JP2009522683A - Iris recognition system and iris recognition method using mobile terminal equipped with stereo camera - Google Patents

Abstract

The present invention obtains a stereo image of a face using two or more cameras or a corresponding method, and a mobile terminal equipped with a stereo camera so that it can be complemented even if the size of the image changes with distance The present invention relates to a face recognition and / or iris recognition system and an iris recognition method using a machine. In the conventional iris recognition methods implemented in many systems, an iris image is captured and used using a camera with automatic zoom adjustment and auto focus adjustment functions. However, considering the volume and price factors. It is practically impossible to install and use it on a mobile terminal. Therefore, in the present invention, a user obtains an iris image by installing a short-focus lens having a large depth of focus in a mobile terminal equipped with a stereo camera to obtain a focused image in which the iris image is in focus. If the position is not appropriate, a message is sent to the user so that an iris image can be easily obtained. In addition, the present invention is configured such that the recognition rate does not decrease even when the image correction operation based on the distance is performed and the size of the iris image is changed.
[Selection] Figure 1

Description

  The present invention relates to a method and system for performing face recognition and / or iris recognition on a camera-equipped mobile terminal such as a mobile phone, a portable terminal or a notebook computer equipped with a camera. The present invention relates to an iris recognition system and an iris recognition method using a mobile terminal equipped with a stereo camera that can reduce a volume while using a camera and increase a recognition rate.

  Generally, in the case of existing keys, access cards, etc., there is a lot of room for theft, loss, duplication, etc., and the security is relatively low, and it is necessary to carry a cellphone and remember a password. There are disadvantages to say. Therefore, research on personal identification technology that is more secure and convenient for this purpose is being conducted.

  As one of them, the biometric recognition system is gradually becoming commonly used. In the trend, biometric recognition means that biometric information (fingerprint, face, iris, cornea, hand pattern, instep vein, voice, etc.) that differs from person to person can be extracted and discriminated using a camera. A personal identification system that relatively uses iris recognition is widely used by photographing a corresponding living body and extracting information for recognition.

  A dedicated camera system is used to photograph the iris. There are two main methods for capturing a face and / or iris image for recognition as follows.

  The first method is a position adjustment function using a stereo camera for face recognition, as disclosed in Korean Patent Application No. 10-2003-0002822 (“Iris Recognition System and Iris Recognition Method Using Stereo Face Recognition”). After executing the above, there is a method of capturing an in-focus iris image by grasping the exact position of the iris.

  The second method is an iris that is focused using a camera with Auto Zooming and Auto Focusing functions, such as those used by LG, Panasonic, OKI and others. There is a way to take an image.

  The latter method is evaluated as a difficult technique to be applied to a mobile terminal because the volume of the camera increases and the production cost increases.

  On the other hand, recently, mobile terminals equipped with a camera have begun to be widely used, and research on a system and a method for performing face recognition and / or iris recognition on such mobile terminals is at the beginning. is there.

  The present invention was invented in view of the above circumstances. The first object of the present invention is to shoot an image suitable for face recognition and / or iris recognition by mounting a stereo camera on a mobile terminal. To provide an iris recognition system and an iris recognition method using a mobile terminal equipped with a stereo camera capable of correcting a deviation in image size due to distance through distance calculation between the camera and the face. is there.

  The second object of the present invention is to calculate the user's position from the stereo image and then to the user's voice or voice if the user's face position is not suitable for taking a face and / or iris image. An iris recognition system and iris recognition method using a mobile terminal equipped with a stereo camera that can be adjusted by easily moving the camera to a position suitable for face recognition and / or iris recognition by informing with other characters or images Is to provide.

  A third object of the present invention is to perform iris recognition using a mobile terminal equipped with a stereo camera that uses a special infrared filter mechanically or electronically to increase the sensitivity of the camera during iris recognition. A system and an iris recognition method are provided.

  To achieve this, the present invention provides a stereo camera that is mounted on a mobile terminal and captures an iris image, a digital camera chip that converts an analog image captured by the stereo camera into a digital image, and the digital camera chip And a controller for receiving iris recognition, face recognition, or iris recognition and face recognition by receiving the digital image output through the video input unit for controlling the video input.

  In the above, the stereo camera may be configured to use two or more cameras or to acquire two or more images through one image sensor using two or more optical lenses in one image sensor. It is characterized by that.

  In the above, the stereo camera is installed so as to mechanically or electronically control the special infrared filter, and at the same time, infrared illumination is provided when necessary, and the camera sensitivity is enhanced in the infrared region to obtain a clear iris image. Is characterized by the fact that

  In addition, the iris recognition method using a mobile terminal equipped with a stereo camera according to the present invention uses a stereo camera using a short-focus lens with a large depth of focus to use a face, iris, or face. A step of generating a stereo image by photographing an iris, a step of determining whether or not the stereo image is suitable for personal identification, and a result of the determination step are determined that the stereo image is an image suitable for iris recognition. A step of calculating a distance between the camera and the face from the stereo image, a step of performing normalization for correcting the size of the image using the distance information, It complements the deviation of the image size due to the distance between the faces to improve the accuracy of iris recognition.

  In the above, when it is determined that the stereo image is not suitable for personal identification, after the position of the user is calculated from the stereo image, a step of notifying the user of the position movement by voice, text, or image is executed. Then, the camera is adjusted by moving the camera lightly at a position suitable for face recognition and / or iris recognition.

  Further, in the above, the step of determining whether or not the stereo image is suitable for personal identification is performed by extracting a boundary line formed by the pupil and the iris with a circle, and conforming to personal identification when the extracted circle is cut. It is characterized by judging that it is not.

  Since the present invention as described above can easily obtain an iris image by sending a message to a user using a mobile terminal equipped with a stereo camera and can obtain a corrected iris image, it is highly recognized. Rate recognition and / or iris recognition can be performed, and iris recognition using a camera with a large volume and high auto-zoom and auto-focus functions like existing methods It has the advantage that face recognition and / or iris recognition with a high recognition rate can be performed on a small mobile terminal without a system.

  Hereinafter, the configuration and operation of a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram of the essential parts of an iris recognition system according to the present invention. The stereo camera (10) images the left and right eyeballs, particularly the iris region including the pupil, and the analog image captured by the stereo camera (10) is converted into a digital image by the digital camera chip (20). The digital image output from the digital camera chip (20) is input to the controller (40) through the video input unit (30).

  As a means for controlling the overall operation of the mobile terminal, the controller (40) extracts iris regions from the digital image in the present invention, generates iris information therefrom, and stores them in the storage means (50). Compared with the already registered reference iris information, it acts to confirm whether or not they are the same person. When confirming whether or not they are the same person using another external system, only the iris recognition template is calculated and output.

  The output terminal of the controller (40) is connected to an infrared illumination unit (60) for increasing the sensitivity of the camera, and a voice output unit (70) for outputting a guidance message as a voice signal to the user and a character. Is connected to a display unit (80), and a keypad (90) for a user to operate the iris recognition function is connected.

  As shown in FIG. 2A, the stereo camera (10) comprises a CCD camera (10A) and a CCD camera (10B) in a stereo system. For example, the CCD camera (10A) takes an image of the left eye. In the CCD camera (10B), after the right eye is photographed, an iris recognition operation as described later is executed, or one CCD as shown in FIG. (Charge Coupled Device) (12) is divided into two regions, and separate prism lenses (13A) and (13B) are installed in the respective CCD portions, and the left and right eyes are respectively connected to the respective prism lenses (13A) and (13B). The stereo image can be extracted by making it appear in the corresponding part of the CCD (12). In addition, the stereo camera (10) is installed so that the infrared filter can be mechanically or electronically driven, and at the same time, the infrared illumination unit (60) is installed so that it can be turned on electronically. The controller (40) is installed so as to control the availability of these operations by operating the keypad (90).

  Referring to the operation of the present invention as described above through the flowchart shown in FIG. 3, when the user tries to recognize the iris using the mobile terminal, the keypad (90) is provided. After starting an action such as pressing the <Start> button, the eye position is moved to an appropriate position on the entire surface of the stereo camera (10). At this time, although there are two ways for the iris recognition function to proceed, the first method is to passively press the button with the meaning of <Iris image collection complete> on the keypad (90). As a second method, there is a method in which a sensor capable of detecting a user's movement is attached to the mobile terminal to automatically move to the next stage.

  When the imaging of the iris is completed in this way, the input iris image is transmitted to the controller (40) through the video input unit (30). The controller (40) is roughly divided into three or more functions. The first function is a preprocessor function that determines whether the input iris image is suitable for iris recognition, and the second function is a function that converts the input iris image with an iris recognition template. The third function is a function that compares the input template with a registered template and outputs a result value.

  In the first function of the controller (40), if the iris image is not suitable for iris recognition, i.e. it is out of focus and dim, and the iris position is out of range of the camera and only part of the iris is collected In some cases, re-photographing is guided to the user using an audio mesh through the audio output unit (60) or other effective means such as a display unit (80).

  This is because the iris image must come into a predetermined area of the CCD (12), and if the area is removed, a part of the iris area will be cut off. This is because an accurate iris recognition cannot be performed due to the loss of information.

  The method for determining when the iris image leaves the region is as follows. As shown in FIG. 4, the iris and the pupil can be expressed by two circles with the boundary as a reference. FIG. 4A shows an image extracted so as to be suitable for iris recognition, and FIG. 4B shows an image that is not suitable for iris recognition, as shown in FIG. Since the region is removed, the pupil and iris region can be analyzed to determine whether the image is suitable for iris recognition.

  On the other hand, since the iris information is lost when the fixed area is removed as well as when a part of the iris is blocked by the eyelid etc., in this case, the method of opening the eyes by a physical method is used. Must be resolved. Even when the user is too close to the camera or far away from the camera, the determined area is removed. Since a stereo camera is used, it can be easily determined in such a case.

  When the iris image is out of the area, after detecting the situation using the above method, an appropriate voice message or text message is sent through the voice output unit (70) or the display unit (80) like The method of outputting and moving the position of the user can be used.

  In the third function, the registered template may have been stored in the storage means inside the mobile terminal according to the purpose of the mobile terminal, or connected to the long-distance server through the mobile network function. It may be received. When using a registered template stored in such a long-distance server, the template generated by shooting for iris authentication can be sent to the server side and the result value can be passed to reduce the data transmission amount. it can.

  FIG. 5 is a diagram for explaining a method of calculating a distance between a stereo camera and an object. Using a CCD camera (10A) (10B) constituting the stereo camera (10) to capture a stereo face image and calculating the distance between the camera and the face or iris, and using a short focus lens with a large depth of focus Therefore, a method for correcting the size deviation of the iris image due to the distance is necessary, and this will be described with reference to FIG.

  By measuring the distance on the X axis between the center of the right eye and the left eye through the stereo image, the distance from the camera to the object, that is, the eye can be evaluated. That is, it is possible to grasp the three-dimensional position through two images viewed from different viewpoints with respect to the same object.

  In order to formulate this, several terms are defined as follows. The left image is an L-image and the right image is an R-image, and these are defined as a stereo-pair. Since L-image and R-image indicate the same point on the object surface, this is expressed as a corresponding point. For example, as shown in FIG. 5, the point A located in the space is displayed as an R point in the R-image and as an L point in the L-image. Therefore, L and R become corresponding points. Similarly, the L ′ and R points can be obtained from the B branch in the space where the A point has moved.

At this time, if reference data for distance measurement is obtained in advance through a camera calibration process, the distance is measured through the mismatch at one point of the L-image and the corresponding point on the R-image. be able to.
Generally, it is as follows.

Here, D _X and D _Y are projected values, and represent a mismatch of the point (x, y) with respect to R-image on the OX and OY axes. L (x, y) represents R-image and R-image, respectively, and N (x, y) represents noise generated by conditions such as light and shadow and a changed state. It is a function to represent.

In FIG. 5, the objective plane OXY is perpendicular to the camera lens and is displayed at l at an appropriate distance from the camera. z = ζ (x, y) represents a field for evaluating the surface, and z represents a distance from the target surface (z = 0). The deviation of the distance from the specific point of the object is represented by Δl = ζ (x, y). Points on object surface are registered in fundamental mismatch (basic disparity) d _θ. The deviation of the discrepancy value for some such points represents Δd. The target surface includes point B. In this case, B causes a basic mismatch (d _θ = L′−R).

Point A is not placed on the destination plane, and in fact its mismatch has other values (d _A = LR). Usually, the distance between feature points on the surface is much smaller than the distance between the object and the camera. Therefore, such a relationship can be expressed as follows.

From this, the formula for evaluating distance is derived as follows.

  FIG. 6 is a diagram for explaining a method of standardizing the deviation of the iris image size according to the distance according to the present invention. Data between the inner and outer boundaries of the iris image is transformed by a polar coordinate method.

  As shown in FIG. 6, the center of the inner boundary and the outer boundary of the iris do not necessarily coincide with each other, and each of them is divided at an angle having m equal intervals. The image segment obtained from the i-th inner boundary segment to the i-th outer boundary segment is divided into n radial samples. Each sample represented by p (r, θ) is calculated by a bilinear interpolation method or the like.

  At this time, 0 degrees as a reference is displayed in the 6 o'clock direction, indicating the direction immediately below the center of the pupil, and gradually increasing the angle counterclockwise. When the value is 0, the lower address is displayed from the pixel closest to the inner boundary, and the next pixel is obtained by gradually increasing the angle with respect to a circle having the same radius. This process is repeated until one circle is finished.

The next process repeats the same process for a circle with the next radius. That is, all the data obtained by the polar coordinate method can be displayed as n × m samples. A simple formula for determining the Base Size is as follows:
B = K / (D−D ₀ )

Here, D is the distance from the camera to the eye measured in the face position adjustment process, and K and D ₀ are constant values evaluated in the camera calibration process.

It is a principal part block diagram of the iris recognition system by this invention. 1 is a diagram illustrating an embodiment of a stereo camera according to the present invention. 3 is a flowchart for explaining an iris recognition method according to the present invention. 4 is a diagram for explaining whether an iris image photographed by the present invention is appropriate for personal identification; 3 is a diagram illustrating a method for calculating a distance between a stereo camera and an object according to the present invention. 3 is a diagram for explaining a method for standardizing a size deviation of an iris image according to a distance according to the present invention;

Explanation of symbols

10 stereo camera, 10A, 10B CCD camera, 12 CCD, 13A, 13B prism lens, 14 infrared filter, 20 digital camera chip, 30 video input unit, 40 controller, 50 storage means, 60 infrared illumination unit, 70 audio output unit, 80 display, 90 keypad

Claims (6)

An iris recognition device using a mobile terminal including a stereo camera, a digital camera chip and a video input unit,
The mobile terminal operates in cooperation with an iris image registered and stored in another mobile terminal, a long-distance server or a security device,
The iris recognition device
A stereo camera having a short focus lens with a large depth of focus for capturing a stereo image by photographing a face and an iris;
Means for converting the stereo image obtained by the stereo camera into a digital signal and calculating a distance between the stereo camera and the iris;
Whether the stereo image is an iris image suitable for personal identification is determined by determining whether the calculated distance information is in focus and whether the position of the iris is out of the shooting range of the camera. A means of determining whether or not
Iris recognition using a mobile terminal equipped with a stereo camera having means for extracting an iris region from the stereo image and further acquiring a standardized iris image using a polar transformation method and a complement method apparatus.   The stereo camera acquires a left iris image and a right iris image using two or more cameras, or uses two or more optical lenses in one image sensor to obtain two or more images as one image sensor. The iris recognition apparatus using a mobile terminal equipped with the stereo camera according to claim 1, wherein the iris recognition apparatus is configured to acquire the image through the mobile terminal.   The means for acquiring the stereo image is provided with a special infrared filter so that it can be mechanically or electronically controlled to increase the camera sensitivity in the infrared region so that a clear iris image can be acquired. The iris recognition apparatus using a mobile terminal equipped with a stereo camera according to claim 1 or 2, wherein left and right stereo images of the iris are acquired. In an iris recognition method using a mobile terminal including a stereo camera to improve iris recognition accuracy,
Acquiring a stereo image of the face and / or iris using a stereo camera with a short focus lens having a large depth of focus;
Based on the acquired stereo image, it is determined whether the image is in focus and whether the position of the iris has left the shooting range of the camera, thereby determining whether the stereo image is an image suitable for personal identification. And the stage of
Calculating the distance between the stereo camera and the iris from the stereo image when it is determined that the acquired stereo image is an image suitable for iris recognition;
In order to correct the change in the size of the iris image using the distance information, a plurality of circles having the same radius with respect to the center of the pupil are formed, and each circle is divided by a certain angle to polar coordinates. An iris recognition method using a mobile terminal equipped with a stereo camera, comprising: obtaining a standardized size iris image using a polar coordinate transformation and a complement method for forming   In the step of determining whether or not the image is suitable for personal identification, if it is determined that the acquired stereo image is not suitable for personal identification, the user is based on the stereo camera based on the acquired stereo image. 5. The iris using a mobile terminal equipped with a stereo camera according to claim 4, further comprising a step of notifying the user of the movement of the position by voice, text or image after calculating the position coordinates of the iris. Recognition method.   The step of determining whether or not the acquired stereo image is suitable for personal identification is performed by extracting a boundary line formed by the pupil and the iris with an ellipse, and when the extracted ellipse is blocked by a region other than the iris 6. The iris recognition method using a mobile terminal equipped with a stereo camera according to claim 4 or 5, further comprising a step of determining that the identification is not suitable.