JP2012155405A - Biological image photography system, biological image acquisition method, and program - Google Patents

Abstract

An object of the present invention is to obtain an image capable of accurately detecting the posture of a living body part reflected in an image having high suitability as authentication biometric information.
A first calculation unit calculates an index representing suitability as authentication biometric information in biometric authentication for the image based on an image of a biological part acquired by an imaging unit. The selection unit 13 determines the imaging environment when the next image acquired by the imaging unit 11 next is acquired based on the index of the biological part image acquired by the imaging unit 11 before the next image. Select and switch between environment and second environment. The first environment is an environment used for acquiring an image used as authentication biometric information, and the second environment is an environment used for acquiring an image used for detecting posture information of a living body part. The output unit 14 outputs information indicating the result of the selection in association with the next image acquired by the imaging unit 11 under the imaging environment related to the selection result.
[Selection] Figure 3

Description

  The technical field discussed in this specification relates to a biometric authentication technique for performing personal authentication using human body characteristics such as fingerprints of hands, palm veins, and faces.

  In modern society, identity verification is required in various situations. In recent years, biometric authentication technology that performs personal authentication by using the characteristics of each part of the human body such as fingerprints, veins, faces, etc. has become widespread as one method for accurately performing identity verification. For example, biometric authentication is used to determine whether to enter or leave a restricted area where only authorized people can enter, whether to log in to a personal computer, whether to access various services such as online transactions, etc. It's being used.

  In order to perform such biometric authentication, first, as a user's biometric information, for example, an image such as a fingerprint, a vein, or a face is acquired in advance and recorded as a registered biometric information of the user on a recording medium. . Thereafter, when the identity verification for using the service as described above becomes necessary, the biometric information of the user is acquired again in the same manner as at the time of registration. Then, the biometric information (authenticated biometric information) acquired at this time is compared with the registered biometric information recorded on the recording medium, and the level of similarity between the two is determined. Here, if the similarity is higher than a predetermined threshold, an authentication result indicating that the person is the person is obtained.

  In order to perform such biometric authentication with high accuracy, an image of a biological part (biological image), which is biometric information used for authentication, can be acquired at the same position and posture during registration and verification. preferable. However, there are actually many cases where such photographing cannot be performed, and this is one of the factors that reduce the authentication accuracy.

  This is because, for example, it is usually extremely difficult to hold a living body part at the same position and the same posture with respect to a sensor that acquires a biological image (for example, a camera that captures a living body part). Also, in many cases, it is difficult to take such an image because the user forgets at which position / posture the image of the living body part was imaged at the time of registration. Furthermore, since the human body has a large degree of freedom in posture and shape depending on the part, even if the same part is imaged, the obtained biological image is slightly different in posture and shape each time the image is taken. turn into. For example, a biological part such as a palm is a biological part having a very high degree of freedom in posture and shape, so that the shape of the palm in an image obtained by photographing with a camera is slightly different.

  Several methods are known for avoiding a decrease in authentication accuracy due to such differences in position, posture, and shape between registration and verification. One of them is to shoot with the body part firmly fixed at the same position, posture and shape. However, this method places a great burden on the user and is not generally preferred. In addition, it may take a considerable time to perform such fixing.

  As another method, a plurality of biometric images acquired by imaging a biometric part of the same user at various different positions, postures, and shapes are used as authentication biometric information, and one registered biometric information is registered. There is one in which an image is collated with the plurality of biological images. In order to acquire such a plurality of living body images at the time of authentication, the living body part that is freely presented to the sensor (camera) by the user is acquired without fixing the living body part as described above. There is a technique to do. However, with this method, the relative positions and postures of the acquired biological parts with respect to the sensors become uneven. Therefore, as a technique for eliminating this irregularity, a technique is known in which the distance and posture of a living body part with respect to a sensor are detected, and the acquired biological image is selected and corrected according to the detection result. However, since the size of the living body part varies from person to person, the area of the image of the living body part shown in the image cannot be used as information on the distance of the living body part with respect to the sensor. Therefore, in this technique, based on how the spot light is projected on the living body part when the spot light is irradiated to the living body part, information such as the distance and angle of the living body part with respect to the sensor is obtained. The distance and posture are detected.

  As another background technique, a technique is known in which a most balanced front image is selected from a series of face images obtained by photographing a face based on the area and brightness of the face region. Yes.

  In addition, a technique is known in which an image obtained by continuously photographing a face is extracted as a best shot image when the amount of change in the position of face parts such as eyes and mouth is a predetermined value or more.

JP 2007-10346 A JP 2005-227957 A JP 2009-89077 A

  The spot light used in the technology for detecting the distance and posture of the living body part described above is inappropriate for illumination of the living body part at the time of photographing for obtaining a biological image used for authentication. This is because, when a living body part is imaged by illuminating with such spot light, information necessary for biometric authentication included in the obtained biometric image is blurred. . For this reason, the detection of the distance and posture of the living body part performed using this technology is performed by illuminating the living body part during the continuous shooting with the camera for obtaining various biological images for authentication. It is necessary to switch from acquisition to spot light.

  FIG. 1 is a first example of a plurality of images obtained by photographing a palm, which is a living body part, with a camera. This first example is an example in which imaging for a biometric image for authentication and imaging for detection of a distance and posture of a biological body are alternately performed.

  The cross-shaped marks drawn on some of the 13 images from image A to image M shown as the first example are for detecting the distance and posture of the living body part. It expresses that the spotlight is reflected in the palm image. That is, in this first example, a total of six images B, D, F, H, J, and L on which the mark is drawn are used for detecting the distance and posture of the living body part. It is an image. Accordingly, the remaining seven images A, C, E, G, I, K, and M are biological images taken using illumination for acquiring biological images.

  However, among these seven images, the image A and the image M are extremely small in the size of the palm image because the distance from the palm camera at the time of shooting is too far, and the authentication biometric information Not suitable for. On the other hand, the image G is too close to the palm camera at the time of photographing, and the palm image protrudes excessively from the image, which is also not suitable as authentication biometric information. Therefore, in this first example, only four images C, E, I, and K, which are surrounded by a dashed ellipse in FIG. It was not possible.

  In this way, the reduction in the number of images that can be used as authentication biometric information in biometric authentication means that the number of times that biometric authentication processing can be performed in a series of operations of holding the palm over the camera at the time of identification is reduced. Means.

  Even if the biometric part presented at the time of identity verification is the same as that at the time of registration, the biometric information obtained differs slightly depending on the distance and orientation of the biometric part from the camera. There is some identity rejection rate that cannot be correctly verified by the authentication process. For this reason, in biometric authentication, generally, the biometric authentication process is repeated several times using a plurality of pieces of authenticated biometric information (retry), thereby reducing the overall identity rejection rate. Therefore, if the number of images that can be used as authentication biometric information decreases as described above, the overall rejection rate may increase accordingly.

  Therefore, for example, consider reducing the frequency of imaging for detecting the distance and posture of the living body part and increasing the frequency of imaging for the biometric image for authentication by the reduced amount.

  FIG. 2 is a second example of a plurality of images obtained by photographing a palm, which is a living body part, with a camera. This second example is an example of a case where imaging for detecting the distance and posture of a living body is performed once every time imaging for a biometric image for authentication is performed four times.

  In this second example, a total of two images D and I on which a cross-shaped mark similar to the first example described above is drawn are used for detecting the distance and posture of the living body part. It is an image. Accordingly, a total of 11 images of the remaining images A, B, C, E, F, G, H, J, K, L, and M are captured using the illumination for acquiring the biological image. It is. However, as in the first example described above, a total of three images A, G, and M are not suitable as authentication biometric information. Therefore, in this second example, a total of eight images B, C, E, F, H, J, K, and L surrounded by a broken-line ellipse in FIG. It becomes an image having the aptitude.

  Thus, in the second example, more images than the first example can be obtained as images having suitability as authentication biometric information. However, in this second example, the images used for detection of the distance and posture of the living body part are only the two images D and I in total. For this reason, in particular, the distance and posture of the palm camera shown in the image obtained by shooting at a time away from the time of shooting for the images D and I are considerably different from those detected from the images D and I. It is thought that it has become.

  Thus, reducing the frequency of imaging for detecting the distance and posture of the living body part is inconvenient for obtaining information on the distance and posture of the living body part at the time of shooting for the image as the authentication biometric information. It becomes. If the biometric image is corrected based on such low-accuracy information, the accuracy of biometric authentication may be reduced.

  In view of the above-described problems, the biometric image capturing system described later in this specification makes it possible to acquire an image that can accurately detect the posture of a living body part reflected in an image having high suitability as authentication biometric information.

  One of the biological image photographing systems described later in this specification includes an imaging unit, a first calculation unit, a selection unit, and an output unit. Here, the imaging unit acquires images of the biological part by sequentially imaging the biological part at a predetermined time interval. The first calculation unit calculates an index representing suitability as authentication biometric information in biometric authentication for the image based on the image acquired by the imaging unit. The selection unit selects a shooting environment between the first environment and the second environment at the time of shooting the next image, which is an image acquired next by the shooting unit, and switches the shooting environment to the selected environment. . Here, the first environment is an environment used for acquiring an image used as authentication biometric information in biometric authentication, and the second environment is an acquisition of an image used for detecting posture information that is information on the posture of a biological part. It is the environment used for. The selection unit selects the imaging environment based on the above-described index calculated by the first calculation unit with respect to an image acquired by the imaging unit imaging the living body part before the next image. The output unit associates and outputs the shooting environment selection information indicating the result of the selection by the selection unit and the next image acquired by the shooting unit under the shooting environment related to the selection result.

  In addition, one of the biological image acquisition methods described later in this specification is based on the image acquired by an imaging apparatus that first acquires images of the biological part by sequentially imaging the biological part at a predetermined time interval. An index indicating the suitability as authentication biometric information in biometric authentication is calculated. Next, the shooting environment at the time of shooting the next image, which is the next image acquired by the imaging device, is used as an index for the image acquired by imaging the living body part before the next image. Based on the first environment and the second environment described above. Next, the above-described shooting environment is switched to the selected environment. Then, the shooting environment selection information representing the selection result and the above-described next image acquired by the shooting apparatus under the shooting environment related to the selection result are output in association with each other.

  One of the programs described later in this specification causes a computer to perform the following processing. In this process, first, based on the images acquired by the imaging device that sequentially captures the biological parts at predetermined time intervals and acquires the images of the biological parts, the suitability of the images as the authentication biometric information in the biometric authentication. An index representing is calculated. Next, the shooting environment at the time of shooting the next image, which is the next image acquired by the imaging device, is used as an index for the image acquired by imaging the living body part before the next image. Based on the first environment and the second environment described above. Next, the above-described shooting environment is switched to the selected environment. Then, the shooting environment selection information representing the selection result and the above-described next image acquired by the shooting apparatus under the shooting environment related to the selection result are output in association with each other.

  The biometric image capturing system described later in this specification has an effect of acquiring an image that can accurately detect the posture of a living body part reflected in an image having high suitability as authentication biometric information.

It is a 1st example of the image obtained by image | photographing a palm. It is a 2nd example of the image obtained by image | photographing a palm. It is a functional block diagram of one Example of a biological image imaging system. It is a figure explaining the method of the determination of the imaging timing of the biological body part for the acquisition of the image for posture information detection. It is a detailed functional block diagram about the biological image imaging system of FIG. It is a figure explaining the calculation method of a biometric detection score. It is an example of the structure of an image data information table. It is a hardware structural example of a computer. It is the flowchart (the 1) which illustrated the processing content of the 1st example of a biometric image imaging control process. It is the flowchart (the 2) which illustrated the processing content of the 1st example of a biometric image imaging control process. It is a functional block diagram of another example of a living body image photographing system. It is the flowchart which illustrated the processing content of the 2nd example of biological image imaging | photography control processing.

  First, FIG. 3 will be described. FIG. 3 is a functional block diagram of an embodiment of the biological image photographing system. The biometric image capturing system 10 captures a biometric part of a person to be authenticated and acquires a biometric image used as authentication biometric information in biometric authentication.

  As illustrated in FIG. 3 using a solid line, the biological image photographing system 10 includes a photographing unit 11, a first calculating unit 12, a selecting unit 13, and an output unit 14. In addition, as illustrated in FIG. 3 using a broken line, the biological image capturing system 10 may further include a detection unit 15, an estimation unit 16, and a second calculation unit 17.

The imaging unit 11 sequentially captures a biological part at a predetermined time interval and acquires an image of the biological part.
The first calculation unit 12 calculates an index representing suitability as authentication biometric information in biometric authentication for the image based on the above-described image acquired by the imaging unit 11.

  The selection unit 13 selects a shooting environment between the first environment and the second environment at the time of shooting the next image, which is an image that the shooting unit 11 acquires next, and selects the shooting environment as the selected environment. Switch to. Here, the first environment is an environment used for acquiring an image used as authentication biometric information in biometric authentication, and the second environment is an acquisition of an image used for detecting posture information that is information on the posture of a biological part. It is the environment used for. The selection unit 13 selects the imaging environment based on the above-described index calculated by the first calculation unit 12 for the image acquired by the imaging unit 11 by imaging the living body part before the next image. .

  The output unit 14 associates the shooting environment selection information indicating the result of the selection by the selection unit 13 with the above-described next image acquired by the shooting unit 11 under the shooting environment according to the selection result. Output.

  In the biometric image capturing system 10 configured as described above, when an image acquired by the image capturing unit 11 has suitability as authentication biometric information, the image capturing unit 11 acquires the next image after the image. The image is shot in a shooting environment (second environment) for acquiring an image for detecting posture information. Therefore, the posture information detected from the next image is obtained by photographing an image acquired by the photographing unit 11 immediately before obtaining the next image (that is, an image having suitability as authentication biometric information). It can be said that the posture of the living body part is accurately represented.

  Note that the first calculation unit 12 may calculate, for example, the area value of the region of the image of the biological part shown in the image acquired by the imaging unit 11 as the above-described index. In this case, the selection unit 13 determines that the area value of the image acquired by the imaging unit 11 by imaging the biological part before imaging of the next image is a predetermined number of conditions. When at least one of them is met, the second environment is selected as the shooting environment. The selection unit 13 selects the first environment as a shooting environment when none of the predetermined plurality of conditions is met.

  Here, one of the predetermined plurality of conditions described above may be, for example, a case where the following two conditions are simultaneously satisfied. One of the two conditions represents that the aforementioned area value for the previous image is wider than a predetermined first threshold value set as a lower limit width suitable for use as authentication biometric information in biometric authentication. It is that. Note that the previous image is an image acquired by the imaging unit 11 by imaging the living body part immediately before imaging the next image. Another one of the two conditions is that the area value of the image acquired by the imaging unit 11 by imaging the biological part immediately before imaging the previous image is more than the first threshold value. It means that it is narrow.

  Further, another one of the predetermined plurality of conditions may be, for example, a case where the following two conditions are simultaneously satisfied. One of these two conditions is that the above-mentioned area value for the above-mentioned previous image is wider than a predetermined second threshold value set as an optimum width for use as authentication biometric information in biometric authentication. It is to represent. Another one of the two conditions is that the area value described above for the image acquired by the imaging unit 11 imaging the living body part immediately before imaging the previous image is the second threshold value. It means that it is narrower than that.

  Further, another one of the predetermined conditions described above may be, for example, a case where the following two conditions are simultaneously satisfied. One of these two conditions is that the above-mentioned area value for the above-mentioned previous image is narrower than a predetermined third threshold value set as a lower limit width suitable for use as authentication biometric information in biometric authentication. It represents that. Another one of the two conditions is that the area value described above for the image acquired by the imaging unit 11 by imaging the biological part immediately before imaging the previous image is the third threshold value. It is a condition that represents a wider area.

  In addition, the selection unit 13 switches the illumination for illuminating the living body part between the first illumination and the second illumination according to the result of the selection, thereby changing the environment for the imaging described above to the first environment and the first environment. You may make it switch between two environments. Here, the first illumination is illumination used for photographing an image used as authentication biometric information, and the second illumination is illumination used for photographing an image used for detecting posture information.

The detection unit 15 detects posture information about the biological part using the image acquired by the imaging unit 11 by imaging the biological part under the second environment described above.
The estimation unit 16 estimates posture information at the time when the imaging unit 11 performs imaging on the above-described next image under the above-described first environment. The estimation unit 16 performs this estimation based on the posture information detected by the detection unit 15 using the images acquired by the imaging unit 11 imaging the living body part under the second environment before and after the time point. Do.

  The detection unit 15 and the estimation unit 16 are provided in the biometric image capturing system 10, so that the next image acquired under the capturing environment (first environment) for acquiring the image for authentication biometric information can be captured. The posture information of the living body part can be obtained by estimation.

  At this time, the detection unit 15 detects, for example, the distance between the body part and the imaging position of the imaging unit 11 when the body part is imaged as the posture information. In this case, the estimation unit 16 calculates the distance between the living body part and the imaging position of the imaging unit 11 at the time when the imaging unit 11 performs imaging for the above-described next image. This distance is subjected to an interpolation calculation based on the distance detected by the detection unit 15 using the image acquired by the imaging unit 11 imaging the living body part in the second environment before and after the above-described time point. Is calculated by The estimation unit 16 uses this calculation result as a result of posture information estimation.

  The 2nd calculation part 17 calculates the parameter | index showing the height of the authentication precision estimated when biometric authentication is implemented using the above-mentioned next image as authentication biometric information. The second calculation unit 17 calculates the index using the above-described index calculated by the first calculation unit 12 for the next image acquired by the imaging unit 11 by imaging the living body part under the first environment described above. The estimation unit 16 performs the estimation based on the posture information estimated for the next image.

  When the biological image capturing system 10 includes the second calculation unit 17, the output unit 14 has a high authentication accuracy in which the index calculated by the second calculation unit 17 among the above-described next images is equal to or greater than a predetermined value. Output only those that represent. By doing in this way, only the biometric image suitable as authentication biometric information in biometric authentication can be output from the biometric image capturing system 10.

The operation of the biological image capturing system 10 configured as described above will be described in more detail.
The living body image photographing system 10 does not regularly perform photographing for detecting posture information of a living body part at a constant cycle as in the above-described technique. Instead, the timing of the imaging is determined based on an image obtained by imaging the living body part in the imaging environment for acquiring an image used as authentication biometric information by the previous imaging unit 11.

The imaging unit 11 acquires an image by imaging the living body part. The photographing unit 11 repeatedly performs this photographing at a predetermined time interval (for example, 30 frames / second equivalent to moving image photographing).
The first calculation unit 12 calculates the area of the image of the living body part shown in the image acquired by the imaging unit 11. In order to calculate this area, the first calculation unit 12 first identifies an image of a living body part included in the image.

In the present embodiment, the image of the living body part is identified from the image by examining the brightness of each pixel constituting the image.
In general, in a captured image of a living body part, a background image area that is not a living body part is dark and therefore has a relatively small pixel value. However, since an image area of a living body part is brighter than the background, the pixel value is relatively large. Therefore, in this embodiment, an appropriate threshold value is set in advance in the first calculation unit 12 (for example, when the range of possible values is 0 to 255, the pixel value 128 is set as the threshold value). And the 1st calculation part 12 estimates that the pixel whose pixel value is smaller than the threshold value in the image which the imaging | photography part 11 acquired comprises the background, and the pixel whose pixel value is larger than the threshold value is estimated. It is estimated that the image is composed of a living body image.

  Note that another method may be adopted as a method of identifying the image of the living body part by the first calculation unit 12. For example, various methods such as a method of extracting the contour of an image and a method of identifying by the color of a pixel (for example, a method of classifying pixels by skin color and other colors) can be employed. However, in this embodiment, since the imaging unit 11 repeatedly images a living body part at a short time interval, it is preferable to employ an identification method that can be processed in a short time.

  Next, the first calculation unit 12 calculates the area of the image of the living body part thus identified from the image acquired by the imaging unit 11. In this embodiment, among the pixels constituting the image, the number of pixels determined to constitute the biological part image as described above is counted, and this count result is calculated as the area value calculation result. It is said. The first calculation unit 12 uses a value normalized by dividing the count result by the area of the entire image (that is, the total number of pixels constituting the image) as the area value calculation result. May be.

  The area value calculated by the first calculation unit 12 as described above is used as an index representing the suitability as authentication biometric information in biometric authentication. In the following description, this index is referred to as “biological detection score”.

  It can be considered that the larger the value of the living body detection score, the larger the living body part appears in the image. Generally, the larger the body part appears in the image, the greater the amount of information about the body part obtained from the image. Therefore, as authentication biometric information in biometric authentication, it is preferable to use an image having a large biometric detection score. However, caution is required when the position at the time of imaging of the living body part is too close to the imaging unit 11 and a portion that is effective for biometric authentication protrudes from the image as in the image G in FIGS. 1 and 2. It is.

  As described above, based on the value of the biometric detection score calculated by the first calculation unit 12, it is determined whether or not the image acquired by the imaging unit 11 has suitability as authentication biometric information in biometric authentication. be able to.

Next, a method for determining the timing of imaging of a living body part for obtaining an image for detecting posture information will be described with reference to FIG.
In FIG. 4, in the uppermost row, examples of images obtained by the imaging unit 11 sequentially imaging the living body part (palm) are arranged from the left end to the right direction as the imaging time elapses. At the time of this imaging, the living body part initially moved in a direction approaching the imaging unit 11, but thereafter moved in a direction away from the imaging unit 11. The graph in the second row illustrates the biological detection score calculated by the first calculation unit 12 for each image arranged in the uppermost row, and the horizontal axis represents the passage of time.

  When attention is paid to the graph of the living body detection score, the living body detection score of the image A first acquired by the imaging unit 11 is a small value. The living body detection score of the image B acquired by the photographing unit 11 next to the image A is larger than that of the image A, and reaches the “detection start reference score” shown in FIG.

  The detection start reference score is a threshold that is set in advance in the selection unit 13 as a lower limit of the area of the image of the living body part that is suitable for use as authentication biometric information. It is equivalent.

  When the living body detection score for the image acquired by the imaging unit 11 exceeds the detection start reference score, the selection unit 13 performs imaging when the imaging unit 11 captures the biological part after imaging for this image. As the environment, the second environment described above is selected. Then, according to the selection result, the imaging environment is changed from the previous first environment (that is, the environment used for acquiring the image used as the authentication biometric information) to the second environment (that is, the detection of the posture information of the biological part). To the environment used to acquire the image used for More specifically, the selection unit 13 changes the illumination that illuminates the living body part from the first illumination (that is, the illumination used to capture an image used as authentication biometric information) to the second illumination according to the selection result. (That is, illumination used for capturing an image used for detecting posture information). In the present embodiment, as the first illumination, illumination that uniformly illuminates the entire body part is used, and as the second illumination, the above-described spot light illumination is used.

  In the example of FIG. 4, when the living body detection score of the image B reaches the detection start reference score, the selection unit 13 switches the illumination of the living body part from the first illumination to the second illumination. The image C is obtained by imaging the living body part by the imaging unit 11 under the illumination after the switching. Therefore, in the image C, the cross-shaped mark described above is drawn on the image. In this way, when the imaging unit 11 acquires the image C, posture information of the living body part that is extremely close to the time of acquiring the image B having the suitability as the authentication biometric information is acquired immediately after the image B. It can be obtained from image C.

  Thereafter, when the imaging unit 11 completes imaging for the image C, the selection unit 13 switches the illumination of the living body part from the second illumination to the first illumination, and returns the imaging environment from the second environment to the first environment. The imaging unit 11 repeats subsequent imaging of the body part under the first environment, and obtains images D, E, and F. The biometric detection scores for these images continue to increase, reaching the “optimum detection score” shown in FIG.

  The optimum detection score is a threshold value preset in the selection unit 13 as the area of the image of the living body part where the image acquired by the imaging unit 11 is optimal for use as authentication biometric information, and corresponds to the second threshold value described above. To do.

  When the living body detection score for the image acquired by the imaging unit 11 exceeds the optimum reference score, the selection unit 13 uses the second imaging unit 11 described above as an imaging environment when the imaging unit 11 captures a biological part. Select the environment again. Then, according to the selection result, the shooting environment is switched from the first environment to the second environment. That is, the selection unit 13 switches the illumination that illuminates the living body part from the first illumination to the second illumination according to the result of the selection.

  In the example of FIG. 4, when the living body detection score of the image F reaches the optimum reference score, the selection unit 13 switches the illumination of the living body part from the first illumination to the second illumination. The image G is acquired by the imaging unit 11 imaging a living body part under the illumination after the switching. Therefore, in the image G, the cross-shaped mark described above is drawn on the image. As the imaging unit 11 acquires the image G in this way, posture information of the living body part that is extremely close to the acquisition of the image F that is optimal as the authentication biometric information is obtained from the image G acquired immediately after the image F. be able to.

  Thereafter, when the imaging unit 11 completes imaging of the image G, the selection unit 13 switches the illumination of the living body part from the second illumination to the first illumination, and returns the imaging environment from the second environment to the first environment. The imaging unit 11 repeats subsequent imaging of the body part under the first environment, and obtains images H, I, J, and K. The biometric detection scores for these images have turned to a decreasing trend, and in the image K, the “detection end reference score” shown in FIG.

  The detection end reference score is a threshold value preset in the selection unit 13 as the lower limit of the area of the image of the biological part suitable for use as the authentication biometric information by the image acquired by the imaging unit 11, It is equivalent. Note that the detection end reference score may be the same value as the above-described detection start reference score.

  When the living body detection score for the image acquired by the imaging unit 11 falls below the detection end reference score, the selection unit 13 sets the above-described imaging environment as the imaging environment when the imaging unit 11 captures the living body part next time. Select the second environment again. Then, according to the selection result, the shooting environment is switched from the first environment to the second environment. That is, the selection unit 13 switches the illumination that illuminates the living body part from the first illumination to the second illumination according to the result of the selection.

  In the example of FIG. 4, when the living body detection score of the image K reaches the detection end reference score, the selection unit 13 switches the illumination of the living body part from the first illumination to the second illumination. The image L is acquired by the imaging unit 11 imaging a living body part under the illumination after the switching. Therefore, the above-described cross-shaped mark is drawn on the image L. In this way, when the imaging unit 11 acquires the image L, posture information of the living body part that is extremely close to the time of acquiring the image K having the suitability as the authentication biometric information is acquired immediately after the image K. It can be obtained from the image L.

  Thereafter, when the imaging unit 11 completes imaging of the image L, the selection unit 13 switches the illumination of the living body part from the second illumination to the first illumination, and returns the imaging environment from the second environment to the first environment. The imaging unit 11 performs subsequent imaging of the subsequent image M under the first environment.

  The output unit 14 outputs the image acquired by the imaging unit 11 in association with the imaging environment selection information indicating the result of selection of the imaging environment by the selection unit 13, that is, the imaging environment at the time of imaging for each image. .

  As described above, the living body image capturing system 10 in FIG. 3 performs the image capturing performed after the image capturing according to the evaluation result of the suitability as the authentication biometric information based on the area value of the image of the living body part in the acquired image. Is to be implemented for detecting body part posture information. By doing in this way, especially favorable attitude | position information can be obtained about the biological body part reflected in the biometric image which is authentication biometric information required in implementation of biometric authentication. Moreover, by doing in this way, the frequency of imaging | photography for acquisition of the image for the detection of attitude | position information can be reduced, and many images can be acquired as authentication biometric information by that much.

  When comparing the image illustrated in FIG. 4 with the image illustrated in FIG. 1 described above, in the photographing example of FIG. 1, only four images having the suitability as authentication biometric information were obtained. In the photographing example of FIG. 4, eight images having suitability as authentication biometric information can be obtained.

  The detection unit 15 detects posture information about a living body part at the time of photographing for each image, using the images C, G, and L photographed as described above. In the present embodiment, the detection unit 15 performs the detection using the above-described known technique, and based on how the spot light is reflected on the living body part when the spot light is irradiated on the living body part, Information on the distance of the part to the imaging unit 11 is obtained and used as the detection result of the posture information of the living body part.

  The estimation unit 16 obtains the posture information of the living body part at the time of photographing the images D and E photographed as described above, and the images C and G acquired for detecting the posture information immediately before and immediately after the photographing. It estimates based on the attitude | position information which the detection part 15 detected using. In addition, the estimation unit 16 acquires the posture information of the living body part at the time of photographing the images H, I, and J photographed as described above for the detection of the posture information immediately before and after the photographing. Estimation is performed based on the posture information detected by the detection unit 15 using the images G and L.

  In the present embodiment, the estimation unit 16 detects the distance from the imaging unit 11 of the biological part at the time of imaging the images D and E, and the imaging unit 11 of the biological part at the time of imaging the images C and G detected by the detection unit 15. This is estimated by performing an interpolation calculation based on the distance from. In addition, the estimation unit 16 detects the distance from the imaging unit 11 of the biological part at the time of imaging the images H, I, and J, and the imaging unit 11 of the biological part at the time of imaging the images G and L detected by the detection unit 15. This is estimated by performing an interpolation calculation based on the distance from.

  The third graph in FIG. 4 represents the relationship between the lapse of the imaging time of the biological part by the imaging unit 11 and the posture information of the biological part. The horizontal axis of this graph represents the passage of the imaging time of the biological part by the imaging unit 11, and the vertical axis represents the posture information (distance from the imaging part 11 of the biological part). Points corresponding to the posture information of the living body part (distance from the imaging unit 11 of the living body part) detected by the detection unit 15 from the images C, G, and L are plotted on this graph. In addition, points corresponding to the posture information of the living body part at the time of imaging for the images D, E, H, I, and J estimated by the estimation unit 16 by the interpolation calculation are also plotted on or near this graph.

  As described above, the estimation unit 16 performs the above-described estimation on the posture information of the living body part at the time of imaging for the images D, E, H, I, and J for which the posture information is not detected by the detection unit 15. Earn by When the detection unit 15 and the estimation unit 16 obtain the posture information of the living body part at the time of capturing each image, the output unit 14 outputs the posture information in association with each image. Good. If the posture information obtained in this way is used for biometric information, it can be expected to improve the accuracy of biometric authentication.

  As described above, the biometric image capturing system 10 in FIG. 1 uses the accurate posture information about the biological part shown in the biometric image, which is the vital authentication biometric information in performing biometric authentication, for other biometric images. The posture information of the living body part is estimated. Therefore, it is possible to obtain an estimation result that is relatively close to true posture information about these biological images.

  For example, as described above, the imaging of the image illustrated in FIG. 2 is performed by performing imaging for an image for detecting posture information of a living body part at a low frequency that is a constant cycle. In the case of FIG. 2, the images for detecting the posture information are images D and G. When the posture information of other biological images is estimated based on the posture information obtained from these images, for example, in the images B, F, K, L, etc., high estimation accuracy cannot be expected for the posture information. it is obvious. On the other hand, in the imaging of the image illustrated in FIG. 4, good posture information estimation accuracy can be expected for any biological image.

  In addition, instead of detecting the posture information for the images B, F, and K in FIG. 4 from the images C, G, and L, respectively, the estimation unit 16 is based on the posture information from the images C, G, and L. You may make it estimate and acquire.

  By the way, as the authentication biometric information in biometric authentication, it is preferable to use a biometric image having a large biometric detection score to a certain extent, but if it is excessively large, the suitability as authentication biometric information decreases. This is because the posture of the living body part shown in the living body image also affects its suitability. Therefore, biometric authentication conformity, which is an index representing the level of authentication accuracy estimated when biometric authentication is performed using the biometric image as authentication biometric information based on the biometric detection score and posture information about the biometric image. A score may be calculated. The second calculation unit 17 calculates the biometric authentication conformity score.

  In the present embodiment, the second calculation unit 17 firstly sets “posture information optimal for biometric authentication” as shown in the third graph in FIG. The amount of deviation from the “right posture value (distance)” is calculated. Note that the optimum posture value (distance) for biometric authentication is a value set in advance in the second calculation unit 17. Next, the second calculation unit 17 performs a calculation for combining the biometric detection score and the deviation amount for each biometric image after giving a predetermined weighting as necessary. The value obtained in this way is used as a biometric matching score.

  The graph in the fourth row in FIG. 4 illustrates the biometric authentication conformity score obtained for each image. In this example of the graph, the biometric authentication conformity scores of the image E and the image I indicate high values. If biometric authentication is performed using these as authentication biometric information, extremely good authentication accuracy can be expected.

  When the biometric authentication conformity score for each image is obtained by the second calculation unit 17, the output unit 14 outputs the biometric authentication conformance score with a predetermined value instead of outputting each image and the shooting environment selection information in association with each other. Only an image representing the high authentication accuracy is output. By performing biometric authentication using the biometric image output in this way as authentication biometric information, it can be expected that the time required for biometric authentication will be shortened and that very good authentication accuracy will be obtained.

  Next, FIG. 5 will be described. FIG. 5 is a detailed functional block diagram of the biological image photographing system 10 of FIG. The biometric image capturing system 10 captures a biometric part of the person to be authenticated, acquires a biometric image to be used as authentication biometric information in biometric authentication, and sends the obtained biometric image to the biometric authentication device 20.

  The correspondence between the functional blocks illustrated in FIG. 5 and the functional blocks illustrated in FIG. 3 will be described. The image capturing unit 31 and the image storage unit 32 correspond to the capturing unit 11, and the living body detection score calculating unit 33. Corresponds to the first calculation unit 12. Further, the posture photographing condition storage unit 34, the posture photographing timing determination unit 35, the illumination unit 36, and the illumination control unit 37 correspond to the selection unit 13, and the biometric authentication compatible image selection unit 38 and the image transmission unit 39 correspond to the output unit 14. Correspond. The posture information calculation unit 41 and the posture information storage unit 42 correspond to the detection unit 15, the posture information interpolation unit 43 corresponds to the estimation unit 16, and the biometric authentication suitability score calculation unit 44 corresponds to the second calculation unit 17. .

  The image capturing unit 31 is an image capturing device that sequentially captures a living body part at predetermined time intervals and acquires an image of the living body part. The image capturing unit 31 is a camera configured using an image sensor unit using, for example, a CMOS (Complementary Metal Oxide Semiconductor) or a CCD (Charge Coupled Device).

  The image storage unit 32 is a storage unit that sequentially stores images acquired by the image capturing unit 31. The storage capacity of the image storage unit 32 is arbitrary, but a capacity sufficient to store an appropriate number of images according to the type of biometric authentication and the usage pattern is prepared.

  Each time the image storage unit 32 stores the image acquired by the image capturing unit 31, the biological detection score calculation unit 33 reads the stored image and calculates the area of the image of the biological part shown in the image. Then, the obtained area value is output as a living body detection score. The calculation method of the biological detection score by the biological detection score calculation unit 33 according to the present embodiment will be described with reference to FIG.

  The biometric detection score calculation unit 33 first reads the acquired image P newly stored in the image storage unit 32, and converts the constituent pixels into white and black based on the result of the size comparison between the pixel value and a predetermined threshold value. The binarized image Q is obtained by binarization. The biological detection score calculation unit 33 counts the number of white pixels in the binarized image Q (that is, the pixel constituting the image of the biological part in the acquired image P). The living body detection score calculation unit 33 outputs the counting result as a living body detection score.

If there is a margin in the calculation performance, the calculation of the area of the image of the living body part in the acquired image P by the living body detection score calculation unit 33 may be performed by a more accurate method.
The posture imaging condition storage unit 34 sets and stores in advance a condition for determining whether or not the imaging of the living body part to be performed next by the image capturing unit 31 is for acquiring an image for detecting posture information. It is a storage unit. Specifically, the conditions stored in the posture photographing condition storage unit 34 are the above-described detection start reference score, optimum detection score, and detection end reference score.

  The posture imaging timing determination unit 35 determines whether or not the biological detection score calculated by the biological detection score calculation unit 33 matches the condition stored in the posture imaging condition storage unit 34, and the determination result. Is output to the illumination control unit 37.

  The illumination unit 36 is illumination that illuminates a living body part that is imaged by the image capturing unit 31. The illumination unit 36 has two types of illumination, ie, illumination that uniformly illuminates the entire body part as the first illumination described above, and illumination of the spot light described above as the second illumination described above. Two types of illumination can be switched. In addition, visible light may be used for these illuminations, and light other than visible light, such as near infrared rays, may be used.

  The illumination control unit 37 controls which of the two types of illumination the illumination unit 36 has to illuminate the living body part based on the determination result by the posture imaging timing determination unit 35. More specifically, the illumination control unit 37 normally causes the illumination unit 36 to perform illumination of the living body part using the first illumination described above. When the posture imaging timing determination unit 35 determines that the living body detection score matches the condition stored in the posture imaging condition storage unit 34, the lighting unit 36 is controlled to illuminate the biological part. Switch to the one using the second illumination described above. After that, when the image capturing unit 31 finishes capturing the living body part under the second illumination, the illumination control unit 37 controls the illumination unit 36 to use the first illumination for the illumination of the living body part. To return.

  The biometric matching image selection unit 38 sequentially reads out the images stored in the image storage unit 32 and outputs them to the image transmission unit 39. When the biometric authentication conformity score calculation unit 44 calculates the biometric authentication conformity score, the image selected based on the biometric authentication conformance score is read from the image storage unit 32 and output to the image transmission unit 39. To do.

The image transmission unit 39 transmits the image sent from the biometric authentication compatible image selection unit 38 and sends it to the biometric authentication device 20.
The biometric authentication device 20 performs an image correction process on the image received from the biometric image capturing system 10 based on posture information about the image. Then, verification is performed using the corrected image as authentication biometric information, and it is confirmed whether or not it matches the preregistered user's registered biometric information.

  The posture information calculation unit 41 reads an image acquired by the image photographing unit 31 by photographing a biological part under the second illumination from the image storage unit 32, and detects posture information about the biological part using the image. To do. More specifically, the posture information calculation unit 41 calculates the distance of the living body part from the image capturing unit 31 based on how the spot light is reflected on the living body part using the known technique described above. Thus, the detection result of the posture information of the living body part is used. Further, the posture information calculation unit 41 may further obtain, for example, angle value information indicating the inclination of the living body part as the other posture information.

The posture information storage unit 42 stores the posture information calculated by the posture information calculation unit 41 together with information for identifying from which image the posture information is detected.
The posture information interpolation unit 43 performs an interpolation calculation based on the posture information stored in the posture information storage unit 42, and estimates posture information of a living body part at the time of photographing an image acquired by the image photographing unit 31 under the first illumination. To do.

The biometric authentication conformity score calculation unit 44 is based on the biometric authentication score calculated by the biometric detection score calculation unit 33 and the posture information calculated by the posture information calculation unit 41 and the posture information interpolation unit 43 for each image. The score is calculated and output to the biometric matching image selection unit 38. As a calculation formula for this biometric authentication conformity score, a biometric authentication is actually performed using sample images in which the biometric part is shown in various postures, and a calculation formula is obtained such that the score increases as the authentication accuracy increases. As this calculation formula, for example, the following formula can be adopted.
Biometric authentication conformity score = biometric detection score / abs (attitude information-optimum attitude value)

  In the above equation, “posture information” is the distance from the imaging unit 11 of the biological part, and “optimal posture value” is “optimal for biometric authentication” shown in the third graph in FIG. “Attitude value (distance)”. “Abs ()” represents a function that outputs the absolute value of the value in parentheses.

  The above formula is very simple. The larger the biometric detection score (the area of the image of the body part), the more suitable for biometric authentication, and the posture information closer to the optimum posture value is suitable for biometric authentication. This is a formula that can be processed very simply and at high speed. In this equation, the correlation between the living body detection score and the posture value is not particularly considered.

  Note that the biometric authentication suitability score calculation unit 44 may obtain a score by referring to a table created based on an experiment instead of using a mathematical formula in order to obtain the biometric authentication suitability score.

  When the biometric authentication conformity score is received from the biometric authentication conformity score calculation unit 44, the biometric authentication conformity image selection unit 38 has an authentication accuracy with a biometric authentication conformity score of a predetermined value or more among images read from the image storage unit 32. Only the image representing the height of the image is output to the image transmission unit 39. Then, the image transmission unit 39 transmits the image sent from the biometric matching image selection unit 38 and sends it to the biometric authentication device 20.

  Note that the image transmission unit 39 may transmit a biometric detection score and a biometric authentication matching score for an image to be transmitted, as necessary. Moreover, you may make it transmit as needed also about the image for the detection of the posture information about the said biological body part which the image imaging part 31 image | photographed and acquired under the 2nd illumination.

  In addition, information representing the determination result by the posture shooting timing determination unit 35 may be further stored in the image storage unit 32. Further, the biometric detection score acquired by the biometric detection score calculation unit 33, the posture information acquired by the posture information calculation unit 41 and the posture information interpolation unit 43, and the biometric authentication conformity score calculation unit 44 are acquired in the image storage unit 32. A biometric score may be stored.

Here, FIG. 7 will be described. FIG. 7 illustrates an example of the structure of the image data information table stored in the image storage unit 32.
The table of FIG. 7 includes items of “imaging serial number”, “type”, “biometric detection score”, “detected posture information”, “interpolated posture information”, and “biometric authentication conformity score”.

  The “shooting serial number” is a number indicating the shooting order of each image. By this number, the various types of information shown in the image data information table and the image shooting unit 31 stored in the image storage unit 32 are acquired. Are associated with the image data.

  “Type” is information indicating the determination result of the posture shooting timing determination unit 35 for the image specified by “shooting serial number”, that is, information indicating the shooting environment at the time of shooting for this image. Here, the “biological image” indicates that this image was taken by illuminating the living body part using the first illumination used for taking an image for authentication biometric information. In addition, the “posture image” represents that this image was taken by illuminating the living body part using the second illumination used for imaging for detecting posture information of the living body part. Yes.

“Biometric detection score” is the value of the biological detection score acquired by the biological detection score calculation unit 33 for an image whose “type” is “biological image”.
“Detected posture information” is posture information acquired by the posture information calculation unit 41 from an image whose “type” is “posture image”, and is a distance from the image photographing unit 31 of the living body part at the time of photographing the image. .

  The “interpolation posture information” is an estimation result of posture information acquired by the posture information interpolation unit 43 by interpolation calculation for an image whose “type” is “biological image”, and an image photographing unit of the biological part at the time of photographing the image It is the distance from 31. In the table example of FIG. 7, for an image whose “type” is “posture image”, the same value as “detected posture information” is stored as “interpolation posture information”.

“Biometric authentication suitability score” is the value of the biometric authentication suitability score acquired by the biometric authentication suitability score calculation unit 44 for an image whose “type” is “biometric image”.
When such an image data information table is stored in the image storage unit 32, the image transmission unit 39 reads information about the image from the table and transmits it together with the image when transmitting the image. You may do it.

The biological image photographing system 10 in FIG. 5 operates as described above.
Note that some components of the biological image capturing system 10 illustrated in FIGS. 3 and 5 can be configured using a computer having a standard configuration.

Here, FIG. 8 will be described. FIG. 8 illustrates a hardware configuration example of a computer.
The computer 50 includes an MPU 51, a ROM 52, a RAM 53, a hard disk device 54, an input device 55, a display device 56, an interface device 57, and a recording medium drive device 58. These components are connected via a bus line 59, and various data can be exchanged under the management of the MPU 51.

An MPU (Micro Processing Unit) 51 is an arithmetic processing unit that controls the operation of the entire computer 50.
A ROM (Read Only Memory) 52 is a read-only semiconductor memory in which a predetermined basic control program is recorded in advance. The MPU 51 reads out and executes this basic control program when the computer 50 is activated, thereby enabling operation control of each component of the computer 50.

  A RAM (Random Access Memory) 53 is a semiconductor memory that can be written and read at any time and used as a working storage area as needed when the MPU 51 executes various control programs.

  The hard disk device 54 is a storage device that stores various control programs executed by the MPU 51 and various data. The MPU 51 can perform various control processes by reading and executing a predetermined control program stored in the hard disk device 54.

  The input device 55 is, for example, a keyboard device or a mouse device. For example, when operated by the administrator of the biological image capturing system 10, the input device 55 acquires input of various information from the administrator associated with the operation content, The acquired input information is sent to the MPU 51.

The display device 56 is, for example, a liquid crystal display, and displays various texts and images according to display data sent from the MPU 51.
The interface device 57 manages the exchange of various information with various devices connected to the computer 50.

  The recording medium driving device 58 is a device that reads various control programs and data recorded on the portable recording medium 60. The MPU 51 can read out and execute a predetermined control program recorded on the portable recording medium 60 via the recording medium driving device 58 to perform various control processes described later. As the portable recording medium 60, for example, a flash memory equipped with a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a USB (Universal Serial Bus) standard connector. and so on.

  In order to configure some components of the biological image capturing system 10 using such a computer 50, for example, a control program for causing the MPU 51 to perform a biological image capturing control process described below is created. The created control program is stored in advance in the hard disk device 54 or the portable recording medium 60. In this program, for example, the hard disk device 54 is caused to function as the image storage unit 32, the posture shooting condition storage unit 34, and the posture information storage unit 42. The interface device 57 of the computer 50 is connected to the image capturing unit 31 and the illumination unit 36, and the computer 50 controls the image capturing unit 31 and the illumination unit 36 to perform imaging of a living body part. The captured image is stored in the computer 50. The biometric authentication device 20 is also connected to the interface device 57 so that various images and information can be sent to the biometric authentication device 20. Then, a predetermined instruction is given to the MPU 51 to read and execute this control program. By doing so, it is possible to provide the computer 50 with the functions that the components of the biological image capturing system 10 have.

  Next, FIGS. 9 and 10 will be described. 9 and 10 are flowcharts illustrating a first example of the processing content of the biological image capturing control processing. A first example of this control processing is performed by the biological image photographing system 10 in FIG.

9 and 10, the biometric image capturing control process is a process from S101 to S112, and the process of S113 is a biometric authentication process performed by the biometric authentication device 20.
When this control process is started, first, in S101 of FIG. 9, the illumination control is performed so that the illumination unit 36 performs illumination of the living body part using the first illumination described above, which uniformly illuminates the entire living body part. Performed by the unit 37.

Next, in S <b> 102, the image capturing unit 31 captures a living body part under the first illumination, and performs processing for storing the obtained image in the image storage unit 32.
Next, in S103, a process of reading the image stored in the image storage unit 32 by the process of S102, and obtaining a living body detection score for the image by calculating the area of the image of the living body part shown in the image. The living body detection score calculation unit 33 performs.

  Next, in S104, the posture detection processing is performed to determine whether the living body detection score obtained by the processing in S103 matches any of the conditions stored in advance in the posture shooting condition storage unit 34. The imaging timing determination unit 35 performs this. As described above, the condition stored in the posture shooting condition storage unit 34 is a condition used as a criterion for determining whether or not to perform shooting for acquiring an image for detecting posture information. Are the above-described detection start reference score, optimum detection score, and detection end reference score.

  In the determination process of S104, when it is determined that the living body detection score matches any of the conditions (when the determination result is Yes), the process proceeds to S105. On the other hand, when it is determined that the living body detection score does not match any of the conditions (when the determination result is No), the process returns to S101 and the above-described process is executed again.

Next, in S <b> 105, the illumination control unit 37 performs a process of causing the illumination unit 36 to perform illumination of the living body part using the second illumination described above, which illuminates the illumination of the spot light described above.
Next, in S106, the imaging unit 31 performs imaging of the living body part under the second illumination, and performs processing for storing the obtained image in the image storage unit 32.

  Next, in S107, the image stored in the image storage unit 32 by the process of S106 is read, and the posture information calculation unit 41 detects posture information about the living body part using the image, and the obtained posture is obtained. Processing for storing the information in the posture information storage unit 42 is performed.

  Next, in S108, whether the number of posture information detection images stored in the image storage unit 32 and acquired in S106 has reached a predetermined number (at least two). The posture information calculation unit 41 performs processing for determining whether or not. Here, when it is determined that the number of the images has reached the predetermined number (when the determination result is Yes), the process proceeds to S109 (FIG. 10). On the other hand, when it is determined that the number of images is still less than the predetermined number (when the determination result is No), the process returns to S101 and the above-described process is performed again.

  The process proceeds to FIG. 10, and in S109, the attitude information stored in the attitude information storage unit 42 by the process of S107 is read out, and an interpolation operation based on the attitude information is performed to obtain the acquired image under the first illumination. The posture information interpolation unit 43 performs processing for estimating posture information.

  Next, in S110, the process of calculating the biometric authentication suitability score as described above is performed based on the biometric detection score obtained by the process of S103 and the posture information obtained by the processes of S107 and S109 for each image. The score calculation unit 44 performs this.

Next, in S111, an image is read from the image storage unit 32, and a process of selecting only an image representing a high authentication accuracy with a biometric authentication conformity score equal to or higher than a predetermined value is performed. Next, in S112, the image transmission unit 39 performs a process of transmitting the image selected in the process of S111 and the posture information about the image to the biometric authentication device 20. The process up to this point is the biological image capturing control process.

  Next, in S113, the biometric authentication device 20 performs biometric authentication processing. In this process, the biometric authentication device 20 first performs a process of receiving various types of information sent from the biometric image capturing system 10 in the process of S112. Then, an image correction process is performed on the image among them based on the posture information about the image. Then, verification is performed using the corrected image as authentication biometric information, and it is confirmed whether or not it matches the preregistered user's registered biometric information.

When the process of S113 is completed, the processes of FIGS. 9 and 10 are finished.
In the biometric authentication process of S113, if it is determined that the authentication biometric information and the registered biometric information do not match, the biometric image capturing system 10 repeatedly executes the biometric image capturing control process described above a predetermined number of times. May be. In this case, the biometric authentication device 20 performs the biometric authentication process every time an image as authentication biometric information is newly obtained by repeating this biometric image capturing control process. At this time, the biometric authentication device 20 makes an authentication result that the identity has been confirmed if both the authentication biometric information and the registered biometric information match at least once in the repetition, and both must match in all the repetitions. In this case, the authentication result indicates that the identity has not been verified.

  By operating as described above, the biometric image capturing system 10 of the present embodiment captures a biometric part of the person to be authenticated, and acquires a biometric image used as authentication biometric information in biometric authentication.

  By the way, the biometric authentication apparatus 20 may perform the selection based on the biometric matching score for the image used as the authentication biometric information performed in the biometric image capturing system 10 of FIG. By doing in this way, the structure of the biological image imaging system 10 can be simplified.

Here, FIG. 11 will be described. FIG. 11 is a functional block diagram of another embodiment of the biological image photographing system.
In the biometric image capturing system 70 of FIG. 11, functional blocks having the same functions as those provided in the biometric image capturing system 10 of FIG. Of the descriptions of these functional blocks, descriptions of the same functions as those of the biological image photographing system 10 are omitted here.

  The biometric image capturing system 70 in FIG. 11 is different from the biometric image capturing system 10 in FIG. 5 in that it includes a posture information calculation unit 41, a posture information storage unit 42, a posture information interpolation unit 43, a biometric authentication matching score calculation unit 44, and a biometric authentication. Each functional block of the suitable image selection unit 38 is deleted. Therefore, each functional block is provided in the biometric authentication device 80 in FIG. 11 together with the biometric authentication processing function provided in the biometric authentication device 20 in FIG.

  In the living body image capturing system 70 of FIG. 11, the image storage unit 32 is associated with an image captured by the image capturing unit 31 under illumination switched based on the determination result by the posture capturing timing determination unit 35. Thus, information representing the determination result is further stored. In addition, the image transmission unit 39 sequentially reads and transmits the images stored in the image storage unit 32 together with the determination result information of the posture shooting timing determination unit 35 associated with the image. Based on these images and the information of the determination result, the biometric authentication device 80 calculates posture information, estimates posture information, calculates a biometric authentication suitability score, and selects an image suitable for biometric authentication. Biometric authentication is performed using an image as authentication biometric information.

  Next, FIG. 12 will be described. 9 and 10 are flowcharts illustrating a second example of the processing content of the biological image capturing control processing. A second example of this control process is performed by the biological image photographing system 70 of FIG.

In the process of FIG. 12, the biometric image capturing control process is a process from S201 to S208, and the process of S209 is a biometric authentication process performed by the biometric authentication device 80.
When this control process is started, first, in S201, the illumination control unit 37 performs a process for causing the illumination unit 36 to illuminate the entire body part uniformly using the first illumination described above. Do.

  Next, in S202, the image capturing unit 31 performs imaging of the living body part under the first illumination, and the obtained image and information on the imaging environment when the image is obtained are information at the time of the imaging. Processing for storing the selection information of the illumination (that is, the first illumination) in the image storage unit 32 is performed.

  Next, in S203, a process of reading the image stored in the image storage unit 32 by the process of S202, and obtaining a living body detection score for the image by calculating the area of the image of the living body part reflected in the image. The living body detection score calculation unit 33 performs.

  Next, in S204, the posture detection processing is performed to determine whether or not the living body detection score obtained by the processing in S203 matches any of the conditions stored in the posture shooting condition storage unit 34 in advance. The imaging timing determination unit 35 performs this. As described above, the condition stored in the posture shooting condition storage unit 34 is a condition used as a criterion for determining whether or not to perform shooting for acquiring an image for detecting posture information. Are the above-described detection start reference score, optimum detection score, and detection end reference score.

  In the determination process of S204, when it is determined that the living body detection score matches any of the conditions (when the determination result is Yes), the process proceeds to S205. On the other hand, when it is determined that the biometric detection score does not match any of the conditions (when the determination result is No), the process proceeds to S207.

Next, in S205, the illumination control unit 37 performs processing for causing the illumination unit 36 to illuminate the living body part using the second illumination described above, which illuminates the spot light illumination described above.
Next, in S206, the image capturing unit 31 performs imaging of the living body part under the second illumination, and the obtained image and information of the imaging environment when the image is obtained are information at the time of the imaging. Processing for storing the selection information of the illumination (that is, the second illumination) in the image storage unit 32 is performed.

  Next, in S207, a process for determining whether a predetermined number or more of biometric detection scores obtained for each image by the process of S203 is equal to or more than the lower limit of values suitable for use as authentication biometric information is performed. The transmission unit 39 performs this. Here, when it is determined that a predetermined number of biometric detection scores satisfying this condition have been obtained (when the determination result is Yes), the process proceeds to S208. On the other hand, when it is determined that the number of biometric detection scores that match this condition is less than the predetermined number (when the determination result is Yes), the process returns to S201, and the above-described process is performed again.

  In S208, a process of sequentially reading and transmitting the images stored in the image storage unit 32 together with the illumination selection information associated with the image (that is, information on the determination result of the posture shooting timing determination unit 35). Performed by the image transmission unit 39. The process up to this point is the biological image capturing control process.

  Next, in S209, the biometric authentication device 80 performs biometric authentication processing. In this process, the biometric authentication device 80 first performs a process of receiving various types of information sent from the biometric image capturing system 70 in the process of S208. Next, based on the received image and information on the determination result, calculation of posture information, estimation of posture information, calculation of a biometric authentication suitability score, and selection of an image suitable for biometric authentication are performed. Then, an image correction process is performed on the selected image based on the posture information about the image. Then, verification is performed using the corrected image as authentication biometric information, and it is confirmed whether or not it matches the preregistered user's registered biometric information.

When the process of S209 described above is completed, the process of FIG.
In the biometric authentication process in S209, if it is determined that the authentication biometric information and the registered biometric information do not match, the biometric image capturing system 70 repeatedly executes the above-described biometric image capturing control process a predetermined number of times. May be. In this case, the biometric authentication device 80 performs the biometric authentication process every time an image as authentication biometric information is newly obtained by repeating the biometric image capturing control process. At this time, the biometric authentication device 80, if both the authentication biometric information and the registered biometric information match at least once, the authentication result indicates that the identity has been confirmed, and both must match in all the repetitions. In this case, the authentication result indicates that the identity has not been verified.

  The biometric image capturing system 70 of the present embodiment operates as described above, captures a biometric part of the person to be authenticated, and acquires a biometric image used as authentication biometric information in biometric authentication.

DESCRIPTION OF SYMBOLS 10, 70 Living body imaging | photography system 11 Imaging | photography part 12 1st calculation part 13 Selection part 14 Output part 15 Detection part 16 Estimation part 17 2nd calculation part 20, 80 Biometric authentication apparatus 31 Image imaging part 32 Image memory | storage part 33 Biometric detection score Calculation unit 34 Attitude imaging condition storage unit 35 Attitude imaging timing determination unit 36 Illumination unit 37 Illumination control unit 38 Biometric authentication compatible image selection unit 39 Image transmission unit 41 Attitude information calculation unit 42 Attitude information storage unit 43 Attitude information interpolation unit 44 Biometric authentication Compliance score calculation unit 50 computer 51 MPU
52 ROM
53 RAM
54 hard disk device 55 input device 56 display device 57 interface device 58 recording medium drive device 59 bus line 60 portable recording medium

Claims (11)

An imaging unit that sequentially images a living body part at predetermined time intervals to acquire an image of the living body part;
Based on the image acquired by the imaging unit, a first calculation unit that calculates an index representing the suitability of the image as authentication biometric information in biometric authentication;
The shooting environment at the time of shooting the next image, which is the image to be acquired next by the imaging unit, is described with respect to the image acquired by the imaging unit by imaging the living body part before the next image. Based on the index calculated by one calculation unit, the first environment used for acquiring an image used as authentication biometric information in biometric authentication, and used for acquiring an image used for detecting posture information that is posture information of the living body part A selection unit that selects between the second environment and the shooting environment to the selected environment;
An output unit that outputs the shooting environment selection information representing the result of the selection by the selection unit and the next image acquired by the shooting unit under the shooting environment according to the selection result;
A living body image photographing system comprising: The first calculation unit calculates, as the index, an area value of a region of the image of the living body part reflected in the image acquired by the imaging unit;
In the selection unit, the area value of the image acquired by the imaging unit imaging the living body part before imaging the next image is set to at least one of a plurality of predetermined conditions. When the two conditions match, the second environment is selected as the shooting environment, and when none of the predetermined plurality of conditions is met, the first environment is selected as the shooting environment.
The living body image photographing system according to claim 1.   One of the predetermined conditions is that the area value of the previous image, which is an image acquired by the imaging unit imaging the biological part immediately before imaging the next image, This means that the imaging unit is wider than a predetermined first threshold value set as a lower limit width suitable for use as authentication biometric information in authentication, and the imaging unit immediately before imaging the previous image The living body image photographing system according to claim 2, wherein the area value of the image acquired by photographing is expressed as a condition indicating that the area value is narrower than the first threshold value.   One of the predetermined conditions is that the area value of the previous image, which is an image acquired by the imaging unit imaging the biological part immediately before imaging the next image, This means that the image is larger than a predetermined second threshold value set as an optimum area for use as authentication biometric information in authentication, and the imaging unit detects the biological site immediately before imaging the previous image. The living body image photographing system according to claim 2 or 3, wherein the area value of the image obtained by photographing represents that the area value is narrower than the second threshold value.   One of the predetermined conditions is that the area value of the previous image, which is an image acquired by the imaging unit imaging the biological part immediately before imaging the next image, It represents that it is narrower than a predetermined third threshold value set as the lower limit width suitable for use as authentication biometric information in authentication, and the imaging unit immediately before imaging the previous image 5. The condition according to claim 2, wherein the area value of the image obtained by photographing the image is larger than the third threshold value. 5. The biological image photographing system described.   The selection unit uses illumination for illuminating the living body part, first illumination used for photographing an image used as the authentication biological information, and photographing of an image used for detecting the posture information, according to the selection result. 6. The environment of the photographing is switched between the first environment and the second environment by switching between the second illumination and the second illumination. 6. Biological imaging system. A detection unit for detecting posture information about the living body part using the image acquired by the imaging unit shooting the living body part under the second environment;
The posture information is estimated at the time when the image capturing unit has captured the next image under the first environment, and the image capturing unit performs the living body under the second environment before and after the time point. An estimation unit that performs based on posture information detected by the detection unit using the image acquired by imaging a site;
The living body image photographing system according to any one of claims 1 to 6, further comprising: The detection unit detects, as the posture information, a distance between the living body part and an imaging position of the imaging unit when the living body part is imaged,
The estimation unit performs interpolation based on the distance detected by the detection unit using the image acquired by the imaging unit imaging the living body part under the second environment before and after the time point. By calculating, the distance between the living body part and the imaging position of the imaging unit at the time when the imaging unit performed imaging for the next image is calculated, and the calculation result is used to estimate the posture information. As a result,
The living body image photographing system according to claim 7. The index calculated by the first calculation unit for the next image acquired by the imaging unit imaging the biological part under the first environment, and the posture estimated by the estimation unit for the next image And a second calculation unit that calculates an index representing a level of authentication accuracy estimated when the biometric authentication is performed using the next image as the authentication biometric information based on the information,
Instead of outputting the shooting environment selection information and the next image in association with each other, the output unit has a high authentication accuracy in which the index calculated by the second calculation unit in the next image is a predetermined value or more. Output only what represents
The living body image photographing system according to claim 7 or 8, characterized in that. Based on the image acquired by the imaging device that sequentially captures the biological part at predetermined time intervals and acquires the image of the biological part, an index representing the suitability of the image as authentication biometric information in biometric authentication is calculated. ,
The shooting environment at the time of shooting the next image, which is the next image acquired by the imaging device, the image about the image acquired by imaging the living body part before the next image. Based on the index, between a first environment used for acquiring an image used as authentication biometric information in biometric authentication and a second environment used for acquiring an image used for detecting posture information that is posture information of the living body part Select with
Switch the shooting environment to the selected environment,
Shooting environment selection information representing the selection result and the next image acquired by the shooting device under the shooting environment related to the selection result are output in association with each other.
The biological image acquisition method characterized by the above-mentioned. Based on the image acquired by the imaging device that sequentially captures the biological part at predetermined time intervals and acquires the image of the biological part, an index representing the suitability of the image as authentication biometric information in biometric authentication is calculated. ,
The shooting environment at the time of shooting the next image, which is the next image acquired by the imaging device, the image about the image acquired by imaging the living body part before the next image. Based on the index, between a first environment used for acquiring an image used as authentication biometric information in biometric authentication and a second environment used for acquiring an image used for detecting posture information that is posture information of the living body part Select with
Switch the shooting environment to the selected environment,
Shooting environment selection information representing the selection result and the next image acquired by the shooting device under the shooting environment related to the selection result are output in association with each other.
A program that causes a computer to execute processing.