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] Known examples of this type of system include those that capture images of a living body's iris for iris authentication. For example, Patent Document 1 discloses a technology that adjusts the brightness value of a display according to 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 of focus and exposure within a solid-state imaging device. Patent Document 5 discloses changing image size and focus depending on the individual iris structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-073369 [Patent Document 2] International Publication No. 2009 / 016846 [Patent Document 3] Japanese Patent Publication No. 2020-071627 [Patent Document 4] Japanese Patent Application Publication No. 2018-185749 [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 that are capable of appropriately capturing an iris image. [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 capturing the image, an execution means for determining an appropriate imaging distance based on the brightness when capturing the image, and a standing position guidance means for guiding the living body to a standing position that achieves 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 explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing the hardware configuration of an iris imaging system according to a first embodiment. [Figure 2] 1 is a block diagram showing a functional configuration of an iris imaging system according to a first embodiment. [Figure 3] 10A and 10B 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 image capturing system according to the first embodiment. [Figure 5] FIG. 10 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 the flow of operations of the iris image capturing system according to a modified example of the first embodiment. [Figure 7] 10 is a graph (part 1) showing the relationship between brightness and imaging distance. [Figure 8] 10 is a graph (part 2) showing the relationship between brightness and imaging distance. [Figure 9] 10 is a graph (part 3) showing the relationship between brightness and imaging distance. [Figure 10] 10 is a graph (part 4) showing the relationship between brightness and imaging distance. [Figure 11] FIG. 10 is a block diagram showing the functional configuration of an iris imaging system according to a third embodiment. [Figure 12] 10 is a flowchart showing the flow of operations of the iris image capturing system according to the third embodiment. [Figure 13] FIG. 10 is a block diagram showing the functional configuration of an iris imaging system according to a fourth embodiment. [Figure 14] 10 is a flowchart showing the flow of operations of the iris image capturing 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. 10 is a block diagram showing the 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 when guiding a standing position. [Figure 18] This is a conceptual diagram (part 2) showing an example of a display when guiding a standing position. [Figure 19] 10 is a flowchart showing the flow of operations of the iris image capturing system according to the fifth embodiment. [Figure 20] FIG. 13 is a block diagram showing the functional configuration of an iris imaging system according to a sixth embodiment. [Figure 21] 10A and 10B 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 image capturing system according to the sixth embodiment. [Figure 23] FIG. 13 is a block diagram showing the 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 image capturing system according to the seventh embodiment. [Figure 25] FIG. 13 is a block diagram showing the functional configuration of an iris imaging system according to an eighth embodiment. [Figure 26] 13 is a flowchart showing the flow of operations of the iris image capturing system according to the eighth embodiment. [Figure 27] FIG. 13 is a block diagram showing the functional configuration of an iris imaging system according to a modified example of the eighth embodiment. [Figure 28] FIG. 13 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 INVENTION

[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, RAM 12, ROM 13, storage device 14, input device 15, output device 16, camera 20, and sensor 21 are connected via a data bus 17.

[0013] The processor 11 loads a computer program. For example, the processor 11 is configured to load 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 load a computer program stored in a computer-readable storage medium using a storage medium reading device (not shown). The processor 11 may acquire (i.e., load) the computer program from a device (not shown) located 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 loaded computer program. In particular, in this embodiment, when the processor 11 executes the loaded computer program, a functional block for executing a process of capturing an iris image is realized within 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 operating in parallel.

[0014] The RAM 12 temporarily stores computer programs executed by the processor 11. The RAM 12 temporarily stores data that is temporarily used by the processor 11 while the processor 11 is executing the computer programs. 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 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 saved 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 input instructions 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 information related to the iris imaging system 10 to the outside. 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] Camera 20 is a camera capable of capturing an image of the iris of a living subject. Camera 20 may be configured as, for example, a near-infrared camera. Camera 20 may be positioned so that its imaging range includes the area around the face and eyes of the living subject. 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 a sensor capable of detecting information different from illuminance and indirectly detecting illuminance from that 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 its functions. 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, for example, in 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 referred to as "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 brightness (i.e., illuminance) when the imaging unit 110 captures an iris image. The illuminance acquisition unit 120 may acquire information about brightness directly from, for example, an illuminance sensor, or may acquire information about brightness indirectly from information not directly related to illuminance. The illuminance acquisition unit 120 may acquire information about brightness from, for example, time information. In this case, the illuminance acquisition unit 120 may acquire information about brightness using a map or the like that indicates the relationship between time and brightness, which is prepared in advance.

[0025] The execution unit 130 is configured to be able to execute control to reduce the distance (hereinafter referred to as "imaging distance" as appropriate) between the iris of the living body and the image capture unit 110 when the image capture unit 110 captures an iris image, based on information related to brightness acquired by the illuminance acquisition unit 120. The execution unit 130 may decide whether or not to execute control based on brightness, for example, or may change the amount of control or the content of 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 pupil size) 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 it is too large.

[0027] As shown in FIG. 3, the size of a living subject'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 capturing unit 110. As a result, the iris image may not be captured in an appropriate state, which may cause unintended inconvenience.

[0028] For example, when an iris image is used for iris authentication, a change in the state of the iris may prevent normal authentication operations. Specifically, if the pupil becomes too small, the iris pattern located just outside the pupil contracts, reducing the circumferential resolution of the pupil. On the other hand, if the pupil becomes too large, the entire iris is compressed in the radial direction of the pupil, reducing the radial resolution. The iris imaging system 10 according to this embodiment aims to acquire an appropriate iris image (specifically, an iris image with sufficient resolution) even when 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 with the imaging distance shortened according to the illuminance.

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

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

[0034] The modified examples described below differ only in some configurations and operations from the first embodiment, 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 explanations 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 includes, as processing blocks for realizing its functions, an imaging unit 110, an illuminance acquisition unit 120, an execution unit 130, an iris detection unit 210, an iris feature extraction unit 220, an iris feature matching unit 230, and an iris feature registration database 240. That is, the iris imaging system 10 according to the modification further includes, in addition to the configuration of the iris imaging system 10 according to the first embodiment (see FIG. 2), the iris detection unit 210, the iris feature extraction unit 220, the iris feature matching unit 230, and the iris feature registration database 240. Note that each of the iris detection unit 210, the iris feature extraction unit 220, and the iris feature matching unit 230 may be realized, for example, by the above-described processor 11 (see FIG. 1). The iris feature registration database 240 may be configured to include the above-described storage device 14 (see FIG. 1).

[0036] The iris detection unit 210 is configured to be able to detect an area where 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 related to the detected position of the iris to the iris feature amount extraction unit 220.

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

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

[0039] The iris feature registration database 240 is configured to be able to store registered feature amounts used for matching by the iris feature matching unit 230. The registered feature amounts may be data registered in advance. The registered feature amounts stored in the iris feature registration database 240 are configured to be able to be read out by the iris feature matching unit 230 as needed.

[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 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).

[0042] Next, the iris detection unit 210 detects an area where the iris exists from the iris image (step S104), and the iris feature amount extraction unit 220 extracts iris feature amounts from the area where 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 Effects) Next, the technical effects obtained by the iris imaging system 10 according to the first embodiment will be described.

[0045] As described with reference to FIGS. 1 to 6 , the iris imaging system 10 according to the first embodiment controls the imaging distance (i.e., the distance between the iris of a living subject and the imaging unit 110) to be reduced based on the illuminance (brightness) when capturing an iris image. As the imaging distance is reduced, the iris is captured closer. Therefore, the resolution of the iris image is higher than before the imaging distance was reduced. Therefore, the iris imaging system 10 according to the first embodiment makes it possible to capture a high-resolution iris image, taking into account the size of the pupil, which varies depending on the brightness. In particular, in a configuration for performing iris authentication (i.e., matching iris feature amounts) described in the modified example, a high-resolution iris image is often required to accurately extract the feature amounts. Therefore, the technical effects described above are particularly pronounced when 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. The second embodiment describes the control executed in the first embodiment described above (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 in 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 in which the iris image is captured becomes brighter. Note that the execution unit 130 may also 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 when capturing an iris image exceeds a predetermined threshold. 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 but 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] 10, the execution unit 130 may perform control to shorten the imaging distance not only when the environment when capturing an iris image becomes brighter but also when it becomes darker. As already explained, the size of the pupil may not only become too small when it is brighter but also become too large when it is darker (see FIG. 3). Therefore, in a situation where the environment when capturing an iris image 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 control for approaching a single target imaging distance has been described above, the target distance may have a certain range. For example, control may be performed so that the imaging distance falls within a certain range before and after the target imaging distance.

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

[0054] As explained in Figures 7 to 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 becomes possible to capture a high-resolution iris image taking into account the variation in pupil size depending on the brightness. Similarly, if similar control is performed in the dark, it becomes 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 Figures 11 and 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 estimate the pupil diameter of a living subject from the brightness when capturing an image. As already described, the size of a living subject's pupil changes depending on the environmental brightness (see FIG. 3). Therefore, by using information related to brightness, it is possible to estimate the pupil diameter of the living subject at that time. Note that the pupil diameter estimation unit 131 may be configured to estimate the pupil diameter using time information, etc., in addition to information related to brightness. The information on the pupil diameter estimated by the pupil diameter estimation unit 131 is used in the control executed by the execution unit 130. That is, in the third embodiment, control is performed to reduce the imaging distance based on the pupil diameter estimated from the brightness. For example, when it is bright, an imaging distance is calculated so that the number of pixels around the pupil is equal to or greater than a certain value and the entire iris is captured at an appropriate size, and control is performed to reduce the imaging distance. On the other hand, when it is dark, an imaging distance is calculated so that the number of pixels in the radial direction between the iris and the pupil is equal to or greater than a certain value and the entire iris is captured at an appropriate size, and control is performed to reduce the imaging distance. Here, capturing a larger iris image increases the resolution and makes the iris pattern clearer. However, even a slight deviation in the position of the iris can result in the iris going off-screen, potentially preventing the entire image from being captured. Also, getting too close can result in the image going beyond the focusable range. Therefore, these trade-offs must be taken into account when determining the appropriate iris size and imaging distance.

[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 shorten the imaging distance (step S103). Note that if the execution unit 130 determines that it is not necessary to execute control to shorten the imaging distance (if the pupil diameter does not require shortening the imaging distance), the image capturing unit 110 may capture an iris image in a state where the control by the execution unit 130 is not executed.

[0063] (Technical Effects) Next, the 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 performed to reduce the imaging distance based on the pupil diameter. In this way, it is possible to capture a high-resolution iris image by more specifically considering the fluctuation in pupil size depending on the brightness.

[0065] <Fourth embodiment> An iris imaging system 10 according to a fourth embodiment will be described with reference to Fig. 13 to Fig. 15. The fourth embodiment differs from the third embodiment described above only in some configurations and operations, 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 elements as those shown in Fig. 11 are denoted by the same reference numerals.

[0067] 13, the iris imaging system 10 according to the fourth embodiment is configured to include, 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, 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 store information indicating the relationship between brightness when capturing an iris image and the pupil diameter of a living subject. Pupil diameter database 140 may store, for example, the relationship between brightness and pupil diameter as a map, or may store a formula or the like for calculating pupil diameter from brightness. The information stored in pupil diameter database 140 may be prepared in advance (i.e., accumulated through prior experiments, simulations, etc.), or may be configured to be able to update the stored information as appropriate. Pupil diameter database 140 may store 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 execution unit 130 executes control to reduce the imaging distance, and then the imaging unit 110 captures an iris image of the living body (step S103).

[0073] (Example of configuration when accumulating data) Next, an example of the configuration when data is stored in the pupil diameter database 140 will be described with reference to Fig. 15. Fig. 15 is a block diagram showing the 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, iris imaging system 10 according to the modification of the fourth embodiment is configured to include, 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, 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), 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. 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 each be the same as those described in the modified example of the first embodiment (see FIG. 5). The pupil diameter calculation unit 250 may be realized, for example, in the above-mentioned processor 11 (see FIG. 1).

[0075] The pupil diameter calculation unit 250 is configured to calculate the pupil diameter from the area where the pupil is detected by the iris detection unit 210. A specific method for calculating the pupil diameter from an image can be appropriately implemented using existing technology, and therefore detailed description thereof will be omitted here. The pupil diameter calculation unit 250 is configured 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 each time the pupil diameter calculation unit 250 calculates the pupil diameter (in other words, each time the imaging unit 110 captures an iris image). In this manner, the pupil diameter database 140 may store new information related to the pupil diameter using the imaging results of the imaging unit 110. However, the pupil diameter database 140 may also store information other than the pupil diameter calculated by the pupil diameter calculation unit 250. Once a certain amount of information has been accumulated, statistical processing may be performed on the newly stored 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 the mean, median, or mode) may be calculated for each illuminance level, and the map for calculating pupil diameter from illuminance may be updated. In this case, the correspondence may be calculated not only using the newly added value, but also taking into account previously accumulated information. Furthermore, if pupil diameter is stored in association with time information, similar statistical processing 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 created by utilizing the relationship between brightness and time period.

[0076] (Technical Effects) Next, the 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 elements 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 guidance unit 132.

[0080] The standing position guiding unit 132 is configured to be able to issue a notification to a living body (i.e., a subject whose iris image is captured) urging them to move. The standing position guiding unit 132 may issue a notification to the subject urging them to move closer to the imaging unit 110. The standing position guiding unit 132 may issue the 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 urging the subject to move. Alternatively, the standing position guiding unit 132 may output a sound from a microphone urging the subject to move. A specific example of a guidance method used 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 the standing position is guided by the above-mentioned standing position guidance 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 the standing position is guided. Fig. 18 is a conceptual diagram (part 2) showing a display example when the standing position is guided.

[0082] As shown in FIG. 17, the standing position guidance unit 132 may display a message encouraging the subject to move along with the image of the subject. In the example shown in FIG. 17, the message "Please move a little closer to the camera" is displayed, but a specific distance to move may also be displayed. For example, a specific amount of movement, such as "Please move 10 cm closer," may be displayed. Alternatively, a frame indicating 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 also change as the subject moves. For example, when the target approaches the appropriate position, a message such as "That's OK" may be displayed. When the user gets 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 simultaneously display the message and announce the message by voice. Alternatively, no message may be displayed and only an audio announcement may be made. The distance to the subject may be estimated from the size and positional relationship of facial features in the image, or the size of the iris, or may be measured using a separate distance sensor or the like. The above-mentioned prompt message may then be changed using the distance obtained. For example, an appropriate imaging distance may be found within the focusable range, and control may be performed to approach that distance.

[0083] As shown in FIG. 18 , the standing position guidance unit 132 may use an indicator to prompt the subject to move. The indicator may include, for example, red, orange, yellow, or green lamps, and is configured to light up the corresponding lamp depending on the positional relationship between the subject and the image capture unit 110. Specifically, if the subject is too close or too far from the image capture unit 110, a red lamp lights up. As the subject approaches the image capture unit 110, the lamp changes color from orange to yellow, and when the subject is close enough, a green lamp lights up. Note that the indicator may be configured to guide the subject's standing position using a blinking pattern rather than a lamp color. For example, if the subject is far away from the image capture unit 110, the blinking cycle may become faster, and as the subject approaches the appropriate position, the blinking cycle may become slower, and the blinking may stop when the subject is in the appropriate position. The indicator described above may be configured using, for example, an LED lamp, or may be realized by displaying an image on a display or the like.

[0084] Instead of the indicator described above, a contour of the subject may be superimposed on the display to guide the subject so that the subject fits exactly within the contour. In this case, the size of the superimposed contour may vary depending on the brightness when capturing the iris image or the current pupil diameter of the subject. More specifically, when the capturing environment is very bright or very dark, a larger contour may be displayed to bring the subject closer, whereas when the capturing environment is only slightly bright or slightly dark, a slightly larger contour may be displayed to bring the subject slightly closer. Similarly, when the subject's pupil diameter is significantly different from the appropriate value, a larger contour may be displayed to bring the subject closer, whereas when the pupil diameter is only slightly different, a slightly larger contour may be displayed to bring the subject slightly 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 guiding unit 132 guides the target person to a standing position so as to achieve the determined imaging distance (step S502).

[0088] Thereafter, 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 Effects) Next, the technical effects obtained by the iris imaging system 10 according to the fifth embodiment will be described.

[0090] 16 to 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, by guiding the subject's standing position, it is possible to achieve an appropriate imaging distance according to the brightness. The configuration of the fifth embodiment is particularly effective in cases where, for example, the subject stands still 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 elements 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 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 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 bring it closer to 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 brought. 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 for 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, a specific example of changing the focus position of the imaging unit 110 by the focus position changing unit 133 will be 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 first, second, and third focus positions are set in the imaging unit 110. In this case, the focus position changing unit 133 changes each of the first, second, and third focus positions to a position that reduces the imaging distance. The focus position changing unit 133 may change the focus position so that the imaging distance decreases as the environment in which the image is captured becomes brighter. The focus position changing unit 133 may also change the focus position so that the focus position falls within an imaging range determined based on brightness. Note that, in the example shown in FIG. 21 , the first, second, and third focus positions are all changed by the same amount, but 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 the imaging range falls within the determined imaging range (step S602).

[0100] Thereafter, 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 Effects) Next, the technical effects obtained by the iris imaging system 10 according to the sixth embodiment will be described.

[0102] 20 to 22, in the iris imaging system 10 according to the sixth embodiment, control is executed to change the focus position of the imaging unit 110 in order to reduce the imaging distance. In this way, the imaging distance changes by changing the focus point of the imaging unit 110, and it becomes possible to achieve an appropriate imaging distance according to the brightness. The configuration of the sixth embodiment is particularly effective in cases where, for example, an image of a subject is captured multiple times while the subject moves within the imaging range of the imaging unit 110. In other words, when the subject moves in a direction approaching the camera, this is effective in cases where an image is captured multiple times while the focus position is shifted as the subject moves.

[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 elements 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, which may each be realized by, for example, the above-mentioned processor 11 (see FIG. 1).

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

[0107] When the resolution enhancement determination unit 150 determines that the resolution enhancement process should be performed, the resolution enhancement execution unit 160 executes the resolution enhancement process using the image captured by the image capture unit 110. The resolution enhancement execution unit 160 may execute the resolution enhancement process using one iris image, or may execute the resolution enhancement process using multiple iris images. The resolution enhancement 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 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).

[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 high resolution processing is to be executed (step S701: YES), the high resolution execution unit 160 executes high resolution processing using the image captured by the imaging unit 110 (step S702). On the other hand, if it is determined that high resolution processing is not to be executed (step S701: NO), the high resolution execution unit 160 does not execute high resolution processing (i.e., the processing of step S702 is omitted).

[0112] (Technical Effects) Next, the 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, and therefore 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 a high-resolution process is executed in addition to control for changing the imaging distance according to brightness, but it is also possible to execute the high-resolution process without controlling for changing the imaging distance. That is, it is also possible to execute only the high-resolution process according to the brightness when capturing an iris image. Even in this case, the above-mentioned technical effects are 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 only in part of the configuration and operation from the first to seventh embodiments described above, and other parts may be the same as 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 elements as those shown in Fig. 2 are denoted by the same reference numerals.

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

[0118] The pupil diameter acquisition unit 310 is configured to be able to acquire information regarding the pupil diameter of a living body. The pupil diameter acquisition unit 310 may acquire information regarding 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 used to acquire the pupil diameter does not need to be an in-focus image. Therefore, the pupil diameter may be acquired using an image captured at a point or time different from the focus 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 technology, 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 image capturing system 10 according to the eighth embodiment operates, ,Ma First, the pupil diameter acquisition unit 310 acquires information relating to 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, if the pupil diameter is too small, the execution unit 130 may execute control such that the imaging distance becomes shorter as the pupil diameter becomes smaller. Alternatively, for example, if the pupil diameter is too large compared to the iris diameter, the execution unit 130 may execute control such that the imaging distance becomes shorter 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.

[0122] Next, the image capturing unit 110 captures an iris image of the living body after the execution unit 130 executes control to shorten the imaging distance (step S103). Therefore, the iris image is captured with the imaging distance shortened according to the pupil diameter. Note that if the execution unit 130 determines that it is not necessary to execute control to shorten the imaging distance (if the pupil diameter does not require shortening the imaging distance), the image capturing unit 110 may capture the iris image without executing control by the execution unit 130.

[0123] (Variation) 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 the 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 denoted by the same reference numerals. Fig. 28 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.

[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 a description 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 where 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 each time an iris image is acquired.

[0127] 28 is an example in which the focus position changing unit 133 (see FIG. 20) changes the focus position of the imaging unit 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 unit 133 changes the focus position based on the pupil diameter acquired by the pupil diameter acquisition unit 310.

[0128] In this case, the pupil diameter acquisition unit 310 first acquires the pupil diameter from the iris image captured at the first focus position. Therefore, the focus position is not changed at the timing of the first image capture. On the other hand, for the second and third images, the focus position is changed based on the pupil diameter acquired in the first image capture, 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 focus position, the focus position for the first image capture is not changed, but the focus position for the second and subsequent images is changed.

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

[0130] (Technical Effects) Next, the 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 subject and the imaging unit 110) based on the pupil diameter of the living subject. 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, the iris imaging system 10 according to the eighth embodiment makes it 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 manages facility entrance and exit. Specifically, the system may operate such that if iris authentication is successful, the subject is permitted to enter or exit, and if iris authentication is unsuccessful, the subject is not permitted to enter or exit (prohibited). In this case, the subject's entrance and exit management may be realized by a walk-through authentication gate, and the gate may be controlled to open or close depending on the result of iris authentication. Then, the control of changing the focusing position as described above (see, for example, FIGS. 21 and 22) may be performed depending on the brightness and pupil diameter at the time of 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 payment processing. Specifically, the system may be applied to a system that operates such that, if iris authentication is successful, payment processing is executed using a payment method associated with the subject, and, if iris authentication is unsuccessful, payment processing 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 for guiding the subject's standing position, as already described (see, for example, FIGS. 17 and 18), may be implemented according to the brightness and pupil diameter when capturing an image.

[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 iris image may be used to execute authentication processing for unlocking the lock screen of the smartphone. 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 their hand and operate it, guidance information may be displayed to guide the subject to move the smartphone closer to or farther away from their 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-described 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. In other words, a computer-readable recording medium is also included in the scope of each embodiment. Furthermore, each embodiment includes not only a recording medium on which the above-described program is recorded, but also the program itself.

[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. The scope of each embodiment is not limited to programs recorded on the recording media that execute processing by themselves, but also includes programs that run on an OS in cooperation with other software and functions of an expansion board to execute processing.

[0138] This disclosure may be modified as appropriate within the scope of the claims and the gist or idea of ​​the invention that can be read from the entire specification, and iris imaging systems, iris imaging methods, and computer programs incorporating such modifications are also included in the technical idea 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 capturing the image, 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 brightness when capturing the image.

[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, the brighter the environment when capturing the image.

[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 the 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 capturing the image 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 focus 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 increasing means for generating a high resolution image from the 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, and is characterized in that it operates a computer to acquire brightness when capturing the image and, based on the brightness when capturing the image, execute control to reduce the distance between the iris of the living body and the imaging means when capturing the image.

[0150] (Appendix 11) The recording medium described in Supplementary Note 11 is a recording medium having the computer program described in Supplementary Note 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 the iris of a living body; an illuminance acquisition means for acquiring brightness when capturing the image; an execution means for determining an appropriate imaging distance for imaging the iris based on 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; An iris imaging system comprising:

2. The execution means estimates the distance to the living body from at least one of the size of the 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, thereby guiding 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 depending on the positional relationship between the living body and the imaging 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. An iris imaging method using an imaging means for capturing an image including an iris of a living body, comprising: Acquire brightness when capturing the image; determining an imaging distance appropriate for imaging the iris based on brightness when the image is captured; The living body is guided to a standing position so as to achieve the imaging distance.

1. An iris imaging method comprising:

10. An iris imaging method using an imaging means for capturing an image including an iris of a living body, comprising: Acquire brightness when capturing the image; determining an imaging distance appropriate for imaging the iris based on 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 that causes a computer to operate in such a manner.

Images