Imaging system, imaging method, and computer program

Abstract

To appropriately capture an image around the eyes of a subject.SOLUTION: An imaging system (10) includes first control means (110) that controls imaging means (20) to capture a first image of a subject (500) at a first pixel density, detection means (120) that detects the position of the subject's eyes from the first image, setting means (130) that sets a peripheral area around the subject's eyes on the basis of the position of the eyes, and second control means (140) that controls the imaging means to capture a second image of the peripheral area at a second pixel density higher than the first pixel density. According to such an imaging system, it is possible to appropriately capture an image around the eyes of the subject.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to the technical field of an imaging system, an imaging method, and a computer program for imaging a subject.

Background Art

[0002] As such a system, one that captures an image for iris authentication is known. For example, Patent Document 1 discloses a technique for detecting a subject's face and eyes and identifying an area of interest of the iris. Patent Document 2 discloses a technique for generating a low-resolution image from a high-resolution image and performing pupil detection from the low-resolution image.

[0003] As other related techniques, Patent Document 3 discloses a technique for synthesizing a plurality of images to generate a wide-angle composite image.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] An iris camera for capturing an image for iris authentication is generally set to have a high pixel count and a narrow angle of view. Therefore, due to restrictions on communication speed and angle of view range, it is difficult to capture a wide-angle image that allows the iris camera to detect the eye position of a subject. None of the above-cited documents mention such problems, and there is room for improvement.

[0006] This disclosure is made in view of the above-mentioned problems, and aims to provide an imaging system, imaging method, and computer program capable of appropriately capturing images of the area around the eyes of a subject. [Means for solving the problem]

[0007] One aspect of the imaging system of this disclosure includes: a first control means for controlling the imaging means to capture a first image of a subject at a first pixel density; a detection means for detecting the position of the subject's eyes from the first image; a setting means for setting a peripheral region which is the area around the subject's eyes based on the position of the eyes; and a second control means for controlling the imaging means to capture a second image of the peripheral region at a second pixel density higher than the first pixel density.

[0008] One aspect of the imaging method of this disclosure involves controlling an imaging means to capture a first image of a subject at a first pixel density, detecting the position of the subject's eyes from the first image, setting a peripheral region that is around the subject's eyes based on the eye position, and controlling the imaging means to capture a second image of the peripheral region at a second pixel density higher than the first pixel density.

[0009] One aspect of the computer program of this disclosure involves controlling an imaging means to capture a first image of a subject at a first pixel density, detecting the position of the subject's eyes from the first image, setting a peripheral region that is around the subject's eyes based on the eye position, and operating the computer to control the imaging means to capture a second image of the peripheral region at a second pixel density higher than the first pixel density. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing the hardware configuration of the imaging system according to the first embodiment. [Figure 2] This is a block diagram showing the functional configuration of the imaging system according to the first embodiment. [Figure 3]It is a flowchart showing the operation flow of the imaging system according to the first embodiment. [Figure 4] It is a conceptual diagram showing the imaging timing and imaging range of the first image and the second image according to the first embodiment. [Figure 5] It is a block diagram showing the functional configuration of the imaging system according to the second embodiment. [Figure 6] It is a flowchart showing the operation flow of the imaging system according to the second embodiment. [Figure 7] It is a conceptual diagram showing the imaging timing and imaging range of the first image and the second image according to the second embodiment. [Figure 8] It is a block diagram showing the functional configuration of the imaging system according to the third embodiment. [Figure 9] It is a flowchart showing the operation flow of the imaging system according to the third embodiment. [Figure 10] It is a block diagram showing the functional configuration of the imaging system according to the fourth embodiment. [Figure 11] It is a flowchart showing the operation flow of the imaging system according to the fourth embodiment. [Figure 12] It is a conceptual diagram showing the imaging timing and imaging range of the first image and the second image according to the fifth embodiment. [Figure 13] It is a conceptual diagram showing the operation when imaging a low-resolution first image by thinning out pixels. [Figure 14] It is a conceptual diagram showing the operation when imaging the first image by restricting the imaging area to be small.

Modes for Carrying Out the Invention

[0011] Hereinafter, embodiments of an imaging system, an imaging method, and a computer program will be described with reference to the drawings.

[0012] <First Embodiment> The imaging system according to the first embodiment will be described with reference to FIGS. 1 to 4.

[0013] (Hardware Configuration) First, while referring to FIG. 1, the hardware configuration of the imaging system 10 according to the first embodiment will be described. FIG. 1 is a block diagram showing the hardware configuration of the imaging system according to the first embodiment.

[0014] As shown in FIG. 1, the 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 imaging system 10 may further include an input device 15 and an output device 16. The processor 11, the RAM 12, the ROM 13, the storage device 14, the input device 15, and the output device 16 are connected via a data bus 17.

[0015] 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, ROM 13, and 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 also obtain (i.e., read) a computer program from a device (not shown) located outside the imaging system 10 via a network interface. The processor 11 controls the RAM 12, storage device 14, input device 15, and output device 16 by executing the read computer program. In this embodiment in particular, when the processor 11 executes the read computer program, a functional block for imaging a subject is realized within the processor 11. Furthermore, the processor 11 may use one of the following: CPU (Central Processing Unit), GPU (Graphics Processing Unit), FPGA (field-programmable gate array), DSP (Demand-Side Platform), or ASIC (Application Specific Integrated Circuit), or multiple of them may be used in parallel.

[0016] RAM12 temporarily stores computer programs executed by processor 11. RAM12 also temporarily stores data that processor 11 uses temporarily while it is executing computer programs. RAM12 may be, for example, D-RAM (Dynamic RAM).

[0017] ROM 13 stores computer programs executed by processor 11. ROM 13 may also store other static data. ROM 13 may be, for example, a P-ROM (Programmable ROM).

[0018] The storage device 14 stores data that the imaging system 10 will save for a long period of time. The storage device 14 may also 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 drive, a magneto-optical disk drive, an SSD (Solid State Drive), and a disk array device.

[0019] The input device 15 is a device that receives input instructions from the user of the imaging system 10. The input device 15 may include, for example, at least one of a keyboard, a mouse, and a touch panel.

[0020] The output device 16 is a device that outputs information related to the imaging system 10 to the outside. For example, the output device 16 may be a display device (e.g., a display) capable of displaying information related to the imaging system 10.

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

[0022] As shown in Figure 2, the imaging system 10 according to the first embodiment is connected to the iris camera 20. The imaging system 10 includes a first control unit 110, an eye position detection unit 120, an ROI setting unit 130, and a second control unit 140 as processing blocks for realizing its functions. The first control unit 110, the eye position detection unit 120, the ROI setting unit 130, and the second control unit 140 may be implemented, for example, in the processor 11 (see Figure 1) described above.

[0023] The first control unit 110 is configured to control the iris camera 20 so that it can capture a first image of the subject. The first image is used to detect the position of the subject's eyes and is captured with a relatively low first pixel density. The first image is captured so that, for example, the entire subject fits within the imaging range.

[0024] The eye position detection unit 120 uses the first image captured under the control of the first control unit 110 to detect the eye position of the subject (i.e., where the eyes are located). Note that existing technologies can be appropriately used for detecting the eye position of the subject from the image, so a more detailed explanation is omitted here. The information regarding the eye position of the subject detected by the eye position detection unit 120 is output to the ROI setting unit.

[0025] The ROI setting unit 130 is configured to set an ROI (Region of Interest) for imaging the iris of a subject based on the eye position of the subject detected by the eye position detection unit 120. The ROI is set as the region that the subject's eye will pass through at the focus point of the iris camera 20. Note that existing technologies can be appropriately used for setting the ROI from the eye position, so a more detailed explanation is omitted here. Information regarding the ROI set by the ROI setting unit 130 is output to the second control unit 140.

[0026] The second control unit 140 is configured to control the iris camera 20 so that a second image of the subject can be captured. The second image is captured as an image of the region set by the ROI setting unit 130, and is captured with a second pixel density higher than the first pixel density (i.e., the pixel density when the first image was captured). As a result, the second image is a high-resolution image of the area around the subject's eye.

[0027] (Flow of operations) Next, the operation flow of the imaging system 10 according to the first embodiment will be described with reference to Figure 3. Figure 3 is a flowchart showing the operation flow of the imaging system according to the first embodiment.

[0028] As shown in Figure 3, when the imaging system 10 according to the first embodiment is in operation, the first control unit 110 first controls the iris camera 20 to capture a first image of the subject (step S101). The first image is captured with a first pixel density.

[0029] Next, the eye position detection unit 120 detects the eye position of the subject from the first image (step S102). Then, the ROI setting unit 130 sets the ROI based on the detected eye position (step S103).

[0030] Next, the second control unit 140 controls the iris camera 20 to capture a second image in the set ROI (step S104). The second image is captured with a second pixel density that is higher than the first pixel density.

[0031] (Technical effects) Next, the technical effects obtained by the imaging system 10 according to the first embodiment will be described with reference to Figure 4. Figure 4 is a conceptual diagram showing the imaging timing and imaging range of the first and second images according to the first embodiment.

[0032] As shown in Figure 4, in the imaging system 10 according to the first embodiment, a first image is captured with a first pixel density, and then a second image is captured with a second pixel density. In particular, since the first pixel density is lower than the second pixel density, the amount of data for the first image can be made relatively smaller. Therefore, it is possible to prevent the amount of data for the first image, which requires a relatively wide field of view, from becoming large. As a result, the time required for communication and processing of the first image can be shortened, and processing from capturing the first image to capturing the second image (for example, processing to detect eye position, processing to set ROI, etc.) can be executed smoothly.

[0033] While it is conceivable to install a separate dedicated camera (i.e., a low-resolution camera) to capture the first image, this could lead to increased costs and a highly complex system. However, according to the imaging system of the first embodiment, the iris camera 20 can capture both the first image (i.e., an image for detecting the eye position and setting the ROI) and the second image (i.e., a high-resolution image of the iris). Therefore, the iris image of the subject can be appropriately captured without causing the aforementioned increased costs and highly complex system. Furthermore, having multiple types of cameras requires the user to face each camera, which can make the user aware of the cameras' presence and be cumbersome. According to the imaging system 10 of the first embodiment, even with just an iris camera with a narrow field of view, the eye position can be identified and the iris region identified with a low-resolution image. In addition, there is no need for the user to be aware of the cameras.

[0034] <Variation> The following describes modifications of the first embodiment. Note that these modifications can also be combined.

[0035] (First variation) The first control unit 110 may capture a first image, for example, when the subject reaches a predetermined trigger position. The timing of the subject reaching the trigger position may be detected, for example, by various sensors installed around the trigger position.

[0036] (Second variation) The second control unit 140 may, for example, capture a second image when the subject reaches a preset focus point of the iris camera 20. The second control unit 140 may also predict the timing when the subject reaches the focus point and capture multiple second images in succession around that timing.

[0037] (Third variation) The second image captured under the control of the second control unit 140 may be input to a biometric authentication unit (not shown) and used for iris authentication of the subject. This biometric authentication unit may be provided as part of the imaging system 10, or it may be located outside the imaging system 10 (for example, on an external server or in the cloud). As existing technologies can be appropriately adopted for authentication processing using the iris image (i.e., the second image), a more detailed explanation is omitted here.

[0038] <Second Embodiment> The imaging system 10 according to the second embodiment will be described with reference to Figures 5 to 7. The second embodiment differs from the first embodiment described above only in some configurations and operations; other parts are generally the same. Therefore, the following will describe in detail the parts that differ from the first embodiment, and will omit explanations of other overlapping parts as appropriate.

[0039] (Hardware configuration) The hardware configuration of the imaging system 10 according to the second embodiment may be the same as the hardware configuration of the first embodiment described in Figure 1. Therefore, a description of the hardware configuration of the imaging system 10 according to the second embodiment will be omitted.

[0040] (Functional configuration) Next, the functional configuration of the imaging system 10 according to the second embodiment will be described with reference to Figure 5. Figure 5 is a block diagram showing the functional configuration of the imaging system according to the second embodiment. Note that in Figure 5, the same reference numerals are used for components as in Figure 2.

[0041] As shown in Figure 5, the imaging system 10 according to the second embodiment is connected to each of the first iris camera 21, the second iris camera 22, and the third iris camera 23 (hereinafter sometimes collectively referred to as "iris cameras 20"). That is, the imaging system 10 according to the second embodiment is configured to control imaging by multiple iris cameras 20. The imaging system 10 also includes a first control unit 110, an eye position detection unit 120, an ROI setting unit 130, and a second control unit 140 as processing blocks to realize its functions.

[0042] (Flow of operations) Next, the operation flow of the imaging system 10 according to the second embodiment will be described with reference to Figure 6. Figure 6 is a flowchart showing the operation flow of the imaging system according to the second embodiment. Note that in Figure 6, the same reference numerals are used for the same processes as shown in Figure 3.

[0043] As shown in Figure 6, when the imaging system 10 according to the second embodiment is in operation, the first control unit 110 first controls the first iris camera 21, the second iris camera 22, and the third iris camera 23 to capture a first image of the subject (step S201). It is preferable that the first image is captured at the same time by each iris camera 20, but a slight difference in the timing of the captures is acceptable.

[0044] Next, the eye position detection unit 120 detects the eye position of the subject from multiple first images (step S102). Then, the ROI setting unit 130 sets the ROI based on the detected eye position (step S103).

[0045] Next, the second control unit 140 controls the iris camera 20 to capture a second image in the set ROI (step S104). Note that the second image only needs to be captured by one of the first iris camera 21, second iris camera 22, and third iris camera 23. In other words, it is not necessary for each of the iris cameras 20 to capture a second image separately. The iris camera 20 that captures the second image can be determined, for example, according to the ROI set by the ROI setting unit 130. Specifically, the second image should be captured by the iris camera 20 whose imaging range includes the ROI.

[0046] (Technical effects) Next, the technical effects obtained by the imaging system 10 according to the second embodiment will be described with reference to Figure 7. Figure 7 is a conceptual diagram showing the imaging timing and imaging range of the first and second images according to the second embodiment. Note that in Figure 7, the same reference numerals are used for components as shown in Figure 4.

[0047] As shown in Figure 7, in the imaging system 10 according to the second embodiment, a first image is captured by multiple iris cameras 20, and the eye position is detected and the ROI is set from these images. In particular, if only one first image is captured, the eye may not be included in the imaging range depending on the situation. However, by capturing multiple first images, a wider area can be captured, and as a result, the likelihood of capturing the eye position increases. Therefore, an appropriate ROI can be set from the eye position, and a second image (i.e., a high-resolution iris image) can be captured more appropriately.

[0048] Furthermore, the multiple first images do not necessarily have to be captured using multiple iris cameras 20; multiple first images may be captured using a single iris camera 20. Specifically, for example, the position of a single camera may be moved as appropriate to capture first images from multiple angles. Even in this case, the above-mentioned technical effects can be obtained by combining the multiple first images to generate a wide-angle image.

[0049] <Third Embodiment> The imaging system 10 according to the third embodiment will be described with reference to Figures 8 and 9. The third embodiment differs from the first and second embodiments described above only in some configurations and operations; other parts are generally the same. Therefore, the following will describe in detail the parts that differ from the first and second embodiments, while omitting explanations of other overlapping parts as appropriate.

[0050] (Hardware configuration) The hardware configuration of the imaging system 10 according to the third embodiment may be the same as the hardware configuration of the first embodiment described in Figure 1. Therefore, a description of the hardware configuration of the imaging system 10 according to the third embodiment will be omitted.

[0051] (Functional configuration) Next, the functional configuration of the imaging system 10 according to the third embodiment will be described with reference to Figure 8. Figure 8 is a block diagram showing the functional configuration of the imaging system according to the second embodiment. Note that in Figure 8, the same reference numerals are used for components as those shown in Figures 2 and 5.

[0052] As shown in Figure 8, the imaging system 10 according to the third embodiment includes a first control unit 110, an eye position detection unit 120, an ROI setting unit 130, a second control unit 140, and an image synthesis unit 210 as processing blocks for realizing its functions. In other words, the imaging system 10 according to the second embodiment is configured to include an image synthesis unit 210 in addition to the configuration of the second embodiment (see Figure 5).

[0053] The image synthesis unit 210 is configured to synthesize the first images captured by the first iris camera 21, the second iris camera 22, and the third iris camera 23. The first iris camera 21, the second iris camera 22, and the third iris camera 23 are positioned so that their imaging ranges do not significantly overlap. Therefore, when the first images captured by each iris camera 20 are synthesized, a single wide-angle image can be generated. The wide-angle image generated by the image synthesis unit 210 is output to the eye position detection unit 110. The image synthesis unit 210 can be implemented, for example, in the processor 11 (see Figure 1) described above.

[0054] (Flow of operations) Next, the operation flow of the imaging system 10 according to the third embodiment will be described with reference to Figure 9. Figure 9 is a flowchart showing the operation flow of the imaging system according to the third embodiment. Note that in Figure 9, the same reference numerals are used for the same processes as shown in Figures 3 and 6.

[0055] As shown in Figure 9, when the imaging system 10 according to the third embodiment is in operation, the first control unit 110 first controls the first iris camera 21, the second iris camera 22, and the third iris camera 23 to capture a first image of the subject (step S201).

[0056] Next, the image synthesis unit 210 synthesizes multiple first images captured by the first iris camera 21, the second iris camera 22, and the third iris camera 23 (step S202). Subsequently, the eye position detection unit 120 detects the eye position of the subject from the wide-angle image obtained by synthesizing the multiple first images (step S102). Then, the ROI setting unit 130 sets the ROI based on the detected eye position (step S103).

[0057] Next, the second control unit 140 controls the iris camera 20 to capture a second image in the set ROI (step S104).

[0058] (Technical effects) Next, the technical effects obtained by the imaging system 10 according to the third embodiment will be described.

[0059] As explained in Figures 8 and 9, in the imaging system 10 according to the third embodiment, images captured by multiple iris cameras 20 are combined to generate a single wide-angle image. In particular, the iris cameras 20 are often set to have a relatively narrow field of view because they are required to capture images of the subject's iris in high resolution. However, according to the imaging system 10 according to the third embodiment, a wide-angle image is generated from the first images captured by multiple iris cameras 20. Therefore, even if the field of view of each individual iris camera is narrow, a wide-angle image suitable for detecting eye position can be obtained.

[0060] <Fourth Embodiment> The imaging system 10 according to the fourth embodiment will be described with reference to Figures 10 and 11. The fourth embodiment differs from the first to third embodiments described above only in some configurations and operations; other parts are generally the same. Therefore, the following will describe in detail the parts that differ from the first to third embodiments, and will omit explanations of other overlapping parts as appropriate.

[0061] (Hardware configuration) The hardware configuration of the imaging system 10 according to the fourth embodiment may be the same as the hardware configuration of the first embodiment described in Figure 1. Therefore, a description of the hardware configuration of the imaging system 10 according to the fourth embodiment will be omitted.

[0062] (Functional configuration) Next, the functional configuration of the imaging system 10 according to the fourth embodiment will be described with reference to Figure 10. Figure 10 is a block diagram showing the functional configuration of the imaging system according to the fourth embodiment. Note that in Figure 10, the same reference numerals are used for components as those shown in Figures 2, 5, and 8.

[0063] As shown in Figure 10, the imaging system 10 according to the fourth embodiment includes a first control unit 110, an eye position detection unit 120, an ROI setting unit 130, a second control unit 140, and an eye region determination unit 220 as processing blocks for realizing its functions. In other words, the imaging system 10 according to the fourth embodiment is configured to further include the eye region determination unit 220 in addition to the configuration of the second embodiment (see Figure 5).

[0064] The eye region determination unit 220 is configured to determine whether or not the eye region is included in the first image captured by each of the first iris cameras 21, 2, and 3. In other words, the eye region determination unit 220 is configured to determine which of the multiple first images captured by the second and third iris cameras 22 and 3 contains the eye region. The determination result of the eye region determination unit 220 (i.e., information regarding the first image containing the eye region) is output to the eye position detection unit 110. The eye region determination unit 220 can be implemented, for example, in the processor 11 (see Figure 1) described above.

[0065] (Flow of operations) Next, the operation flow of the imaging system 10 according to the fourth embodiment will be described with reference to Figure 11. Figure 11 is a flowchart showing the operation flow of the imaging system according to the fourth embodiment. Note that in Figure 11, the same reference numerals are used for the same processes as shown in Figures 3, 6, and 9.

[0066] As shown in Figure 11, when the imaging system 10 according to the fourth embodiment is in operation, the first control unit 110 first controls the first iris camera 21, the second iris camera 22, and the third iris camera 23 to capture a first image of the subject (step S201).

[0067] Next, the eye region determination unit determines whether or not an eye region exists in a plurality of first images captured by the first iris camera 21, the second iris camera 22, and the third iris camera 23 (step S203). Subsequently, the eye position detection unit 120 detects the eye position of the subject from the first images that have been determined to contain an eye region (step S102). Then, the ROI setting unit 130 sets an ROI based on the detected eye position (step S103).

[0068] Next, the second control unit 140 controls the iris camera 20 to capture a second image in the set ROI (step S104).

[0069] (Technical effects) Next, the technical effects obtained by the imaging system 10 according to the fourth embodiment will be described.

[0070] As explained in Figures 10 and 11, in the imaging system 10 according to the fourth embodiment, it is determined whether or not the eye region is included in the first image captured by the multiple iris cameras 20, and the eye position is detected from the first image that includes the eye region. Therefore, it is possible to detect the eye position more efficiently compared to the case where the eye position is detected from all first images.

[0071] <Fifth Embodiment> The imaging system 10 according to the fifth embodiment will be described with reference to Figure 12. The fifth embodiment specifically describes other methods for capturing the first image, and the hardware configuration, functional configuration, and operation flow of the system may be the same as those of the first to fifth embodiments described above. For this reason, the following will describe in detail the parts that differ from the first to fifth embodiments, and will omit explanations of other overlapping parts as appropriate.

[0072] (Multiple images of the first image) First, with reference to Figure 12, the timing of the first image acquisition by the imaging system 10 according to the fifth embodiment will be described in detail. Figure 12 is a conceptual diagram showing the acquisition timing and imaging range of the first and second images according to the fifth embodiment. Note that in Figure 12, the same reference numerals are used for components as those shown in Figures 4 and 7.

[0073] As shown in Figure 12, in the imaging system according to the fifth embodiment, the first iris camera 21, the second iris camera 22, and the third iris camera 23 each capture a first image at different timings. Specifically, the first iris camera 21 captures a first image when the subject 500 reaches the first trigger point. The second iris camera 22 captures a first image when the subject 500 reaches the second trigger point. The third iris camera 23 captures a first image when the subject 500 reaches the third trigger point. In this way, by setting up multiple trigger points at different times, multiple first images will be captured at different timings.

[0074] The eye position of subject 500 can be detected from each of the multiple first images captured as described above. For example, the eye position may be detected using all of the multiple first images, or the first image containing the eye region may be selected from the multiple first images, and the eye position may be detected using only the first image containing the eye region.

[0075] Furthermore, it is preferable that the multiple iris cameras 20 be configured such that the overlapping area of ​​their imaging ranges is sufficiently large. In this way, even if the height of the subject 500 varies, at least one iris camera 20 can capture the face of the subject 500 without interruption.

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

[0077] As explained in Figure 12, in the imaging system 10 according to the fifth embodiment, multiple first images are captured at different timings. Even in this case, it is possible to detect the eye position of the subject 500, just as when multiple first images are captured simultaneously.

[0078] <Sixth Embodiment> The imaging system 10 according to the sixth embodiment will be described with reference to Figure 13. The third embodiment specifically describes a method for reducing the resolution when capturing the first image, and the hardware configuration, functional configuration, and operation flow of the system may be the same as those of the first to fifth embodiments described above. For this reason, the following will describe in detail the parts that differ from the first to fifth embodiments, and will omit explanations of other overlapping parts as appropriate.

[0079] (Reduced resolution due to pixel decimation) First, with reference to Figure 13, the reduction in resolution of the first image in the imaging system 10 according to the sixth embodiment will be explained. Figure 13 is a conceptual diagram showing the operation when pixels are downsampled to capture a low-resolution first image.

[0080] As shown in Figure 13, in the imaging system 10 according to the sixth embodiment, the resolution of the first image is reduced by downsampling pixels in the iris camera 20. Specifically, the first control unit 110 reduces the number of pixels read out when capturing the first image, for example, by using a technique such as binning. As a result, the pixel density of the first image decreases. On the other hand, the second control unit 140 does not downsample pixels when capturing the second image (however, the imaging area is limited to the ROI). In this way, the pixel density of the second image is higher compared to the first image.

[0081] Furthermore, the amount of pixel decimation may be varied depending on the location in the imaging area. In other words, the amount of pixel decimation does not have to be uniform across the entire imaging area. For example, the amount of decimation may be reduced in areas where there is a high probability of eye regions being present, and increased in areas where there is a low probability of eye regions being present.

[0082] (Technical effects) Next, the technical effects obtained by the imaging system 10 according to the sixth embodiment will be described.

[0083] As explained in Figure 13, in the imaging system 10 according to the sixth embodiment, the resolution of the first image is reduced by downsampling pixels. Therefore, it is possible to prevent the amount of data in the first image from becoming large and to shorten the time required for communication and processing of the first image.

[0084] <Seventh Embodiment> The imaging system 10 according to the seventh embodiment will be described with reference to Figure 14. The seventh embodiment specifically describes a method for reducing the amount of data when capturing the first image, and the system's hardware configuration, functional configuration, and operation flow may be the same as those of the first to sixth embodiments described above. Therefore, the following will describe in detail the parts that differ from the first to sixth embodiments, and will omit explanations of other overlapping parts as appropriate.

[0085] (Limitations on the imaging area) First, with reference to Figure 14, the reduction of the data volume of the first image in the imaging system 10 according to the seventh embodiment will be explained. Figure 14 is a conceptual diagram showing the operation when capturing the first image by limiting the imaging area to a small size.

[0086] As shown in Figure 14, in the imaging system 10 according to the seventh embodiment, the amount of data in the first image is reduced by limiting (i.e., narrowing) the imaging area of ​​the iris camera 20. Specifically, the first control unit 110 does not read out pixels from at least one of the upper and lower portions of the imaging area (for example, an area where it is estimated that the subject's eyes are unlikely to be located) when capturing the first image. As a result, the amount of data in the first image is reduced. Furthermore, as explained in the sixth embodiment, the first image is captured with pixels downsampled, so the pixel density is also reduced. Therefore, the amount of data in the first image is significantly reduced.

[0087] Furthermore, in addition to or instead of reading out the upper and lower portions mentioned above, at least one of the pixels in the right and left portions of the imaging area may be omitted. For example, if the subject is walking through the center of a passageway (for example, if an arrow is painted on the floor and the subject is guided to the center of the passageway), the likelihood of the subject's eyes being included in the right and left portions of the imaging area is low. Therefore, by omitting at least one of the pixels in the right and left portions of the imaging area, the amount of data in the first image can be efficiently reduced.

[0088] (Technical effects) Next, the technical effects obtained by the imaging system 10 according to the seventh embodiment will be described.

[0089] As explained in Figure 14, in the imaging system 10 according to the seventh embodiment, further reduction in the amount of data of the first image is achieved by narrowing the imaging area of ​​the iris camera 20. Therefore, it is possible to prevent the amount of data of the first image from becoming large and to shorten the time required for communication and processing of the first image.

[0090] <Note> The embodiments described above may also be described in the following appendix, but are not limited to these.

[0091] (Note 1) The imaging system described in Appendix 1 is characterized by comprising: a first control means for controlling the imaging means to capture a first image of a subject at a first pixel density; a detection means for detecting the position of the subject's eyes from the first image; a setting means for setting a peripheral region which is the area around the subject's eyes based on the position of the eyes; and a second control means for controlling the imaging means to capture a second image of the peripheral region at a second pixel density higher than the first pixel density.

[0092] (Note 2) The imaging system described in Appendix 2 is the imaging system described in Appendix 1, characterized in that the first control means processes the pixels of the imaging means to reduce the first pixel density to a lower value than the second pixel density.

[0093] (Note 3) The imaging system described in Appendix 3 is the imaging system described in Appendix 1 or 2, characterized in that the first control means reduces the amount of data of the first image by limiting the imaging area of ​​the imaging means to a small size.

[0094] (Note 4) The imaging system described in Appendix 4 is an imaging system described in any one of Appendix 1 to 3, characterized in that the imaging means includes a plurality of cameras, and the first control means controls the imaging means to capture a first image with each of the plurality of cameras.

[0095] (Note 5) The imaging system described in Appendix 5 is an imaging system described in any one of Appendix 1 to 4, characterized in that the detection means detects the position of the subject's eyes from a composite image obtained by combining a plurality of first images.

[0096] (Note 6) The imaging system described in Appendix 6 is the imaging system described in any one of Appendix 1 to 5, characterized in that the first control means controls the imaging means to capture the first image when the subject reaches a predetermined trigger position.

[0097] (Note 7) The imaging system described in Appendix 7 is the imaging system described in any one of Appendix 1 to 6, characterized in that the second imaging means controls the imaging means to capture a second image when the subject reaches a preset focus point.

[0098] (Note 8) The imaging system described in Appendix 8 is the imaging system according to any one of claims 1 to 7, further comprising authentication means for performing iris authentication of the subject using the second image.

[0099] (Note 9) The imaging method described in Appendix 9 is characterized by controlling the imaging means to capture a first image of a subject at a first pixel density, detecting the position of the subject's eyes from the first image, setting a peripheral region that is around the subject's eyes based on the eye position, and controlling the imaging means to capture a second image of the peripheral region at a second pixel density higher than the first pixel density.

[0100] (Note 10) The computer program described in Appendix 10 is a computer program characterized by controlling an imaging means to capture a first image of a subject at a first pixel density, detecting the position of the subject's eyes from the first image, setting a peripheral region that is around the subject's eyes based on the eye position, and operating the computer to control the imaging means to capture a second image of the peripheral region at a second pixel density higher than the first pixel density.

[0101] This disclosure may be modified as appropriate, without contradicting the gist or idea of ​​the invention as can be inferred from the claims and the specification as a whole, and imaging systems, imaging methods, and computer programs with such modifications are also included in the technical idea of ​​this disclosure. [Explanation of Symbols]

[0102] 10 Imaging System 20 Iris Camera 21. First Iris Camera 22. Second Iris Camera 23. Third Iris Camera 110 First Control Unit 120 Eye position detection unit 130 ROI setting section 140 Second Control Unit 210 Image synthesis department 220-item field determination department 500 written type

Claims

1. A first control means controls the imaging means to capture a first image of the subject at a first pixel density when the subject is at a first position, A detection means for detecting the position of the subject's eyes from a first image captured when the subject is in the first position, Setting means for setting a peripheral region which is the predicted area around the subject's eyes when the subject is in a second position, based on the position of the subject's eyes when the subject is in a first position, A second control means controls the imaging means to capture a second image of the peripheral region with a second pixel density higher than the first pixel density when the subject is at the second position. Equipped with, The first control means controls a plurality of imaging means to capture a first image, each including different regions of the subject, at a first pixel density when the subject is at a first position. The detection means detects the position of the subject's eyes from a composite image obtained by combining a plurality of the first images. An imaging system characterized by the following:

2. The first control means reduces the amount of data in the first image by limiting the imaging area to a smaller size through a first operation in which at least one of the pixels in the upper and lower ends of the imaging area of ​​the imaging means is not read. The imaging system according to feature 1.

3. The first control means reduces the amount of data in the first image by limiting the imaging area to a smaller size through a second operation in which at least one of the pixels in the rightmost and leftmost portions of the imaging area of ​​the imaging means is not read. The imaging system according to feature 1.

4. The second control means, when the subject is at the second position, causes one of the plurality of imaging means capable of imaging the peripheral region to image the peripheral region at the second pixel density. The imaging system according to feature 1.

5. When the subject is in a first position, the imaging means is controlled to capture a first image of the subject with a first pixel density. The position of the subject's eyes is detected from the first image taken when the subject is in the first position. Based on the position of the subject's eyes when the subject is in the first position, a peripheral region is set which is the predicted area around the subject's eyes when the subject is in the second position. The imaging means is controlled to capture a second image of the peripheral region with a second pixel density higher than the first pixel density. When the subject is in the first position, the plurality of imaging means are controlled to capture a first image, each containing different regions of the subject, at the first pixel density. The position of the subject's eyes is detected from a composite image obtained by combining multiple first images. An imaging method characterized by the following:

6. When the subject is in a first position, the imaging means is controlled to capture a first image of the subject with a first pixel density. The position of the subject's eyes is detected from the first image taken when the subject is in the first position. Based on the position of the subject's eyes when the subject is in the first position, a peripheral region is set which is the predicted area around the subject's eyes when the subject is in the second position. When the subject is at the second position, the imaging means is controlled to capture a second image of the peripheral region with a second pixel density higher than the first pixel density. When the subject is in the first position, the plurality of imaging means are controlled to capture a first image, each containing different regions of the subject, at the first pixel density. The position of the subject's eyes is detected from a composite image obtained by combining multiple first images. A computer program characterized by causing a computer to operate in a certain manner.

Images