JP2008052510A - Iris imaging apparatus, iris authentication apparatus, iris imaging method, iris authentication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new and improved iris imaging apparatus for suppressing power consumption required for illumination and reducing glare for a subject. <P>SOLUTION: The iris imaging apparatus 10 is provided with an imaging part 13 for imaging eyes of the subject, a luminance distribution analysis part 19 for generating luminance distribution information by analyzing a luminance distribution of an iris region in an eye image picked up by the imaging part 13, and an adjusting part 20 for adjusting brightness of a photographic lighting 12 and/or a setting parameter of the imaging part 13 on the basis of the luminance distribution information. The brightness of the lighting and the setting parameter of the imaging part can be properly adjusted according to iris characteristics of the subject and the brightness of a photographic environment, thereby minimizing the brightness of the lighting. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an iris imaging device, an iris authentication device, an iris imaging method, and an iris authentication method.

  An iris authentication device is a device that performs personal authentication using iris information obtained by imaging a human eye (see, for example, Patent Documents 1 and 2). FIG. 1 is a configuration example of a conventional iris authentication device 1. As shown in FIG. 1, the iris authentication apparatus 1 captures an imaging illumination 2 that illuminates the eyes 9 (face) of the registrant / authenticated person to be imaged and the eyes 9 of the registrant / authenticated person. An image pickup unit 3 composed of an image pickup device (CCD or the like), a lighting control unit 4 that controls the illumination 2 and the image pickup unit 3, and an iris processing engine 5 that processes the picked-up eye image to generate iris code information. And an information storage unit 6 for storing the generated iris code information together with the identification information of the registrant, an operation interface unit 7 (hereinafter referred to as “operation I / F unit 7”), and the iris authentication apparatus 1 as a whole. And a control unit 8. About the illumination 2 and the imaging part 3, there exist both what used the infrared band and what used the visible light band according to a use etc.

  FIG. 2 is an example of an information configuration for each registrant stored in the conventional information storage unit 6. In the example of FIG. 2, the number, name, and iris code information are stored in association with each registrant.

  3 is a flowchart showing the operation of the conventional iris authentication apparatus 1 shown in FIG. 1, wherein FIG. 3A shows a registration procedure and FIG. 3B shows an authentication procedure. As shown in FIG. 3A, in the registration procedure, first, the registrant inputs the person's name to the iris authentication device 1 using the operation I / F unit 7 (S1), and instructs the start of the registration operation (S2). ). The iris authentication device 1 detects the eyes using the image of the registrant's face imaged by the imaging unit 3 (S3), and when the eyes are detected, the illumination 2 is turned on (S4). An image of the eye is captured by the imaging unit 3 while the illumination 2 is turned on (S5), and the illumination 2 is turned off after the imaging of the eye image (S6). The captured eye image is image-processed by the iris processing engine 5 and iris code information corresponding to the image of the iris region unique to each individual (code information representing the characteristics of the registrant's iris; hereinafter referred to as “iris code”). ) Is generated (S7). As a result, it is determined whether or not the iris code is properly generated (S8). If the iris code is properly generated, the iris code is stored in the name information of the registrant input in step S1, And the registration number are stored in the information storage unit 6 (S9). On the other hand, if the generation of the iris code fails for some reason, a retry process is performed, and the above-described processes (S3 to S7) are repeated.

  As shown in FIG. 3B, in the authentication procedure, first, the person to be authenticated inputs identification information such as a name or registration number registered in advance using the operation I / F unit 7 (S11). Is started (S12). The iris authentication device 1 detects the eyes using the face image of the person to be authenticated that is imaged by the imaging unit 3 (S13), and starts lighting the illumination 2 when the eyes are detected (S14). While the illumination 2 is turned on, an image of the eye is captured by the imaging unit 3 (S15), and the illumination 2 is turned off after imaging (S16). The captured eye image is subjected to image processing by the iris processing engine 5, and an iris code corresponding to the image in the iris region is generated (S17). As a result, it is determined whether or not the iris code has been properly generated (S18). If the generation of the iris code has failed for some reason, a retry process is performed, and the above-described processes (S13 to S17) are repeated. . On the other hand, if the generation of the iris code is successful, the iris code of the registrant corresponding to the identification information such as the name or registration number input in step S11 is read from the information storage unit 6 (S19), Compared with the iris code of the person to be authenticated generated in step S17, it is verified whether or not both iris codes match (S20). As a result, if they match, it is determined that the person to be authenticated is the registrant (S21), and if they do not match, it is determined that the person to be authenticated is not the registrant (S22).

Japanese Patent Publication No. 5-84166 JP 2003-331265 A

  However, the eye image picked up by the conventional iris authentication apparatus 1 has a problem that an individual difference of the iris for each person to be imaged and a difference depending on the image pickup environment occur as follows.

  FIG. 4 is a distribution diagram illustrating an example of the appearance frequency of the luminance value for each pixel of the iris region S from the captured eye image. As shown in FIG. 4A, the iris region S is a donut-shaped region between the iris outer circumference circle A and the pupil circle B in the subject's eye. In the eye image, the luminance frequency distribution for all the pixels in the iris region S is obtained in the luminance value distribution diagram of FIG. As shown in FIG. 4 (b), the luminance distribution of the photographed iris shows a different tendency for each registrant / authenticated person depending on race and individual differences, even when illuminated with the same brightness. It is known. Further, it has been experimentally confirmed that when the brightness of the iris shows a low distribution as a whole, the feature of the iris hardly appears and a brighter illumination is required.

  Furthermore, when visible light is used for illumination, the brightness distribution is lower, so the brightness distribution is higher than the Oriental black / brown eyes that require brighter illumination. It is generally said that western blue and green eyes that do not need to feel more dazzling.

  Also, the quality of the obtained eye image varies depending on the brightness of the imaging environment for registration / authentication (the surrounding environment where the eye image is captured). For example, in an eye image captured in a relatively bright environment, the surroundings are reflected in the eye more often, so relatively bright illumination is required, whereas the image is captured in a relatively dark environment. In the eye image, since the reflection is small, there is a difference that the illumination may be relatively dark. In particular, an apparatus that captures an image using the visible light band requires brighter illumination when the imaging environment is relatively bright than when the imaging environment is relatively dark in order to reduce noise caused by reflection. This has been confirmed by experiments.

  As described above, in the conventional iris imaging method, the maximum brightness that is sufficient for any condition is sufficient for the illumination 2 in FIG. Saino lighting has been used. For this reason, excessive light irradiation may cause an increase in power consumption required for illumination, and when using visible light illumination, the person to be imaged feels more dazzling than necessary. There was a problem of letting it go.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to suppress power consumption required for illumination and to reduce glare felt by the person to be imaged. A new and improved iris imaging device, iris authentication device, iris imaging method, and iris authentication method are provided.

  In order to solve the above-described problem, according to one aspect of the present invention, a luminance distribution is analyzed by analyzing a luminance distribution of an imaging unit that images the eye of the person to be imaged, and an iris region of the eye image captured by the imaging unit. An iris comprising: a luminance distribution analysis unit that generates information; and an adjustment unit that adjusts the brightness of illumination for imaging and / or setting parameters of the imaging unit based on the luminance distribution information An imaging device is provided.

  With this configuration, the brightness of the illumination and the setting parameters of the imaging unit are adjusted according to the luminance distribution information generated by analyzing the eye image obtained by imaging the eye of the person to be imaged. Depending on the imaging environment, the brightness of the illumination and the setting parameters of the imaging unit can be adjusted appropriately. Therefore, the brightness of the illumination can be adjusted to the minimum necessary, so that the power consumption of the illumination can be suppressed and the glare felt by the person to be imaged can be reduced.

  In addition, the information processing unit further includes an information storage unit that stores the luminance distribution information generated by the luminance distribution analysis unit in association with the identification information of the person to be imaged. The brightness of the illumination and / or the setting parameters of the imaging unit may be adjusted based on the luminance distribution information corresponding to the subject to be imaged stored in the information storage unit. As a result, the brightness distribution information of the imaged person's iris is registered in advance in the information storage unit together with the registrant's identification information, and at the time of re-imaging, the luminance distribution information corresponding to the imaged person is read from the information storage unit. By appropriately adjusting the brightness of the illumination and the setting parameters of the imaging unit, it is possible to capture an eye image of appropriate quality according to the characteristics of the iris of the person being imaged.

  The luminance distribution analysis unit analyzes the luminance distribution of the eye image captured by the imaging unit to generate luminance distribution information, and the adjustment unit determines the brightness of the imaging environment based on the luminance distribution information. Then, the brightness of the illumination and / or the setting parameters of the imaging unit may be adjusted according to the brightness of the imaging environment. Thus, before capturing a formal eye image, an image captured with the illumination turned off is analyzed in advance to obtain luminance distribution information, and the brightness of the imaging environment is determined using this luminance distribution information. By adjusting the brightness of the illumination and the parameters of the imaging unit in accordance with the brightness of the environment, an eye image with an appropriate quality according to the brightness of the imaging environment can be captured during formal imaging.

  In order to solve the above-described problem, according to another aspect of the present invention, an iris that generates iris information from the above-described iris imaging device and an eye image of a registrant or a person to be authenticated captured by the imaging unit. An information generation unit, an information storage unit that stores iris information and luminance distribution information in association with registrant identification information, an iris information generated by the iris information generation unit, and an information storage unit in advance. There is provided an iris authentication device comprising: a collation unit that collates the stored iris information of a registrant.

  With this configuration, at the time of authentication of the person to be authenticated, the brightness distribution information corresponding to the person to be authenticated registered in the information storage unit is used to appropriately adjust the brightness of the illumination and the setting parameters of the imaging unit, An appropriate eye image can be captured according to the iris characteristics of the person to be authenticated and the brightness of the imaging environment. Therefore, since the brightness of the illumination can be adjusted to the minimum necessary, the power consumption of the illumination can be suppressed and the glare felt by the person to be authenticated can be reduced.

  In order to solve the above problem, according to another aspect of the present invention, an imaging step of imaging an eye of a person to be imaged by an imaging unit, and a luminance distribution of an eye image captured by the imaging unit are analyzed. A luminance distribution analysis step for generating luminance distribution information, and an adjustment step for adjusting the brightness of the illumination for imaging and / or the setting parameters of the imaging unit based on the luminance distribution information. An iris imaging method is provided.

  In addition, the information processing unit further includes an information storage step of storing the luminance distribution information generated in the luminance distribution analysis step in the information storage unit in association with the identification information of the person to be imaged. When imaging again, the brightness of the illumination and / or the setting parameters of the imaging unit may be adjusted based on the luminance distribution information corresponding to the person to be imaged stored in the information storage unit.

  In the luminance distribution analysis step, the iris region of the eye image captured by the imaging unit is analyzed to generate luminance distribution information. In the adjustment step, the brightness of the imaging environment is determined based on the luminance distribution information. Then, the brightness of the illumination and / or the setting parameters of the imaging unit may be adjusted according to the brightness of the imaging environment.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, at the time of registration, a first imaging step of imaging a registrant's eyes by an imaging unit, and a registrant imaged in the first imaging step A first iris information generating step for generating iris information from the eye image of the first, a first luminance distribution analyzing step for analyzing the luminance distribution of the iris region of the registrant's eye image and generating first luminance distribution information; An information storage step of storing iris information and first luminance distribution information in the information storage unit in association with identification information of the registrant, and an information storage unit when imaging the eye of the person to be authenticated by the imaging unit during authentication A first adjustment step of adjusting the brightness of the illumination for imaging and / or the setting parameters of the imaging unit based on the first luminance distribution information corresponding to the authenticated person stored in With the imaging unit A second imaging step for imaging the eye of the person to be authenticated, a second iris information generation step for generating iris information from the eye image of the person to be authenticated imaged in the second imaging step, and a second iris information generation step The iris authentication method is characterized in that it includes a collation step of collating the iris information of the person to be authenticated generated in step 1 with the iris information of the registrant stored in the information storage unit.

  A second luminance distribution analyzing step for analyzing the luminance distribution of the eye image picked up by the image pickup unit and generating second luminance distribution information when the eye of the person to be authenticated is picked up by the image pickup unit at the time of authentication; The brightness of the imaging environment is determined based on the second brightness distribution information generated in the second brightness distribution analysis step, and the brightness of the illumination adjusted in the first adjustment step is determined according to the brightness of the imaging environment. And / or a second adjustment step of further adjusting the setting parameters of the imaging unit.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, at the time of registration, a first imaging step of imaging a registrant's eyes by an imaging unit, and a registrant imaged in the first imaging step A first iris information generating step for generating iris information from the eye image, an information storing step for storing the iris information in the information storage unit in association with the identification information of the registrant, and an authentication unit by the imaging unit at the time of authentication When the person's eyes are imaged, the luminance distribution of the eye image captured by the imaging unit is analyzed to generate second luminance distribution information, and the second luminance distribution analyzing step and the second luminance distribution analyzing step are generated. A second adjustment step of determining the brightness of the imaging environment based on the second luminance distribution information, and adjusting the brightness of the illumination and / or the setting parameter of the imaging unit according to the brightness of the imaging environment; , The adjustment A second imaging step for imaging the eye of the person to be authenticated by the imaging unit, and a second iris information generation step for generating iris information from the eye image of the person to be authenticated captured in the second imaging step. And a verification step for verifying the iris information of the person to be authenticated generated in the second iris information generation step and the iris information of the registrant stored in the information storage unit. A method is provided.

  As described above, according to the present invention, the brightness of the illumination can be adjusted to the minimum necessary according to the luminance distribution of the eye image of the imaged person, so that the power consumption required for the illumination is suppressed and the imaged person feels The glare can be reduced.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  In the following, an example in which the iris imaging apparatus and iris imaging method of the present invention are applied to an iris authentication apparatus and iris authentication method for performing personal authentication will be described, but the present invention is not limited to such an example. Absent.

(First embodiment)
First, the iris authentication device 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram illustrating a configuration of the iris authentication device 10 according to the present embodiment.

  As shown in FIG. 5, the iris authentication apparatus 10 according to the present embodiment includes an imaging illumination 12, an imaging unit 13, an imaging control unit 14, an iris processing engine 15, an information storage unit 16, and an operation interface. A unit 17 (hereinafter referred to as “operation I / F unit 17”), a control unit 18, a luminance distribution control unit 19, and an adjustment unit 20 are provided. As described above, the iris authentication device 10 according to the present embodiment is different from the conventional device (see FIG. 1) in that the luminance distribution analysis unit 19 and the adjustment unit 20 are added.

  The illumination 12 is illumination for imaging the eye 9 of the person to be imaged (registrant / authenticated person) by the imaging unit 13, and illuminates the face of the person to be imaged. The imaging unit 13 is a device for imaging the registrant / authenticated person's eyes 9. The imaging unit 13 includes, for example, an optical system composed of various lenses, a lens driving unit, an imaging element (such as a CCD) that photoelectrically converts light incident from the optical system, and a predetermined output to an image output from the imaging element. And an image processing unit that performs image processing (for example, white balance adjustment, gain adjustment, gamma correction, etc.). The illumination 12 and the imaging unit 13 may use light in the infrared band or may use light in the visible light band depending on the application or the like. Now, an example will be described in which visible light is irradiated from the illumination 12 to illuminate the eye 9 of the person to be imaged, and this is imaged by the imaging unit 13 to obtain an eye image.

  The imaging control unit 14 controls the operations of the illumination 12 and the imaging unit 13. For example, the imaging control unit 14 increases or decreases the brightness of the illumination 12 based on an instruction from the control unit 18 or the adjustment unit 20, or sets parameters of the imaging unit 13 (for example, iris, focus, shutter speed, white balance). Parameter for determining camera characteristics such as gain). The imaging control unit 14 outputs the eye image obtained from the imaging unit 13 to the iris processing engine 15 and the luminance distribution analysis unit 19.

  The iris processing engine 15 includes an iris information generation unit 151, a data management unit 153, and a matching unit 155.

  The iris information generation unit 151 performs image processing on the eye image captured by the imaging unit 13, extracts features of the iris region S (see FIG. 4), and generates iris information. This iris information is data representing the characteristics of the iris region S of the subject's eye, and an individual can be identified (biometric authentication) by the iris information. The iris information can be generated using any known method, and detailed description thereof is omitted here. In this embodiment, iris code information (hereinafter referred to as “iris code”) obtained by coding feature data of an iris image is used as the iris information. However, the present invention is not limited to such an example, and for example, an iris region The S image itself may be iris information.

  The data management unit 153 uses the information storage unit 16 to manage various registration information (registrant name, registration number, iris code, brightness distribution, etc.) necessary for iris authentication for each registrant. Specifically, at the time of registration, the data management unit 153 associates the registrant's iris code generated by the iris information generation unit 151 with the registrant's identification information (name, registration number, etc.) for each registrant. Are registered in the information storage unit 16. Further, the data management unit 153, at the time of authentication, selects the iris corresponding to the identification information of the registrant designated by the person to be authenticated using the operation I / F unit 17 from the iris codes stored in the information storage unit 16. Read the code.

  At the time of authentication, the collation unit 155 uses the iris code of the person to be authenticated generated by the iris information generation unit 151 and the iris code of the registrant read from the information storage unit 16 based on the designation of the person to be authenticated. A check is made to determine whether both iris codes match. Thereby, it can be authenticated whether the to-be-authenticated person imaged is the registrant himself.

  The information storage unit 16 includes, for example, a non-volatile memory such as a flash memory or a storage device such as a hard disk drive. The information storage unit 16 stores various registration information necessary for the iris authentication for each registrant. Specifically, as illustrated in FIG. 6, the information storage unit 16 stores a registered person's name, registration number, iris code, and luminance distribution information in association with each other. As described above, the registration information according to the present embodiment is different from the conventional method (see FIG. 2) in that brightness distribution information is added in addition to the name, the registration number, and the iris code. Note that the registration number may be assigned automatically (for example, sequentially) by the data management unit 153, or may be manually set by the registrant. The luminance distribution information is information generated by a luminance distribution analysis unit 19 described later. In the present embodiment, the name and registration number are used as the identification information of the registrant. However, the present invention is not limited to this example. As long as it is information that can identify the registrant, for example, it may be an ID uniquely assigned to each registrant.

  The operation I / F unit 17 is an input device for a registrant / authenticated person to input data, and includes, for example, various buttons, a keyboard, a mouse, a touch panel, and the like. The registrant / authenticated person can input his / her name or instruct the operation of the iris authentication apparatus 10 by operating the operation I / F unit 17. Moreover, the control part 18 is comprised with a microcontroller etc., and controls the iris authentication apparatus 10 whole.

  The luminance distribution analysis unit 19 analyzes the luminance distribution of the iris region S of the eye image captured by the imaging unit 13 and generates luminance distribution information (first luminance distribution information) that is an analysis result of the luminance distribution. For example, the luminance distribution analysis unit 19 calculates the luminance values for all the pixels in the iris region S in the eye image, calculates the average value, variance, or median value of the total luminance values, and calculates these average luminance values. The luminance distribution or the luminance central value can be used as the luminance distribution information. At the time of registration, the luminance distribution information is output from the luminance distribution analysis unit 19 to the iris processing engine 15 and stored in the information storage unit 16 together with the iris data and the like by the data management unit 153 as registration information. Further, at the time of authentication, this luminance distribution information may be directly output from the luminance distribution analysis unit 19 to the adjustment unit 20 and used as reference information such as brightness adjustment of the illumination 12.

  The adjustment unit 20 adjusts the brightness of the imaging illumination 12 based on the luminance distribution information. Specifically, at the time of authentication, the adjustment unit 20 reads out the luminance distribution information corresponding to the person to be authenticated to be imaged from the information storage unit 16, and determines the brightness of the illumination 12 according to the luminance distribution information. Set to. Thereby, for example, when the eye of the person to be authenticated is an oriental black / brown eye that requires bright illumination because the iris luminance distribution is relatively low, the adjustment unit 20 compares the illumination 12. On the other hand, in the case of Western blue / green eyes that do not require bright illumination because the iris luminance distribution is relatively high, the illumination 12 can be relatively dark. Further, even if the iris luminance distribution is different among individuals of the same race, the adjusting unit 20 makes the illumination 12 relatively dark when the iris luminance distribution of the person to be authenticated is high. When the iris luminance distribution of the person to be authenticated is low, the illumination 12 is made relatively bright. As described above, the adjustment unit 20 can adjust the brightness of the illumination 12 to an appropriate brightness according to the racial / individual difference of the iris luminance distribution based on the iris luminance information registered in the information storage unit 16.

Here, a specific example of the brightness adjustment of the illumination 12 according to the iris luminance distribution will be described with reference to FIG. FIG. 7 is a graph showing a specific example of the eye luminance distribution for each individual, and shows the result of counting the number of pixels of each luminance in the captured eye image. In FIG. 7, an example of the average brightness and the light intensity of the illumination 12 suitable for the brightness of three persons, a low brightness person (average 90), a high person (average 165), and an intermediate person (average 125). Is shown. The light intensity is expressed in units of irradiance [μw / cm ² ] by the illumination 12, but the actual control of the illumination 12 controls the drive current [mA] of the LEDs constituting the illumination 12. Therefore, this drive current is also shown in FIG. The required light intensity and drive current are not limited to the illustrated example, and can be set to different values depending on the characteristics of the imaging unit 13 (camera) and the illumination 12 (LED).

  As shown in FIG. 7, the luminance average value and the appropriate light intensity are adjusted so as to be approximately inversely proportional. That is, when the luminance average of the captured eye image is high, the light intensity to be irradiated is adjusted to be small (the illumination 12 is darkened), whereas when the luminance average is low, the light to be irradiated is adjusted. The intensity is adjusted to be large (the illumination 12 is brightened). As shown in FIG. 7, luminance measurement and iris authentication of a large number of human eyes are actually performed, and an appropriate light intensity with the highest iris authentication accuracy can be obtained for each average luminance. Thereby, it is possible to take an image by adjusting the light intensity at which the iris pattern is most easily visible according to the luminance distribution of each person's eyes, that is, the brightness of the illumination 12, so that the accuracy of iris authentication can be improved.

  In the present embodiment, the adjustment unit 20 adjusts the brightness of the illumination 12 based on the luminance distribution information, but is not limited to this example. For example, the adjustment unit 20 may adjust setting parameters (for example, camera characteristics such as shutter speed, white balance, and gain) of the imaging unit 13 based on the luminance distribution information read from the information storage unit 16. Good. This also makes it possible to capture an eye image having an appropriate luminance according to the iris luminance distribution of the person to be authenticated without making the illumination 12 excessively bright.

  Next, an iris authentication method using the iris authentication device 10 according to the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart illustrating the operation of the iris authentication apparatus 10 according to the present embodiment illustrated in FIG. 5. FIG. 8A illustrates a registration procedure and FIG. 8B illustrates an authentication procedure.

  As shown in FIG. 8A, in the registration procedure, first, the registrant inputs the person's name to the iris authentication apparatus 10 using the operation I / F unit 17 (S101), and instructs the start of the registration operation (S102). ). The iris authentication apparatus 10 detects the eyes using the image of the registrant's face imaged by the imaging unit 13 (S103), and starts lighting the illumination 12 when the eyes are detected (S104). The brightness of the illumination 12 at this time is set to a predetermined standard brightness set in advance by the photographing control unit 14 to the same extent as in the conventional method. While the illumination 12 is turned on, the imaging unit 13 captures an eye image of the registrant (S105: first imaging step), and after the eye image is captured, the illumination 12 is turned off (S106).

  Next, the iris information generation unit 151 of the iris processing engine 15 performs image processing on the captured eye image, and an iris code corresponding to the image of the registrant's iris region S (code information representing the characteristics of the registrant's iris). ) Is generated (S107: first iris information generation step). Then, the iris information generation unit 151 determines whether or not the iris code has been properly generated (S108). As a result, if the iris code generation has failed for some reason, a retry process is performed, and the above-described processing is performed. The above processing (S103 to S107) is repeated.

  On the other hand, when the iris code information is appropriately generated, the process proceeds to step S109, where the luminance distribution analysis unit 19 analyzes the luminance distribution of the iris region S of the eye image captured in step S105, and the registrant's Luminance distribution information (first luminance distribution information) corresponding to the iris is generated (S109: first luminance distribution analysis step). Examples of the luminance distribution information include an average value, a variance, a median value, etc., for the luminance values of all the pixels in the iris region S. Thereafter, the data management unit 153 associates the luminance distribution information, the iris code generated in step S107, the name of the registrant input in step S101, and the registration number assigned automatically, for example. Then, it is stored in the information storage unit 16 as registration information (S110: information storage step).

  As shown in FIG. 8B, in the authentication procedure, first, the person to be authenticated inputs identification information such as a registered name or registration number using the operation I / F unit 17 (S112). Is started (S114).

  Then, the adjustment unit 20 of the iris authentication apparatus 10 searches the data in the information storage unit 16 based on the identification information such as the input name, and the luminance distribution information corresponding to the person to be authenticated is stored in the information storage unit. 16 and the brightness of the illumination 12 is set to a brightness that matches the brightness distribution information (S116: first adjustment step). As a method of adjusting the brightness of the illumination 12 set here, for example, when a luminance average value is stored as luminance distribution information, a standard luminance average value and a stored luminance average value are calculated. There is a method of taking the difference and increasing or decreasing the standard brightness according to the difference. For example, when the stored average luminance value is larger than the standard luminance value, the brightness of the illumination 12 is darkened by an amount corresponding to the difference between the two, while the stored average luminance value is the standard. If it is smaller than the typical luminance value, the brightness of the illumination 12 is increased by an amount corresponding to the difference between the two. As described above, in this step S116, the brightness of the illumination 12 is set to an appropriate brightness according to the brightness distribution of the iris of the person to be imaged according to the brightness distribution information of the authenticator stored at the time of registration. Is done.

  Next, eyes are detected using the face image of the person to be authenticated imaged by the imaging unit 13 (S118). When the eyes are detected, the imaging control unit 14 that has received an instruction from the adjustment unit 20 Lighting of the illumination 12 is started at the brightness set in step S116 (S120), and an image of the eye of the person to be authenticated is captured by the imaging unit 13 while the illumination 12 is lit (S122: second imaging step). ). At the time of this imaging, the brightness of the illumination 12 is set to an appropriate brightness according to the luminance distribution of the iris of the person to be authenticated in step S116 described above, so that the person to be authenticated is dazzled with the illumination 12 brighter than necessary. Therefore, it is possible to capture an eye image having an appropriate luminance for performing iris authentication. After the eye image is captured, the illumination 12 is turned off (S124).

  Next, the iris information generation unit 151 of the iris processing engine 15 performs image processing on the captured eye image to generate an iris code corresponding to the image of the iris area S of the person to be authenticated (S126: second iris) Information generation step). Then, the iris information generation unit 151 determines whether or not the iris code has been properly generated (S128). As a result, when the generation of the iris code fails for some reason, a retry process is performed, and the above-described processing is performed. The above processing (S118 to S126) is repeated.

  On the other hand, when the iris code is successfully generated, the collation unit 155 of the iris processing engine 15 stores the iris code of the registrant corresponding to the identification information such as the name or the registration number input in step S112. The data is read from the unit 16 (S130), and the iris code of the registrant is compared with the iris code of the person to be authenticated generated in step S126 so as to collate whether or not both iris codes match (S132). : Verification step). As a result, if they match, it is determined that the person to be authenticated is the registrant (S134), and if they do not match, it is determined that the person to be authenticated is not the registrant (S136).

  In the authentication flow of FIG. 8B described above, the example in which the brightness of the illumination 12 is adjusted in step S116 when an eye image for iris authentication is captured has been described, but the present invention is not limited to this example. For example, the adjustment unit 20 adjusts the setting parameters (for example, shutter speed, white balance, gain, etc.) of the imaging unit 13 according to the luminance distribution information of the iris area S of each person to be authenticated, and the imaged eye It is also possible to improve the quality of the image.

  To explain with a specific example, when the luminance value of the eye of the person to be authenticated is lower than the reference luminance, for example, the gain is increased by several tens of percent, and the white balance red intensity is It can be adjusted by increasing the shutter release time and illumination irradiation time by several tens of percent. On the other hand, when the luminance value is higher than the reference luminance, for example, it is possible to adjust the gain, the red intensity of the white balance, the shutter opening time, and the irradiation time of the illumination 12 by reducing the numerical values by several tens of percent. It should be noted that when the luminance value is low, the red intensity of the white balance is increased because the red component of the iris looks best, and thus the iris portion becomes slightly brighter by increasing the red intensity.

  As described above, according to the first embodiment of the present invention, the iris characteristic of the registrant is recorded as an iris code at the time of registration, and the illumination 12 having the minimum brightness suitable for the characteristic is obtained at the time of authentication. It is possible to obtain an eye image having a quality appropriate for iris authentication. In general operation, the registration process is performed only once for the first time, but the subsequent authentication process is continuously performed a plurality of times, so that it is possible to reduce the power consumption of the illumination 12 as a whole. . Furthermore, when the illumination 12 is visible light, it is possible to reduce glare that the person to be authenticated feels during authentication.

(Second Embodiment)
Next, an iris authentication device 10 according to a second embodiment of the present invention and an iris authentication method using the same will be described.

  The iris authentication apparatus 10 according to the second embodiment has substantially the same functional configuration as the iris authentication apparatus 10 according to the first embodiment described above (see FIG. 5) except for the following points. The detailed description is omitted.

  In the iris authentication apparatus 10 according to the second embodiment, the luminance distribution analysis unit 19 analyzes the eye image captured by the imaging unit 13 while the illumination 12 is turned off, in addition to the function of the first embodiment. The brightness distribution information is generated. Furthermore, in addition to the function of the first embodiment, the adjustment unit 20 adjusts the brightness of the imaging environment (the surrounding environment when imaging is performed) based on the luminance distribution information obtained when the illumination 12 is turned off. Judgment is made and the brightness of the illumination 12 is adjusted according to the brightness of the imaging environment.

  Specifically, the luminance distribution analysis unit 19 at the time of authentication, the luminance of the iris region S of the eye image captured by the imaging unit 13 in a state where the illumination 12 is not illuminated on the face of the person to be authenticated before the illumination 12 is turned on. The distribution is analyzed to generate luminance distribution information (second luminance distribution information). As the second luminance distribution information, as in the first luminance distribution information generated at the time of registration described above, for example, the average value, variance, median value, and the like of the luminance values of all the pixels in the iris region S of the eye image, etc. Can be used.

  In addition, the adjustment unit 20 determines the brightness of the imaging environment based on the second luminance distribution information input from the luminance distribution analysis unit 19 at the time of authentication. As a result of the determination, if the imaging environment is bright When the judgment is made, the illumination 12 is relatively bright because there are many reflections of the surrounding objects on the eyes. On the other hand, when the imaging environment is determined to be dark, the reflections of the surroundings on the eyes are small. Adjust so that is relatively dark.

  More specifically, at the time of authentication, the second luminance distribution information is obtained by analyzing the eye image captured by the imaging unit 13 in a state where the illumination 12 is turned off, and obtaining the second luminance distribution information. The luminance distribution information reflects the brightness of the imaging environment. For example, when imaging is performed in a relatively dark imaging environment such as outdoors at night or in a dark room, the second luminance distribution information (for example, luminance average value) obtained by analyzing a dark eye image is a relatively small value. When imaging is performed in a relatively bright imaging environment such as outdoors during the day or in a bright room, the second luminance distribution information (for example, luminance average value) obtained by analyzing a bright eye image is a relatively large value. Therefore, the adjustment unit 20 determines the brightness of the imaging environment based on the second luminance distribution information generated from the eye image captured in the imaging environment at the time of authentication, and according to the brightness of the imaging environment. Thereafter, the brightness of the illumination 12 when an eye image for iris authentication is captured can be adjusted to an appropriate brightness.

  Note that the brightness of the imaging environment using the second luminance distribution information as described above is determined by, for example, the luminance of the sclera region (white-eye portion) in addition to the analysis of the luminance distribution of the iris region S in the eye image. This can be realized by analyzing the distribution.

  Next, an iris authentication method using the iris authentication apparatus 10 according to the second embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing the operation of the authentication procedure of the iris authentication apparatus 10 according to the second embodiment. The registration procedure according to the second embodiment is substantially the same as the registration procedure according to the first embodiment described above (see FIG. 8A), and thus detailed description thereof is omitted.

  As shown in FIG. 9, in the authentication procedure according to the second embodiment, first, the person to be authenticated inputs identification information such as a registered name or registration number using the operation I / F unit 17. Then, the start of the authentication operation is instructed (S214).

  Then, the adjustment unit 20 of the iris authentication device 10 searches the data in the information storage unit 16 based on the identification information such as the input name, and the luminance distribution information (first luminance) corresponding to the person to be authenticated. Distribution information) is read from the information storage unit 16, and the brightness of the illumination 12 is set to a brightness suitable for the first luminance distribution information (S216: first adjustment step). The adjustment method of the brightness of the illumination 12 in the first adjustment step can be the same as the above method (see step S116 in FIG. 8B). Thus, in this step S216, according to the first luminance distribution information of the authenticator stored at the time of registration, the brightness of the illumination 12 is an appropriate brightness according to the luminance distribution of the iris of the subject to be imaged. Set to

  Next, eyes are detected using the face image of the person to be authenticated imaged by the imaging unit 13 (S218). Thus, even before the illumination 12 is turned on, the face of the person to be authenticated is continuously imaged by the imaging unit 13, and the iris engine 15 has eyes in the continuously imaged image. If it exists, the position of the eye is detected.

  In this way, when an eye is detected from an image that is turned off, the luminance distribution analysis unit 19 analyzes the luminance distribution of the eye image used for the detection, generates second luminance distribution information, and Based on the second luminance distribution information, the adjustment unit 20 determines how bright the current imaging environment is and how much the surrounding object is reflected in the eyes of the person to be authenticated. In accordance with the determination result, the brightness setting value of the illumination 12 set in step S216 is increased or decreased (S220: second adjustment step). For example, if the second luminance distribution information detects a difference from the standard luminance distribution and the imaging environment is brighter than the reference brightness, and it is determined that the reflection of peripheral objects on the eye increases, When the brightness setting value of the set illumination 12 is increased, and the imaging environment is darker than the reference brightness, and it is determined that the reflection of the peripheral object on the eye is reduced, the set illumination Decrease the brightness setting value of 12. In this way, considering not only the characteristics of the certifier's iris but also the brightness of the imaging environment, the brightness of the illumination 12 is set to the appropriate minimum brightness necessary for capturing an eye image of a desired image quality. It can be readjusted.

  Thereafter, the imaging control unit 14 that has received an instruction from the adjustment unit 20 starts lighting the illumination 12 with the brightness readjusted in step S220 (S221). Then, an image of the eye of the person to be authenticated is captured (S222: second imaging step). At the time of this imaging, the brightness of the illumination 12 is set to an appropriate brightness according to the brightness distribution of the iris of the person to be authenticated and the brightness of the current imaging environment by steps S216 and S220 described above. It is possible to capture an eye image having an appropriate luminance for performing iris authentication without causing the person to be authenticated to feel dazzling with the illumination 12 brighter than necessary. After the eye image is captured, the illumination 12 is turned off (S224).

  Next, the iris information generation unit 151 of the iris processing engine 15 performs image processing on the eye image captured in step S222, and generates an iris code corresponding to the image of the authentication target's iris region S (S226: Second iris information generation step). Then, the iris information generation unit 151 determines whether or not the iris code has been properly generated (S228). As a result, if the iris code generation fails for some reason, a retry process is performed, and the above-described processing is performed. The above processing (S218 to S226) is repeated.

  On the other hand, when the iris code is successfully generated, the collation unit 155 of the iris processing engine 15 stores the iris code of the registrant corresponding to the identification information such as the name or registration number input in step S212. The data is read from the unit 16 (S230), and the iris code of the registrant is compared with the iris code of the person to be authenticated generated in step S226 to check whether both iris codes match (S232). : Verification step). As a result, if they match, it is determined that the person to be authenticated is the registrant (S234), and if they do not match, it is determined that the person to be authenticated is not the registrant (S236).

  In the authentication flow of FIG. 9 described above, the example in which the brightness of the illumination 12 is adjusted in steps S216 and S220 when an eye image for iris authentication is captured has been described. However, the present invention is limited to this example. Not. For example, the adjustment unit 20 adjusts the setting parameters (for example, shutter speed, white balance, gain, etc.) of the photographing unit 13 according to the luminance distribution information of the eye images of each person to be authenticated, and the photographed eye image It is also possible to improve the quality. Since the specific method for adjusting the setting parameters is as described above, detailed description thereof is omitted.

  As described above, according to the second embodiment of the present invention, at the time of authentication, illumination with a minimum brightness that matches not only the characteristics of the authenticator's iris but also the brightness of the imaging environment at the time of authentication. 12 can be used to obtain an eye image of an appropriate quality for iris authentication. Therefore, it is possible to further reduce the power consumption required for the illumination 12 at the time of authentication, and when the illumination 12 is visible light, it is possible to reduce the glare felt by the person to be authenticated at the time of authentication.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, the example in which the iris imaging apparatus and the iris imaging method of the present invention are applied to the iris authentication apparatus and the iris authentication method for performing personal authentication has been described, but the present invention is not limited to such an example. The iris imaging apparatus and the iris imaging method of the present invention are various as long as the brightness distribution of the iris area of the eye image captured in the past is used to adjust the brightness of the illumination and the setting parameters of the imaging unit. The present invention can be applied to an imaging apparatus and an imaging method, and can be applied to, for example, an iris imaging apparatus and an iris imaging method for medical diagnosis and the like.

  In the second embodiment, the illumination 12 is adjusted according to the individual difference of the iris based on the first luminance distribution information (first adjustment step S216), and the brightness of the imaging environment based on the second luminance distribution information. Although the operation example which combined adjustment of the illumination 12 according to (2nd adjustment step S216) was demonstrated, this invention is not limited to this example. For example, it is of course possible to omit the first adjustment step S216 and perform the second adjustment step S220 alone.

  In the second embodiment, the luminance distribution of the eye image captured by the imaging unit 13 while the illumination 12 is turned off is analyzed to generate second luminance distribution information (S219), and the second luminance distribution information is included in the second luminance distribution information. Although the brightness of the imaging environment is determined based on the brightness of the illumination 12 (S220), the present invention is not limited to this example. For example, it is possible to analyze the luminance distribution of the eye image captured by the imaging unit 13 while the illumination 12 is lit and generate second luminance distribution information to determine the brightness of the imaging environment. In this case, the “brightness” represented by the second luminance distribution information is obtained by adding “brightness due to illumination 12” to “brightness of the imaging environment”. Can be determined.

It is a block diagram which shows the structure of the conventional iris authentication apparatus. It is explanatory drawing which shows the registration information stored in the conventional information storage part. It is a flowchart which shows the registration procedure in the conventional iris authentication apparatus. It is a flowchart which shows the authentication procedure in the conventional iris authentication apparatus. It is the distribution map which showed the luminance distribution example of the iris area | region in the imaged eye image. It is a block diagram which shows the structure of the iris authentication apparatus concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the registration information stored in the information storage part concerning the embodiment. It is a graph which shows the specific example of the luminance distribution of the eye for every individual concerning the embodiment. It is a flowchart which shows the registration procedure in the iris authentication device concerning the embodiment. It is a flowchart which shows the authentication procedure in the iris authentication apparatus concerning the embodiment. It is a flowchart which shows the registration procedure in the iris authentication device concerning the 2nd Embodiment of this invention.

Explanation of symbols

9 Eye 10 Iris Authentication Device 12 Illumination 13 Imaging Unit 14 Imaging Control Unit 15 Iris Processing Engine 16 Information Storage Unit 17 Operation Interface Unit 18 Control Unit 19 Luminance Distribution Analysis Unit 20 Adjustment Unit 151 Iris Information Generation Unit 153 Data Management Unit 155 Verification Unit S Iris area

Claims (10)

An imaging unit for imaging the eye of the person to be imaged;
A luminance distribution analyzing unit that analyzes luminance distribution of an iris region of the eye image captured by the imaging unit and generates luminance distribution information;
An adjustment unit that adjusts the brightness of the illumination for imaging and / or the setting parameters of the imaging unit based on the luminance distribution information;
An iris imaging apparatus comprising: An information storage unit that stores the luminance distribution information generated by the luminance distribution analysis unit in association with the identification information of the person to be imaged;
When the imaging unit picks up the eye of the person to be imaged again, the adjustment unit determines the brightness of the illumination based on the luminance distribution information corresponding to the person to be imaged stored in the information storage unit. The iris imaging device according to claim 1, wherein setting parameters of the imaging unit are adjusted. The luminance distribution analysis unit analyzes the luminance distribution of the eye image captured by the imaging unit, and generates the luminance distribution information,
The adjustment unit determines the brightness of the imaging environment based on the luminance distribution information, and adjusts the brightness of the illumination and / or the setting parameter of the imaging unit according to the brightness of the imaging environment. The iris imaging apparatus according to claim 1 or 2, wherein An iris imaging device according to claim 1;
An iris information generating unit that generates iris information from an eye image of a registrant or person to be authenticated imaged by the imaging unit;
An information storage unit for storing the iris information and the luminance distribution information in association with the identification information of the registrant;
A collation unit that collates the iris information of the person to be authenticated generated by the iris information generation unit with the iris information of the registrant stored in advance in the information storage unit;
An iris authentication apparatus comprising: An imaging step of imaging the eye of the person to be imaged by the imaging unit;
A luminance distribution analysis step of analyzing the luminance distribution of the eye image captured by the imaging unit and generating luminance distribution information;
An adjustment step of adjusting the brightness of the illumination for imaging and / or the setting parameters of the imaging unit based on the luminance distribution information;
An iris imaging method comprising: An information storage step of storing the luminance distribution information generated in the luminance distribution analysis step in an information storage unit in association with the identification information of the person to be imaged;
In the adjustment step, when the imaging unit captures the eye of the imaged person again, the brightness of the illumination is based on the luminance distribution information corresponding to the imaged person stored in the information storage unit. 6. The iris imaging method according to claim 5, wherein a setting parameter of the imaging unit is adjusted. In the luminance distribution analysis step, an iris region of an eye image captured by the imaging unit is analyzed to generate the luminance distribution information,
In the adjustment step, the brightness of the imaging environment is determined based on the luminance distribution information, and the brightness of the illumination and / or the setting parameter of the imaging unit is adjusted according to the brightness of the imaging environment. The iris imaging method according to claim 5 or 6, characterized in that: A first imaging step of imaging the registrant's eyes by the imaging unit at the time of registration;
A first iris information generation step for generating iris information from the registrant's eye image captured in the first imaging step;
A first luminance distribution analyzing step of analyzing the luminance distribution of the iris region of the registrant's eye image and generating first luminance distribution information;
An information storage step of storing the iris information and the first luminance distribution information in an information storage unit in association with identification information of the registrant;
At the time of authentication, when imaging the eye of the person to be authenticated by the imaging unit, the brightness of the illumination for imaging is based on the first luminance distribution information corresponding to the person to be authenticated stored in the information storage unit. And / or a first adjustment step of adjusting a setting parameter of the imaging unit;
A second imaging step of imaging the eye of the person to be authenticated by the imaging unit in the adjusted state;
A second iris information generation step of generating iris information from the eye image of the person to be authenticated imaged in the second imaging step;
A collating step for collating the iris information of the person to be authenticated generated in the second iris information generating step with the iris information of the registrant stored in the information storage unit;
The iris authentication method characterized by including. A second luminance distribution analyzing step of generating second luminance distribution information by analyzing a luminance distribution of an eye image imaged by the imaging unit when imaging the eye of the person to be authenticated by the imaging unit during the authentication; When;
The brightness of the imaging environment is determined based on the second brightness distribution information generated in the second brightness distribution analysis step, and the brightness adjusted in the first adjustment step is determined according to the brightness of the imaging environment. A second adjustment step of further adjusting illumination brightness and / or setting parameters of the imaging unit;
The iris authentication method according to claim 8, comprising: A first imaging step of imaging the registrant's eyes by the imaging unit at the time of registration;
A first iris information generation step for generating iris information from the registrant's eye image captured in the first imaging step;
An information storage step of storing the iris information in an information storage unit in association with the identification information of the registrant;
A second luminance distribution analyzing step for analyzing the luminance distribution of the eye image captured by the imaging unit and generating second luminance distribution information when imaging the eye of the person to be authenticated by the imaging unit during authentication; ;
Based on the second luminance distribution information generated in the second luminance distribution analysis step, the brightness of the imaging environment is determined, and according to the brightness of the imaging environment, the brightness of the illumination, and / or A second adjustment step of adjusting setting parameters of the imaging unit;
A second imaging step of imaging the eye of the person to be authenticated by the imaging unit in the adjusted state;
A second iris information generation step of generating iris information from the eye image of the person to be authenticated imaged in the second imaging step;
A collation step of collating the iris information of the person to be authenticated generated in the second iris information generation step with the iris information of the registrant stored in the information storage unit;
The iris authentication method characterized by including.

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