213 will be described in detail. This is a flowchart showing an example of the process of adjusting the imaging parameter 213 .

[0037] In step S501, the camera control unit 204 determines whether Figure 4 The representative value 215 calculated in step S406 shown in the example is within the specified range. For example, the camera control unit 204 determines whether Figure 4 The exemplary step S406 is to determine whether the representative value 215 of each of the plurality of frames constituting the moving image 214 calculated is within a predetermined range.

[0038] Alternatively, the camera control unit 204 may also determine Figure 4 The exemplary step S406 calculates whether the average value of the representative values ​​215 for each of the plurality of frames constituting the dynamic image 214 is within a predetermined range. Alternatively, the image capture control unit 204 may determine whether the representative value 215 of the image of one selected frame among the representative values ​​215 for each of the plurality of frames constituting the dynamic image 214 calculated in step S406 is within a predetermined range.

[0039] If the representative value 215 is within the specified range in step S401, the control unit 202 does not adjust the imaging parameters and transfers to step S402. Figure 4On the other hand, if the representative value 215 is greater than the specified range in step S501, the control unit 202 transfers to Figure 6 Illustrated step S601.

[0040] When the representative value 215 is less than the prescribed range in step S501, the camera control unit 204 determines in step S502 whether the exposure time included in the camera parameter 213 can be extended. When the exposure time included in the camera parameter 213 is shorter than the shooting time interval determined by the optimal frame rate 212, the camera control unit 204 determines that the exposure time can be extended. For example, when the optimal frame rate 212 is 60fps, when the exposure time is shorter than 1 / 60 seconds, the camera control unit 204 determines that the exposure time can be extended. On the other hand, when the exposure time included in the camera parameter 213 is longer than the shooting time interval determined by the optimal frame rate 212, the camera control unit 204 determines that the exposure time cannot be extended.

[0041] If the imaging control unit 204 determines that the exposure time can be extended in step S502, the imaging control unit 204 extends the exposure time based on the flicker frequency fq in step S503. In the processing, the camera control unit 204 adjusts the exposure time included in the camera parameter 213 when the representative value 215 is smaller than the prescribed range and the exposure time included in the camera parameter 213 is shorter than the shooting time interval determined by the optimal frame rate 212.

[0042] Specifically, the camera control unit 204 adjusts the exposure time included in the camera parameter 213 by selecting any one of the multiple exposure time candidates calculated based on the optimal frame rate 212 and setting the exposure time included in the camera parameter 213. For example, the camera control unit 204 adjusts the exposure time included in the camera parameter 213 by changing the exposure time included in the camera parameter 213 from N / fq to (N+1) / fq to extend the exposure time included in the camera parameter 213. N is a positive integer. For example, when the flash frequency fq is 120 Hz and the exposure time included in the camera parameter 213 is 1 / 120 seconds, the camera control unit 204 changes the exposure time included in the camera parameter 213 to 2 / 120. Furthermore, for example, when the frequency fq of the flicker is 100 Hz and the exposure time included in the imaging parameter 213 is 1 / 100 second, the imaging control unit 204 changes the exposure time included in the imaging parameter 213 to 1 / 50 (= 2 / 100) second. As described above, the imaging control unit 204 sets the exposure time so as to be equal to or less than the imaging time interval determined by 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 parameter 213 and transfers to the process of Figure 4 Illustrated step S408.

[0044] If the imaging control unit 204 cannot extend the exposure time in step S502 , the imaging control unit 204 determines in step S504 whether the sensitivity included in the imaging parameter 213 is equal to or less than the upper limit of sensitivity. The upper limit of sensitivity is set by the measuring device 100 and stored in the storage unit 201 .

[0045] In step S504, when the sensitivity included in the imaging parameter 213 is higher than the upper limit value, in step S505, the imaging control unit 204 causes the storage unit 201 to store a new upper limit value of sensitivity that is higher than the upper limit value of sensitivity stored in the storage unit 201. Alternatively, in step S505, the imaging control unit 204 causes the output unit 207 to output a message for notifying that imaging cannot be performed properly due to the dark imaging environment. The output unit 207 may also cause a display (not shown) connected to the measuring device 100 to display characters representing a message for notifying that imaging cannot be performed properly due to the dark shooting environment. Alternatively, the output unit 207 may cause a speaker (not shown) connected to the measuring device 100 to output a sound representing a message for notifying that imaging cannot be performed properly due to the dark shooting environment. Then, the control unit 202 ends the process of adjusting the imaging parameter 213 and transfers to the process of Figure 4 Illustrated step S408.

[0046] On the other hand, when the sensitivity included in the imaging parameter 213 is below the upper limit value in step S504, the imaging control unit 204 adjusts the sensitivity included in the imaging parameter 213 by setting a new sensitivity greater than the sensitivity included in the imaging parameter 213 as the sensitivity included in the imaging parameter 213 in step S506. That is, the imaging control unit 204 adjusts the sensitivity included in the imaging parameter 213 in step S506 by setting a new sensitivity greater than the sensitivity included in the imaging parameter 213 when the representative value 215 is less than the prescribed range, the exposure time included in the imaging parameter 213 is greater than the photographic time interval, and the sensitivity included in the imaging parameter 213 is less than the upper limit value of the sensitivity. By the above, by In the processing of step S504 and step S506, the imaging control unit 204 adjusts the sensitivity included in the imaging parameter 213 when the representative value 215 is less than the prescribed range and the exposure time included in the imaging parameter 213 is longer than the shooting time interval determined by the optimal frame rate 212. Then, the control unit 202 ends the processing of adjusting the imaging parameter 213 and transfers to step S506. Figure 4 Illustrated step S408.

[0047] Next, refer to Figure 6 , the processing when the representative value 215 is larger than the prescribed range is explained. Figure 6 It shows that Figure 5 This is a flowchart of an example of the process of adjusting the imaging parameters 213 .

[0048] exist Figure 5 When 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 parameter 213 is greater than the lower limit sensitivity value. The lower limit sensitivity value is set by the measuring device 100 and stored in the storage unit 201 .

[0049] On the other hand, when the sensitivity included in the imaging parameter 213 is greater than the lower limit value of sensitivity in step S601, the imaging control unit 204 adjusts the sensitivity included in the imaging parameter 213 by setting a new sensitivity smaller than the sensitivity included in the imaging parameter 213 as the sensitivity included in the imaging parameter 213 in step S602. That is, the imaging control unit 204 adjusts the sensitivity included in the imaging parameter 213 by setting a new sensitivity smaller than the sensitivity included in the imaging parameter 213 when the representative value 215 is greater than the prescribed range and the sensitivity included in the imaging parameter 213 is greater than the lower limit value of sensitivity. Figure 5 Step S501, The camera control unit 204 adjusts the sensitivity of the camera parameter 213 when the representative value 215 is greater than the specified range and the sensitivity of the camera parameter 213 is greater than the lower limit of the sensitivity. Then, the control unit 202 ends the process of adjusting the camera parameter 213 and transfers to Figure 4 Illustrated step S408.

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

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

[0052] If the imaging control unit 204 can 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, through the processing of step S501, step S601, and step S603 to step S604, the imaging control unit 204 adjusts the exposure time included in the imaging parameter 213 when the representative value 215 is greater than the prescribed range and the sensitivity included in the imaging parameter 213 is less than the sensitivity lower limit value.

[0053] Specifically, the camera control unit 204 adjusts the exposure time included in the camera parameter 213 by selecting any one of the multiple exposure time candidates calculated based on the optimal frame rate 212 and setting the exposure time included in the camera parameter 213. For example, the camera control unit 204 shortens the exposure time included in the camera parameter 213 by changing the exposure time included in the camera parameter 213 from N / fq to (N-1) / fq. N is a positive integer. For example, when the flash frequency fq is 120 Hz and the exposure time included in the camera parameter 213 is 1 / 60 (2 / 120) seconds, the camera control unit 204 changes the exposure time included in the camera parameter 213 to 1 / 120. Furthermore, for example, when the flicker frequency fq is 100 Hz and the exposure time included in the imaging parameter 213 is 1 / 50 (1 / 100) second, the imaging control unit 204 changes the exposure time included in the imaging parameter 213 to 1 / 100 (=1 / 100) second. As described above, the imaging control unit 204 sets the exposure time so as to be equal to or less than the imaging time interval determined by 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 parameter 213 and transfers to the process of Figure 4 Illustrated step S408.

[0055] On the other hand, when the imaging control unit 204 cannot shorten the exposure time in step S603, in step S604, the imaging control unit 204 causes the storage unit 201 to store a new lower sensitivity limit value that is lower than the lower sensitivity limit value stored in the storage unit 201. Alternatively, in step S604, the imaging control unit 204 causes the output unit 207 to output a message to remind the living body that the imaging environment cannot be properly imaged because it is bright. The output unit 207 may also display characters indicating a message to remind the living body 102 on a display (not shown) connected to the measuring device 100. Alternatively, the output unit 207 may cause a speaker (not shown) connected to the measuring device 100 to output a sound indicating a message to remind the living body 102. Then, the control unit 202 ends the process of adjusting the imaging parameter 213 and transfers to the process of Figure 4 Illustrated step S408.

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

[0057] (Second Embodiment) Reference Figures 7 to 9 , the second embodiment is described. In addition, in the drawings, the same or equivalent elements are represented by the same reference numerals, and repeated descriptions are omitted. For the configurations and processes having substantially the same functions as other embodiments, the same reference numerals are marked and their descriptions are omitted, and the differences from other embodiments are described.

[0058] Figure 7 It is a block diagram showing an example of the configuration of the measurement device 100 according to this embodiment. Figure 7 The measuring device 100 shown in the example is Figure 2 The illustrated measuring device 100 is different in that: Figure 7 The illustrated measurement device 100 includes a flicker detection unit 701 , and a frame rate table 711 is stored in the storage unit 201 .

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

[0060] Figure 8 711 is a diagram showing an example of a frame rate table 711. In the frame rate table 711, a registered frequency is associated with a registered frame rate. Specifically, in the frame rate table 711, a frame rate for which the absolute value of the difference between the registered frequency and an integer multiple of the registered frame rate is greater than a threshold is registered as the registered frame rate.

[0061] For example, when the registration frequency is 120 Hz, the registration frame rate is 50 fps. Also, for example, when the registration frequency is 100 Hz, the registration frame rate is 60 fps. And, Figure 8 The registration frequency and registration frame rate shown are examples and are not intended to limit the registration frequency and registration frame rate to the following examples: Figure 8 The numerical values ​​shown are as follows.

[0062] For example, the registration frequency and the registration frame rate may be associated with each other and registered in the frame rate table 711 according to the manufacturer or model of the measurement device 100. Alternatively, the user may input the registration frequency and the registration frame rate using an operation unit (not shown) provided in the measurement device 100, and register the registration frequency and the registration frame rate in the frame rate table 711 in association with each other.

[0063] Fig. 9 FIG. 2 is a flowchart showing an example of the operation of the measuring device 100 according to the present embodiment. In this example, when the measuring device 100 is started, the control unit 202 starts Fig. 9 The processing of step S901 is shown as an example. The control unit 202 starts Fig. 9 At the time of the processing of step S901 illustrated in the example, it is assumed that the frame rate table 711 is stored in the storage unit 201 .

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

[0065] In step S902, the flicker detection unit 701 determines whether flicker is detected. For example, the flicker detection unit 701 calculates the brightness value based on the pixel values ​​of the pixels in the prescribed area included in the image captured in order to detect the presence or absence of flicker. The prescribed area is an area different from the body surface. In this case, the flicker detection unit 701 detects the timing of the peak of the temporal change of the brightness value based on the timing signal representing the temporal change of the calculated brightness value. When the peak timing of the temporal change of the brightness value is periodic, the flicker detection unit 701 determines that flicker is detected. For example, when the peak timing of the temporal change of the brightness value is a cycle caused by a preset flicker, the flicker detection unit 701 determines that flicker is detected. On the other hand, when the peak timing of the temporal change of the brightness value is not periodic, the flicker detection unit 701 determines that flicker is not detected. In addition, the flicker detection unit 701 can capture the camera range at multiple frame rates, and when the period of the peak timing of the temporal change of the brightness value is different at different frame rates, it is determined that flicker is detected.

[0066] If it is determined in step S902 that flicker is not detected, in step S903, the image capture control unit 204 determines the predetermined frame rate to be the optimal frame rate 212. The processing in step S903 is the same as that in step S904. Figure 4 The processing of step S402 illustrated in FIG. 1 is the same as that of step S402, so detailed description is omitted. Then, the control unit 202 transfers the processing to Figure 4 Illustrated step S404.

[0067] On the other hand, when flicker is detected in step S902, in step S904, the flicker detection unit 701 detects the frequency fq of the flicker. For example, when the flicker detection unit 701 detects the timing of the peak value of the luminance value changing with time, the flicker detection unit 701 detects the frequency fq of the flicker based on the time interval of the detected timing. Alternatively, the flicker detection unit 701 may calculate a spectrum related to a time series signal representing the time change of the luminance value. Then, the flicker detection unit 701 may detect the peak frequency in a prescribed frequency band in the calculated spectrum as the flicker frequency fq.

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

[0069] In step S906, the imaging control unit 204 determines the registration frame rate associated with the selected registration frequency in the frame rate table 711 as the optimal frame rate 212. Then, the control unit 202 transfers the processing to Figure 4 Illustrated step S404.

[0070] As described above, the measuring device 100 of this embodiment detects the presence or absence of flicker and images the living body 102 at a frame rate pre-registered according to the flicker frequency fq. Thus, the measuring device 100 of this embodiment can suppress the influence of noise caused by flicker and can image the living body 102 at the highest possible frame rate.

[0071] (Third Embodiment) Reference Figures 10 to 12 The third embodiment is described. In the drawings, the same or equivalent elements are represented by the same reference numerals, and repeated descriptions are omitted. The same reference numerals are marked on the components and processes having substantially the same functions as those of other embodiments, and their descriptions are omitted, and the differences from other embodiments are described.

[0072] Fig.10 It is a block diagram showing an example of the configuration of the measurement device 100 according to this embodiment. Fig.10 The measuring device 100 illustrated in Figure 7The measurement device 100 illustrated in FIG. 1 is different in that: Fig.10 The measuring device 100 illustrated in FIG. 1 includes an imaging interval calculation unit 1001 and an imaging control unit 1002 instead of the imaging control unit 204 .

[0073] The imaging interval calculation unit 1001 calculates the actual frame rate fr based on the time difference between acquiring the images constituting the moving image 214 .

[0074] The imaging controller 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 controller 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 prescribed range.

[0075] Fig.11 This is a flowchart showing an example of the operation of the measurement device 100 according to this embodiment. Fig.11 The processing of steps S1101 to S1106 is similar to Fig. 9 The processes of step S901 to step S906 illustrated in the example are the same, so the detailed description is omitted.

[0076] In step S1107, the imaging control unit 1002 controls the imaging unit 101 to acquire the dynamic image 214, so that the imaging unit 101 captures the biological body 102 according to the exposure time and sensitivity included in the imaging parameter 213. Then, the imaging unit 101 outputs each image constituting the acquired dynamic image 214 to the pixel value calculation unit 203.

[0077] In step S1108, the camera control unit 1002 obtains the time at which each image constituting the dynamic image is obtained in step S1107. For example, when the camera control unit 1002 obtains the time at which the image is obtained, the camera control unit 1002 stores the time information in the storage unit 201, and the time information associates the frame number assigned to the image with the time at which the image is obtained.

[0078] In step S1109, the pixel value calculation unit 203 determines the region of interest for each image constituting the acquired dynamic image 214. In step S1110, the pixel value calculation unit 203 calculates the representative value 215 of the pixel value of the region of interest for each image constituting the acquired dynamic image 214. The processing of steps S806 to S807 is similar to that of step S807. Figure 4 The processing of steps S308 to S309 illustrated in the example is the same, so the detailed description is omitted.

[0079] In step S1111, the image capture control unit 204 performs a process of adjusting the image capture parameter 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 image capture parameter 213 are as follows: Then, the control unit 202 transfers the processing to Fig.12 Illustrated step S1201.

[0080] Fig.12 It shows that Fig.11 A flowchart of an example of the operation of the measuring device.

[0081] In step S1201, the imaging interval calculation unit 1001 calculates the image interval of a predetermined number of frames according to the Fig.11 The actual frame rate fr is calculated based on the time difference of the time acquired in step S1108 illustrated in FIG. 10. For example, the imaging interval calculation unit 1001 acquires the time information from the storage unit 201 and calculates the time difference of the images of the predetermined number of frames acquired.

[0082] For example, when the prescribed 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 two consecutive frames are acquired as the time difference. The time t0 is the time at which the image of the frame is acquired at the previous time in the two consecutive frames. The time t1 is the time at which the image of the frame is acquired after the time t0 in the two consecutive frames. And the imaging interval calculation unit 1001 calculates the inverse 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 of 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 based on the time difference between acquiring images of two consecutive frames among the three or more frames.

[0084] For example, when the predetermined number of frames is N frames, the time at which the image of each frame is acquired is time t i N represents an integer greater than 3, and i represents an integer greater than 0 and less than N-1. In this case, the frame rates of two consecutive frames in the N frames are 1 / (t k -t k-1 k is an integer greater than 1 and less than N-1. The imaging interval calculation unit 1001 calculates the representative value of the frame rate associated with two consecutive frames among the N frames as the actual frame rate fr. For example, the imaging interval calculation unit 1001 calculates the actual frame rate fr by fr=(ΣN-1 k＝1 (1 / (t k -tk-1 For example, when N=4, the imaging interval calculation unit 1001 calculates the actual frame rate fr by the calculation formula of fr=(1 / (t3-t2)+1 / (t2-t1)+1 / (t1-t0)) / 3.

[0085] Alternatively, the imaging interval calculation unit 1001 may calculate the imaging interval by fr=(N-1) / (t N-1 For example, when the predetermined number of frames is 30 frames, the imaging interval calculation unit 1001 calculates the actual frame rate fr by fr=29 / (t 29 -t0) to calculate the actual frame rate fr.

[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, the imaging control unit 1002 determines in step S1203 whether the actual frame rate fr is lower than the optimal frame rate 212. Fig.11 The camera control unit 1002 sets the new exposure time ET2 to be shorter than the exposure time when each image constituting the acquired dynamic image is acquired in step S1107. The camera control unit 1002 sets the new exposure time ET2 to be shorter than the exposure time when each image constituting the acquired dynamic image is acquired, so that the actual frame rate fr2 thereafter is higher than the actual frame rate fr1 when the image is acquired in step S1107. Then, the control unit 202 transfers the processing to Fig.11 Illustrated step S1107.

[0087] On the other hand, when the actual frame rate fr is equal to or higher than the optimal 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 optimal frame rate 212 is within a predetermined range.

[0088] In step S1204, if the difference between the actual frame rate fr and the optimal frame rate 212 is not within the predetermined range, the control unit 202 returns the process to step S1205. Fig.11 On the other hand, if the difference between the actual frame rate fr and the optimal frame rate 212 is within the prescribed range in step S1204, the camera control unit 1002 controls the camera unit 101 to acquire the dynamic image 214 in step S1205 so that the dynamic image 214 is obtained as shown in FIG. Fig.11 The optimal frame rate determined in the exemplary step S1103 or step S1106 is Fig.11The living body 102 is imaged at the exposure time included in the imaging parameter 213 adjusted in step S1111 and the sensitivity included in the imaging parameter 213 adjusted in step S1111. Then, 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 camera control unit 204 determines whether the camera unit 101 has captured the subject 102 for a predetermined time. If the camera unit 101 has not captured the subject 102 for a predetermined time in step S409, the control unit 202 returns the process to step S404. On the other hand, if the camera unit 101 has captured the subject 102 for a predetermined time in step S1206, the control unit 202 returns the process to step S409. Figure 4 Illustrated step S409.

[0090] As described above, the measurement device 100 of this embodiment adjusts the imaging parameter 213 according to the actual frame rate fr so as to approach the optimal frame rate 212. Thus, the measurement device 100 of this embodiment can control the exposure time to reduce flicker and adjust the sensitivity in order to capture the surface of the living body at a brightness suitable for acquiring information on the living body, even when the actual frame rate fr is lower than the optimal frame rate 212, by using the processing time of the imaging unit 101 and the processing time of the pixel value calculation unit 203.

[0091] (Variation 1 of the Third Embodiment) As a first modification of the measurement device 100 of the present embodiment, the imaging control unit 1002 may determine the optimum frame rate 212 using a predetermined calculation formula according to the frequency fq of flicker. For example, the image capture control unit 1002 may determine the value obtained by dividing the flicker frequency fq by the integer N as the optimal frame rate 212. For example, when the flicker frequency fq is 120 Hz, the image capture control unit 1002 may determine 60 fps (=120 / 2) as the optimal frame rate 212. Alternatively, when the flicker frequency fq is 100 Hz, the image capture control unit 1002 may determine 50 fps (=100 / 2) as the optimal frame rate 212.

[0092] (Variation 2 of the Third Embodiment) As a second modification of the measurement device 100 of the present embodiment, when the upper limit value of the frame rate can be set, the imaging control unit 1002 may determine the upper limit value of the frame rate to be the optimal frame rate 212 determined in step S1103 or step S1106. In this way, the imaging control unit 1002 can prevent the actual frame rate fr from exceeding the optimal frame rate 212. As a result, the imaging control unit 1002 can easily set the difference between the actual frame rate fr and the optimal frame rate 212 within a predetermined range.

[0093] (Variation 3 of the Third Embodiment) As a third variation of the measuring device 100 of this embodiment, the imaging control unit 1002 may adjust the exposure time at intervals longer than a predetermined time interval. Fig.11 If the difference between the actual frame rate fr and the optimal frame rate 212 is not within the prescribed range after the shortest switching time has elapsed since the imaging parameter 213 was adjusted in step S1111, the control unit 202 returns the process to step S1112. Fig.11 Step S1107 is illustrated. Thus, the imaging control unit 1002 can prevent the exposure time from being frequently changed when the difference between the actual frame rate fr and the optimal frame rate 212 is not within a predetermined range.

[0094] (Variation 4 of the Third Embodiment) As a fourth modification of the measurement device 100 of the present embodiment, the scintillation-related information 211 may be stored in the storage unit 201 .

[0095] Fig.13 This is a block diagram showing an example of the configuration of the measurement device 100 according to this modification. Fig.13 The measuring device 100 illustrated in Fig.10 The measurement device 100 illustrated in FIG. 1 is different in that: Fig.13 The measuring device 100 illustrated in FIG. 7 does not include the flicker detection unit 701 .

[0096] The imaging control unit 1002 of this modification example determines the optimal frame rate 212 based on the presence or absence of flicker indicated by the flicker-related information 211 or the frequency fq of flicker indicated by the flicker-related information 211. Thus, the measuring device 100 of this modification example can make the actual frame rate fr approach the optimal frame rate based on the frequency fq of flicker set according to the lighting.

[0097] The present disclosure is not limited to the above-mentioned embodiments, and various changes can be made within the scope of the claims. The embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Moreover, by combining the technical solutions disclosed in each embodiment, new technical features can be formed.

Claims

1. A measuring device, characterized in that: have: The camera unit is used to photograph living organisms to obtain dynamic images; a pixel value calculation unit that calculates a representative value of pixel values ​​of pixels in a region of interest including the image of the biological body based on each image constituting the dynamic image; as well as The imaging control unit sets the exposure time and sensitivity based on the optimum frame rate and the representative value so that the representative value falls within a predetermined range. The imaging unit captures an image of the living body at the optimal frame rate, exposure time, and sensitivity.

2. The measuring device according to claim 1, wherein The imaging control unit adjusts the sensitivity when the representative value is smaller than the predetermined range and the exposure time is longer than the imaging time interval determined by 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.

3. The measuring device according to claim 1, wherein The imaging control unit adjusts the exposure time when the representative value is greater than the predetermined range and the sensitivity is less than a sensitivity lower limit value. When the representative value is larger than the prescribed range and the sensitivity is larger than the sensitivity lower limit value, the sensitivity is adjusted.

4. The measuring device according to claim 2 or 3, characterized in that Adjusting the exposure time means selecting any one of a plurality of exposure time candidates calculated based on the optimal frame rate to set the exposure time.

5. The measuring device according to claim 1, wherein The imaging control unit sets the exposure time so as to be equal to or shorter than an imaging time interval determined based on the optimal frame rate.

6. The measuring device according to claim 2, characterized in that , The measuring device adjusts the sensitivity by setting a new sensitivity greater than the sensitivity when the representative value is smaller than the prescribed range, the exposure time is longer than the photographing time interval, and the sensitivity is smaller than an upper limit value of sensitivity.

7. The measuring device according to claim 3, characterized in that The measuring device adjusting the sensitivity includes setting a new sensitivity that is 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.

8. A determination method, characterized in that: have: The process of photographing a living organism to obtain dynamic images; a step of calculating a representative value of pixel values ​​of pixels in a region of interest including the image of the living body from each image constituting the dynamic image; as well as The step of setting the exposure time and the sensitivity based on the optimum frame rate and the representative value so that the representative value is within a predetermined range, In the step of acquiring the dynamic image, the living body is photographed at the optimal frame rate, the exposure time, and the sensitivity.

9. A computer-readable recording medium storing a program, characterized in that: The recording medium enables the computer to execute the following functions: The function of photographing living organisms to obtain dynamic images; a function of calculating a representative value of pixel values ​​of pixels in a region of interest including the image of the living body from each image constituting the dynamic image; A function of setting exposure time and sensitivity based on an optimum frame rate and the representative value in such a manner that the representative value is within a predetermined range; and A function for calculating a pulse wave signal based on the temporal variation of the representative value, In the function of acquiring the dynamic image, the living body is photographed at the optimal frame rate, the exposure time, and the sensitivity.

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