Iris imaging system, iris imaging method and computer program

Abstract

To pick up an iris image with a high resolution in accordance with brightness.SOLUTION: An iris imaging system includes: imaging means for picking up an image including the iris of a living body; illuminance obtaining means for obtaining brightness when the image is picked up; executing means for determining an appropriate imaging distance based on the brightness when the image is picked up; and position guiding means for guiding a standing position for the living body so as to accomplish the imaging distance. Such an iris imaging system enables a pick-up of an appropriate iris image even if the size of the iris is changing.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to the technical fields of an iris imaging system, an iris imaging method, and a computer program for imaging the iris of a living subject. [Background technology]

[0002] As an example of this type of system, a system that captures an image of a living body's iris for iris authentication is known. For example, Patent Document 1 discloses a technology that adjusts the brightness value of a display according to the pupil size. Patent Document 2 discloses a technology that guides a user to an appropriate position when capturing an iris image. Patent Document 3 discloses a technology that performs high-resolution processing on an iris image. Patent Document 4 discloses a technology that completes control related to focus and exposure inside a solid-state imaging device. Patent Document 5 discloses changing the image size and focus depending on the individual iris structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-073369 A [Patent Document 2] International Publication No. 2009 / 016846 [Patent Document 3] JP 2020-071627 A [Patent Document 4] JP 2018-185749 A [Patent Document 5] Special Publication No. 2017-502366 Summary of the Invention [Problem to be solved by the invention]

[0004] This disclosure has been made in consideration of, for example, the above cited documents, and aims to provide an iris imaging system, an iris imaging method, and a computer program capable of appropriately capturing an image of the iris. [Means for solving the problem]

[0005] One aspect of the iris imaging system disclosed herein comprises an imaging means for capturing an image including the iris of a living body, an illuminance acquisition means for acquiring the brightness when the image is captured, an execution means for determining an appropriate imaging distance based on the brightness when the image is captured, and a standing position guidance means for guiding the living body to a standing position that is the imaging distance.

[0006] One aspect of the iris imaging method disclosed herein is an iris imaging method that uses an imaging means to capture an image including the iris of a living body, and obtains the brightness when the image is captured, determines an appropriate imaging distance based on the brightness when the image is captured, and guides the living body to a standing position that achieves the imaging distance.

[0007] One aspect of the computer program of this disclosure is an iris imaging method that uses an imaging means to capture an image including the iris of a living body, and operates a computer to obtain brightness when the image is captured, determine an appropriate imaging distance based on the brightness when the image is captured, and guide the living body to a standing position that achieves the imaging distance. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a hardware configuration of an iris imaging system according to a first embodiment. [Diagram 2] 1 is a block diagram showing a functional configuration of an iris imaging system according to a first embodiment. [Diagram 3] 1A and 1B are conceptual diagrams showing examples in which the pupil is too small and too large. [Figure 4] 4 is a flowchart showing the flow of operations of the iris imaging system according to the first embodiment. [Diagram 5] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to a modified example of the first embodiment. [Figure 6] 10 is a flowchart showing a flow of operations of the iris image capturing system according to a modified example of the first embodiment. [Figure 7] 1 is a graph (part 1) showing the relationship between brightness and imaging distance. [Figure 8] 2 is a graph showing the relationship between brightness and imaging distance (part 2). [Figure 9] 13 is a graph (part 3) showing the relationship between brightness and imaging distance. [Figure 10] 4 is a graph showing the relationship between brightness and imaging distance (part 4). [Figure 11] FIG. 11 is a block diagram showing a functional configuration of an iris imaging system according to a third embodiment. [Figure 12] 13 is a flowchart showing the flow of operations of the iris imaging system according to the third embodiment. [Figure 13] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to a fourth embodiment. [Figure 14] 13 is a flowchart showing the flow of operations of the iris imaging system according to the fourth embodiment. [Figure 15] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to a modified example of the fourth embodiment. [Figure 16] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to a fifth embodiment. [Figure 17] This is a conceptual diagram (part 1) showing an example of a display for guiding standing positions. [Figure 18] This is a conceptual diagram (part 2) showing an example of a display for guiding standing positions. [Figure 19] 13 is a flowchart showing the flow of operations of the iris imaging system according to the fifth embodiment. [Figure 20] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to a sixth embodiment. [Figure 21] 11A and 11B are conceptual diagrams showing an example of a focus position before and after change. [Figure 22] 13 is a flowchart showing the flow of operations of the iris imaging system according to the sixth embodiment. [Diagram 23] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to a seventh embodiment. [Figure 24] 13 is a flowchart showing the flow of operations of the iris imaging system according to the seventh embodiment. [Diagram 25] FIG. 13 is a block diagram showing a functional configuration of an iris imaging system according to an eighth embodiment. [Figure 26] 20 is a flowchart showing the flow of operations of the iris imaging system according to the eighth embodiment. [Figure 27] FIG. 23 is a block diagram showing a functional configuration of an iris imaging system according to a modified example of the eighth embodiment. [Figure 28] FIG. 23 is a conceptual diagram showing an example of changing the focus position in an iris imaging system according to a modified example of the eighth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of an iris imaging system, an iris imaging method, and a computer program will be described with reference to the drawings.

[0010] First Embodiment An iris imaging system according to a first embodiment will be described with reference to FIGS.

[0011] (Hardware configuration) First, the hardware configuration of an iris imaging system 10 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the hardware configuration of the iris imaging system according to the first embodiment.

[0012] 1, an iris imaging system 10 according to the first embodiment includes a processor 11, a RAM (Random Access Memory) 12, a ROM (Read Only Memory) 13, and a storage device 14. The iris imaging system 10 may further include an input device 15 and an output device 16. The iris imaging system 10 may further include a camera 20 and a sensor 21. The processor 11, the RAM 12, the ROM 13, the storage device 14, the input device 15, the output device 16, the camera 20, and the sensor 21 are connected via a data bus 17.

[0013] The processor 11 reads a computer program. For example, the processor 11 is configured to read a computer program stored in at least one of the RAM 12, the ROM 13, and the storage device 14. Alternatively, the processor 11 may read a computer program stored in a computer-readable storage medium using a storage medium reading device (not shown). The processor 11 may obtain (i.e., read) a computer program from a device (not shown) disposed outside the iris imaging system 10 via a network interface. The processor 11 controls the RAM 12, the storage device 14, the input device 15, and the output device 16 by executing the computer program that the processor 11 reads. In particular, in this embodiment, when the processor 11 executes the computer program that the processor 11 reads, a functional block for executing a process of capturing an iris image is realized in the processor 11. Furthermore, the processor 11 may be one of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an FPGA (field-programmable gate array), a DSP (Demand-Side Platform), and an ASIC (Application Specific Integrated Circuit), or may be a combination of multiple processors in parallel.

[0014] The RAM 12 temporarily stores a computer program executed by the processor 11. The RAM 12 temporarily stores data that is temporarily used by the processor 11 when the processor 11 is executing the computer program. The RAM 12 may be, for example, a D-RAM (Dynamic RAM).

[0015] The ROM 13 stores computer programs executed by the processor 11. The ROM 13 may also store other fixed data. The ROM 13 may be, for example, a programmable ROM (P-ROM).

[0016] The storage device 14 stores data that is to be stored long-term by the iris imaging system 10. The storage device 14 may operate as a temporary storage device for the processor 11. The storage device 14 may include, for example, at least one of a hard disk device, a magneto-optical disk device, an SSD (Solid State Drive), and a disk array device.

[0017] The input device 15 is a device that receives an input instruction from a user of the iris imaging system 10. The input device 15 may include, for example, at least one of a keyboard, a mouse, and a touch panel.

[0018] The output device 16 is a device that outputs to the outside information related to the iris imaging system 10. For example, the output device 16 may be a display device (for example, a display) that can display information related to the iris imaging system 10.

[0019] The camera 20 is a camera capable of capturing an image of the iris of a living body. The camera 20 may be configured as, for example, a near-infrared camera. The camera 20 may be disposed in a position such that the imaging range thereof includes the face and the periphery of the eyes of the living body. The camera 20 may be a camera that captures still images or a camera that captures moving images.

[0020] The sensor 21 is a sensor capable of detecting illuminance around the camera. The sensor 21 is configured to be capable of outputting information related to the detected illuminance. The sensor 21 may be a sensor capable of directly detecting illuminance, or may be a sensor capable of detecting information different from illuminance and indirectly detecting illuminance from the information.

[0021] (Functional configuration) Next, the functional configuration of the iris imaging system 10 according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the functional configuration of the iris imaging system according to the first embodiment.

[0022] As shown in Fig. 2, the iris imaging system 10 according to the first embodiment is configured to include an imaging unit 110, an illuminance acquisition unit 120, and an execution unit 130 as processing blocks for realizing the functions thereof. The imaging unit 110 may be configured to include, for example, the above-mentioned camera 20 (see Fig. 1). The illuminance acquisition unit 120 may be configured to include, for example, the above-mentioned sensor 21 (see Fig. 1). The execution unit 130 may be realized in, for example, the above-mentioned processor 11 (see Fig. 1).

[0023] The imaging unit 110 is configured to be able to capture an image of the iris of a living body. The imaging unit 110 may have a function of outputting the captured image of the iris of the living body (hereinafter, appropriately referred to as an "iris image") to the outside of the system. The iris image captured by the imaging unit 110 may be used for iris authentication, for example.

[0024] The illuminance acquisition unit 120 is configured to be able to acquire the brightness (i.e., illuminance) when the imaging unit 110 captures an iris image. The illuminance acquisition unit 120 may acquire information about the brightness directly from, for example, an illuminance sensor, or may acquire information about the brightness indirectly from information that is not directly related to the illuminance. The illuminance acquisition unit 120 may acquire information about the brightness from, for example, time information. In this case, the illuminance acquisition unit 120 may acquire information about the brightness using a map or the like that indicates the relationship between time and brightness that is prepared in advance.

[0025] The execution unit 130 is configured to be capable of executing control for shortening the distance (hereinafter, appropriately, "imaging distance") between the iris of the living body and the imaging unit 110 when the imaging unit 110 captures an iris image, based on information related to brightness acquired by the illuminance acquisition unit 120. The execution unit 130 may determine whether or not to execute control based on brightness, for example, or may change the amount of control or the content of control in the control. The specific content of the control executed by the execution unit 130 will be described in detail in other embodiments described later.

[0026] (Changes in the iris) Next, changes in the iris (particularly changes in the size of the pupil) depending on the environment will be specifically described with reference to Fig. 3. Fig. 3 is a conceptual diagram showing an example in which the pupil is too small and an example in which the pupil is too large.

[0027] As shown in FIG. 3, the size of a living body's pupil changes depending on the brightness. Specifically, in a bright environment, the pupil becomes smaller. On the other hand, in a dark environment, the pupil becomes larger. When the size of the pupil changes in this way, the state of the iris also changes accordingly. Therefore, the change in pupil size has a significant effect on the iris image captured by the image capture unit 110. As a result, the iris image cannot be acquired in an appropriate state, which may cause unintended inconvenience.

[0028] For example, when an iris image is used for iris authentication, if the state of the iris changes, there is a risk that normal authentication operation cannot be performed. Specifically, if the pupil becomes too small, the iris pattern located just outside the pupil shrinks, and the resolution in the circumferential direction of the pupil decreases. On the other hand, if the pupil becomes too large, the entire iris is compressed in the radial direction of the pupil, and the resolution in the radial direction decreases. The iris imaging system 10 according to this embodiment aims to obtain an appropriate iris image (specifically, an iris image with sufficient resolution) even if the size of the pupil changes as described above.

[0029] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the flow of operations of the iris imaging system according to the first embodiment.

[0030] 4, when the iris imaging system 10 according to the first embodiment operates, the illuminance acquisition unit 120 first acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0031] Next, the execution unit 130 executes control to shorten the imaging distance based on the illuminance acquired by the illuminance acquisition unit 120 (step S102). After the execution unit 130 executes control to shorten the imaging distance, the imaging unit 110 captures an iris image of the living body (step S103). Thus, the iris image is captured in a state where the imaging distance is shortened according to the illuminance.

[0032] In addition, when the execution unit 130 determines that it is not necessary to execute control to reduce the imaging distance (when the illuminance is such that it is not necessary to reduce the imaging distance), the imaging unit 110 may capture an iris image in a state in which control by the execution unit 130 is not being executed.

[0033] (Modification) Next, an iris imaging system 10 according to a modified example of the first embodiment will be described with reference to Figs. 5 and 6. Fig. 5 is a block diagram showing a functional configuration of an iris imaging system according to a modified example of the first embodiment. In Fig. 5, the same elements as those shown in Fig. 2 are given the same reference numerals. Fig. 6 is a flowchart showing the flow of operation of the iris imaging system according to the modified example of the first embodiment. In Fig. 6, the same processes as those shown in Fig. 4 are given the same reference numerals.

[0034] The modified example described below differs from the first embodiment only in some configurations and operations, and other parts may be the same as the first embodiment (see Figs. 1 to 4). Therefore, the following will describe in detail the parts that differ from the first embodiment already described, and will omit descriptions of other overlapping parts as appropriate.

[0035] As shown in Fig. 5, the iris imaging system 10 according to the modification of the first embodiment is configured to include an imaging unit 110, an illuminance acquisition unit 120, an execution unit 130, an iris detection unit 210, an iris feature amount extraction unit 220, an iris feature amount matching unit 230, and an iris feature amount registration database 240 as processing blocks for realizing the functions of the iris imaging system 10. That is, the iris imaging system 10 according to the modification is configured to further include the iris detection unit 210, the iris feature amount extraction unit 220, the iris feature amount matching unit 230, and the iris feature amount registration database 240 in addition to the configuration of the iris imaging system 10 according to the first embodiment (see Fig. 2). Each of the iris detection unit 210, the iris feature amount extraction unit 220, and the iris feature amount matching unit 230 may be realized, for example, in the above-mentioned processor 11 (see Fig. 1). The iris feature amount registration database 240 may be configured to include the above-mentioned storage device 14 (see Fig. 1).

[0036] The iris detection unit 210 is configured to be able to detect an area in which the iris exists from the iris image (in other words, the position of the iris in the image). The iris detection unit 210 is configured to output information relating to the detected position of the iris to the iris feature amount extraction unit 220.

[0037] The iris feature amount extraction unit 220 is configured to be able to extract iris feature amounts from the area in which the iris detected by the iris detection unit 210 exists. The feature amount here is information used for iris authentication (i.e., matching process with registered data). The iris feature amount extraction unit 220 may extract a plurality of types of feature amounts. The feature amount extracted by the iris feature amount extraction unit 220 is configured to be output to the iris feature amount matching unit 230.

[0038] The iris feature matching unit 230 is configured to match the feature extracted by the iris feature extraction unit 220 (hereinafter referred to as "extracted feature") with the feature registered in the iris feature registration database 240 (hereinafter referred to as "registered feature") described later, and output a matching result related to the iris. The iris feature matching unit 230 outputs the matching result based on, for example, the degree of match between the extracted feature and the registered feature. For example, the iris feature matching unit 230 may output a result of matching OK when the degree of match between the extracted feature and the registered feature is equal to or greater than a predetermined threshold, and may output a result of matching NG when the degree of match is less than the predetermined value.

[0039] The iris feature amount registration database 240 is configured to be capable of storing registered feature amounts used for matching by the iris feature amount matching unit 230. The registered feature amounts may be data registered in advance. The registered feature amounts stored in the iris feature amount registration database 240 are configured to be capable of being read out by the iris feature amount matching unit 230 as appropriate.

[0040] 6, when the iris imaging system 10 according to the modification of the first embodiment operates, the illuminance acquisition unit 120 first acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0041] Next, the execution unit 130 executes control to reduce the imaging distance based on the illuminance acquired by the illuminance acquisition unit 120 (step S102). After the execution unit 130 executes control to reduce the imaging distance, the imaging unit 110 captures an iris image of the living body (step S103).

[0042] Next, the iris detection unit 210 detects an area in which the iris exists from the iris image (step S104), and the iris feature amount extraction unit 220 extracts an iris feature amount from the area in which the iris exists (step S105).

[0043] Next, the iris feature matching unit 230 matches the extracted feature extracted by the iris feature extraction unit 220 with the registered feature stored in the iris feature registration database 240 (step S106). Then, the iris feature matching unit 230 outputs the matching result (step S107).

[0044] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the first embodiment will be described.

[0045] As described in FIG. 1 to FIG. 6, in the iris imaging system 10 according to the first embodiment, control is executed to reduce the imaging distance (i.e., the distance between the iris of a living body and the imaging unit 110) based on the illuminance (brightness) when capturing an iris image. When the imaging distance is reduced, the iris is captured closer. Therefore, the resolution of the iris image is higher than before the imaging distance is reduced. Therefore, according to the iris imaging system 10 according to the first embodiment, it is possible to capture a high-resolution iris image by taking into account the size of the pupil that varies depending on the brightness. In particular, in the configuration for performing iris authentication (i.e., matching of iris features) described in the modified example, a high-resolution iris image is often required to accurately extract the features. Therefore, the above-mentioned technical effect is prominently exhibited in the case of performing iris authentication.

[0046] <Second embodiment> An iris imaging system 10 according to the second embodiment will be described with reference to Fig. 7 to Fig. 10. Note that the second embodiment describes the control executed in the above-mentioned first embodiment (i.e., a specific example of the control executed by the execution unit 130), and the system configuration, operation flow, etc. may be the same as those of the first embodiment (see Figs. 1 to 6). Therefore, in the following, descriptions of parts that overlap with the first embodiment already described will be omitted as appropriate.

[0047] (How to set the imaging distance) First, a method for setting the imaging distance in the iris imaging system 10 according to the second embodiment will be specifically described with reference to Fig. 7 to Fig. 10. Fig. 7 is a graph (part 1) showing the relationship between brightness and imaging distance. Fig. 8 is a graph (part 2) showing the relationship between brightness and imaging distance. Fig. 9 is a graph (part 3) showing the relationship between brightness and imaging distance. Fig. 10 is a graph (part 4) showing the relationship between brightness and imaging distance.

[0048] As shown in Fig. 7, the execution unit 130 may execute control so that the imaging distance (i.e., the distance between the iris of the living body and the imaging unit 110) becomes closer as the environment becomes brighter when the iris image is captured. Note that the execution unit 130 may execute control so as to change the imaging distance within a predetermined range. For example, in the example shown in Fig. 7, the imaging distance is controlled within the range of Dmax to Dmin.

[0049] As shown in Fig. 8, the execution unit 130 may perform control so as to change the imaging distance when the brightness exceeds a predetermined threshold when capturing an iris image. For example, in the example shown in Fig. 8, when the brightness is less than the predetermined threshold, the imaging distance is controlled to be Dmax, and when the brightness is equal to or greater than the predetermined threshold, the imaging distance is controlled to be Dmin.

[0050] As shown in Fig. 9, the execution unit 130 may perform control to change the imaging distance using two or more thresholds. For example, in the example shown in Fig. 9, when the brightness is less than threshold A, the imaging distance is controlled to be Dmax, when the brightness is equal to or greater than threshold A and less than threshold B, the imaging distance is controlled to be D1, and when the brightness is equal to or greater than threshold B, the imaging distance is controlled to be Dmin.

[0051] As shown in Fig. 10, the execution unit 130 may perform control to shorten the imaging distance not only when the environment when the iris image is captured becomes bright, but also when it becomes dark. As already described, the size of the pupil may not only become too small when it is bright, but also become too large when it is dark (see Fig. 3). Therefore, in a situation where the environment when the iris image is captured is dark and it is expected that the size of the pupil will become too large, the execution unit 130 may similarly perform control to shorten the imaging distance.

[0052] Although the above describes the control for approaching one target imaging distance, the target distance may have a certain range. For example, the control may be performed so that the imaging distance falls within a certain range before and after the target imaging distance.

[0053] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the second embodiment will be described.

[0054] As described in Fig. 7 to Fig. 10, in the iris imaging system 10 according to the second embodiment, the brighter the environment when capturing an image, the closer the imaging distance is. In this way, it is possible to capture a high-resolution iris image taking into account the variation in pupil size depending on the brightness. Similarly, if the same control is performed in the dark, it is possible to capture a high-resolution iris image taking into account the variation in pupil size depending on the darkness.

[0055] <Third embodiment> An iris imaging system 10 according to the third embodiment will be described with reference to Fig. 11 and Fig. 12. The third embodiment differs from the first and second embodiments in some configurations and operations, and other parts may be the same as the first and second embodiments. Therefore, in the following, explanations of parts that overlap with the embodiments already described will be omitted as appropriate.

[0056] (Functional configuration) First, the functional configuration of the iris imaging system 10 according to the third embodiment will be described with reference to Fig. 11. Fig. 11 is a block diagram showing the functional configuration of the iris imaging system according to the third embodiment. In Fig. 11, the same components as those shown in Fig. 2 are denoted by the same reference numerals.

[0057] 11, the iris imaging system 10 according to the third embodiment is configured to include, as processing blocks for realizing its functions, an imaging unit 110, an illuminance acquisition unit 120, and an execution unit 130. In particular, in the iris imaging system 10 according to the third embodiment, the execution unit 130 includes a pupil diameter estimation unit 131.

[0058] The pupil diameter estimation unit 131 is configured to be able to estimate the pupil diameter of the living body from the brightness when the image is captured. As already described, the size of the pupil of the living body changes depending on the brightness of the environment (see FIG. 3). Therefore, by using information on the brightness, it is possible to estimate the pupil diameter of the living body at that time. The pupil diameter estimation unit 131 may be configured to be able to estimate the pupil diameter using time information or the like in addition to information on the brightness. The information on the pupil diameter estimated by the pupil diameter estimation unit 131 is used for the control executed by the execution unit 130. That is, in the third embodiment, control is executed to approach the imaging distance based on the pupil diameter estimated from the brightness. For example, when it is bright, an imaging distance is obtained at which the number of pixels on the circumference of the pupil is a certain value or more and the entire iris is imaged at an appropriate size, and the imaging distance is controlled to approach the imaging distance. On the other hand, when it is dark, an imaging distance is obtained at which the number of pixels in the radial direction between the iris and the pupil is a certain value or more and the entire iris is imaged at an appropriate size, and the imaging distance is controlled to approach the imaging distance. Here, the larger the iris is captured, the higher the resolution will be and the clearer the iris pattern will be. However, even a slight deviation in the position of the iris will cause it to go outside the screen, and there is a possibility that the entire iris will not be captured. Also, if it gets too close, it may go beyond the focusable range. For this reason, the appropriate iris size is determined by considering these trade-offs, and the imaging distance is determined.

[0059] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the third embodiment will be described with reference to Fig. 12. Fig. 12 is a flowchart showing the flow of operations of the iris imaging system according to the third embodiment. In Fig. 12, the same processes as those shown in Fig. 4 are denoted by the same reference numerals.

[0060] 12, when the iris imaging system 10 according to the third embodiment operates, the illuminance acquisition unit 120 first acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0061] Next, the pupil diameter estimation unit 131 in the execution unit 130 estimates the pupil diameter of the living body from the illuminance acquired by the illuminance acquisition unit 120 (step S301). Then, the execution unit 130 executes control to reduce the imaging distance based on the pupil diameter estimated by the pupil diameter estimation unit 131 (step S302).

[0062] Thereafter, the image capturing unit 110 captures an iris image of the living body after the execution unit 130 executes control to reduce the imaging distance (step S103). Note that if the execution unit 130 determines that it is not necessary to execute control to reduce the imaging distance (if the pupil diameter is such that it is not necessary to reduce the imaging distance), the image capturing unit 110 may capture an iris image in a state in which the control by the execution unit 130 is not being executed.

[0063] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the third embodiment will be described.

[0064] 11 and 12, in the iris imaging system 10 according to the third embodiment, the pupil diameter is estimated from the brightness when an image is captured, and control is executed to reduce the imaging distance based on the pupil diameter. In this way, it becomes possible to capture a high-resolution iris image by more specifically considering the variation in pupil size according to the brightness.

[0065] <Fourth embodiment> An iris imaging system 10 according to the fourth embodiment will be described with reference to Fig. 13 to Fig. 15. The fourth embodiment differs from the third embodiment in part of its configuration and operation, and other parts may be the same as the first to third embodiments. Therefore, in the following, explanations of parts that overlap with the embodiments already described will be omitted as appropriate.

[0066] (Functional configuration) First, the functional configuration of the iris imaging system 10 according to the fourth embodiment will be described with reference to Fig. 13. Fig. 13 is a block diagram showing the functional configuration of the iris imaging system according to the fourth embodiment. In Fig. 13, the same components as those shown in Fig. 11 are denoted by the same reference numerals.

[0067] As shown in Fig. 13, the iris imaging system 10 according to the fourth embodiment is configured to include, as processing blocks for realizing its functions, an imaging section 110, an illuminance acquisition section 120, an execution section 130 having a pupil diameter estimation section 131, and a pupil diameter database 140. That is, the iris imaging system 10 according to the fourth embodiment further includes a pupil diameter database 140 in addition to the configuration of the third embodiment (see Fig. 11). The pupil diameter database 140 may be configured to include, for example, the above-mentioned storage device 14 (see Fig. 1).

[0068] Pupil diameter database 140 is configured to be able to accumulate information indicating the relationship between the brightness when capturing an iris image and the pupil diameter of a living body. Pupil diameter database 140 may store, for example, the relationship between brightness and pupil diameter as a map, or may store a formula for calculating pupil diameter from brightness. The information accumulated in pupil diameter database 140 may be prepared in advance (i.e., accumulated through prior experiments, simulations, etc.), but may also be configured to be able to update the accumulated information as appropriate. Pupil diameter database 140 may accumulate the relationship between brightness and time information and pupil diameter.

[0069] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the fourth embodiment will be described with reference to Fig. 14. Fig. 14 is a flowchart showing the flow of operations of the iris imaging system according to the fourth embodiment. In Fig. 14, the same processes as those shown in Fig. 12 are denoted by the same reference numerals.

[0070] 14, when the iris imaging system 10 according to the fourth embodiment operates, the illuminance acquisition unit 120 first acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0071] Next, the pupil diameter estimation unit 131 in the execution unit 130 estimates the pupil diameter of the living body using the illuminance acquired by the illuminance acquisition unit 120 and the information stored in the pupil diameter database 140 (step S401). Then, the execution unit 130 executes control to reduce the imaging distance based on the pupil diameter estimated by the pupil diameter estimation unit 131 (step S302).

[0072] Thereafter, the image capturing unit 110 captures an iris image of the living body after the execution unit 130 executes control to reduce the imaging distance (step S103).

[0073] (Example of configuration when accumulating data) Next, a configuration example for storing data in the pupil diameter database 140 will be described with reference to Fig. 15. Fig. 15 is a block diagram showing a functional configuration of an iris imaging system according to a modified example of the fourth embodiment. In Fig. 15, the same elements as those shown in Figs. 5 and 13 are denoted by the same reference numerals.

[0074] 15, the iris imaging system 10 according to the modification of the fourth embodiment includes, as processing blocks for realizing its functions, an imaging unit 110, an illuminance acquisition unit 120, an execution unit 130 having a pupil diameter estimation unit 131, a pupil diameter database 140, an iris detection unit 210, an iris feature amount extraction unit 220, an iris feature amount matching unit 230, an iris feature amount registration database 240, and a pupil diameter calculation unit 250. That is, the iris imaging system 10 according to the modification of the fourth embodiment further includes, in addition to the configuration of the fourth embodiment (see FIG. 13), the iris detection unit 210, the iris feature amount extraction unit 220, the iris feature amount matching unit 230, the iris feature amount registration database 240, and the pupil diameter calculation unit 250. Each of the iris detection unit 210, the iris feature amount extraction unit 220, the iris feature amount matching unit 230, and the iris feature amount registration database 240 may be similar to those described in the modified example of the first embodiment (see FIG. 5). Also, the pupil diameter calculation unit 250 may be realized in, for example, the above-mentioned processor 11 (see FIG. 1).

[0075] The pupil diameter calculation unit 250 is configured to be able to calculate the pupil diameter from the region where the pupil detected by the iris detection unit 210 exists. As for a specific method of calculating the pupil diameter from an image, since existing technology can be appropriately adopted, detailed description here is omitted. The pupil diameter calculation unit 250 is configured to be able to appropriately store information related to the calculated pupil diameter in the pupil diameter database 140. Therefore, new information is stored in the pupil diameter database 140 every time the pupil diameter is calculated by the pupil diameter calculation unit 250 (in other words, every time an iris image is captured by the imaging unit 110). In this way, the pupil diameter database 140 may be configured to store new information related to the pupil diameter using the imaging result of the imaging unit 110. However, the pupil diameter database 140 may be configured to store information other than the pupil diameter calculated by the pupil diameter calculation unit 250. Then, when a certain amount of information is accumulated, a statistical process may be performed on the newly accumulated information to update the map or formula representing the relationship between brightness and pupil diameter. For example, statistics of pupil diameter (representative values ​​such as average, median, and mode) may be calculated for each illuminance, and the map for calculating pupil diameter from illuminance may be updated. In this case, the correspondence may be calculated not only from the newly added value, but also by taking into account already stored information. In addition, if pupil diameter is stored in correspondence with time information, a similar statistical process may be performed for each time period. In this case, a map or formula for calculating pupil diameter from time period information instead of brightness may be obtained by utilizing the relationship between brightness and time period.

[0076] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the fourth embodiment will be described.

[0077] 13 to 15, in the iris imaging system 10 according to the fourth embodiment, the pupil diameter is estimated using information stored in the pupil diameter database 140. In this way, the pupil diameter can be estimated with high accuracy using the stored information, and therefore it is possible to more appropriately execute control to reduce the imaging distance.

[0078] <Fifth embodiment> An iris imaging system 10 according to the fifth embodiment will be described with reference to Fig. 16 to Fig. 19. The fifth embodiment differs from the first to fourth embodiments in some configurations and operations, and other parts may be the same as the first to fourth embodiments. Therefore, in the following, explanations of parts that overlap with the embodiments already described will be omitted as appropriate. (Functional configuration) First, the functional configuration of the iris imaging system 10 according to the fifth embodiment will be described with reference to Fig. 16. Fig. 16 is a block diagram showing the functional configuration of the iris imaging system according to the fifth embodiment. In Fig. 16, the same components as those shown in Fig. 2 are denoted by the same reference numerals.

[0079] 16, the iris imaging system 10 according to the fifth embodiment is configured to include, as processing blocks for realizing its functions, an imaging unit 110, an illuminance acquisition unit 120, and an execution unit 130. In particular, in the iris imaging system 10 according to the fifth embodiment, the execution unit 130 includes a standing position guiding unit 132.

[0080] The standing position guiding unit 132 is configured to be capable of issuing a notification to a living body (i.e., a subject whose iris image is captured) to encourage movement. The standing position guiding unit 132 may issue a notification to encourage the subject to approach the imaging unit 110. The standing position guiding unit 132 may issue a notification to the subject via, for example, the output device 16 (see FIG. 1). Specifically, the standing position guiding unit 132 may display an image or a message on a display to encourage the subject to move. Alternatively, the standing position guiding unit 132 may output a sound from a microphone to encourage the subject to move. A specific example of a guiding method by the standing position guiding unit 132 will be described in more detail below.

[0081] (Example of display when guiding) Next, a display example when guiding a standing position by the above-mentioned standing position guiding unit 132 will be specifically described with reference to Fig. 17 and Fig. 18. Fig. 17 is a conceptual diagram (part 1) showing a display example when guiding a standing position. Fig. 18 is a conceptual diagram (part 2) showing a display example when guiding a standing position.

[0082] As shown in FIG. 17, the standing position guiding unit 132 may display a message encouraging the target to move together with the image of the target. In the example shown in FIG. 17, a message saying "Please move a little closer to the camera" is displayed, but a specific amount of movement may be displayed. For example, a specific amount of movement such as "Please move 10 cm closer" may be displayed. Alternatively, a frame showing the target's approximate position may be superimposed on the display, and a message such as "Please move so that you fit within the frame" may be displayed. The content of the displayed message may change with the target's movement. For example, when the target approaches to a good position, a message such as "That's OK" may be displayed. When the user approaches too close, a message such as "You're too close. Please move a little further away" may be displayed. Furthermore, a speaker may be connected to display the message and announce the message by voice at the same time. Alternatively, the message may not be displayed and only the voice announcement may be made. The distance to the target may be estimated from the size of the facial parts on the image, the positional relationship of the parts, or the size of the iris, or may be measured using a separate distance sensor or the like. The above-mentioned prompting message may be changed using the obtained distance. For example, an appropriate imaging distance may be obtained within the focusable range, and control may be performed so as to approach that distance.

[0083] As shown in FIG. 18, the standing position guiding unit 132 may encourage the movement of the subject using an indicator. The indicator is provided with, for example, red, orange, yellow, and green lamps, and is configured to light up the corresponding lamps according to the positional relationship between the subject and the imaging unit 110. Specifically, when the subject is too close or too far from the imaging unit 110, a red lamp is lit. Then, as the subject approaches the imaging unit 110, the lamps that are lit change in the order of orange and yellow, and when the subject is just close enough, a green lamp is lit. The indicator may be configured to guide the standing position by the blinking pattern of the lamp, rather than the color of the lamp. For example, when the standing position is far away, the blinking cycle becomes faster, when the standing position approaches an appropriate position, the blinking cycle becomes slower, and when the standing position is in an appropriate position, the blinking stops. The indicator as described above may be configured using, for example, an LED lamp, or may be realized by image display on a display or the like.

[0084] Instead of the indicator described above, the contour of the subject may be superimposed on the display and the subject may be guided to fit exactly within the contour. In this case, the superimposed contour may vary in size depending on the brightness when the iris image is captured or the current pupil diameter of the subject. More specifically, when the imaging environment is very bright or very dark, a larger contour may be displayed to bring the subject closer, whereas when the imaging environment is slightly bright or slightly dark, a slightly larger contour may be displayed to bring the subject closer. Similarly, when the pupil diameter of the subject is significantly different from the appropriate value, a larger contour may be displayed to bring the subject closer, whereas when the pupil diameter is slightly different, a slightly larger contour may be displayed to bring the subject closer.

[0085] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the fifth embodiment will be described with reference to Fig. 19. Fig. 19 is a flowchart showing the flow of operations of the iris imaging system according to the fifth embodiment. In Fig. 19, the same processes as those shown in Fig. 4 are denoted by the same reference numerals.

[0086] 19, when the iris imaging system 10 according to the fifth embodiment operates, first, the illuminance acquisition unit 120 acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0087] Next, the execution unit 130 determines an appropriate imaging distance based on the illuminance acquired by the illuminance acquisition unit 120 (step S501). Then, the standing position guidance unit 132 guides the target person to a standing position so as to achieve the determined imaging distance (step S502).

[0088] After that, the image capturing unit 110 confirms that the subject has moved to an appropriate position by the standing position guiding unit 132, and captures an iris image of the living body (step S103). Note that if the subject does not move to an appropriate position despite having been guided to a standing position, the image capturing process may be stopped and a system administrator or the like may be notified.

[0089] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the fifth embodiment will be described.

[0090] As described in Fig. 16 to Fig. 19, in the iris imaging system 10 according to the fifth embodiment, control is executed to guide the subject's standing position in order to reduce the imaging distance. In this way, it is possible to realize an appropriate imaging distance according to the brightness by guiding the subject's standing position. The configuration of the fifth embodiment is particularly effective in cases where, for example, the subject stops in front of the imaging unit 110 to be imaged.

[0091] Sixth Embodiment An iris imaging system 10 according to the sixth embodiment will be described with reference to Fig. 20 to Fig. 22. The sixth embodiment differs from the first to fifth embodiments in some configurations and operations, and other parts may be the same as the first to fifth embodiments. Therefore, in the following, explanations of parts that overlap with the embodiments already described will be omitted as appropriate.

[0092] (Functional configuration) First, the functional configuration of the iris imaging system 10 according to the sixth embodiment will be described with reference to Fig. 20. Fig. 20 is a block diagram showing the functional configuration of the iris imaging system according to the sixth embodiment. In Fig. 20, the same components as those shown in Fig. 2 are denoted by the same reference numerals.

[0093] 20, the iris imaging system 10 according to the sixth embodiment is configured to include, as processing blocks for realizing the functions thereof, an imaging unit 110, an illuminance acquisition unit 120, and an execution unit 130. Particularly, in the iris imaging system 10 according to the sixth embodiment, the execution unit 130 includes a focus position changing unit 133.

[0094] The focus position changing section 133 is configured to be able to change the focus position of the imaging section 110. The focus position changing section 133 changes the focus position of the imaging section 110 so as to approach the imaging section 110 itself. The focus position changing section 133 may be configured to be able to adjust how close the focus position of the imaging section 110 is to be. When multiple focus positions are set for the imaging section 110, the focus position changing section 133 may be configured to be able to change at least one of the focus positions. A specific method of changing the focus position by the focus position changing section 133 will be described in more detail below.

[0095] (Example of changing the focus position) Next, an example of changing the focus position of the imaging unit 110 by the focus position changing unit 133 will be specifically described with reference to Fig. 21. Fig. 21 is a conceptual diagram showing an example of the focus position before and after the change.

[0096] As shown in FIG. 21, it is assumed that the first, second, and third focus positions are set in the imaging unit 110. In this case, the focus position change unit 133 changes each of the first, second, and third focus positions to the side where the imaging distance becomes smaller. The focus position change unit 133 may change the focus position so that the imaging distance becomes smaller as the environment when capturing an image becomes brighter. The focus position change unit 133 may change the focus position so that it falls within the imaging range determined based on the brightness. Note that, in the example shown in FIG. 21, the first, second, and third focus positions are changed by the same amount collectively, but the multiple focus positions may be changed independently.

[0097] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the sixth embodiment will be described with reference to Fig. 22. Fig. 22 is a flowchart showing the flow of operations of the iris imaging system according to the sixth embodiment. In Fig. 22, the same processes as those shown in Fig. 4 are denoted by the same reference numerals.

[0098] 22, when the iris imaging system 10 according to the sixth embodiment operates, the illuminance acquisition unit 120 first acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0099] Next, the execution unit 130 determines the imaging range based on the illuminance acquired by the illuminance acquisition unit 120 (step S601). Then, the focus position change unit 133 changes the focus position of the imaging unit 110 so that it falls within the determined imaging range (step S602).

[0100] After that, the imaging unit 110 captures an iris image of the living body at the focus position changed by the focus position changing unit 133 (step S103). Note that the focus position changing unit 113 may change the magnification of the imaging unit 110 in addition to or instead of changing the focus position.

[0101] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the sixth embodiment will be described.

[0102] As described in Fig. 20 to Fig. 22, in the iris imaging system 10 according to the sixth embodiment, control is executed to change the focal position of the imaging unit 110 in order to reduce the imaging distance. In this way, the imaging distance is changed by changing the focal point of the imaging unit 110, and it is possible to realize an appropriate imaging distance according to the brightness. The configuration of the sixth embodiment is particularly effective in cases where, for example, an object person is imaged multiple times while moving within the imaging range of the imaging unit 110. That is, when an object person moves in a direction approaching the camera, it is effective in cases where an object person is imaged multiple times while shifting the focal position with the movement.

[0103] Seventh embodiment An iris imaging system 10 according to the seventh embodiment will be described with reference to Fig. 23 and Fig. 24. The seventh embodiment differs from the first to sixth embodiments in some configurations and operations, and other parts may be the same as the first to sixth embodiments. Therefore, in the following, explanations of parts that overlap with the embodiments already described will be omitted as appropriate.

[0104] (Functional configuration) First, the functional configuration of the iris imaging system 10 according to the seventh embodiment will be described with reference to Fig. 23. Fig. 23 is a block diagram showing the functional configuration of the iris imaging system according to the seventh embodiment. In Fig. 23, the same components as those shown in Fig. 2 are denoted by the same reference numerals.

[0105] 23, the iris imaging system 10 according to the seventh embodiment is configured to include, as processing blocks for realizing its functions, an imaging section 110, an illuminance acquisition section 120, an execution section 130, a high resolution determination section 150, and a high resolution execution section 160. That is, in addition to the configuration of the first embodiment (see FIG. 2), the iris imaging system 10 according to the seventh embodiment has the high resolution determination section 150 and the high resolution execution section 160, each of which may be realized in, for example, the above-mentioned processor 11 (see FIG. 1).

[0106] The high resolution determination unit 150 is configured to be able to determine whether or not to execute high resolution processing based on the illuminance acquired by the illuminance acquisition unit 120. The high resolution determination unit 150 determines to execute high resolution processing when the resolution in the circumferential direction of the iris image is reduced due to high illuminance. Alternatively, the high resolution determination unit 150 may determine to execute high resolution processing when the resolution in the radial direction of the iris image is reduced due to low illuminance. The high resolution determination unit 150 stores, for example, a threshold value set for illuminance, and determines to execute high resolution processing when the acquired illuminance is equal to or greater than the threshold value, and determines not to execute high resolution processing when the acquired illuminance is less than the threshold value.

[0107] When the high resolution determination unit 150 determines that high resolution processing should be performed, the high resolution execution unit 160 executes the high resolution processing using the image captured by the imaging unit 110. The high resolution execution unit 160 may execute the high resolution processing using one iris image, or may execute the high resolution processing using multiple iris images. The high resolution execution unit 160 pupil The resolution enhancement execution unit 160 may execute a resolution enhancement process that takes into account the degree of contraction of the image. The resolution enhancement execution unit 160 may execute a resolution enhancement process that utilizes, for example, an existing super-resolution technique. The resolution enhancement execution unit 160 may also execute processes such as enlargement and sharpening, or may use a super-resolution method based on deep learning. However, the method of the resolution enhancement process executed by the resolution enhancement execution unit 160 is not particularly limited.

[0108] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the seventh embodiment will be described with reference to Fig. 24. Fig. 24 is a flowchart showing the flow of operations of the iris imaging system according to the seventh embodiment. In Fig. 24, the same processes as those shown in Fig. 4 are denoted by the same reference numerals.

[0109] 24, when the iris imaging system 10 according to the seventh embodiment operates, the illuminance acquisition unit 120 first acquires the illuminance around the imaging unit 110 (step S101). The illuminance acquisition unit 120 outputs the acquired illuminance to the execution unit 130.

[0110] Next, the execution unit 130 executes control to reduce the imaging distance based on the illuminance acquired by the illuminance acquisition unit 120 (step S102). After the execution unit 130 executes control to reduce the imaging distance, the imaging unit 110 captures an iris image of the living body (step S103).

[0111] Next, the high resolution determination unit 150 determines whether or not to execute high resolution processing based on the illuminance acquired by the illuminance acquisition unit 120 (step S701). If it is determined that the high resolution processing is to be executed (step S701: YES), the high resolution execution unit 160 executes the high resolution processing using the image captured by the imaging unit 110 (step S702). On the other hand, if it is determined that the high resolution processing is not to be executed (step S701: NO), the high resolution execution unit 160 does not execute the high resolution processing (i.e., the processing of step S702 is omitted).

[0112] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the seventh embodiment will be described.

[0113] 23 and 24, in the iris imaging system 10 according to the seventh embodiment, a process for increasing the resolution of the iris image captured by the imaging unit 110 is executed. In this way, the resolution of the iris image is increased by the high-resolution process, so that it is possible to suppress a decrease in resolution due to brightness and acquire an appropriate iris image.

[0114] In the above example, a configuration has been described in which the image capturing distance is changed according to the brightness, and the resolution increasing process is executed, but the image capturing distance may not be changed and the resolution increasing process may be executed. That is, the resolution increasing process may be executed only according to the brightness when capturing the iris image. Even in this case, the above-mentioned technical effect is appropriately achieved.

[0115] Eighth embodiment An iris imaging system 10 according to the eighth embodiment will be described with reference to Fig. 25 to Fig. 28. The estimation system 10 according to the eighth embodiment differs from the first to seventh embodiments in part of its configuration and operation, and other parts may be the same as those of the first to seventh embodiments. Therefore, in the following, explanations of parts that overlap with the embodiments already described will be omitted as appropriate.

[0116] (Functional configuration) First, the functional configuration of the iris imaging system 10 according to the eighth embodiment will be described with reference to Fig. 25. Fig. 25 is a block diagram showing the functional configuration of the iris imaging system according to the eighth embodiment. In Fig. 25, the same components as those shown in Fig. 2 are denoted by the same reference numerals.

[0117] As shown in Fig. 25, the iris imaging system 10 according to the eighth embodiment is configured to include an imaging section 110, a pupil diameter acquisition section 310, and an execution section 130 as processing blocks for realizing the functions of the system. That is, the iris imaging system 10 according to the eighth embodiment is provided with a pupil diameter acquisition section 310 instead of the illuminance acquisition section 120 in the configuration of the first embodiment (see Fig. 2). The pupil diameter acquisition section 310 may be realized, for example, in the above-mentioned processor 11 (see Fig. 1).

[0118] The pupil diameter acquisition unit 310 is configured to be able to acquire information on the pupil diameter of the living body. The pupil diameter acquisition unit 310 may acquire information on the pupil diameter from, for example, an image of the pupil of the living body. In this case, the pupil diameter acquisition unit 310 may acquire the pupil diameter from an image captured by the imaging unit 110, or may acquire the pupil diameter from an image captured by another imaging unit 110. Note that the image for acquiring the pupil diameter does not have to be an image in focus. Therefore, the pupil diameter may be acquired using an image captured at a point or time different from the focal position of the imaging unit 110. Note that a specific method for acquiring the pupil diameter from an image can be appropriately adopted from existing technologies, and therefore a detailed description thereof will be omitted here.

[0119] (Operation flow) Next, the flow of operations of the iris imaging system 10 according to the eighth embodiment will be described with reference to Fig. 26. Fig. 26 is a flowchart showing the flow of operations of the iris imaging system according to the eighth embodiment. In Fig. 26, the same processes as those shown in Fig. 4 are denoted by the same reference numerals.

[0120] As shown in FIG. 26, when the iris imaging system 10 according to the eighth embodiment operates, ,Ma First, the pupil diameter acquisition unit 310 acquires information on the pupil diameter of the living body (step S801). The pupil diameter acquisition unit 310 outputs the acquired pupil diameter to the execution unit .

[0121] Next, the execution unit 130 executes control to shorten the imaging distance based on the pupil diameter acquired by the pupil diameter acquisition unit 310 (step S802). For example, when the pupil diameter is too small, the execution unit 130 may execute control to shorten the imaging distance as the pupil diameter becomes smaller. Alternatively, for example, when the pupil diameter is too large compared to the iris diameter, the execution unit 130 may execute control to shorten the imaging distance as the pupil diameter becomes larger. Furthermore, the execution unit 130 may execute control to shorten the imaging distance only when the pupil diameter exceeds a predetermined threshold value.

[0122] Next, the image capturing unit 110 captures an iris image of the living body after the execution unit 130 executes control to reduce the imaging distance (step S103). Thus, the iris image is captured with the imaging distance reduced according to the pupil diameter. If the execution unit 130 determines that it is not necessary to execute control to reduce the imaging distance (if the pupil diameter does not require the imaging distance to be reduced), the image capturing unit 110 may capture the iris image without the control by the execution unit 130 being executed.

[0123] (Modification) Next, an iris imaging system 10 according to a modified example of the eighth embodiment will be described with reference to Figs. 27 and 28. Fig. 27 is a block diagram showing a functional configuration of an iris imaging system according to a modified example of the eighth embodiment. In Fig. 27, the same elements as those shown in Figs. 5 and 25 are given the same reference numerals. Fig. 28 is a conceptual diagram showing an example of changing the focusing position in the iris imaging system according to the modified example of the eighth embodiment.

[0124] The modified example described below differs from the eighth embodiment only in some configurations and operations, and other parts may be the same as the eighth embodiment (see Figs. 25 and 26). Therefore, the following will describe in detail the parts that differ from the eighth embodiment already described, and will omit descriptions of other overlapping parts as appropriate.

[0125] 27, the iris imaging system 10 according to the modification of the eighth embodiment is configured to include, as processing blocks for realizing its functions, an imaging unit 110, a pupil diameter acquisition unit 310, an execution unit 130, an iris detection unit 210, an iris feature amount extraction unit 220, an iris feature amount matching unit 230, and an iris feature amount registration database 240. That is, the iris imaging system 10 according to the modification is configured to further include the iris detection unit 210, the iris feature amount extraction unit 220, the iris feature amount matching unit 230, and the iris feature amount registration database 240 in addition to the configuration of the eighth embodiment (see FIG. 25).

[0126] In particular, in the modification of the eighth embodiment, the pupil diameter acquisition unit 310 acquires information about the pupil diameter based on the region in which the iris is present detected by the iris detection unit 210. In this case, the pupil diameter acquisition unit 310 may acquire the pupil diameter only when the iris image is acquired for the first time, or may acquire the pupil diameter every time the iris image is acquired.

[0127] 28 is an example in which the focus position changing section 133 (see FIG. 20) changes the focus position of the imaging section 110, as described in the sixth embodiment. In the iris imaging system 10 according to the modification of the eighth embodiment, the focus position changing section 133 changes the focus position based on the pupil diameter acquired by the pupil diameter acquisition section 310.

[0128] In this case, the pupil diameter acquisition unit 310 first acquires the pupil diameter from the iris image captured at the first focusing position. Therefore, the focusing position is not changed at the first imaging timing. On the other hand, for the second and third imaging, the focusing position is changed based on the pupil diameter acquired in the first imaging, so the imaging distance is closer than before the change. In this way, when acquiring the pupil diameter from an actually captured image and changing the focusing position, it is sufficient to not change the first focusing position, but to change the focusing position from the second imaging onwards.

[0129] In addition to changing the focal position as described above, the size of the pupil may be intentionally changed by changing the intensity of the illumination. For example, after capturing an image at the first capturing timing shown in FIG. 28, the illumination may be brightened and the second and third capturing images may be performed with the pupil contracted.

[0130] (Technical effect) Next, technical effects obtained by the iris imaging system 10 according to the eighth embodiment will be described.

[0131] As described in Figs. 25 to 28, in the iris imaging system 10 according to the eighth embodiment, control is executed to reduce the imaging distance (i.e., the distance between the iris of the living body and the imaging unit 110) based on the diameter of the living body's pupil. When the imaging distance is reduced, the iris is imaged closer. Therefore, the resolution of the iris image is higher than before the imaging distance was reduced. Therefore, according to the iris imaging system 10 according to the eighth embodiment, it is possible to capture a high-resolution iris image taking into account the size of the pupil.

[0132] <Specific application examples> Next, specific application examples of the iris imaging system 10 according to each of the above-described embodiments will be described.

[0133] (Facility entry and exit management) The iris imaging system 10 according to each of the above-described embodiments may be applied to a system that performs facility entrance / exit management. Specifically, the system may be applied to a system that operates to permit the subject to enter / exit when the iris authentication is successful, and not permit (prohibit) the subject to enter / exit when the iris authentication is unsuccessful. In this case, the subject's entrance / exit management may be realized by a walk-through authentication gate, and the gate may be controlled to open / close depending on the result of the iris authentication. Then, the control of changing the focusing position already described (see, for example, FIG. 21 or FIG. 22) may be performed depending on the brightness and pupil diameter when imaging.

[0134] (Payment terminal) The iris imaging system 10 according to each of the above-described embodiments may be applied to a system for performing a payment process. Specifically, the system may be applied to a system that operates such that, if the iris authentication is successful, the payment process is executed using a payment method associated with the subject, and, if the iris authentication is unsuccessful, the payment process is not permitted (or the subject is prompted to select another payment method not associated with the subject (e.g., cash payment)). In this case, the control (see, for example, FIG. 17 or FIG. 18) that guides the subject's standing position as described above may be performed according to the brightness and pupil diameter when the image is captured.

[0135] (Smartphone) The iris imaging system 10 according to each of the above-described embodiments may be applied to various authentication processes in a smartphone (or other mobile terminal) owned by a subject. For example, an authentication process for unlocking a lock screen of the smartphone may be executed using an iris image. In this case, for example, after an iris image is captured by a built-in camera of the smartphone, the lock screen may be unlocked if iris authentication is successful, and the lock screen may be maintained if iris authentication is unsuccessful. Note that since it is assumed that the subject will hold the smartphone in his / her hand and operate it, guidance information may be displayed to move the smartphone closer to or farther away from the face in order to adjust the distance between the imaging unit 110 and the subject.

[0136] The scope of each embodiment also includes a processing method in which a program that operates the configuration of each embodiment to realize the functions of the above-mentioned embodiments is recorded on a recording medium, the program recorded on the recording medium is read as code, and the program is executed on a computer. That is, a computer-readable recording medium is also included in the scope of each embodiment. Furthermore, not only the recording medium on which the above-mentioned program is recorded, but also the program itself is included in each embodiment.

[0137] Examples of recording media that can be used include floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, magnetic tapes, non-volatile memory cards, and ROMs. In addition, the scope of each embodiment does not include those that execute processing by themselves recorded on the recording media, but also those that execute processing by operating on an OS in cooperation with other software and functions of an extension board.

[0138] This disclosure may be modified as appropriate within the scope that does not deviate from the gist or idea of ​​the invention that can be read from the claims and the entire specification, and iris imaging systems, iris imaging methods, and computer programs incorporating such modifications are also included in the technical ideas of this disclosure.

[0139] <Additional Notes> The above-described embodiment may be further described as follows, but is not limited to the following.

[0140] (Appendix 1) The iris imaging system described in Appendix 1 is an iris imaging system characterized by comprising an imaging means for capturing an image including the iris of a living body, an illuminance acquisition means for acquiring the brightness when the image is captured, and an execution means for executing control to reduce the distance between the iris of the living body and the imaging means when the image is captured, based on the brightness when the image is captured.

[0141] (Appendix 2) The iris imaging system described in Appendix 2 is the iris imaging system described in Appendix 1, characterized in that the execution means reduces the distance between the iris of the living body and the imaging means when capturing the image as the environment when capturing the image becomes brighter.

[0142] (Appendix 3) The iris imaging system described in Appendix 3 is the iris imaging system described in Appendix 1 or 2, characterized in that the execution means estimates a pupil diameter of the living body from the brightness when the image is captured, and reduces the distance between the iris of the living body and the imaging means when the image is captured based on the estimated pupil diameter.

[0143] (Appendix 4) The iris imaging system described in Appendix 4 is the iris imaging system described in Appendix 3, characterized in that the estimation means further includes a storage means for storing information indicating the relationship between the brightness when the image is captured and the pupil diameter of the living body, and the adjustment means estimates the pupil diameter of the living body using the information stored in the storage means.

[0144] (Appendix 5) The iris imaging system described in Appendix 5 is the iris imaging system described in any one of Appendixes 1 to 4, characterized in that the execution means notifies the living body to move in order to reduce the distance between the iris of the living body and the imaging means when capturing the image.

[0145] (Appendix 6) The iris imaging system described in Appendix 6 is the iris imaging system described in any one of Appendixes 1 to 5, characterized in that the execution means changes the focusing position of the imaging means in order to reduce the distance between the iris of the living body and the imaging means when capturing the image.

[0146] (Appendix 7) The iris imaging system described in Appendix 7 is the iris imaging system described in any one of Appendixes 1 to 6, further comprising a high resolution enhancement means for generating a high resolution image from an image captured by the imaging means based on the brightness when the image is captured.

[0147] (Appendix 8) The iris imaging system described in Appendix 8 is an iris imaging system characterized by comprising an imaging means for capturing an image including the iris of a living body, a pupil diameter acquisition means for acquiring information regarding the pupil diameter of the living body, and an execution means for executing control to reduce the distance between the iris of the living body and the imaging means when capturing the image based on the information regarding the pupil diameter of the living body.

[0148] (Appendix 9) The iris imaging method described in Appendix 9 is an iris imaging method that uses an imaging means to capture an image including the iris of a living body, and is characterized in that the brightness when the image is captured is obtained, and based on the brightness when the image is captured, control is performed to reduce the distance between the iris of the living body and the imaging means when the image is captured.

[0149] (Appendix 10) The computer program described in Appendix 10 is an iris imaging method that uses an imaging means to capture an image including the iris of a living body, characterized in that it operates a computer to acquire brightness when the image is captured, and, based on the brightness when the image is captured, execute control to reduce the distance between the iris of the living body and the imaging means when the image is captured.

[0150] (Appendix 11) The recording medium described in Appendix 11 is a recording medium having the computer program described in Appendix 10 recorded thereon. [Explanation of symbols]

[0151] 10 Iris Imaging System 11 Processors 20 Camera 21 Sensors 110 Imaging unit 120 Illuminance acquisition section 130 Executive Department 131 Pupil diameter estimation section 132 Standing Position Guidance Section 133 Focus position change unit 140 Pupil Diameter Database 150 High resolution determination section 160 High Resolution Execution Department 210 Iris detection unit 220 Iris feature extraction unit 230 Iris feature matching unit 240 Iris Feature Registration Database 250 Pupil diameter calculation section 310 Pupil diameter acquisition section

Claims

1. An imaging means for capturing an image including an iris of a living body; An illuminance acquisition means for acquiring brightness when the image is captured; An execution means for determining an appropriate imaging distance based on the brightness when the image is captured; a standing position guiding means for guiding the living body to a standing position so as to achieve the imaging distance; 1. An iris imaging system comprising:

2. The execution means estimates the distance to the living body from at least one of the size of a facial part on the image, the positional relationship of the part, and the size of the iris. The iris imaging system of claim 1 .

3. The execution means measures the distance to the living body using a distance sensor. The iris imaging system of claim 1 .

4. The standing position guidance means displays an image of the living body and a message encouraging the living body to move on a display to guide the living body to a standing position. An iris imaging system according to any one of claims 1 to 3.

5. The standing position guidance means displays the message on the display and announces the message by voice through a speaker. The iris imaging system of claim 4.

6. The standing position guidance means displays the message together with the distance to the living body. The iris imaging system of claim 4.

7. The standing position guidance means guides the living body to a standing position using an indicator in which a corresponding lamp is turned on according to a positional relationship between the living body and the image capturing means. An iris imaging system according to any one of claims 1 to 3.

8. The standing position guidance means displays an outline of the living body on a display in a superimposed manner to guide the living body to a standing position. The iris imaging system according to any one of claims 1 to 3.

9. 1. An iris imaging method using an imaging means for capturing an image including an iris of a living body, comprising: Acquire the brightness when capturing the image; determining an appropriate imaging distance based on the brightness when the image is captured; The living body is guided to a standing position so as to achieve the imaging distance.

13. An iris imaging method comprising:

10. 1. An iris imaging method using an imaging means for capturing an image including an iris of a living body, comprising: Acquire the brightness when capturing the image; determining an appropriate imaging distance based on the brightness when the image is captured; The living body is guided to a standing position so as to achieve the imaging distance. A computer program for causing a computer to operate in such a manner.

Images