WO2005084011A1

WO2005084011A1 - Apparatus for shooting image for authentication

Info

Publication number: WO2005084011A1
Application number: PCT/JP2005/003048
Authority: WO
Inventors: Shuichi Horiguchi
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-02-26
Filing date: 2005-02-24
Publication date: 2005-09-09
Also published as: JP2005244549A

Abstract

A focused image for authentication can be taken even if a person to be authenticated is in motion or movement. An apparatus for shooting an image for authentication has a lens (2) for collecting incoming light from a person (1) to be authenticated, a light splitting prism (3) for splitting the incoming light collected by the lens (2), and imaging means (4a, 4b, 4c) arranged at positions having different light path lengths (Da, Db, Dc) from the center point of the lens (2) and imaging each of the incoming light split by the light splitting prism (3). As a result, the depth of field is three times that of the case with one imaging means, and a focused image for authentication can be easily obtained even if the person (1) to be authenticated is in movement.

Description

Specification

Authentication imaging device

Technical field

The present invention relates to an authentication image capturing apparatus used in a security system, and in particular, to an authentication image capturing apparatus capable of capturing an in-focus authentication image even when a subject is moving. About.

Background art

[0002] With the spread of security systems, various types of personal authentication devices have been installed in various places. Some of these personal authentication devices use a camera, that is, an imaging device, to capture an authentication image. For example, in an iris authentication device, an iris image of a person to be authenticated is captured by a camera. In an apparatus that performs authentication based on a retinal pattern, an image of the retina is captured by a camera through a pupil of the subject.

[0003] Furthermore, an individual who takes a photograph of the face of a traveler at an airport or the like, extracts correlated features such as the positions of eyes and nose, and compares and compares the features with registered features such as persons requiring attention. Some security systems use authentication devices.

[0004] In the personal authentication apparatus using these cameras, the subject may be stationary for photographing, but in order to shorten the waiting time of the subject, even if the subject is moving, It is necessary to be able to capture an in-focus image. In addition, even when the subject is imaged with the subject stationary, the subject is not completely stationary, so that even if the subject is slightly moved, it is possible to capture an in-focus image. Need to be

[0005] However, it is difficult to always keep the moving subject in focus even when the auto-focus (AF) function provided in the camera is activated. The reason is that it takes time to search for the in-focus position with the AF function.

[0006] Therefore, conventionally, as described in Patent Document 1 below, in addition to a camera for capturing an image for authentication, two cameras for detecting the position of a person to be authenticated by a three-point method are separately provided. The focus function narrows the range searched by the AF function around the position of the moving subject detected by these position detection cameras so that the focus position can be obtained in a short time. Patent Document 1: JP-A-2000-5149

Disclosure of the invention

Problems to be solved by the invention

[0008] However, in the above-described related art, if the position of the person to be authenticated is not detected by using a camera for position detection in addition to the camera for capturing an image for authentication, the moving person is in focus. There was a problem that an authentication image could not be captured.

An object of the present invention is to provide an authentication image capturing apparatus that can capture an in-focus authentication image even when the user is moving without using a camera for detecting the user. To provide.

Means for solving the problem

[0010] An authentication image capturing apparatus according to the present invention includes a lens for condensing incident light from a person to be authenticated, a light splitting prism for dividing the incident light condensed by the lens into a plurality of light beams, It is characterized by comprising a plurality of image pickup means arranged at positions where the lengths of the optical path lengths of the central point forces are different, and each of which picks up the incident light split by the light splitting prism.

[0011] With this configuration, the depth of field is increased by the number of times of the number of imaging units, and a focused authentication image can be captured even when the verifier is moving or moving.

[0012] The authentication image capturing apparatus of the present invention further includes a filter unit that detects a high-frequency component amount included in each captured image captured by the plurality of image capturing units, and an image captured by each of the image capturing units. A control unit that selects, as an authentication image, an image having the highest amount of high-frequency components among a plurality of images.

With this configuration, it is possible to quickly select the most focused image suitable for authentication from among the authentication images captured by the plurality of imaging units.

[0014] The authentication image capturing apparatus of the present invention further includes a lens driving unit that drives a lens to adjust a focus position of the lens, and the control unit is imaged by each of the imaging units. It is characterized in that the lens driving means is controlled in accordance with the magnitude comparison result of the amount of high frequency components included in each captured image to control the moving speed of the focus position adjustment.

[0015] With this configuration, the focus position of the lens is adjusted according to the moving speed of the person to be authenticated. Therefore, it is easy to capture an in-focus authentication image even while the subject is moving.

[0016] In the authentication image capturing apparatus according to the present invention, the two image capturing means arranged before and after in the order of the length of the optical path length may be used when one of the image capturing means captures an image of the person to be authenticated. The depth of field and the depth of field when capturing the image of the person to be authenticated by the other imaging means are arranged so as to be continuous.

[0017] According to this configuration, since the depth of field of each imaging unit is continuous, an in-focus authentication image is reliably obtained by any of the imaging units.

The invention's effect

According to the present invention, an in-focus authentication image can be captured even when the subject is moving or moving by expanding the depth of field using a plurality of image capturing means. The waiting time of the person can be shortened.

Brief Description of Drawings

FIG. 1 is a configuration diagram of an optical system of an image pickup device for authentication according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of the authentication image capturing apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a processing procedure of the authentication image capturing apparatus according to the first embodiment of the present invention.

[4] Functional block diagram of authentication image capturing apparatus according to second embodiment of the present invention

FIG. 5 is a flowchart showing a processing procedure of the authentication image capturing apparatus according to the second embodiment of the present invention.

FIG. 6 is an explanatory diagram of processing contents of an authentication image capturing apparatus according to a second embodiment of the present invention. FIG. 7 is a configuration diagram of an optical system of the authentication image capturing apparatus according to a third embodiment of the present invention. Explanation of reference numerals

[0020] 1 Subject's eyes

2, 8, 10 lenses

3, 11 light splitting prism

4a, 4b, 4c, 12a, 12b, 12c, 12d Solid-state image sensor

5a, 5b, 5c 6 Operation control section

9 Stepper motor

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment)

FIG. 1 is a configuration diagram of an optical system of the authentication image capturing apparatus according to the first embodiment of the present invention. The authentication image capturing apparatus according to the present embodiment is provided for capturing an iris image of the eye 1 of the person to be authenticated, and three eyes 1 are shown in FIG. Move to express things.

The optical system of the authentication image pickup device includes a fixed-focus lens 2 for condensing incident light from the eye 1 of the person to be authenticated, and a condensed light, which is arranged at a rear stage of the lens 2 and divides the condensed light into three. Light splitting prism 3. Then, a first solid-state imaging device 4a that captures an image of the first split light split by the light splitting prism 3, a second solid-state imaging device 4b that captures an image of the second split light, and a third solid-state imaging device A third solid-state imaging device 4c for capturing an image is provided.

[0024] The optical path length (referred to as Da) between the center point O of the lens 2 and the first solid-state imaging device 4a, and the optical path length between the center point O of the lens 2 and the second solid-state imaging device 4b ( Db) and the optical path length (Dc) between the center point O of the lens 2 and the third solid-state imaging device 4c so that they are different from each other by a predetermined distance t so that they do not become the same length. The solid-state imaging devices 4a, 4b, and 4c are arranged. That is, when the central solid-state imaging device 4b is arranged at the focus position, the solid-state imaging device 4a is arranged at the front focus position and the solid-state imaging device 4c is arranged at the rear focus position.

FIG. 2 is a functional block diagram of the authentication image capturing device according to the first embodiment of the present invention. In FIG. 2, the solid-state imaging devices 4a, 4b, and 4c are equivalently arranged on the optical axis of the lens 2 with respect to the solid-state imaging device 4a.

The authentication image capturing device captures a captured image of the first solid-state imaging device 4a (hereinafter, a captured image captured by the first solid-state imaging device 4a is referred to as a captured image A), and includes the captured image A in the captured image A. A band-pass filter (BPF) 5a for detecting the amount of high-frequency components in a predetermined frequency range, and a captured image of the second solid-state imaging device 4b (hereinafter, a captured image captured by the second solid-state imaging device 4b is referred to as a captured image B). The high frequency of the predetermined frequency range included in the captured image B A band-pass filter (BPF) 5b for detecting the amount of wave components and an image captured by the third solid-state image sensor 4c (hereinafter, an image captured by the third solid-state image sensor 4c is referred to as an image C) are captured. A band pass filter (BPF) 5c for detecting an amount of high frequency components in a predetermined frequency range included in the captured image C.

[0027] The authentication image capturing device of the present embodiment further includes an arithmetic control unit 6 that captures the detection output of each bandpass filter 5a, 5b, 5c and outputs a selection control signal described later. Although not shown, the authentication image capturing apparatus has a function of extracting an image of an iris portion from an image of a subject's eye and a function of performing processing until a feature is encoded from the iris image. And pass the coded feature values to the subsequent authentication device.

Optically speaking in the configuration of the present embodiment, the range where the image A captured by the solid-state imaging device 4a is in focus! / Depth, ie, the depth of field, and the image captured by the solid-state imaging device 4b The position of the solid-state image sensor 4b with respect to the solid-state image sensor 4a is set so that the focused image B is in focus with the depth of field, and similarly, the point of the image B captured by the solid-state image sensor 4b Of the solid-state image sensor 4c with respect to the solid-state image sensor 4b so that the depth of field and the depth of field at which the image C captured by the solid-state image sensor 4c is in focus are continuous. The position is set.

[0029] As a result, the overall depth of field of the present embodiment is three times larger than that of an imaging device using one solid-state imaging device, and even if the person to be authenticated is moving, A focused image of the subject can be captured by any of the three solid-state imaging devices 4a, 4b, and 4c. Therefore, for example, to arrange both the solid-state imaging devices 4a and 4b so that the depth of field of the solid-state imaging device 4a and the depth of field of the solid-state imaging device 4b are continuous, the subject to be authenticated is placed on one of the solid-state imaging devices. When the eye is focused, the amount of high-frequency components contained in the image captured by the other solid-state imaging device should be equal to or more than a predetermined amount.

FIG. 3 is a flowchart of a selection processing procedure executed by the arithmetic control unit 6 in FIG. As described above, the arithmetic control unit 6 selects the most in-focus image among the captured images A, B, and C of the three solid-state imaging devices 4a, 4b, and 4c as follows, and performs selection control. Output a signal.

First, the output of the band-pass filter 5a and the output of the band-pass filter 5b are compared (step S1). If the output of the band-pass filter 5a is large, then the band-pass filter 5a Is compared with the output of the band-pass filter 5c (step S2). As a result, when the output of the bandpass filter 5a is large, that is, when the high-frequency component amount included in the image A is larger than the high-frequency component amount included in each of the image B and the image C, the image A is output. A selection control signal to be selected is output (step S3), and the authentication device at the subsequent stage performs an authentication process using image A.

[0032] As a result of comparing the output of the band-pass filter 5a and the output of the band-pass filter 5b (step S1), if the output of the band-pass filter 5b is greatly increased, then the output of the band-pass filter 5b and the band The output of the pass filter 5c is compared (step S4). As a result, when the output of the band-pass filter 5b is large, a selection control signal for selecting the image B is output (step S5), and the authentication device at the subsequent stage performs the authentication process on the image B.

If the output of the bandpass filter 5c is large as a result of the comparison in step S2, or if the output of the bandpass filter 5c is large as a result of the comparison in step S4, the image C Then, a selection control signal for selecting is output (step S6), and the authentication device at the subsequent stage performs the authentication process on the image C.

As described above, in the present embodiment, among the captured images A, B, and C of the three solid-state imaging devices 4a, 4b, and 4c, the image with the largest high-frequency component amount, that is, the most focused image. The selected image is selected as an image for authentication processing. Also, since the configuration is such that the high-frequency component amount is hardly detected by the band-pass filters 5a, 5b and 5c, high-speed processing is possible. In addition, by using the optical system of the authentication image capturing apparatus according to the present embodiment, the authentication target image is in focus even when the authentication target is moving while the authentication target enters within a wide depth of field. Can be imaged.

(Second Embodiment)

FIG. 4 is a functional configuration diagram of the authentication image capturing device according to the second embodiment of the present invention. In FIG. 4, similarly to FIG. 2, each of the solid-state imaging devices 4a, 4b, and 4c is illustrated and arranged on the optical axis of the lens 2 with respect to the solid-state imaging device 4a.

In the authentication image capturing apparatus of the present embodiment, a lens whose focus position is adjustable is used as the lens 8, and the moving speed of the focus position adjustment is controlled by the stepping motor 9 which receives a control command from the arithmetic control unit 6. Is different from the first embodiment in that This is the same as in the first embodiment.

FIG. 5 is a flowchart showing a processing procedure executed by the arithmetic control unit 6 of the present embodiment. First, it waits for the person to be authenticated to approach (step S11). When the person to be authenticated approaches, each of the solid-state imaging devices 4a, 4b, and 4b capturing an image of the eye 1 of the object to be authenticated. The outputs of the three band-pass filters (BPFs) 5a, 5b, and 5c connected to the respective filters are compared (step S12).

As a result of this comparison, when BPF5a> BPF5b> BPF5c holds, that is, FIG.

If the relationship of (a) is established, the moving speed of the focus position adjustment of the lens 8 is reduced (step S13), and then it is determined whether or not the subject has entered the shooting distance. (Step S14). If the camera enters the shooting distance, the process proceeds to the image selection process (step S15) described with reference to FIG.

If the distance is not within the shooting distance, the process returns to step S12, and the output of each band-pass filter 5a, 5b, 5c is compared again. As a result of the comparison between the bandpass filters 5a, 5b, and 5c, if the relationship shown in FIG. 6A is not established, then, the force / force that the relationship shown in FIG. 6B is established, that is, BPF5a, BPF5b and It is determined whether or not BPF5b> BPF5c holds! / (Step S16).

As a result of this determination, when the relationship shown in FIG. 6B is established, the moving speed of the focus position adjustment of the lens 8 is maintained as it is (step S17), and the process proceeds to step S14 described above. Proceed to determine whether the subject is within the shooting distance.

[0041] As a result of comparing the outputs of the three band-pass filters 5a, 5b, 5c (step S16), if the relationship in Fig. 6 (b) does not hold and the relationship in Fig. 6 (c) holds, The moving speed of the focus position adjustment of the lens 8 is increased (step S18), and the process proceeds to the above-described steps and 14, where it is determined whether or not the subject has entered the shooting distance.

According to the above-described processing, in the present embodiment, the moving speed of the focus lens constituting the lens 8 is controlled to match the moving speed of the person to be authenticated. As in the case of this embodiment, it is possible to keep focusing on, for example, the solid imaging element 4b in the middle while capturing within a wide depth of field. In particular, in the present embodiment, it is easy to capture a focused authentication image without stopping the person to be authenticated. (Third Embodiment)

FIG. 7 is a configuration diagram of an optical system of the authentication image capturing device according to the third embodiment of the present invention. In the first and second embodiments, three solid-state imaging devices are arranged for one lens system via a light splitting prism. However, the present invention is not limited to three, and two solid-state imaging devices are arranged. Alternatively, a configuration in which four or more solid-state imaging devices are arranged may be used.

The third embodiment is an embodiment in which four solid-state imaging devices are arranged, and a light splitting prism 11 that divides the light condensed by the lens 10 into four is arranged at the subsequent stage of the lens 10. In addition, four solid-state imaging devices 12a, 12b, 12c, and 12d are provided for imaging each split light emitted from the light splitting prism 11.

It is the same as in the first and second embodiments that the solid-state imaging devices 12a, 12b, 12c, and 12d are arranged such that the optical path length from the lens center point O is separated by a required distance. Yes, other configurations such as a configuration for selecting an image for authentication based on the amount of high-frequency components included in the captured images of the solid-state imaging devices 12a, 12b, 12c, and 12d are the same as those of the first and second embodiments. The same is true.

As described above, according to each of the above-described embodiments, the depth of field can be increased by using only one lens system, and the in-focus state can be achieved even when the person to be authenticated is moving. It is possible to capture an authentication image.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

This application is based on Japanese Patent Application No. 2004-051007 filed on February 26, 2004, the contents of which are incorporated herein by reference.

Industrial applicability

[0047] The authentication image capturing apparatus according to the present invention can shorten the waiting time of the authenticated person because the range in which the authenticated image can be taken even when the authenticated person moves can be captured. It is possible to capture an image for authentication without stopping a moving subject to be authenticated, which is useful when applied to a personal authentication device using an imaging device such as an iris authentication device.

Claims

The scope of the claims

[1] A lens for condensing incident light from a person to be authenticated, a light splitting prism for dividing the incident light condensed by the lens into a plurality, and an optical path length of a center point force of the lens An image capturing apparatus for authentication, comprising: a plurality of image capturing means arranged at different positions, each capturing an image of the incident light split by the light splitting prism.

[2] Filter means for detecting the amount of high-frequency components included in each of the captured images captured by the plurality of imaging means, and the high-frequency component amount of the plurality of captured images captured by each of the imaging means is maximum. The authentication image capturing apparatus according to claim 1, further comprising control means for selecting a captured image to be used as an authentication image.

[3] A lens driving unit for driving a lens to adjust a focus position of the lens, wherein the control unit compares the magnitude of a high-frequency component amount included in each captured image captured by each of the imaging units. 3. The authentication image pickup device according to claim 2, wherein the lens driving unit is controlled in accordance with the distance to control a moving speed of the focus position adjustment.

[4] The two imaging units arranged before and after in the order of the length of the optical path length are: a depth of field when one of the imaging units captures the image of the person to be authenticated; The authentication image capturing apparatus according to any one of claims 1 to 3, wherein the image capturing apparatus is arranged so that a depth of field when capturing an image is continuous.