JP2008257329A - Face recognition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique to reduce false acceptance errors while minimizing increase in an authentication time and reduction in an authentication rate due to double registration of the same person. <P>SOLUTION: A face recognition apparatus comprises a registered face storage means storing in advance face information of a plurality of registrants, a face information acquisition means for acquiring face information from an image of a subject, a face recognition means for selecting a candidate expected to be identified with the subject from the plurality of registrants, a determination means for determining whether or not the subject is identified with the candidate, and a similar face storage means for storing the subject's face information as similar face information if the subject is not identified. The similar face storage means stores similar face information for each registrant, and the face recognition means executes first face recognition where the subject's face information is collated with each registrant's face information and second face recognition where the subject's face information is collated with the similar face information associated with the registrant selected by the first face recognition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a face collation apparatus, and more particularly to an apparatus for identifying a registrant's face from an unspecified number of faces.

  In a system in which a plurality of faces are registered in advance and a face registered from a large number of unspecified faces is authenticated, there is a problem that another person is mistakenly authenticated as a registered person (hereinafter, such false authentication is performed). This is called “other person acceptance error”, and the probability that another person acceptance error will occur is called the “other person acceptance rate”). In such a system, the input face image is generally compared with all registered face images, the registered face with the highest similarity is taken as a candidate, and the authentication is successful if the similarity exceeds a certain value. Yes.

  Therefore, authentication between registrants can be devised so that the correlation between similarities becomes low by means of learning methods, etc., but in the case of matching non-registrants with registrants, non-registrants Since the characteristics of are unknown, there is a problem that it is difficult to reduce the acceptance rate of others.

  As these measures, when a person can confirm the correctness of the identification result determined by the system, it is expected that the recognition accuracy after that can be improved by manually inputting correct information into the system.

  Conventionally, a method has been used in which all other persons who have been misaccepted by other persons are newly registered and then verified against registered data including other persons (faces registered only for the purpose of removing false authentication are other Distinct from registrants). Next, when another person is collated, since it is authenticated as a newly registered person, no other person acceptance error occurs.

  However, this method has a problem that the number of registered persons increases every time another person acceptance error occurs, and the time required for authentication increases. This is because the image to be verified must be verified against all registered images, and the authentication time increases in proportion to the number of registered users.

  In addition, in this method, when a stranger acceptance error occurs even though it is a face image of a registered person, the face image of the registered person is registered as a different person as an image that has caused another person acceptance error. End up. If the same person is registered as a different person, the authentication rate of that person will decrease.

In Patent Document 1, other registrants B1 to Bn that are likely to be erroneously recognized as the registrant A are registered in the misrecognized person list, and the registrant A is registered according to the number n registered in the list. A method for changing the recognition condition at the time of matching is proposed. If this method is used, it is expected that the identification accuracy between the registrant A and the other registrants B1 to Bn can be improved. However, this method does not contribute to the reduction of other person acceptance errors due to images of unregistered persons, and the above-described conventional problems (enhancement of authentication time due to registration of other person acceptance error images and double use of the same person). It also cannot solve the decline in authentication rate due to registration.
JP 2005-182184 A

The present invention has been made in view of the above circumstances, and the purpose of the present invention is to prevent errors in accepting other people while suppressing as much as possible an increase in authentication time and a decrease in authentication rate due to double registration of the same person. The object is to provide a technique for reducing this.

  In order to achieve the above object, the present invention adopts the following configuration.

  A first aspect of the present invention is a face collation device, which is a registered face storage unit that stores face information of a plurality of registrants in advance, and a face information acquisition unit that acquires face information from an image of a person to be collated. A face matching means for selecting a candidate who is estimated to be the same person as the person to be collated from the plurality of registrants by face matching; and whether or not the person to be collated and the candidate are the same person. Determination means for determining, and similar face storage means for storing face information of the person to be collated determined to be not the same person by the determination means as similar face information. Here, the similar face storage means stores the similar face information for each registrant, and the face collating means compares the face information of the person to be collated with the face information of each registrant. And the second face matching for matching the face information of the person to be matched with the similar face information associated with the registrant selected as a result of the first face matching. .

  According to this configuration, the similar face information is accumulated separately from the registrant's face information, so the time required for the first face matching does not increase. Further, similar face information is managed for each registrant, and the collation range in the second face collation is limited to the similar face information corresponding to the registrant selected as a result of the first face collation. The time required for face matching can be reduced as much as possible. Therefore, it is possible to achieve both shortening of the authentication time and reduction of other person acceptance errors.

  Further, even if face information of a registrant A is stored as similar face information of another registrant B, the similar face information is registered by the first face matching from the matching range of the first face matching. Since the user A is also out of the collation range of the second face collation when the user A is selected, the authentication rate of the registrant A is not adversely affected. That is, in the present invention, the authentication rate is not lowered due to double registration of the same person, which has been regarded as a problem in the past.

  In the above-described configuration, the face collating unit is one registrant (provisional candidate) having the highest similarity with the face information of the person to be collated among the plurality of registrants in the first face collation. It is good to pick out. Further, in the second face matching, the face matching unit is configured such that the similarity between the face information of the person to be checked and the face information of the one registrant is equal to the face information of the person to be checked and the one registration. It is preferable that the one registrant is output as the candidate when the degree of similarity with the similar face information associated with the person is larger.

  The determination means may automatically determine whether or not the verification target person and the candidate are the same person, or may allow the user to determine. In the case of automatic determination, the determination unit may determine the identity between the verification target person and the candidate using a unit different from the face verification by the face verification unit. Moreover, when making a user determine, the said determination means is good to display the said collation subject's face image and the said candidate's face image. As a result, the user can easily determine whether or not they are the same person.

  The present invention may be regarded as a face collation apparatus having at least a part of the above means, and the present invention also includes a face collation method including at least a part of the above processing, or a program for realizing such a method. Or as a storage medium for storing the program. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

For example, in the face collation method according to the present invention, a computer that stores face information of a plurality of registrants in advance includes face information acquisition processing in which face information is obtained from an image of a person to be collated, and face collation. The same face matching process for selecting a candidate who is estimated to be the same person as the person to be collated from among the registered persons, and a determination process for determining whether or not the person to be collated and the candidate are the same person A similar face storage process for storing the face information of the person who is determined to be non-human as similar face information, and in the similar face storage process, the computer stores the similar face information for each registrant. In the face collation process, the computer collates the face information of the person to be collated with the face information of each of the registrants, and the face information of the person to be collated is the first face collation. Selected registration as a result of It is characterized in performing a second face collation to be matched with similar face information associated with the.

  According to the present invention, it is possible to reduce other person acceptance errors while suppressing as much as possible an increase in authentication time and a decrease in authentication rate due to double registration of the same person.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

<Device configuration>
FIG. 1 shows a configuration of a face collation apparatus according to an embodiment of the present invention. The face collation device has an imaging unit 1, a face detection unit 2, a face collation unit 3, a registered face storage unit 4, a similar face storage unit 5, a result display unit 6, an input unit 7, and a similar face registration unit 8 as its functions. I have. The face matching device can be configured by a computer including an imaging device, a display device, an input device, and the like in hardware. The above functions are realized in a computer by a program stored in an auxiliary storage device being read into a main storage device and executed by a CPU (Central Processing Unit). However, part or all of the above functions may be configured by a dedicated chip.

  The imaging unit 1 is configured using an imaging device (specifically, a digital video camera or a digital camera) that can capture a moving image or a still image. The imaging unit 1 captures an unspecified person to be collated and inputs the image to a computer.

  The face detection unit 2 is a function (face information acquisition unit) that detects the face of the person to be collated from the input image and extracts the feature amount (face information) of the detected face. Any existing technique may be applied to the face detection processing by the face detection unit 2. For example, (1) a method for detecting a face by template matching using a reference template corresponding to the contour of the entire face, (2) a face by template matching based on a facial organ (eg, eyes, nose, ears). (3) A technique for detecting a vertex such as a head by chroma key processing and detecting a face based on the vertex, and (4) detecting an area close to the skin color and detecting the area as a face. And (5) learning using a teacher signal using a neural network and detecting a face-like area as a face. When a plurality of human faces are detected from the image, the face to be processed may be determined based on predetermined criteria such as face size, orientation, and position. Any type of feature amount extracted as face information may be used. For example, the gray value near the feature point, its periodicity / direction, the positional relationship of the feature point, etc. can be adopted as the feature quantity. The number of feature quantities can be arbitrarily set according to the expected matching accuracy. In general, face information is composed of a set of tens to hundreds of feature amounts.

The face matching unit 3 performs face matching by comparing the face information of the person to be verified acquired by the face detecting unit 2 with the face information stored in the registered face storage unit 4 or the similar face storage unit 5. Function (face matching means). Any existing technique may be applied to the face matching process by the face matching unit 3. For example, the similarity (score) of the face information of the two faces to be compared is calculated, and the score is relatively evaluated (the face with the highest score is selected as a candidate) or absolutely evaluated (A face having a score equal to or higher than a predetermined threshold value is selected as a candidate). The face collation unit 3 of the present embodiment includes a first face collation unit 30 that collates the face information of the person to be collated with the face information of the registrant, and a first face collator that matches the face information of the person to be collated with the face information of the similar person. 2 face collating units 31. However, in terms of mounting, the first face matching unit 30 and the second face matching unit 31 may be separate modules or the same module.

  The registered face storage unit 4 is a function (registered face storage means) that stores face information of a plurality of registrants in advance. Here, the “registrant” is a person who should be identified (a person should be specified) by the face matching device. For example, when this face matching device is applied to a gate system for detecting employees from an unspecified number of passers-by, only employees who are detection targets become registrants.

  On the other hand, the similar face storage unit 5 is a function (similar face storage means) that stores face information of a person who has caused an error in accepting another person (similar person) as similar face information. FIG. 2 conceptually shows the data structure of the similar face storage unit 5. The similar face storage unit 5 stores similar face information for each registrant using the registrant as an index. In the example of FIG. 2, registrant R1 has similar face information R1-1 and R1-2 for two persons, and registrant R2 has three pieces of similar face information R2-1, R2-2, and R2-3. Each is associated. The registrant R3 has no similar face information, which means that no face erroneously determined as the registrant R3 has existed until now.

  The result display unit 6 has a function of displaying the face collation result, and is configured using a display device (specifically, LCD, PDP, etc.). The input unit 7 is a function that receives information input from the user, and is configured using an input device (specifically, a keyboard, a mouse, a touch panel, etc.). The similar face registration unit 8 has a function of registering the face information of the person to be collated who has caused the other person acceptance error in the similar face storage unit 5. The user visually determines whether or not another person has received an error. Specific processing will be described later. In the present embodiment, the result display unit 6, the input unit 7, and the similar face registration unit 8 constitute a determination unit of the present invention.

<Face matching process>
Next, the processing flow of the face collation apparatus will be described with reference to the flowchart of FIG. The process shown in FIG. 3 is executed each time an image is input from the imaging unit 1 at a constant time interval.

  In step S1, the face detection unit 2 detects the face of the person to be verified from the input image, and further acquires the face information.

  In step S <b> 2, the first face collation unit 30 collates the face information of the person to be collated with the face information of each registrant registered in the registered face storage unit 4. That is, for all registrants, the similarity (score) between the face information of the person to be collated and the face information of the registrant is calculated.

  In step S3, the first face matching unit 30 determines a registrant who has the highest score as a temporary candidate.

  In step S4, the first face matching unit 30 checks whether the score of the temporary candidate exceeds a preset threshold value. When the score is equal to or lower than the threshold value (step S4; NO), it is considered that the person to be collated and the temporary candidate are not the same person, and the face collation unit 3 outputs “NG” as the collation result (step S5). On the other hand, when the score exceeds the threshold value (step S4; YES), the process proceeds to the second face collation after step S6.

In step S <b> 6, the second face matching unit 31 refers to the similar face storage unit 5 to check whether similar face information associated with the temporary candidate exists. When there is no similar face information (step S6; NO) (see the registrant R3 in FIG. 2), the second face matching unit 31 outputs the temporary candidate as “candidate”, and the process proceeds to step S10. If there is one or more similar face information (step S6; YES) (see registrant R1 in FIG. 2), the second face matching unit 31 advances the process to step S7.

  In step S7, the second face collating unit 31 collates the face information of the person to be collated with each similar face information (R1-1, R1-2). That is, a similarity (score) is calculated for each similar face information.

  In step S8, the second face collation unit 31 determines the similar face information having the highest score as an error candidate.

  In step S <b> 9, the second face matching unit 31 compares the provisional candidate's score with the wrong candidate's score. When the score of the temporary candidate is larger (step S9; YES), the second face matching unit 31 outputs the temporary candidate as “candidate”, and the process proceeds to step S10. On the other hand, if the score of the wrong candidate is higher or the scores are the same (step S9; NO), the person to be collated is regarded as someone else who is very similar to the provisional candidate, and the face collation unit 3 collates. As a result, “NG” is output (step S5).

  In step S <b> 10, the result display unit 6 displays a face matching result confirmation screen, and requests the user to determine whether or not the matching target person and the candidate are the same person. FIG. 4 is an example of a face matching result confirmation screen. On this screen, the face image of the person to be collated and the face image of the candidate (registrant) are displayed side by side, and information such as the name and registration number of the candidate and the score are also displayed. The user compares the two images and inputs whether or not the collation result is correct.

  When it is determined by the user that the collation result is correct (that is, the collation target person and the candidate are the same person) (step S11; YES), “OK” is output as the collation result (step S12).

  On the other hand, when it is determined by the user that the collation result is not correct (that is, the collation target person and the candidate are not the same person) (step S11; NO), the similar face registration unit 8 performs the collation target person face information. Are additionally registered in the similar face storage unit 5 (step S13). At this time, the similar face registration unit 8 adds the face information of the verification target person to the similar face information of the candidate. As a result, the registrant and the similar person are associated with each other. Then, “NG” is output as the collation result (step S5).

  If NG is output, no output is output, and if OK is output, it is more preferable to display a person name.

  In this embodiment, the user makes a final determination as to whether or not the verification target person and the candidate are the same person, but this final determination can be replaced by automatic processing on the apparatus side. If the identity of the person to be collated and the candidate is determined using means different from the face collation process of the face collation unit 3, the occurrence rate of other person acceptance errors can be suppressed to a considerably low level. For example, compare information other than face information (information read from cards held by the person to be verified, information such as height, body shape, clothes, hairstyle, personal belongings obtained from images, biometric information other than face, etc.) Thus, a process for determining identity can be considered. It is also preferable to use a face matching process with an algorithm different from that of the face matching unit 3 for final determination of identity.

<Advantages>
According to the face collation apparatus of the present embodiment described above, face information of a collation target person who has caused another person acceptance error (that is, determined by the user as not being the same person as the candidate) is registered as similar face information. Is stored separately from the person's face information. Therefore, no matter how many other person acceptance errors occur, the number of registered persons does not increase, and the time required for the first face matching does not increase.

  On the other hand, after the first face collation, the face information of the person to be collated is collated with the similar face information to verify the result of the first face collation, so that it is possible to reduce other person acceptance errors. Can do.

  Moreover, similar face information is managed for each registrant, and the collation range in the second face collation is limited to similar face information associated with the temporary candidate (that is, another person's face that is easily mistaken for the temporary candidate). Is done. Therefore, the time required for the second face matching can be reduced as much as possible, and the result of the first face matching can be verified efficiently.

  Further, even if face information of a registrant A is stored as similar face information of another registrant B, the similar face information is registered by the first face matching from the matching range of the first face matching. Since the user A is also out of the collation range of the second face collation when the user A is selected, the authentication rate of the registrant A is not adversely affected. That is, there is no decrease in authentication rate due to double registration of the same person, which has been regarded as a problem in the past.

<Application example of face matching device>
The face matching device described above is used for the purpose of automatically detecting a specific registrant (in fact, a person who is highly likely to be a registrant) from an unspecified number of people. For example, when there are at most only a few registrants among the 1000 people to be verified, it is not realistic for the user to check the faces of all 1000 people. If the face collation apparatus can narrow down 1000 people to 10 people, the burden on the user will be one-hundred and the effect will be enormous. Specific applications include (1) a system that detects the top customers (= registrants) from a large number of customers at large dealers and notifies them to the sales staff, or (2) airports and stations, etc. Various systems such as a system for detecting a criminal (= registered person) and notifying the security guard can be assumed.

FIG. 1 is a block diagram showing the configuration of the face matching device. FIG. 2 is a diagram conceptually showing the data structure of the similar face storage unit. FIG. 3 is a flowchart showing the flow of processing of the face matching device. FIG. 4 is a diagram illustrating an example of a face matching result confirmation screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up part 2 Face detection part 3 Face collation part 30 1st face collation part 31 2nd face collation part 4 Registration face memory | storage part 5 Similar face memory | storage part 6 Result display part 7 Input part 8 Similar face registration part

Claims (7)

Registered face storage means for storing face information of a plurality of registrants in advance;
Face information acquisition means for acquiring face information from the image of the person to be verified;
Face matching means for selecting a candidate who is estimated to be the same person as the person to be verified from among the plurality of registrants by face matching;
Determination means for determining whether the verification target person and the candidate are the same person;
Similar face storage means for storing face information of the person to be collated determined by the determination means as not being the same person as similar face information,
The similar face storage means stores the similar face information for each registrant,
The face matching means is selected as a result of the first face matching for matching the face information of the person to be collated with the face information of each registrant and the face information of the person to be collated. A face collation apparatus that performs second face collation that collates with similar face information associated with a registrant. The face matching means includes
The face collation according to claim 1, wherein in the first face collation, one registrant having the highest similarity with the face information of the collation target person is selected from the plurality of registrants. apparatus. The face matching means includes
In the second face collation, the similarity between the face information of the collation target person and the face information of the one registrant is related to the face information of the collation target person and the one registrant. 3. The face collation apparatus according to claim 2, wherein when the degree of similarity is greater than face information, the one registrant is output as the candidate. The determination means includes
The face collation apparatus according to claim 1, wherein the face image of the person to be collated and the face image of the candidate are displayed, and the user is determined whether or not they are the same person. A computer storing face information of a plurality of registrants in advance
Face information acquisition processing for acquiring face information from the image of the person to be verified;
A face matching process for selecting a candidate who is estimated to be the same person as the person to be matched from the plurality of registrants by face matching;
A determination process for determining whether or not the verification target person and the candidate are the same person;
Performing similar face storage processing for storing face information of a person to be collated determined not to be the same person as similar face information,
In the similar face storage process, the computer stores the similar face information for each registrant,
In the face matching process, the computer compares the face information of the person to be collated with the face information of each of the registrants, and the face information of the person to be collated in the first face matching. A face collation method comprising: performing a second face collation that collates with similar face information associated with a registrant selected as a result.   The program which makes a computer perform the face collation method of Claim 5.   A computer-readable storage medium storing the program according to claim 6.

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