Mobile terminal, video image acquisition method, and video image acquisition program

Abstract

To provide a portable terminal for acquiring clear video images of a user's face, a video image acquisition method, and a video image acquisition program.SOLUTION: A portable terminal 100 includes: a face determination unit that determines whether or not a face is included in a predetermined area of an image acquired by an image pickup unit; and a video image acquisition unit configured to, when a determination is made that the face is included in the predetermined area, cause the image pickup unit to acquire a video image in a second state, out of a video image in a first state and the video image in the second state higher in image quality than the video image in the first state. The image pickup unit includes a first image pickup unit for acquiring a video image in the first state and a second image pickup unit provided so as to face a direction opposite to a direction in which a display unit for displaying an image faces and acquiring the video image in the second state. The face determination unit determines whether the face is included in the predetermined area only on the image acquired by the second image pickup unit. The video image acquisition unit causes, when the face determination unit determines that the face is included in the predetermined area of the image acquired by the second image pickup unit, the image pickup unit to acquire the video image in the second state.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a mobile terminal, a video image acquisition method, and a video image acquisition program. [Background technology]

[0002] In recent years, technology for capturing moving images using a mobile terminal has been developed. For example, according to the technology disclosed in Patent Document 1, a user of a mobile terminal can capture a moving image of his / her own face by himself / herself, that is, take a so-called selfie. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-161704 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are cases where the image quality of a moving image captured by an imaging unit used for taking a selfie is not good, as expressed by indices such as a signal-to-noise ratio, a dynamic range, or a bit depth of the moving image, and in such cases, a clear moving image of the user's own face cannot be captured.

[0005] The present disclosure has been made in consideration of the above problems. It is an object of one aspect of the present disclosure to provide a mobile terminal, a moving image acquisition method, and a moving image acquisition program that are capable of acquiring a clear moving image of a user's own face. [Means for solving the problem]

[0006] A mobile terminal according to one aspect of the present disclosure includes a face determination unit that determines whether a face is included in a predetermined area of ​​an image acquired by an imaging unit, and a video acquisition unit that, when it is determined that the face is included in the predetermined area, causes the imaging unit to acquire a video of the second state from among a video of a first state and a video of a second state having better image quality than the video of the first state, the imaging unit including a first imaging unit that acquires the video of the first state, and a second imaging unit that is arranged to face in a direction opposite to a side to which a display unit that displays the images faces and acquires the video of the second state, and the face determination unit determines whether the face is included in the predetermined area only for the image acquired by the second imaging unit, When the face determination unit determines that the face is included in the specified area of ​​the image acquired by the second imaging unit, the moving image acquisition unit causes the second imaging unit to acquire a moving image of the second state.

[0007] A moving image acquisition method according to one embodiment of the present disclosure includes the steps of: determining whether a face is included in a predetermined area of ​​an image acquired by an imaging unit; and, when it is determined that the face is included in the predetermined area, causing the imaging unit to acquire a moving image of the second state from among the moving image of the first state and a moving image of a second state having better image quality than the moving image of the first state, wherein the imaging unit includes a first imaging unit that acquires the moving image of the first state, and a second imaging unit that is arranged facing opposite to a side facing a display unit that displays the images, and acquires the moving image of the second state, wherein the face determination unit determines whether the face is included in the predetermined area only for the image acquired by the second imaging unit, and in the acquiring step, when it is determined in the determining step that the face is included in the predetermined area of ​​the image acquired by the second imaging unit, causes the second imaging unit to acquire the moving image of the second state.

[0008] A video acquisition program of one embodiment of the present disclosure is a video acquisition program for causing a computer to function as a face determination unit that determines whether a face is included in a predetermined area of ​​an image acquired by an imaging unit, and a video acquisition unit that, when the face determination unit determines that the face is included in the predetermined area, causes the imaging unit to acquire a video of the second state from among a video of a first state and a video of a second state having better image quality than the video of the first state, wherein the imaging unit includes a first imaging unit that acquires the video of the first state, and a second imaging unit that is arranged to face the opposite side to a side facing a display unit that displays the images, and acquires the video of the second state, wherein the face determination unit determines whether the face is included in the predetermined area only for the image acquired by the second imaging unit, and the video acquisition unit causes the second imaging unit to acquire the video of the second state when the face determination unit determines that the face is included in the predetermined area of ​​the image acquired by the second imaging unit. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a front view of the mobile terminal according to the first embodiment. [Diagram 2] FIG. 2 is a rear view of the mobile terminal of the first embodiment. [Diagram 3] 2 is a functional block diagram of the mobile terminal of the first embodiment. FIG. [Figure 4] FIG. 2 is a diagram showing a state in which a user is acquiring an image of his or her own face using a mobile terminal of embodiment 1, and is a first diagram showing the position of the user's face in the image displayed on the display unit. [Diagram 5] FIG. 2 is a diagram showing a state in which a user is acquiring an image of his or her face using a mobile terminal of embodiment 1, and is a second diagram showing the position of the user's face in the image displayed on the display unit. [Figure 6] FIG. 2 is a first diagram for explaining the positional relationship between a face area, a predetermined area, and an entire image displayed on a display unit of the mobile terminal according to the first embodiment. [Figure 7]FIG. 2 is a second diagram for explaining the positional relationship between the face area, the predetermined area, and the entire image displayed on the display unit of the mobile terminal of the first embodiment. [Figure 8] FIG. 13 is a third diagram for explaining the positional relationship between the face area, the predetermined area, and the entire image displayed on the display unit of the mobile terminal of the first embodiment. [Figure 9] 4 is a flowchart illustrating a control process executed by a control unit of the mobile terminal according to the first embodiment. [Figure 10] 11 is a diagram showing a data table for explaining an example of a notification mode for encouraging movement of the mobile terminal in the first embodiment when the notification unit of the mobile terminal is a sound generating unit. FIG. [Figure 11] FIG. 2 is a diagram for explaining an example of a display mode of bioinformation displayed on a display unit of the mobile terminal according to the first embodiment. [Figure 12] FIG. 13 is a diagram for explaining a state in which the mobile terminal of the second embodiment increases the brightness of the display unit in order to increase the signal-to-noise ratio of a moving image captured by the first imaging unit. [Figure 13] 13 is a flowchart for explaining a control process executed by a control unit of a mobile terminal according to a second embodiment. [Figure 14] 13 is a diagram for explaining a mobile terminal and a control unit and a notification unit of a wearable device according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a mobile terminal, a video image acquisition method, and a video image acquisition program according to the embodiments will be described with reference to the drawings. Note that in each drawing, the same or equivalent elements are given the same reference numerals, and therefore redundant description will not be repeated.

[0011] (Embodiment 1) The mobile terminal 100, the video image acquiring method, and the video image acquiring program according to the first embodiment will be described with reference to FIGS.

[0012] Fig. 1 is a front view of the mobile terminal 100 of the first embodiment. Fig. 2 is a rear view of the mobile terminal 100 of the first embodiment. The mobile terminal 100 of the present embodiment has a size and weight that allows it to be carried by a person. The mobile terminal 100 may be any device such as a smartphone, a tablet, a notebook computer, or a dedicated terminal for acquiring moving images.

[0013] As can be seen from Figures 1 and 2, the mobile terminal 100 of this embodiment has a roughly rectangular outline. The mobile terminal 100 has a plate shape with a front and a back surface facing each other. It is preferable that the mobile terminal 100 of this embodiment is large enough to be held in one hand.

[0014] 1, the mobile terminal 100 includes a display unit D, a first imaging unit C1, and a sound generating unit S on the front side. The display unit D displays an image toward a user standing in front of the mobile terminal 100. The display unit D is configured with a liquid crystal display or the like. The display unit D functions as an example of a notification unit N that notifies information.

[0015] The first imaging unit C1 can capture an image of a user in front of the user. The first imaging unit C1 is used to capture both still images and moving images. The sound generating unit S generates sound toward the user in front of the user. The sound generating unit S is composed of a speaker or the like. The sound generating unit S also functions as an example of the notification unit N that notifies information.

[0016] As shown in FIG. 2, the mobile terminal 100 has a second imaging unit C2 and a light emitting unit L on the back side. The second imaging unit C2 is provided facing the opposite side to the side facing the display unit D. Therefore, the second imaging unit C2 can capture an image of a person on the back side or a landscape positioned on the back side. Like the first imaging unit C1, the second imaging unit C2 is also used to capture still images and moving images. The light emitting unit L is composed of an LED (Light Emitting Diode) or the like. The light emitting unit L also functions as an example of a notification unit N that notifies information.

[0017] 2, the mobile terminal 100 includes a vibration unit V therein. The vibration unit V is made of a member that vibrates when power is supplied. The vibration unit V also functions as an example of a notification unit N that notifies information.

[0018] 3 is a functional block diagram of the mobile terminal 100. As can be seen from FIG. 3, the mobile terminal 100 includes an imaging unit C, a control unit 10, and a notification unit N.

[0019] The imaging section C includes a first imaging section C1 and a second imaging section C2. Each of the first imaging section C1 and the second imaging section C2 is composed of an RGB camera, an infrared camera, or the like. The signal-to-noise ratio (S / N) of the image acquired by the second imaging section C2 is larger than the signal-to-noise ratio of the image acquired by the first imaging section C1.

[0020] Therefore, the second imaging unit C2 can obtain a clearer image than the first imaging unit C1. The signal-to-noise ratio may be, for example, the signal-to-noise ratio of the luminance of the image, or the signal-to-noise ratio of the color components of the image. In this specification, the image includes both a still image and a moving image.

[0021] The control unit 10 is composed of a CPU (Central Processing Unit) 6 and a storage unit 5. The storage unit 5 stores a video image acquisition program P installed from an external recording medium of the mobile terminal 100 or a server capable of communicating with the mobile terminal 100. The video image acquisition program P is for causing the CPU 6 of the control unit (computer) 10 to function as a face determination unit 1, a video image acquisition unit 2, a notification control unit 3, and a biometric information estimation unit 4.

[0022] The CPU 6, in accordance with a control command of the video image acquisition program P stored in the storage unit 5, for example, causes either the first imaging unit C1 or the second imaging unit C2 to acquire a still image or a video image, or causes the notification unit N to notify information. The control process executed by the video image acquisition program P will be described later.

[0023] The above-mentioned CPU 6, which is the main subject of the mobile terminal video acquisition method in the present disclosure, is equipped with a control unit 10 as a computer. The computer executes a video acquisition program to realize the main function of the mobile terminal or video acquisition method in the present disclosure. The computer has a processor that operates according to the video acquisition program as a main hardware configuration. The type of the processor does not matter as long as it can realize the function by executing the video acquisition program. The processor is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). The multiple electronic circuits may be integrated into one chip or may be provided on multiple chips. The multiple chips may be integrated into one device or may be provided on multiple devices. The program is recorded on a non-transitory recording medium such as a computer-readable ROM, an optical disk, or a hard disk drive. The program may be stored in the recording medium in advance, or may be supplied to the recording medium via a wide area communication network including the Internet.

[0024] Specifically, the CPU 6 includes a face determination unit 1, a moving image acquisition unit 2, a notification control unit 3, and a biometric information estimation unit 4. The biometric information estimation unit 4 includes a pulse wave acquisition unit that acquires pulse wave data as biometric information. However, the biometric information may be any information about a living body acquired from a moving image of the living body.

[0025] In this embodiment, the control unit 10 is provided in the mobile terminal 100. However, the control unit 10 does not have to be built into the mobile terminal 100, and may be provided in a server communicatively connected via a telecommunications information network such as the Internet or wireless communication means, as described later.

[0026] The notification unit N includes a light emitting unit L, a sound generating unit S, a vibration unit V, and a display unit D. The notification unit N notifies information that can specify whether the user's face is included in the image. The notification unit N may notify information that can specify whether the user's face is included in a predetermined area of ​​the image. The information that can specify whether the user's face is included in the image will be described later. The notification unit N also notifies movement information. This movement information is information for urging the user to move at least one of the user's face and the mobile terminal 100 so that the user's face is included in the image. For example, when the face of the user H is not included in the image, the notification unit N notifies the user of the direction in which the mobile terminal 100 or the user's face should be moved so that the user's face is included in the image.

[0027] In addition, the notification unit N may notify whether the user's face is included in a predetermined area of ​​the image, instead of notifying whether the user's face is included in the image. This applies to all of the following operations of the notification unit N. In addition, the predetermined area may be the entire image.

[0028] The notification unit N may notify the user of the forward and backward movement direction to encourage the user to relatively move the face or the mobile terminal 100 closer or further away so that the user's face is within a predetermined range of the display unit D. In this case, the notification unit N may notify the forward and backward movement direction of the user's face or the mobile terminal 100 together with the up, down, left, and right movement directions of the user's face or the mobile terminal 100. Furthermore, the notification unit N may notify the forward and backward movement direction of the user's face or the mobile terminal 100 separately from the up, down, left, and right movement directions of the user's face or the mobile terminal 100.

[0029] When acquiring a pulse wave from a moving image, for example, the larger the face in the image, the more pixels can be used to acquire the pulse wave, and therefore the higher the signal-to-noise ratio of the pulse wave. For example, if the face in the image is too large, the face determination unit 1 may not be able to recognize the face in the image as a face. Therefore, it is preferable that the notification unit N executes a notification to encourage the user to move the face so that the entire face of the user is within a predetermined range, for example, within a frame displayed on the display unit D. However, depending on the configuration of the face determination unit 1, even if only a part of the user's face is included in the image, for example, the pulse wave may be accurately acquired. Therefore, the notification unit N may execute a notification to encourage the user to move the face so that only a part of the face, for example, the forehead, is within the predetermined range.

[0030] The light-emitting unit L notifies visual information such as blinking, lighting, or turning off. In the present embodiment, the light-emitting unit L lights up, for example, when the image acquired by the first imaging unit C1 or the second imaging unit C2 includes the user's face. The lighting of the light-emitting unit L is information that can identify that the image acquired by the first imaging unit C1 or the second imaging unit C2 includes the user's face. However, the light-emitting unit L may be used as a flash to acquire a clear moving image when an image is acquired by the second imaging unit C2. The number of the light-emitting units L is not particularly limited.

[0031] When the user's face is not included in the image, the light-emitting unit L may notify the user of the amount to move the mobile terminal 100 or the face by the blinking speed. For example, the light-emitting unit L may urge the user to move the mobile terminal 100 by a longer distance as the number of blinks per unit time increases. In addition, when the mobile terminal 100 has, for example, four arrow-shaped light-emitting units L, the direction indicated by the arrows of the lit light-emitting units L may indicate the direction in which the user's face or the mobile terminal 100 should be moved. In this case, the direction in which the movement should be made is movement information that prompts the user to include his or her own face in the image. In addition, when the mobile terminal 100 has, for example, a light-emitting unit L in which a plurality of LEDs are arranged in a straight line, the order in which the plurality of LEDs emit light may indicate the direction in which the user's face or the mobile terminal 100 should be moved.

[0032] Furthermore, the light-emitting element L may notify the rhythm of the pulse wave data as the bioinformation estimated by the bioinformation estimation unit 4, and the magnitude of the blood pressure and the pulse rate, by the light emission color or light emission rhythm of the light-emitting element L. Furthermore, if the mobile terminal 100 has a plurality of light-emitting elements L, the rhythm of the pulse wave data, and the magnitude of the blood pressure and the pulse rate may be notified by varying the number of light-emitting elements L that emit light or the light emission pattern.

[0033] The sound generating unit S notifies the user of the type of sound or auditory information such as a sound including words. For example, when the image acquired by the first imaging unit C1 or the second imaging unit C2 includes the user's face, the sound generating unit S generates a sound including words expressing that effect. The sound generated by the sound generating unit S is information that can identify that the image acquired by the first imaging unit C1 or the second imaging unit C2 includes the user's face. For example, the sound generating unit S may notify the user that the user's face is included in the image by generating a sound including words such as "OK."

[0034] Furthermore, when the user's face is not included in the image, the sound generating unit S may generate a voice including words that indicate the direction in which the user should move the mobile terminal or the user's face. For example, when the user's face is not included in the image, the sound generating unit S may notify the user of the direction in which the mobile terminal 100 should be moved so that the user's face is included in the image by a voice including words such as "Please move the mobile terminal 100 further to the right."

[0035] The sound generating unit S may be a speaker used as a receiver. The number of the sound generating units S is not particularly limited, as is the number of the light emitting units L. The sound generating unit S may generate voices expressing in words the rhythm of the pulse wave data as the bioinformation estimated by the bioinformation estimation unit 4, as well as the values ​​of the blood pressure and pulse rate.

[0036] The vibration unit V notifies tactile information such as the magnitude or type of vibration of the mobile terminal 100 caused by its own vibration. The vibration unit V may be any type that vibrates the mobile terminal 100 by power. For example, the vibration unit V may notify that the user's face is included in the image by vibrating the mobile terminal 100 or not vibrating. The vibration or non-vibration of the vibration unit V is information that can identify that the user's face is included in the image acquired by the first imaging unit C1 or the second imaging unit C2.

[0037] Also, for example, when the user's face is not included in the image, the vibration unit V may notify the user of the amount of movement of the mobile terminal 100 that is necessary to include the face in the image, depending on the magnitude of the vibration. For example, the vibration unit V may notify the user that the larger the vibration is, the greater the distance the mobile terminal 100 needs to be moved.

[0038] The vibration unit V may be used only when the mobile terminal 100 is set to silent mode and sound cannot be generated by the sound generation unit S. The vibration unit V may notify the rhythm of the pulse wave data as the bioinformation estimated by the bioinformation estimation unit 4, as well as the magnitude of the blood pressure and the pulse rate, by varying the vibration mode of the vibration unit V.

[0039] The display unit D is configured with a liquid crystal display or the like. The display unit D notifies visual information such as characters, symbols, arrows, or figures. The display unit D displays, for example, bioinformation estimated by the bioinformation estimation unit 4, for example, pulse wave data. However, the display unit D may also notify that the user's face is included in the image by visual information such as characters, symbols, arrows, or figures. When the user images the user's image with the second imaging unit C1 of the mobile terminal 100, the user can place a mirror on the back side of the mobile terminal 100 and know whether or not the user's face is included in the image by looking at the display unit D reflected in the mirror.

[0040] The above-mentioned notification unit N may notify the user by a plurality of parts among the light-emitting unit L, the sound generating unit S, the vibration unit V, and the display unit D. For example, when the user's face is included in an image, the sound generating unit S may emit a sound, and at the same time, the vibration unit V may vibrate the mobile terminal 100 and the light-emitting unit L may emit light. In this case, both the sound emitted by the sound generating unit S and the light emitted by the light-emitting unit L are information capable of identifying that the user's face is included in the image acquired by the first imaging unit C1 or the second imaging unit C2.

[0041] In the mobile terminal 100 of the present embodiment described above, when the mobile terminal 100 of the present embodiment causes the biometric information estimation unit 4 described below to estimate biometric information, the mobile terminal 100 operates the face determination unit 1 and the video acquisition unit 2 as follows.

[0042] The face determination unit 1 determines whether or not a user's face is included in an image acquired by the imaging unit C. In this embodiment, the face determination unit 1 determines that a face is not included in an image when a specific part of the face is not included in the image. However, the face determination unit 1 may also determine that a face is not included in an image when the entire face is not included in the image.

[0043] For example, when acquiring pulse wave data, if a moving image of the forehead body surface is preferable as an image of a specific part, the specific part of the face may be the forehead body surface. In this case, the face determination unit 1 may specify the position of the forehead body surface from the position of the eyes, for example, and determine whether the forehead body surface is included in the image. The body surface mainly includes the skin.

[0044] When the face determination unit 1 determines that a face is included in a predetermined area of ​​the image, the video acquisition unit 2 causes the imaging unit C to acquire a video. The video acquisition unit 2 causes the imaging unit C to acquire a video in the second state from among the video in the first state and the video in the second state, which has better image quality than the video in the first state. This makes it possible to acquire a clear video of the face F. The predetermined area may be the entire image, or any part of the image.

[0045] The moving image acquisition unit 2 may be any unit that causes the imaging unit C to acquire an image having relatively good image quality out of an image having relatively poor image quality and an image having relatively good image quality when the face determination unit 1 determines that the image contains a face. In this case, good image quality of a still image or a moving image means high image quality, and specifically means a high signal-to-noise ratio, a wide dynamic range, a deep bit depth, or the like.

[0046] The signal-to-noise ratio is the ratio of signal to noise. The higher the signal-to-noise ratio, the better the image quality. The dynamic range is an index showing the signal reproduction capability of the imaging unit, and is the ratio between the maximum and minimum values ​​of the reproducible signal. The higher the dynamic range, the better the image quality. Bit depth means the amount of information per discrete signal (sample) of a digital signal, that is, the number of quantization bits. The higher the bit depth, the better the image quality. In other words, a video in a second state with good image quality may include at least one of a video with a high signal-to-noise ratio, a video with a high dynamic range, and a video with a high bit depth, compared to the video in the first state.

[0047] In addition, good image quality is also called high image quality. In the following description of the embodiment, good image quality is exemplified by a high signal-to-noise ratio.

[0048] More specifically, the first imaging unit C1 acquires a moving image in a first state. The second imaging unit C2 acquires a moving image in a second state in which the signal-to-noise ratio is higher than that in the first state. Under this condition, when the control unit 10 causes the biometric information estimation unit 4 described later to estimate biometric information, that is, when the face determination unit 1 determines that the image contains a face, the moving image acquisition unit 2 causes the second imaging unit C2 to acquire a moving image in the second state.

[0049] Therefore, the video acquisition unit 2 can acquire a video in the second state having a higher signal-to-noise ratio than the video in the first state acquired by the first imaging unit C1. In other words, a clear video of the face F can be acquired by using the second imaging unit C2 provided to face the opposite side to the side to which the display unit D faces. At this time, the notification control unit 3 causes the notification unit N to notify information that can specify that a face is included in the predetermined area of ​​the image when the face determination unit 1 determines that a face is included in the predetermined area of ​​the image. However, the notification control unit 3 may be any type as long as it causes the notification unit N to notify information that can specify whether or not a face is included in the predetermined area of ​​the image by the face determination unit 1. Therefore, the notification control unit 3 may cause the notification unit N to notify information that can specify that a face is not included in the image when the face determination unit 1 determines that a face is not included in the image.

[0050] The biometric information estimation unit 4 estimates the user's biometric information based on the moving image in the second state, which has a higher signal-to-noise ratio than the first state. In other words, the biometric information of the user is estimated using a clearer moving image. Therefore, the biometric information can be acquired more accurately. In this embodiment, the biometric information is pulse wave data of blood flowing through the blood vessels of the face F. Therefore, the pulse wave data can be acquired more accurately.

[0051] The combination of the first imaging unit C1, which is a front camera, and the display unit D is used for video calling or as a substitute for a handheld mirror. In this case, the user only needs to be able to recognize the face of the other party of the call or his / her own face displayed on the display unit D.

[0052] Therefore, the first imaging unit C1 does not need to have a signal-to-noise ratio as high as that of the second imaging unit C2. On the other hand, the second imaging unit C2, which is a rear camera, is generally used when a clear image is to be obtained. Therefore, the second imaging unit C2 needs to have a higher signal-to-noise ratio than the first imaging unit C1.

[0053] When acquiring pulse wave data based on a moving image as in this embodiment, the imaging unit C needs to have a sensitivity sufficient to detect small changes in the moving image such as pulse wave data, and therefore the first imaging unit C1, which has a low signal-to-noise ratio, cannot acquire accurate pulse wave data.

[0054] Therefore, when acquiring pulse wave data, it is preferable to use the second imaging unit C2 capable of acquiring moving images with a high signal-to-noise ratio. In consideration of this, in this embodiment, moving images for acquiring pulse wave data are acquired by the second imaging unit C2 as a rear camera. As a result, pulse wave data can be accurately acquired based on clear moving images.

[0055] According to the mobile terminal 100 of the present embodiment, it is not necessary to improve the performance of the first imaging unit C1 as a front camera. Therefore, accurate pulse wave data can be obtained without increasing the manufacturing cost of the mobile terminal 100.

[0056] 4 and 5 are diagrams showing an example and another example of the state of image I of user H's face F displayed on display unit D when user H is acquiring an image of himself / herself using mobile terminal 100.

[0057] 4 and 5, in this embodiment, the user H uses the second imaging unit C2, which is provided on the back and has a high signal-to-noise ratio, to capture a clear moving image of his / her own face F. In this case, the user H cannot know whether the image I displayed on the display unit D includes the user H's face F or not.

[0058] Therefore, as shown in Fig. 4, there are cases where the image I displayed on the display unit D does not include a part of the user's face F, and there are cases where the image I displayed on the display unit D includes the entire user's face F, as shown in Fig. 5. In both Figs. 4 and 5, a specific part SP of the body surface of the face F is included in the image I.

[0059] Therefore, when a specific part SP of the body surface of the face F is included in the image I, the biometric information estimation unit 4 can acquire pulse wave data, an example of biometric information, using the moving image of the specific part SP of the body surface acquired by the moving image acquisition unit 2.

[0060] 4 and 5, when pulse wave data is acquired by the second imaging unit C2 as a rear camera, the user H cannot check by looking at the display unit D whether or not the image I acquired by the second imaging unit C2 includes a face F. However, according to the mobile terminal 100 of this embodiment, when the face determination unit 1 determines that the image I acquired by the second imaging unit C2 as a rear camera includes a face F, for example, the sound generation unit S generates a sound or the light emitting unit L lights up. This makes it possible to notify the user H that the face F is included in the image I acquired by the second imaging unit C2.

[0061] 6 to 8 are diagrams each showing an example of a state of a face area FR including a face F of a user H displayed in a predetermined area X of the display unit D when the mobile terminal 100 is in use.

[0062] The face determination unit 1 determines whether or not a face F is included in a predetermined area X of the image I shown in Fig. 6 to Fig. 8. When the face determination unit 1 determines that the face F is not included in the predetermined area X of the image I, the notification control unit 3 causes the notification unit N to notify movement information that prompts the user to move at least one of the face F and the mobile terminal 100 so that the face F is included in the predetermined area X of the image I. This makes it possible to more reliably acquire a clear moving image of the face F.

[0063] The movement information notified by the notification unit N may be the blinking of the light-emitting unit L or the generation of a sound by the sound generation unit S. In this case, the user H moves at least one of the face F and the mobile terminal 100. This allows the video acquisition unit 2 to acquire a video of the face F of the user H with the face F of the user H included within the predetermined area X. Therefore, a clear video of the face F can be acquired more reliably.

[0064] The notification unit N is a sound generating unit S, a vibration unit V provided in the mobile terminal 100, or a light emitting unit L provided in the mobile terminal 100 and facing the side where the second imaging unit C2 faces. By using the notification functions of these parts, a clear moving image of the face F can be obtained more reliably.

[0065] 6 to 8, the face determination unit 1 identifies the proportion of the face area FR including the face F contained in a predetermined area X of the image I. As a result, the face determination unit 1 causes the notification control unit 3 to execute control for notifying the notification unit N of different movement information according to the proportion of the face area FR. Therefore, the position of the face F can be more reliably included in the image I.

[0066] The face determination unit 1 compares the face of the authentication face data stored in the storage unit 5 in advance with the face F included in the predetermined area X of the image I. The face determination unit 1 then determines whether the face F included in the image I and the face of the authentication face data are within a predetermined range of the determination criteria. This determination method may be a known method. As a result, on the condition that the face determination unit 1 determines that the face F included in the predetermined area X of the image I acquired by the second imaging unit C2 and the face of the authentication face data are within the predetermined range of the determination criteria, the moving image acquisition unit 2 causes the second imaging unit C2 to acquire a moving image. In other words, when the user authentication is properly performed, the control unit 10 causes the second imaging unit C2 to acquire a moving image. This can prevent a person other than the person whose authentication face data is stored in the storage unit 5 from estimating biometric information using the mobile terminal 100.

[0067] The control process executed by the control unit 10 of the mobile terminal 100 of this embodiment will be described with reference to FIG.

[0068] First, the control unit 10 starts a moving image acquisition program P for causing the biometric information estimation unit 4 to estimate biometric information based on a touch operation on a touch panel of the display unit D, which also functions as an operation unit. Thereby, in step S1, the control unit 10 starts the second imaging unit C2. Next, in step S2, the moving image acquisition unit 2 causes the second imaging unit C2 to acquire an image I.

[0069] Thereafter, in step S3, a face F is detected in the image I acquired by the second imaging unit C2. Face detection is performed by known techniques. For example, a face detection method may be a machine learning method such as pattern matching. In face detection, the position of the face may be detected, and an individual may be identified from the detected face. In this case, the video acquisition unit 2 may display information on the display unit D related to the position of the face or information identifying an individual together with the biometric information estimated by the biometric information estimation unit 4.

[0070] In step S4, the face determination unit 1 determines whether or not the detected face F is included in the predetermined area X of the image I. If it is determined in step S4 that the face F is not included in the predetermined area X of the image I, in step S5, the notification control unit 3 causes the notification unit N to notify, for example, movement information that prompts the user H to move the mobile terminal 100 so that the face F is included in the predetermined area X of the image I.

[0071] In step S5, for example, the notification control unit 3 executes control to cause the sound generating unit S to generate a voice including a word instructing in which direction the mobile terminal 100 should be moved in order to include the face F in the predetermined area X of the image I. The word instructing in which direction the mobile terminal 100 should be moved is selected, for example, from the data table shown in FIG.

[0072] In step S4, if the face determination unit 1 determines that a face F is included in a specified area X of the image I, in step S6, the notification control unit 3 causes the notification unit N to notify that a face F is included in the specified area X of the image I.

[0073] Thereafter, in step S7, it is determined whether the user authentication is proper or not. If it is determined in step S6 that the user authentication is proper, the control unit 10 executes the process of step S1. Specifically, the face determination unit 1 compares the face data for authentication stored in advance in the storage unit 5 with the face F included in the predetermined area X of the image I, and determines whether the face F is within the same range as the face data for authentication. That is, the face determination unit 1 determines whether the face data for authentication stored in advance and the face F included in the predetermined area X of the image I are within a predetermined determination criterion range. The moving image acquisition unit 2 causes the second imaging unit C2 to acquire a moving image on the condition that the face determination unit 1 has determined that the face data for authentication stored in advance and the face F included in the image are within the predetermined determination criterion range.

[0074] According to this, when an individual's face F stored in the memory unit 5 is requested to have its biometric information estimated, for example, by a person other than the user H or owner of the mobile terminal 100, estimation of that person's biometric information can be prevented.

[0075] If it is determined in step S7 that the user authentication is proper, in step S8, the video acquisition unit 2 acquires a video by the second imaging unit C2. Thereafter, the video acquisition unit 2 acquires the video for, for example, 10 seconds. In step S9, the biometric information estimation unit 4 acquires biometric information, for example, pulse wave data, from the video acquired by the second imaging unit C2.

[0076] The pulse wave data is acquired by a known technique. For example, known methods for acquiring pulse wave data include independent component analysis and pigment component separation. The pulse wave data is acquired using an image of a specific part SP, which mainly includes the body surface, of the face F included in the moving image acquired by the second imaging unit C2. At that time, the pulse wave data of the body surface of the specific part SP of the body surface of the face F is acquired.

[0077] Next, in step S10, blood pressure, pulse rate, and the like as biological information are calculated based on the acquired pulse wave data.

[0078] In step S11, the biological information estimation unit 4 starts the display unit D. Then, in step S12, the biological information estimation unit 4 displays the pulse wave data, blood pressure, pulse rate, etc. on the display unit D. After causing the display unit D to display the waveform of the pulse wave data, the blood pressure value, and the pulse rate value, the biological information estimation unit 4 causes the sound generation unit S to generate a sound to notify the end of estimation of the biological information.

[0079] (Modification) The notification manner in which the notification unit N notifies whether or not a face F is included in the predetermined area X of the image I may be different from the notification manner of the notification unit N in which the pulse wave data is displayed on the display unit D. For example, the sound emitted by the sound generation unit S when notifying whether or not a face F is included in the predetermined area X of the image I may be different from the sound emitted by the sound generation unit S when the display unit D displays the pulse wave data. Also, the color or blinking pattern of the light emitted by the light-emitting unit L when notifying whether or not a face F is included in the predetermined area X of the image I may be different from the color or blinking pattern of the light emitted by the light-emitting unit L when the display unit D displays the pulse wave data.

[0080] Furthermore, the vibration pattern of the vibration unit V when notifying whether or not the face F is included in the predetermined area X of the image I may be different from the vibration pattern of the vibration unit V when the pulse wave data is displayed on the display unit D. In addition, while the vibration unit V may be vibrated when notifying whether or not the face F is included in the predetermined area X of the image I, the sound generating unit S may generate a sound when the pulse wave data is displayed on the display unit D.

[0081] After it is determined that face F is included in the predetermined area X of image I, the notification unit N may continue to notify that face F is included in the predetermined area X of image I until the pulse wave data is displayed on display unit D. For example, after it is determined that face F is included in the predetermined area X of image I, the sound generation unit S may continue to generate the same sound until the pulse wave data is displayed on display unit D.

[0082] Also, after it is determined that face F is included in a predetermined area X of image I, light-emitting unit L may be turned on, and then light-emitting unit L may be turned off immediately before the pulse wave data is displayed on display unit D. Furthermore, after it is determined that face F is included in image I, vibration unit V may continue to vibrate until the pulse wave data is displayed on display unit D.

[0083] The timing of the notification by the notification unit N may be any. For example, only when it is determined that the face F is included in the predetermined area X of the image I, the notification unit N may notify the effect. Also, only when it is determined that the face F is not included in the predetermined area X of the image I, the notification unit N may notify the effect.

[0084] Acquisition of moving images by the second imaging unit C2 for estimating pulse wave data may be started at the same time as it is determined that face F is included in the predetermined area X of image I. Furthermore, acquisition of moving images by the second imaging unit C2 for acquiring pulse wave data may be started after a predetermined time (e.g., one second) has elapsed since it is determined that face F is included in the predetermined area X of image I.

[0085] Furthermore, the second imaging unit C2 may acquire a moving image only when it is determined that the face F of a pre-designated individual is included in the predetermined area X of the image I. Also, the second imaging unit C2 may acquire a moving image even when it is determined that the face F is not included in the predetermined area X of the image I. In this case, the biometric information estimation unit 4 acquires pulse wave data only during the period when it is determined that the face F is included in the predetermined area X of the image I.

[0086] Even during the period when the video acquisition unit 2 is acquiring a video for estimating pulse wave data, the face determination unit 1 may determine whether or not a face F is included in a predetermined area X of image I. When the video acquisition unit 2 is acquiring a video, and it is no longer determined that a face F is included in the predetermined area X of image I, the video acquisition unit 2 may end acquisition of the video.

[0087] In this case, the length of time during which the video acquisition unit 2 acquires the video becomes shorter than the desired time. In this case, the biometric information estimation unit 4 may acquire pulse wave data for a time shorter than the desired time. Also, the biometric information estimation unit 4 may end the control process without acquiring pulse wave data for a time shorter than the desired time. In this case, the video acquisition unit 2 may acquire the image I again, determine whether or not the face F is included in the predetermined area X of the image I, and repeat the acquisition of the video by the video acquisition unit 2 and the determination by the face determination unit 1 until the video for the desired time is acquired. Also, when the face F is not included in the predetermined area X of the image I, the notification control unit 3 may cause the notification unit N to notify that fact.

[0088] When the desired time is not set, the video acquisition unit 2 may continue acquiring the video. For example, the face determination unit 1 may determine whether or not the face F is included in the image I while the video acquisition unit 2 is acquiring the video. In this case, the video acquisition unit 2 may continue acquiring the video until the face determination unit 1 no longer determines that the face F is included in the predetermined area X of the image I. In this case, the biometric information estimation unit 4 may estimate the pulse wave data after the video acquisition unit 2 ends acquiring the video. Furthermore, the biometric information estimation unit 4 may acquire the pulse wave data using the video acquired until the face determination unit 1 determines that the face F is not included in the predetermined area X of the image I while the video acquisition unit 2 is continuing to acquire the video.

[0089] Display unit D may display not only the pulse wave data acquired by biological information estimation unit 4, but also biological related information derived from the pulse wave data. The biological related information includes the above-mentioned blood pressure, pulse rate, respiratory rate, and the like.

[0090] The mobile terminal 100 does not need to include the display unit D. In this case, the biological information acquired by the biological information estimation unit 4, such as pulse wave data, and biological-related information derived from the pulse wave data, may be displayed on another device, such as a wearable device described later.

[0091] Furthermore, the biometric information and bio-related information acquired by the biometric information estimation unit 4 may be transmitted from the storage unit 5 of the mobile terminal 100 to another device. The biometric information and bio-related information acquired by the biometric information estimation unit 4 may be stored in a recording medium separate from the mobile terminal 100, or in a recording medium that is a part of the storage unit 5 in a state that can be separated from the mobile terminal 100.

[0092] Furthermore, the mobile terminal 100 may not include at least one of the face determination unit 1, the video acquisition unit 2, the notification control unit 3, the biometric information estimation unit 4, and the storage unit 5. In this case, the parts not included in the mobile terminal 100 are provided in an external device capable of communicating with the mobile terminal 100. In this case, the mobile terminal 100 exerts the overall functions of the face determination unit 1, the video acquisition unit 2, the notification control unit 3, the biometric information estimation unit 4, and the storage unit 5 by communicating with the external device.

[0093] In particular, the mobile terminal 100 does not need to include the biometric information estimation unit 4. In this case, the mobile terminal 100 may simply have the video acquisition unit 2 operate the second imaging unit C2 to acquire an image I including a face F, and transmit the image I to an external device. In this case, the mobile terminal 100 may receive biometric information from the external biometric information estimation unit 4 and display the biometric information on the display unit D. This can reduce the processing load on the mobile terminal 100.

[0094] In face detection, a face area FR is detected. The notification pattern of the notification unit N may be changed according to the positional relationship between the detected face area FR and a predetermined area X set so that the angle of view is appropriate. For example, as shown in FIG. 6, when the face area FR is included in the predetermined area X, the notification unit N notifies the fact with notification pattern A. As shown in FIG. 7, when a part of the face area FR protrudes from the predetermined area X but the entire face area FR is included in the angle of view, i.e., in the image I, the notification unit N notifies the fact with notification pattern B.

[0095] As shown in FIG. 8, when a part of the face region FR is outside the angle of view, i.e., the image I, the notification unit N notifies this fact with notification pattern C. For example, when the notification unit N is the vibration unit V, the notification patterns A to C are as follows. Notification pattern A is a pattern in which the vibration unit V is not vibrated. Notification pattern B is a pattern in which the vibration unit V is vibrated intermittently. Notification pattern C is a pattern in which the vibration unit V is vibrated continuously.

[0096] The notification control unit 3 may determine the direction in which the face F should be moved or the direction in which the mobile terminal 100 should be moved according to the position of the face F in the image I, and cause the notification unit N to notify the direction of movement. For example, the sound generation unit S may generate one type of sound selected from a plurality of different types of sound according to the direction of movement. In this case, the sound generated by the sound generation unit S may include a word expressing the direction of movement.

[0097] If the sound generating unit S is provided in a location different from the mobile terminal 100, the sound generating unit S may be configured so that when the user H faces in the direction from which the sound is coming, the user H can change the direction of the face F so that the face F is included in the image I.

[0098] The notification control unit 3 may cause the light-emitting unit L or the vibration unit V to emit different types of light or vibration depending on the direction of movement. If the mobile terminal 100 has multiple light-emitting units L, the notification control unit 3 may cause the multiple light-emitting units L to light up sequentially along the direction of movement. Vibration of the vibration unit V or other actions may induce a change in the state of the user H's hands so that the face F is included in the image I.

[0099] (Embodiment 2) Next, a mobile terminal 100 according to the second embodiment will be described. Note that, in the following, the description of the same points as those of the mobile terminal 100 according to the first embodiment will not be repeated. The mobile terminal 100 according to the present embodiment differs from the mobile terminal 100 according to the first embodiment in the following points.

[0100] FIG. 12 is a diagram for explaining a state in which the first imaging unit C1 of the mobile terminal 100 of the present embodiment increases the brightness of the display unit D in order to increase the signal-to-noise ratio.

[0101] As described in the first embodiment, the first imaging unit C1 and the display unit D are provided to face the same side. In this embodiment, the first imaging unit C1 serving as a front camera captures a moving image of the face F of the user H. Therefore, in this embodiment, the second imaging unit C2 described in the first embodiment is basically replaced with the first imaging unit C1.

[0102] As described in the first embodiment, the signal-to-noise ratio of the first imaging unit C1 is smaller than that of the second imaging unit C2. In the present embodiment, the dynamic range or bit depth may be used instead of the signal-to-noise ratio. Therefore, the image acquired by the first imaging unit C1 is less clear than the image acquired by the second imaging unit C2.

[0103] However, in the second embodiment, it is not essential that the image quality of the image acquired by the first imaging unit C1 is not better than the image quality of the image acquired by the second imaging unit C2. The image quality of the image acquired by the first imaging unit C1 may be the same as or better than the image quality of the image acquired by the second imaging unit C2.

[0104] In this embodiment, if the display unit D is used as lighting for the purpose of relatively improving the image quality such as the signal-to-noise ratio, the user cannot see his / her own face on the display unit D. In this case, the control unit 10 executes the notification by the notification unit N described in the first embodiment. In the description of this embodiment, good image quality is exemplified by a high signal-to-noise ratio.

[0105] As shown in FIG. 12, according to the mobile terminal 100 of the present embodiment, when the face determination unit 1 determines that the predetermined area X of the image I contains a face F, the video acquisition unit 2 increases the brightness of the display unit D compared to when the image I is displayed. This increases the signal-to-noise ratio of the first imaging unit C1. As a result, a relatively clear video of the face F of the user H can be acquired using the first imaging unit C1. In this case, it is preferable to make the signal-to-noise ratio of the first imaging unit C1 higher than the signal-to-noise ratio of the second imaging unit C2. In other words, it is preferable to make the video acquired by the first imaging unit C1 clearer than the video acquired by the second imaging unit C2.

[0106] Thereafter, the first imaging unit C1 can be caused to capture a moving image in the second state. This is because a moving image captured in a bright environment allows a clearer moving image to be captured since a greater amount of light is incident on the camera than a moving image captured in a dark environment. According to the mobile terminal 100 of this embodiment, a clear moving image of the face F can be captured by using the display unit D and the first imaging unit C1 facing the same side.

[0107] Instead of the display unit D, the first imaging unit C1 may capture a moving image in the second state with the brightness of a light-emitting unit (with the same structure as the light-emitting unit L) provided on the front (not shown) increased. This also makes it possible to capture a clear moving image of the face F. Therefore, accurate pulse wave data can also be acquired by the mobile terminal 100 of this embodiment. Even when a light-emitting unit provided on the front (not shown) is used, there are cases where the user cannot see his / her own face on the display unit D due to the glare of the light emitted by the light-emitting unit. Even in this case, the control unit 10 may execute notification by the notification unit N described in the first embodiment.

[0108] In this embodiment as well, the notification control unit 3 can cause the notification unit N to notify that a face F is included in a predetermined area X of an image I. The notification control unit 3 can also cause the notification unit N to notify movement information that prompts the user to move at least one of the face F and the mobile terminal 100 so that the face F is included in the predetermined area X of the image I.

[0109] For example, when the image I acquired by the first imaging unit C1 is not displayed on the display unit D, the state of the sound generating unit S, the light emitting unit L, or the vibration unit V may be changed to notify the user H of whether or not the face F is included in the predetermined area X of the image I. When the image I acquired by the first imaging unit C1 is displayed on the display unit D, the user can determine whether or not the face F is included in the predetermined area X of the image I by looking at the face F displayed on the display unit D.

[0110] FIG. 13 is a flow chart for explaining the control executed by the control unit 10 of the mobile terminal 100 of this embodiment.

[0111] The flowchart shown in FIG. 13 differs from the flowchart shown in FIG. 10 in the processes of steps 1A and 8A.

[0112] In step S1A, the control unit 10 activates the first imaging unit C1 instead of the second imaging unit C2. Therefore, in step S2, the first imaging unit C1 acquires an image I. In addition, in step S8A, the biometric information estimation unit 4 acquires a moving image including the face F of the user H by the first imaging unit C1 with the brightness of the display unit D or the light-emitting unit L increased.

[0113] Other than the above, the configuration of the mobile terminal 100 of this embodiment is the same as that of the mobile terminal 100 of embodiment 1. The mobile terminal 100 of this embodiment can also more reliably acquire a clear moving image of the face F.

[0114] (Embodiment 3) Next, a mobile terminal 100 according to the third embodiment will be described. Note that, in the following, the description of the same points as those of the mobile terminal 100 according to the first or second embodiment will not be repeated. The mobile terminal 100 according to the present embodiment differs from the mobile terminal 100 according to the first embodiment in the following points.

[0115] FIG. 14 is a diagram for explaining a notification mode in the case where the notification unit N of the mobile terminal 100 of this embodiment is a wearable device WD.

[0116] The mobile terminal 100 of this embodiment includes an imaging unit C and a communication unit COM1. However, the mobile terminal 100 of this embodiment does not include a control unit 10. The control unit 10 is provided in a server SV that is communicatively connected to the mobile terminal 100 via an electric communication information network such as the Internet IN.

[0117] The server SV functions as a recording medium that stores a moving image acquisition program P in the control unit 10. In this embodiment, the imaging unit C of the mobile terminal 100 is controlled by the control unit 10 of the server SV. The imaging unit C transmits still images or moving images acquired by the imaging unit C to the wearable device WD via the communication unit COM1.

[0118] The wearable device WD is a wristwatch worn on the wrist of a user H. The wearable device WD includes a communication unit COM2 and a notification unit N. The notification unit N includes a display unit D. The wearable device WD transmits an image received from the communication unit COM1 of the mobile terminal 100 to the control unit 10 via the communication unit COM2. Note that the wearable device WD may be part of any accessory such as a helmet, glasses, a hat, gloves, a ring, clothes, or a scarf, as long as it includes the control unit 10 and the communication unit COM1.

[0119] The notification control unit 3 included in the control unit 10 causes the notification unit N to notify the face F when the face determination unit 1 determines that the face F is included in the predetermined area X of the image I. The notification control unit 3 causes the notification unit N to notify the movement information when the face determination unit 1 determines that the face F is not included in the image I. The movement information is information that prompts the user H to move at least one of the face F and the mobile terminal 100 so that the face F is included in the predetermined area X of the image I.

[0120] Furthermore, the biometric information estimation unit 4 displays the estimated biometric information, such as pulse wave data, blood pressure, and pulse rate, on the display unit D. With the mobile terminal 100 of this embodiment, the moving image acquisition unit 2 can also acquire a clear moving image of the face F, and therefore the biometric information estimation unit 4 can acquire accurate pulse wave data.

[0121] The mobile terminal 100 or the video image acquisition method according to the present disclosure is provided with a control unit 10 as a computer. The computer executes a video image acquisition program P to realize the functions of the mobile terminal 100 or the video image acquisition method according to the present disclosure.

[0122] The control unit 10 as a computer has, as its main hardware configuration, a processor (CPU 6) that operates according to a video image acquisition program P. The type of the processor (CPU 6) is not important as long as it can realize functions by executing the video image acquisition program P. The processor (CPU 6) is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). The multiple electronic circuits may be integrated into one chip, or may be provided on multiple chips. The multiple chips may be integrated into one device, or may be provided on multiple devices.

[0123] The video image acquisition program P is recorded on a non-transitory recording medium such as a computer-readable ROM (Read Only Memory), an optical disk, a hard disk drive, etc. The video image acquisition program P may be stored in the recording medium in advance, or may be supplied to the recording medium via a wide area communication network including the Internet. [Explanation of symbols]

[0124] 1 Face detection section 2. Video acquisition unit 3 Notification control section 4. Biometric information estimation unit 100 Mobile Devices C1 First imaging unit C2 Second imaging unit D Display section F face I Image L Light-emitting part N Notification Department S Sound generating section WD Wearable Devices

Claims

1. A first imaging unit that acquires a moving image in a first state; a second imaging unit that is provided facing the opposite side to the side to which a display unit that displays a moving image faces and captures a moving image in a second state having a better image quality than the moving image in the first state; a face determination unit that determines whether a face included in a predetermined area of ​​the image acquired by the second imaging unit and a face in the authentication face data stored in a storage unit are within a range of a predetermined determination criterion; a moving image acquisition unit that causes the second imaging unit to acquire a moving image of the second state on condition that the face determination unit determines that a face included in the specified area of ​​the image and a face in the authentication face data are within the range of the specified determination criteria.

2. The mobile terminal according to claim 1 , further comprising a notification control unit that causes a notification unit to notify information capable of specifying whether or not the face is included in the predetermined area.

3. the notification control unit causes the notification unit to notify movement information when the face determination unit determines that the face is not included in the predetermined area; The mobile terminal according to claim 2 , wherein the movement information is information that prompts the user to move at least one of the face and the mobile terminal so that the face is included in the predetermined area.

4. The mobile terminal according to claim 3 , wherein the movement information is information that prompts the user to move at least one of the face and the mobile terminal forward or backward so that the face is included in the predetermined area.

5. The mobile terminal according to claim 3 or 4, wherein the face determination unit identifies a proportion of a face area including the face contained in the specified area, and causes the notification control unit to execute control to notify the notification unit of the movement information that differs depending on the proportion of the face area.

6. The mobile terminal according to any one of claims 3 to 5, wherein the face includes at least a part of a surface of the face.

7. The mobile terminal according to claim 6 , wherein the at least a portion of the body surface includes a predetermined specific portion of the body surface.

8. The mobile terminal according to claim 3 , wherein the notification control unit transmits the movement information to a wearable device having the notification unit.

9. The mobile terminal according to any one of claims 2 to 8, wherein the notification unit includes at least one of a sound generating unit, a vibration unit provided in the mobile terminal, and a light emitting unit provided in the mobile terminal and facing the side in which the second imaging unit faces.

10. A mobile terminal as described in any one of claims 1 to 9, wherein the second state video having good image quality includes at least one of a video having a high signal-to-noise ratio value, a video having a large dynamic range value, and a video having a large bit depth value compared to the first state video.

11. The mobile terminal according to any one of claims 1 to 10, further comprising a biometric information estimation unit that acquires biometric information based on the moving image.

12. The mobile terminal according to claim 11 , wherein the biological information includes pulse wave data of blood flowing through blood vessels in the face.

13. A step of determining whether a face included in a predetermined area of ​​an image acquired by a first imaging unit which acquires a moving image of a first state, and a second imaging unit which is arranged to face in the opposite direction to the side to which a display unit which displays the moving image faces, and which acquires a moving image of a second state having better image quality compared to the moving image of the first state, and a face included in the face data for authentication stored in a memory unit, are within a predetermined judgment criteria; and a step of causing the second imaging unit to acquire a moving image of the second state on condition that it is determined in the determining step that a face included in the specified area of ​​the image and a face in the authentication face data are within the range of the specified determination criteria.

14. Computer, a first imaging unit that captures a moving image in a first state, and a second imaging unit that is provided facing the opposite side to a side facing a display unit that displays the moving image and captures a moving image in a second state having better image quality than the moving image in the first state, and a face determination unit that determines whether a face included in a predetermined area of ​​an image captured by the second imaging unit and a face in the authentication face data stored in a storage unit are within a range of a predetermined determination criterion; A computer-readable video acquisition program for causing the face determination unit to function as a video acquisition unit that causes the second imaging unit to acquire a video of the second state on condition that the face determination unit determines that the face included in the specified area of ​​the image and the face in the authentication face data are within the range of the specified determination criteria.

Images