The present invention claims priority of Korean Patent Application No. 10-2008-0116625, filed on Nov. 24, 2008, which is incorporated herein by reference.
The present invention relates to an image acquisition apparatus for a multi-modal biometrics system, and, in particular, to the image acquisition apparatus for acquiring facial and iris images for use in a multi-modal biometrics system.
Currently, the field of biometrics is diverging into multi-modal biometrics, long distance biometrics, and user-friendly image acquisition technologies. In particular, the fields of facial and iris recognition are evolving into a multi-modal facial and iris biometric technique because two pieces of biometric information can be acquired from a single facial image and fields of different biometrics can be complemented each other. In particular, an iris recognition technology shows best performance in biometrics.
However, a biometrics system has the disadvantage of a low utilization due to an inconvenient interfacing between a user and the system in iris image acquisition and limited compatibility with facial recognition.
In order to simultaneously acquire facial and iris images, a facial image acquisition apparatus and an iris image acquisition apparatus are separately required. The facial image acquisition apparatus and the iris image acquisition apparatus are provided with respective cameras, and adjust incident angles of their corresponding cameras arranged at upper and lower locations to capture facial and iris images, respectively.
Meanwhile, the technology using the facial image acquisition camera and the iris image acquisition camera may be susceptible to an error due to differences in incident angles and phases and in the photographing areas.
Furthermore, the conventional iris image acquisition camera uses a cold mirror positioned in front of a camera lens and imaging an incident image thereon to enable a user to directly check the location of the eye to be imaged from a short distance, e.g., about 40 cm.
However, although a cold mirror is useful to check an incident image over a short distance, appropriate training is requisite for the convenient use of the cold mirror. Accordingly, it is necessary to develop a user-friendly iris and facial image acquisition technique capable of simultaneously acquiring iris and facial images from a long distance with greater efficiency.
The present invention provides a multi-image acquisition apparatus capable of simultaneously acquiring facial and iris images from a relatively long distance while minimizing error attributable to a phase difference occurring when capturing facial and iris images along a same light path.
In accordance with an aspect of the present invention, there is provided a multi-image acquisition apparatus for use in a biometrics system including a light splitting filter for reflecting or transmitting multi-image lights representing an image of a target subject provided along an identical light path into different bands; a first image sensor for imaging an iris area by capturing a fraction of the multi-image light which has been transmitted through the light splitting filter; a second image sensor for imaging a facial area by capturing a fraction of the multi-image light which has been reflected from the light splitting filter; and a control module for controlling the first sensor and the second sensor and providing the images obtained by the first sensor and second sensor for image recognition.
According to the present invention, images of a facial region and an iris area can be simultaneously acquired using a single camera apparatus and an iris image can be acquired from a long distance (identical to the distance from which a facial image is captured) without requiring a cold mirror. Furthermore, the present invention allows an image of a subject to pass along the same one path of the camera apparatus, thereby minimizing the occurrence rate of error attributable to a phase difference which may occur when facial and iris images are captured using two existing facial recognition and iris recognition cameras. Furthermore, the present invention is configured such that a telescopic lens is added in front of the camera apparatus, so that facial track/recognition and iris recognition can be performed from a long distance and efforts to bring a user's eye to a location near a guidance area within the cold mirror of the camera apparatus to perform iris recognition can be reduced, with the result that it is expected that the usability of the facial and iris image acquisition/recognition system can be considerably increased.
The objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which form a part hereof.
First, the focusing lens 100 is used to improve parallel light for incident light of a target subject for image acquisition along a single light path. In the drawing, the incident light includes infrared rays represented by a thin solid line, and visible rays represented by thick solid lines. In general, an image for facial recognition uses the visible ray band, while an image for iris recognition uses the infrared band.
The infrared illuminator array 102 is arranged in the front surface of the multi-image acquisition apparatus and used to capture an iris image along with the iris image camera 110. The infrared illuminator array 102 emits infrared rays in a specific wavelength band ranging, e.g., from 750 nm to 850 nm. The infrared rays reach the target subject, and are then reflected to the multi-image acquisition apparatus 10 as multi-image light representing the target subject. Intensity of the infrared illuminator array 102 for iris image capture needs to be strengthened in proportion to a distance between the target subject and the multi-image acquisition apparatus.
The light splitting filter 104 is used for reflecting and transmitting the multi-image light to different bands. For example, a beam splitter or a dichroic mirror may be used as the light splitting filter 104. For the application of the beam splitter, it is preferable to design the beam splitter to reflect the multi-image light in the entire visible ray band on the basis of a specific wavelength and to transmit infrared light over a specific band. For the application of the dichroic mirror, it is preferable to design the dichroic mirror to have an infrared filtering function.
The infrared filter 106 is provided for a case where a beam splitter is used as the light splitting filter 104, and is requisite for the acquisition of a more desirable iris image in the iris image sensor 110 to which light in the infrared band is provided. Here, for the purpose of iris recognition from the light in the infrared band, the infrared filter 106 may include an infrared filter capable of passing infrared rays in a band ranging from 750 nm to 850 nm or a long pass infrared filter capable of passing infrared rays in a band above approximately 750 nm.
In order to recognize the iris, a diameter of an iris area needs to be wider than, e.g., 150 pixels and therefore, it is necessary to enlarge and capture an eye area in a facial region. The zoom lens group 108 is employed to guarantee such image quality of the enlarged and captured eye area, and the focusing control of the zoom lens group 108 under the control of the control module 200 allows to enlarge and capture an iris image.
The iris image sensor 110 serves to obtain an iris image from a fraction of the multi-image light. For example, a high-resolution image sensor, more preferably, a low-speed and high-resolution monochrome CCD/CMOS sensor may be used as the iris image sensor.
A lens with a low field of depth may be used to acquire the iris image. In this case, minute focusing adjustment using a distance measurement sensor 112 is required.
Meanwhile, the UV filter 114 may be provided to improve the facial image in a visible band reflected from the light splitting filter 104. Further, the objective lens group 116 is provided to improve the facial image and acquire the facial image of a specific size.
The facial image sensor 120 is used for facial image acquisition from a fraction of the multi-image light. For example, a high-speed image sensor, more preferably, a high-speed and low-resolution CCD/CMOS sensor may be used as the facial image sensor 120.
The control module 200 functions to control the zoom lens group 108, the iris image sensor 110 and the facial image sensor 120 and provides facial and iris images acquired by the image sensor 110 and the facial image sensor 120 to an image recognition apparatus 300 (which will be described later) through the external interfacial terminal 122. Additionally, the control module 200 enables power to be supplied to the multi-image acquisition apparatus 10 through the external interface terminal 122. Further, In order to acquire an iris image through the enlargement of an iris area in a facial image, the control module 200 performs a synchronization process for the acquisition of an eye area from a facial region.
Hereinafter, the operation of the control module 200 is described in detail with reference to
Here, when a facial region enlargement command (to enlarge an eye part for the purpose of iris image acquisition) is received from the multi-image recognition apparatus 300 through the external interface terminal 122, the control unit 26 controls the zoom lens group driving unit 24 so that the zoom lens group 108 is focused. Furthermore, when an iris image and/or facial image acquisition command is received from the image recognition apparatus 300 through the external interface terminal 122, the control unit 26 controls the iris image sensor driving unit 20 and/or the facial image sensor driving unit 22 to acquire the iris and/or facial image and to provide the acquired iris and facial image to the image recognition apparatus 300 through the external interface terminal 122.
As can be seen from
For example, in case where an LCD is used as the indicator 34, a reference screen 32 having an area of interest 36 may be employed so that a facial region of the facial image 30 to be located on the LCD has been located in the area of interest.
A degree of freedom for a facial image is flexible. However, in order to accurate capture an eye area, a facial region needs to be accurately located when a resolution of a camera module is low or it is necessary to enlarge the eye area at high magnification.
The multi-image acquisition apparatus 10 are connected to the image recognition apparatus 300. The image recognition apparatus 300 functions to control the indicator 34 and the multi-image acquisition apparatus 10 and, also, to recognize or authenticate the iris and facial images acquired by the multi-image acquisition apparatus 10 by using an appropriate iris and facial recognition software.
From a face to be imaged 50, a facial region 52 may be imaged by the facial recognition camera 120 and a single eye region 54 or an eye region of two eyes 56 may be imaged by the iris image sensor 110 depending on resolution.
First, a target subject to be imaged is provided to the iris image sensor 110 and the facial image sensor 120 where facial and iris regions are captured to acquire a facial image and an iris image, respectively at step S600.
The facial and iris images are then provided to the image recognition apparatus 300 through the external interface terminal 122, and the components of the face and iris of the subject are extracted from the facial and iris images by the component extraction unit 30 at step S602. The extracted components of the face and iris of the subject are then provided to the facial and iris recognition unit 32.
At this time, if the correction of the iris image has been requested by the user input unit 34 in the image recognition apparatus 300 at step S604, the image recognition apparatus 300 provides a corresponding correction request signal to the control unit 26 in the multi-image acquisition apparatus, and the control unit 26 controls the zoom lens group driving unit 24 so that it focuses the zoom lens group 108, thereby enlarging and capturing an iris area 54 or 56, at step S606.
Further, if the user input unit 34 of the image recognition apparatus 300 requests the correction of the facial image at step S608, the image recognition apparatus 300 provides a corresponding correction request signal to the indicator 34 attached to the front of the image acquisition apparatus, and the indicator 34 displays the captured facial image 52 to rearrange the face region at step S610.
Finally, at step S612 the facial and iris recognition unit 32 recognizes the facial and iris images having separate and corrected results.
While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.
Number | Date | Country | Kind |
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10-2008-0116625 | Nov 2008 | KR | national |