JP2008139973A - Face image authentication system and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device for picking up a face image suitable for being used for personal authentication based on a face image and a face image authentication system whose authenticating precision is improved by applying the imaging device. <P>SOLUTION: This imaging device 1 processes a first image of an authentication object person picked up by an imaging part 12, and detects the luminance of the white of the eye section of the authentication object person. Then, exposure for setting the luminance of the white of the eye section of the authentication object person as a preliminarily set luminance value is predicted as the optimal exposure by using the detected luminance. Furthermore, the face image to be used for the face authentication of the authentication object person is picked up based on the predicted optimal exposure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a face image authentication system and an imaging apparatus that use a face image of a person to be authenticated to authenticate whether or not the person to be authenticated is a registrant.

  Conventionally, there has been a personal authentication system that authenticates an individual using biometric information such as a face, an iris, a fingerprint, and a voiceprint. For example, there is an apparatus that processes a captured image of the iris of an authentication target person captured by an imaging apparatus and authenticates whether the imaging target person is a registrant (see Patent Documents 1 and 2). In Patent Document 1, as a configuration for obtaining a captured image suitable for use in authentication in which the pupil of the authentication target is not too open in the imaging device, infrared or visible when imaging the iris of the authentication target is obtained. It has been proposed to adjust the light emission amount (flash emission amount) based on the brightness around the imaging device and the brightness of the white of the person to be authenticated. Patent Document 2 proposes obtaining a captured image suitable for authentication by adjusting the light emission amount of the flash and the gain of the imaging device from the boundary edge of the black eye and the white eye.

There has also been proposed an imaging apparatus that focuses on a person's eye area and captures an image (see Patent Document 3).
JP 2004-261515 A JP 2005-327161 A Japanese Patent Laid-Open No. 2002-6203

  However, as proposed in Patent Documents 1 and 2, an imaging method that adjusts the amount of infrared or visible light emission so that the pupil of the person to be authenticated does not open too much is authenticated using the face image of the person to be authenticated. Even if it is used for a face image authentication system, a captured image suitable for use in authentication cannot be obtained. Specifically, in Patent Documents 1 and 2, since the control is to adjust the amount of infrared or visible light emission so that the pupil of the person to be authenticated does not open too much, this control images the face of the person to be authenticated. In the captured image obtained at this time, the brightness of the face image of the person to be authenticated is generally lowered, and blackout may occur. Further, when face authentication is performed using such a captured image, there is a problem that authentication accuracy is lowered.

  An object of the present invention is to provide an imaging device capable of capturing a face image having an optimum luminance suitable for use in personal authentication using a face image, and a face image authentication system to which this imaging device is applied and authentication accuracy is improved. It is to provide.

  In order to solve the above-described problems, an imaging apparatus according to the present invention has the following configuration.

(1) In an imaging device including an imaging unit that images a face of an imaging target person located in an imaging region using a solid-state imaging device,
Image capturing means for capturing a face image of the person to be imaged that is captured by the imaging means as a first image;
White eye part detection means for detecting a white eye part of the person to be imaged in the first image captured by the image capturing means;
Luminance detection means for detecting the brightness of the white eye part of the person to be imaged detected by the white eye part detection means;
Adjusting means for adjusting one of exposure or flash emission amount based on the brightness detected by the brightness detecting means when the second image captured by the image capturing means is captured as a captured image.

  In this configuration, before capturing the face image of the imaging subject who is the imaging subject, the white-eye portion detection means processes the first image of the imaging subject being imaged by the imaging means, and this first image The white-eye portion of the person to be imaged at is detected. In addition, the luminance detecting means detects the luminance of the detected white eye part. In the human face, the whitest part is the white eye, and the degree of whiteness of the white eye is said to have small personal variation. That is, the brightness around the imaging area can be determined by detecting the brightness of the white eye by the brightness detection means.

  Then, when the second image captured by the imaging unit is captured as a captured image, the adjustment unit adjusts either the exposure or the flash emission amount based on the luminance detected by the luminance detection unit. Exposure adjustment is adjustment of shutter speed, aperture, and the like. As a result, the face image of the person to be imaged can be imaged almost without being affected by the change in brightness around the imaging area, and as a result, an image free from white stripes or blackouts can be obtained.

  Further, if the person to be imaged is an authentication person who performs personal authentication using a face image, a face image suitable for use in personal authentication using a face image can be captured.

  (2) The adjusting unit adjusts one of the exposure and the flash emission amount based on an estimation result obtained by estimating one of the exposure and the flash emission amount at which the maximum luminance of the white-eye portion becomes a predetermined optimum luminance value. Means.

  With this configuration, it is possible to obtain an image without white stripes or blackouts almost certainly without being affected by skin color, pupil color, or hair color.

  (3) A captured image output unit is provided that outputs the second image captured by adjusting one of exposure or flash light emission amount by the adjustment unit.

  With this configuration, the authentication apparatus can perform authentication using the face image of the person to be imaged output from the imaging apparatus. Thereby, the authentication accuracy in the authentication device can be improved.

  According to the present invention, it is possible to obtain a captured image in which a change in luminance accompanying a change in brightness around the imaging region is suppressed, that is, a face image of the person to be imaged.

  Further, it is possible to obtain a picked-up image without white stripes or blackouts without being affected by skin color, pupil color, or hair color.

  Furthermore, the authentication accuracy of face authentication in the authentication device can be improved.

  Hereinafter, an embodiment of a face image authentication system which is an embodiment of the present invention will be described.

  FIG. 1 is a diagram showing a configuration of a face image authentication system according to an embodiment of the present invention. In the face image authentication system of this embodiment, whether the authentication target person is a registrant using the imaging device 1 that captures the face image of the authentication target person and the face image of the authentication target person captured by the imaging device 1. And an authentication device 2 for authenticating whether or not.

  FIG. 2 is a diagram showing the configuration of the main part of the imaging device of the face image authentication system of this embodiment. The imaging apparatus 1 includes a control unit 11 that controls the operation of the apparatus main body, an imaging unit 12 that images an authentication target person located in the imaging region, and an image process that processes a first image captured by the imaging unit 12. Unit 13, output unit 14 that outputs the second image captured by the imaging unit 12, and autofocus unit 15 that focuses the first image and the second image captured by the imaging unit 12 (hereinafter, referred to as “focusing unit”). AF section 15) and an exposure adjustment section 16 that adjusts the exposure of the first image and the second image captured by the imaging section 12. Although not shown, the control unit 11 is connected to each unit. The imaging unit 12 includes a solid-state imaging device such as a CCD, and inputs an image projected on the solid-state imaging device to the image processing unit 13 as a first image or a second image. The image processing unit 13 processes the first image input from the imaging unit 12, detects the face of the person to be authenticated in the first image, detects the eye of the person to be authenticated, detects the white part of the person to be authenticated, The luminance of the part is detected in this order. The output unit 14 outputs the second image captured by the imaging unit 12 to the authentication device 2. Here, the first image means an image that is not used for authentication whether the authentication target person is a registrant, and the second image is used for authentication whether the authentication target person is a registrant. An image, that is, an image output from the output unit 14 to the authentication device 2 is meant. The AF unit 15 adjusts the position of an imaging lens (not shown) provided in the imaging unit 12 so that the face of the person to be authenticated captured by the imaging unit 12 is in focus. The exposure adjustment unit 16 adjusts a shutter speed, an aperture, and the like when the imaging unit 12 images the person to be authenticated.

  FIG. 3 is a diagram showing the configuration of the main part of the authentication device of the face image authentication system of this embodiment. The authentication device 2 registers the control unit 21 that controls the operation of the device main body, the image input unit 22 that receives the second image from the imaging device 1, and the facial component feature amount data for each registrant. Registrant database 23 (hereinafter referred to as registrant DB 23), the face image (second image) of the person to be authenticated input to the image input unit 22, and the registrant registered in the registrant DB 23. A collation unit 24 that performs collation to determine whether or not the authentication target person is a registrant using the facial part feature amount data, and an output unit 25 that outputs an authentication result in the collation unit 24 are provided. . The image input unit 22 may be configured to receive a second image input by connecting to the imaging device 1 with a wire, or may be provided with a wireless communication unit so that the second image is transmitted by wireless communication with the imaging device 1. The structure which receives an input may be sufficient. The facial feature amount is a characteristic shape of facial parts such as eyes, nose, mouth, and contour. The registrant DB 23 stores, for each registrant, feature amount data indicating the feature amount of the registrant's facial parts in association with each other. The collation unit 24 processes the second image input to the image input unit 22 and extracts the feature amount of the facial part from the face image of the person to be authenticated that has been captured. Then, the extracted feature quantity of the facial part of the person to be authenticated is compared with the feature quantity of the facial part of the registrant registered in the registrant DB 23 to determine whether the authentication target person is a registrant. To do. The output unit 25 outputs the authentication result in the verification unit 24. This authentication result is input to a device connected to the output unit 25. For example, the authentication result is input to a device that opens and closes an electronic lock attached to a room door or a transaction processing device that processes transactions.

  Next, the operation of the face image authentication system according to this embodiment will be described. FIG. 4 is a flowchart showing the operation of the imaging device of the face image authentication system of this embodiment. When the imaging device 1 detects that the person to be authenticated is located within the imaging region of the imaging unit 12, the imaging device 1 executes the process illustrated in FIG. The detection of whether or not the authentication target person is located within the imaging area of the imaging unit 12 may be configured using a human detection sensor that detects the presence or absence of a person, or the first image in the imaging unit 12 May be configured to detect whether or not the authentication target person is located within the imaging region of the imaging unit 12 by detecting the authentication target person by a switch operation by the authentication target person. It may be configured to.

  When the imaging apparatus 1 detects that the authentication target person is located in the imaging region, the autofocus process (in which the focus of the first image captured by the imaging unit 12 is focused on the face of the authentication target person ( AF processing) is performed (s1). The process related to s1 is a process in which the AF unit 15 moves the imaging lens provided in the imaging unit 12 and focuses the first image captured by the imaging unit 12 on the face of the person to be authenticated. Since this AF process is known, the description thereof is omitted here. When the AF processing related to s1 is completed, the image processing unit 13 captures the first image at this time (s2). Also, an AF distance measurement image for AF processing may be captured as the first image. The first image captured in s2 is not an image used for authentication processing. When the first image is captured in the image processing unit 13 in s2, exposure such as shutter speed and aperture may be performed with preset values, or calculated from the luminance of the first image immediately before capture. You may do by value.

  The imaging device 1 processes the first image captured in s2 in the image processing unit 13, and detects the position of the face image of the person to be authenticated in the first image (s3). When the face position is detected in s3, the eye position is detected (s4), and the position of the white eye part is further detected (s5). In this way, the imaging device 1 is configured to detect the position of the eye from the detected face position of the person to be authenticated, and further to detect the position of the white eye portion from the detected eye position. Can be done properly. When detecting the position of the white eye portion in s5, the imaging device detects the luminance of the white eye portion of the person to be authenticated in the first image captured in s2 (s6). In the human face, the whitest part is the white eye, and the degree of whiteness of the white eye is said to have small personal variation. Therefore, the brightness around the imaging region of the imaging unit 12 can be determined by detecting the luminance of the white-eye portion.

  The imaging apparatus 1 estimates the optimum exposure (shutter speed, aperture, etc.) when capturing the second image used for authentication of the person to be authenticated from the brightness of the white eye portion detected in s6 (s7). In s7, using the exposure when the first image is captured in s2 and the peak value of the luminance of the white part of the recognition target person in the first image detected in s6, the luminance of the white part of the authentication target person is used. The exposure at which the peak value of becomes a predetermined value is estimated as the optimum exposure. At this time, one of the shutter speed and the aperture may be a fixed value, and the value at which the optimum exposure is obtained for the other may be calculated, or the value at which the optimum exposure is obtained for both the shutter speed and the aperture may be calculated. Then, the imaging unit 12 captures the face image of the person to be authenticated with the optimal exposure estimated in s7 (s8). The face image of the person to be authenticated captured in s8 is the second image used for face authentication of the person to be authenticated. In s8, the exposure adjustment unit 16 adjusts the shutter speed, the aperture, and the like based on the optimum exposure estimated in s7. The imaging apparatus 1 outputs the face image of the person to be authenticated captured in s8 from the output unit 14 to the authentication apparatus 2 (s9), and ends this process.

  As described above, the imaging device 1 estimates the exposure when the second image used for authentication of the authentication target person is captured using the luminance of the white eye portion in the first image of the authentication target person captured in s2. The second image used for authentication of the person to be authenticated is captured (captured) with the exposure estimated here. In other words, the imaging apparatus 1 can adjust the exposure according to the brightness around the imaging region of the imaging unit 12 and capture a second image used for authentication of the authentication target person. Therefore, the imaging apparatus 1 is hardly affected by the brightness change around the imaging region of the imaging unit 12, and is not affected by skin color, pupil color, or hair color. It is possible to obtain a face image of the person to be authenticated without blackout. That is, the imaging device 1 can capture the face image of the person to be authenticated, which is suitable for use in face authentication.

  FIG. 5 is a flowchart showing the operation of the authentication device of the face image authentication system of this embodiment. When the face image of the person to be authenticated output from the imaging device 1 is input to the image input unit 22, the authentication device 2 executes the processing illustrated in FIG. 5. In the verification unit 24, the verification unit 24 processes the face image of the person to be authenticated input to the image input unit 22, and extracts the feature amount of the face part of the person to be recognized (s11). The authentication device 2 collates the feature amount of the face part of the person to be authenticated extracted in s11 with the feature amount data of the face part of each registrant registered in the registrant database 23, and determines the person to be authenticated from the similarity. An authentication process for determining whether or not is a registrant is performed (s12). The authentication device 2 outputs the authentication result of s12 from the output unit 25 (s13), and ends this process.

  As described above, since the imaging device 1 can capture a face image suitable for use in personal authentication, the authentication accuracy in the authentication device 2 can be sufficiently ensured in the face image authentication system of this embodiment. it can.

  The authentication result output by the authentication device 2 in s23 is input to a device connected to the output unit 25 that opens and closes the electronic lock attached to the door of the room, a transaction processing device that processes transactions, and the like. . And the apparatus into which the authentication result was input performs the process according to the input authentication result, for example, opening and closing of an electronic lock, and transaction processing.

  Next, a face image authentication system according to another embodiment of the present invention will be described. The face image authentication system according to another embodiment is also configured as shown in FIG. As shown in FIG. 6, the difference from the above-described embodiment is that the imaging apparatus 1 includes an irradiation unit 17 that irradiates a person to be authenticated with flash light. The authentication apparatus 2 is illustrated in FIG. 3. It is the structure shown in FIG. The irradiation unit 17 has a light amount adjustment function for adjusting the amount of flash light irradiated to the authentication subject. The operation of the face image authentication system according to another embodiment will be described below.

  FIG. 7 is a flowchart showing the operation of the imaging apparatus according to this another embodiment. In FIG. 7, the same step number (s *) is assigned to the same process as the step shown in FIG. 4. Moreover, the authentication apparatus 2 of this another embodiment performs the process shown in FIG. 5 similarly to the authentication apparatus 2 of the above-mentioned embodiment.

  When the imaging apparatus 1 according to the other embodiment detects that the person to be authenticated is located in the imaging area of the imaging unit 12, the imaging apparatus 1 executes the process illustrated in FIG. Detection of whether or not an authentication target person is located within the imaging area of the imaging unit 12 is the same as in the above-described embodiment. When the imaging apparatus 1 detects that the authentication target person is located in the imaging region, the autofocus process (in which the focus of the first image captured by the imaging unit 12 is focused on the face of the authentication target person ( AF processing) is performed (s1). When the AF processing for s1 is completed, the imaging apparatus 1 determines whether or not the flash emits light based on the peripheral luminance. If no light is emitted, the imaging apparatus 1 operates in the same manner as in the above-described embodiment. From the captured image or the like, the irradiating unit 17 performs pre-light emission with a light amount corresponding to the peripheral luminance (s21), and the first image at the time of pre-light emission is captured (s2). In addition, the shutter speed, the aperture, and the like when the first image is taken into the image processing unit 13 in s2 are set at preset values.

  In the image processing unit 13, the image processing unit 13 performs the processing related to s3 to s6 described in the above-described embodiment on the first image captured in s2, and detects the luminance of the white part of the person to be authenticated. When capturing the second image used for authentication of the authentication target person, the imaging device 1 estimates the optimal amount of flash light to be irradiated to the authentication target person from the brightness of the white eye portion detected in s6 (s22). In s22, in the second image used for authentication of the person to be authenticated, the amount of flash light at which the luminance peak value of the white part of the person to be authenticated becomes a predetermined value is estimated as the optimum light amount. The imaging apparatus 1 estimates the optimum light amount using the light amount at the time of pre-emission and the peak value of the brightness of the white eye portion of the recognition target person in the first image detected in s6. Then, the imaging device 1 causes the irradiation unit 17 to emit light with the optimum light amount estimated in s22 (s23), and the imaging unit 12 captures a face image of the person to be authenticated (s24). The face image of the person to be authenticated captured in s24 is the second image used for face authentication of the person to be authenticated. The exposure when capturing the face image of the test subject in s24 is under the same conditions as in s2. That is, the shutter speed and the aperture are the same in s2 and s24. The imaging device 1 outputs the face image of the person to be authenticated captured in s24 from the output unit 14 to the authentication device 2 (s9), and ends this process.

  As described above, the imaging apparatus 1 according to the other embodiment uses the brightness of the white eye portion of the authentication target person in the first image, and uses the flash when capturing the second image used for authentication of the authentication target person. The light emission amount is estimated, the flash is emitted with the light emission amount estimated here, and a second image used for face authentication of the person to be authenticated is captured (captured). That is, the imaging apparatus 1 adjusts the flash light emission amount according to the brightness around the imaging region of the imaging unit 12 and captures a second image used for face authentication of the person to be authenticated. Therefore, the imaging apparatus 1 according to this other embodiment is also hardly affected by the brightness change around the imaging region of the imaging unit 12 and is also influenced by the skin color, the pupil color, and the hair color. Therefore, it is possible to obtain the face image of the person to be authenticated without white stripes or blackouts. That is, the imaging device 1 can capture the face image of the person to be authenticated, which is suitable for use in face authentication.

  Thereby, also in the face image authentication system according to this another embodiment, the authentication accuracy in the authentication device 2 can be sufficiently ensured.

  In the above-described embodiment, the case where the aperture adjustment and the flash light amount adjustment are performed individually has been described. However, the brightness of the face image used for authentication of the person to be authenticated is reduced by combining the aperture adjustment and the flash light amount adjustment. It is good also as a structure kept constant.

  Further, the imaging device 1 according to the present invention is not only applicable to the face image authentication system, and even if the imaging device alone is not affected by the skin color, pupil color, or hair color, Appropriate images without white stripes or blackout can be obtained.

It is a figure which shows the structure of the face image authentication system concerning embodiment of this invention. It is a figure which shows the structure of the principal part of the imaging device of the face image authentication system of this embodiment. It is a figure which shows the structure of the principal part of the authentication apparatus of the face image authentication system of this embodiment. It is a flowchart which shows operation | movement of the imaging device of the face image authentication system of this embodiment. It is a flowchart which shows operation | movement of the authentication apparatus of the face image authentication system of this embodiment. It is a figure which shows the structure of the principal part of the imaging device of the face image authentication system of this embodiment. It is a flowchart which shows operation | movement of the imaging device of the face image authentication system of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1- Image pick-up device 2- Authentication apparatus 11- Control part 12- Image pick-up part 13- Image processing part 14- Output part 15- Autofocus part (AF part)
16-Exposure adjustment unit 17-Irradiation unit 21-Control unit 22-Image input unit 23-Registrant database 24-Verification unit 25-Output unit

Claims (4)

An imaging device that captures a face image of the person to be authenticated;
In a face image authentication system having an authentication device that authenticates whether or not the authentication target person is a registrant using the face image of the authentication target person imaged by the imaging device,
The imaging device
Imaging means for imaging the face of the person to be authenticated located in the imaging area using a solid-state imaging device;
Image capturing means for capturing the face image of the person to be authenticated as the first image captured by the image capturing means;
White eye part detecting means for detecting a white eye part of the person to be authenticated in the first image captured by the image capturing means;
A luminance detecting means for detecting the luminance of the white eye part of the person to be authenticated detected by the white eye part detecting means;
When the second image captured by the imaging unit is captured as a captured image, the amount of exposure or flash light emission that uses the luminance detected by the luminance detection unit so that the maximum luminance of the white-eye portion is a predetermined optimum luminance value. Adjusting means for adjusting one of the amount of light emitted from the exposure or flash based on the estimation result of estimating one of
A captured image output unit that outputs the second image captured by adjusting one of exposure or flash emission amount by the adjustment unit to the authentication device;
Face image authentication system. In an imaging apparatus including an imaging unit that images a face of an imaging target person located in an imaging region using a solid-state imaging device,
Image capturing means for capturing a face image of the person to be imaged that is captured by the imaging means as a first image;
White eye part detection means for detecting a white eye part of the person to be imaged in the first image captured by the image capturing means;
Luminance detection means for detecting the brightness of the white eye part of the person to be imaged detected by the white eye part detection means;
An image pickup apparatus comprising: an adjustment unit that adjusts one of exposure or flash emission amount based on the luminance detected by the luminance detection unit when the second image captured by the imaging unit is captured as a captured image. .   The adjusting unit is a unit that adjusts one of the exposure and the flash emission amount based on an estimation result obtained by estimating one of the exposure and the flash emission amount at which the maximum luminance of the white-eye portion becomes a predetermined optimum luminance value. The imaging device according to claim 2.   The imaging apparatus according to claim 2, further comprising: a captured image output unit that outputs the second image captured by adjusting one of exposure or flash emission amount by the adjustment unit.

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