KR20000061066A - Automatic focus adjustment method and apparatus for iris recognition system - Google Patents

Abstract

PURPOSE: A method and apparatus for controlling an automatic focus in an iris recognizing system are provided to detect an approach of a person, analyze an extract iris image and determine whether the person wears glasses, and turn on a light emitting diode, thereby preventing a reflection by the glasses. CONSTITUTION: The method for controlling an automatic focus in an iris recognizing system comprises steps of determining a motion feature of a user based on a distance information between a camera (104)and the user, previously estimating a right position before stabilizing of the motion of the user to previously adjust a moving distance of the camera and then adjust a zoom and focusing function, analyzing an iris image to obtain a focusing point. deciding that the image is reflected by a foreign substance if a size of the reflected image is larger than a predetermined value. An apparatus for controlling the automatic focus in the iris recognizing system comprises a motion feature determining portion for deciding motion feature of the user based on the distance information between the camera and the user, a motion controlling portion(203) of the camera, an image treatment portion(204), and a light controlling portion(205).

Description

AUTO FOCUS ADJUSTMENT METHOD AND APPARATUS FOR IRIS RECOGNITION SYSTEM}

The present invention relates to a technique for automatically and accurately extracting the iris image in the iris recognition system, in particular to determine the proximity and stabilization of a person using a distance measuring sensor and to analyze the extracted iris image angle of illumination The present invention relates to a method and apparatus for auto focusing of an iris recognition system that performs an autofocusing function while changing a position.

In the conventional iris image extraction technology, the user looks directly at the screen and moves the focus to adjust the focus. Since a single light source is used, when the user wears the glasses, the user should move the glasses to avoid reflection of the glasses. do.

In another conventional technique proposed to improve such inconvenience in use, two cameras were used to determine the position of a person and an eye, and the other one camera was used to capture an eye to analyze an iris image. In this case, a total of three cameras are used, and a new processing unit is needed to analyze the iris images captured by the two cameras.

For reference, as another example of a conventional recognition system using an iris, U.S. Patent No. 4641349 (Iris Recognition System), 5291560 (Name: Biometric Personal Identification System based on Iris Analysis), 5572596 (Automated, Non-lnvasive) Iris Recognition System and Method).

However, in the conventional iris recognition system such as the former, the automatic zoom and focus function is not provided, so it is inconvenient to use, and in the latter iris recognition system, the convenience of use is provided, but three cameras are used. There was a bug that was costly to add.

Therefore, the technical problem to be achieved by the present invention is to determine the proximity and stabilization of a person using a distance measuring sensor and analyze the extracted iris image to recognize the fact that the glasses are worn in advance so that reflection does not occur at the corresponding position. An autofocus control method and apparatus for performing an autofocus function while lighting a diode is provided.

Figure 1a is an external view of the iris recognition system to which the automatic focus control technology of the present invention is applied.

Figure 1b is an internal schematic diagram of the iris recognition system to which the automatic focus control technique of the present invention is applied.

Figure 2 is an embodiment block diagram of an automatic focus control apparatus according to the present invention.

3 is an explanatory diagram of a reflection avoidance method using glasses in the present invention.

Figure 4 is a signal flow diagram of the automatic focus control method of the iris recognition system according to the present invention.

*** Description of the symbols for the main parts of the drawings ***

101: outer case 102: inner case

103: optical device driver 104: camera

104A: Cold Mirror 104B: Optical Window

105: speaker 106: distance measuring sensor

107: light emitting diode unit for lighting 107A-107C: light emitting diode for lighting

108: external display 201: distance measuring unit

202: operation characteristic determination unit 203: camera operation control unit

204: image processing unit 205: lighting control unit

301: eyes 302: glasses

Automatic focus adjustment method of the iris recognition system for achieving the object of the present invention comprises the first step of measuring the distance between the camera and the user at a predetermined period and determining the operating characteristics of the user based on the distance information; A second step of adjusting a zoom and focus after preliminarily adjusting a moving distance of the camera by predicting an exact position before the user's motion is stabilized; The third step is to analyze the iris image to obtain a degree of focus, and to determine the reflection by the glasses when the size of the reflected image is greater than or equal to a predetermined value, to change the illumination position, and to perform fine adjustment.

Figure 2 is a block diagram of an embodiment of the automatic focus control device of the iris recognition system for achieving the object of the present invention, as shown in this, the distance between the camera and the user at regular intervals using the distance measuring sensor 106 Distance measuring unit 201 for measuring the; An operation characteristic determination unit 202 for determining an operation characteristic of a user based on a distance value continuously input from the distance measurement unit 201; A camera motion control unit 203 for adjusting the moving distance of the camera 104 in accordance with the measured distance and performing an auto focus function; An image processor 204 which analyzes the extracted iris image to determine how light is reflected and to wear glasses; In driving the light emitting diode unit 107, the light control diode 107 is configured of an illumination control unit 205 for selectively lighting a light emitting diode suitable for a surrounding situation among the plurality of light emitting diodes 107A-107C. Referring to Figures 1a, 1b and 3 attached to the operation in detail as follows.

The autofocus method proposed in the present invention is applied to an optical unit [Fig. 1] consisting of a distance measuring sensor 106 and an LED for illumination at different positions.

The distance measuring unit 201 measures the distance between the camera 104 and the user every predetermined time period (for example, 50 ms) using infrared rays, and the operation characteristic determination unit 202 inputs the distance measuring unit 201 from the distance measuring unit 201. The operation characteristic of the user is determined using continuous distance information.

For example, the operation characteristic determination unit 202 measures the operation speed based on the continuous distance information, and finds out whether the user is approaching, moving away, or stopped to confirm his / her identity. . In other words, if the speed is positive, it is determined that it is approaching, if it is negative, it is determined that it is moving away, and if the absolute speed is within a given value, it is assumed that it is stopped.

The camera motion controller 203 receives information such as distance, speed, and acceleration from the motion characteristic determiner 202 and controls the operation of the camera 104 when it is determined that the user is stopped as described above.

When the user starts to move the camera 104 when it is judged to be stopped in this way, the zoom and focus of the camera 104 must be moved from the previous position to the current position, so the distance to be moved is increased so much time to focus. This takes

In consideration of this, when the user's motion is not stabilized, when the user determines the stopping position in advance and moves the camera 104 to the position in advance, the distance to be moved is shortened so that the speed can be improved. .

Determination of the position where the user will stop can be easily known by obtaining the speed and acceleration, and it is possible to predict where the user will stop at what time.

When the user's motion is stabilized, the zoom and focus of the camera 104 are adjusted through the camera motion controller 203 based on the measured distance value. At this time, the user continues to move to some extent, the measured distance value is not the distance to the actual eye 301, and there is a certain measurement error, so fine adjustment should be performed.

To this end, the camera motion control unit 203 analyzes the iris images continuously input from the image processing unit 204 to obtain the focus level. That is, the maximum value while moving the lens until the focus level is suitable for performing the verification. Continue tracking in the direction of this.

In order to always obtain the same size of the iris image, not only the focus lens of the camera 104 but also the zoom lens should be operated together. Therefore, the position of the zoom lens corresponding to the distance and the position of the focus lens are prepared in a table form and stored in the memory, and the zoom and focus are adjusted using the position information according to the distance change, which is good for user confirmation. I can get an iris image. Here, how far the distance is to be processed depends on the focusing performance of the camera 104.

When the user wears the glasses 302, reflection may occur in the iris image depending on the angle between the glasses 302 and each of the light emitting diodes 107A to 107C installed in the light emitting diode unit 107. As a result, the iris image is blurred to reduce the focus level. The lower the focus, the more time it takes to focus and the more difficult it is to identify yourself.

Therefore, the image processing unit 204 detects the degree of reflection in advance before calculating the focus degree and outputs the specular reflection information to the illumination control unit 205. The illumination control unit 205 controls the lighting of the light emitting diodes 107A-107C based on the specular reflection information so as to avoid reflection of the spectacles 302.

When the lighting or off state of the light emitting diodes 107A-107C is changed by the lighting control unit 205, the position reflected by the glasses 302 should be changed accordingly.

To this end, when the spectacle surface is perpendicular to the camera 104, the light emitting diodes 107A and 107B are sufficiently wided so that the light reflected from both LEDs 107A and 107B is not inserted into the iris image. Set it. Nevertheless, if the vertical state is not maintained as shown in FIG. 3, the reflected light by the glasses 302 is incident on the camera 104, such as the light emitting diode 107A, according to the inclined angle.

However, in such a case, when the illumination light emitting diode 107A is turned off and the illumination light emitting diode 107B is turned on, the position reflected by the spectacle surface is changed so that the reflected light is not incident on the camera 104. Damage can be prevented.

Since the radius of curvature of the eye 301 is smaller than that of the glasses 302, the reflection of light by the glasses 302 appears large in the image, and the reflection of light by the general eyes 301 appears small. Therefore, when the size of the reflected image is detected, it is possible to distinguish whether the reflection is caused by the eye 301 or the specular surface. Therefore, the autofocus function can be exhibited while avoiding reflection by the glasses 302.

As described in detail above, the present invention is to determine the proximity and stabilization of a person using a distance measuring sensor and analyze the extracted iris image to recognize the fact that wearing glasses in advance so that reflection does not occur in the corresponding position By performing the auto focusing function while turning on the light emitting diode, the checking operation is easily performed, and the inconvenience of removing the glasses to reduce the error rate caused by the glasses is eliminated.

Claims (7)

Determining a motion characteristic of the user based on distance information between the camera and the user; A second step of adjusting a zoom and focus after preliminarily adjusting a moving distance of the camera by predicting an exact position before the user's motion is stabilized; Analysis of the iris image to obtain the degree of focus, and when the size of the reflected image is a certain value or more is determined by the reflection by the foreign matter, the lighting position is changed and fine adjustment after the third process of the iris recognition system, characterized in that How to adjust auto focus. The method of claim 1, wherein in determining the operating characteristics of the user in the first process, when the driving speed of the user is positive, it is determined that the user is approaching, and when it is negative, it is determined that the user is moving away. Automatic focus control method of the iris recognition system, characterized in that judged to be stopped. The method of claim 1, wherein the third process performs fine adjustment using a tabled zoom and focus lens position. Motion characteristic determination means for grasping the motion characteristic of the user based on the distance measurement value between the user and the camera continuously input; Camera operation control means for adjusting a moving distance of the camera corresponding to the distance measurement value and performing an auto focus function; Image processing means for analyzing the extracted iris image and determining the degree of light reflection and wearing of glasses; Automatic focus control device of the iris recognition system comprising a lighting control means for selectively lighting the lighting device suitable for the surrounding situation. The apparatus of claim 4, wherein the distance measurement value between the user and the camera is a value detected at a predetermined period by the infrared sensor for distance measurement. The apparatus of claim 4, wherein the image processing means comprises means for detecting a degree of reflection. The apparatus of claim 4, wherein a plurality of lighting devices are installed and maintain appropriate intervals between the plurality of illumination devices so that the reflected light is not inserted into the iris image.