Falsification discrimination method for iris recognition system

[0002] 1. Field of the Invention

[0003] The present invention relates to a technique for discriminating falsification of an iris image in an iris recognition system and, more particularly, to a falsification discrimination method for an iris recognition system which makes it possible to capture an image of a pupil when changing the position of the light source in order to prevent an intrusion attempt using a photograph or dynamic image, and determine whether the iris is true or false based on the position reflected from the image.

[0004] 2. Description of the Prior Art

[0005] The pupil of a human eye continues contracting and expanding. In a conventional iris recognition system, the contracted and expanded states of the pupil is detected considering such a characteristic of the eye, and, on the basis of the resulting states, falsifications in a continuous image is discriminated.

[0006] However, in order to detect the contracted and expanded states of the pupil in this manner, a series of steps of finding the position of the pupil and obtaining the radius must be performed repeatedly, so that it takes much time for detection and it is difficult to performing an accurate detection.

[0007] Reference is made to U.S. Pat. No. 4,641,349 “Iris Recognition system”, U.S. Pat. No. 5,291,560 “Biometric Personal identification System base on Iris Analysis, and U.S. Pat. No. 5,572,596 “Automated Non-Invasive iris Recognition System and Method.

[0008] However, in these conventional iris recognition systems, they are constructed in such a manner that it is determined whether the iris is true or false based on the contracted and expanded states of the pupil. Thus, it takes much time for detection and it is difficult to performing an accurate detection. In addition, when a dynamic image in place of a photograph is illuminated continuously, the size of the pupil varies according to the time, thereby making it difficult to discriminate a falsification.

[0009] Accordingly, it is an object of the present invention to provide a falsification discrimination method for an iris recognition system which is capable of analyzing an iris image while changing the position of the light source in a system having many light sources used for a lighting apparatus, and determining whether the iris is true or false based on the reflected position.

[0010] Additional advantages, objects and features of the invention will become more apparent from the description which follows.

[0011] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

[0012] FIG. 1 is a block diagram of an iris recognition system to which a falsification discrimination method in accordance with the present invention is applied;

[0013] FIG. 2 is an illustration of a captured iris image;

[0014] FIG. 3 is an embodiment of a signal flow chart showing a falsification discrimination method in accordance with the present invention;

[0015] FIG. 4 is another embodiment of a signal flow chart showing a falsification discrimination method in accordance with the present invention.

[0016] A preferred embodiment of a falsification discrimination method for an iris recognition system to achieve the object of the present invention comprises a first step(S1 and S2) of imaging an eye of an user when the user approaches a field of view, processing the image signal, and determining whether or not the image is precisely focused, a second step(S3-S8) of selectively lighting LEDs for lighting installed on the both sides of a camera while imaging the eye of the user and detecting the reflected image of a corresponding LED in the image of the iris and pupil, a third step(S9 and S10) of determining that the iris is a falsification and informing the system of the fact if the reflected image of the corresponding LED is not detected in the above steps, and a fourth step(S11, S12, and S13) of determining whether the image is data registered in a database if the reflected image is detected, and informing the system of the confirmation of a living iris if the iris is really recognized or informing the system of the rejection of a non-living iris if the iris is not really recognized.

[0017] Another preferred embodiment of a falsification discrimination method for an iris recognition system to achieve the object of the present invention comprises a first step(S1 and S2) of imaging an eye of the user when the user approaches the field of view, processing the image signal, and capturing the image of the iris and pupil, a second step(S3-S8) of selectively lighting LEDs for lighting installed on the both sides of a camera while imaging the eye of the user and detecting the reflected image of a corresponding LED in the image of the iris and pupil, a third step(S9 and S10) of determining that the iris is a falsification and informing the system of the fact if the reflected image of the corresponding LED is not detected in the above steps, and a fourth step(S11, S12, and S13) of determining whether the image is data registered in a database if the reflected image is detected, and informing the system of the rejection of a non-living iris if the iris is really recognized, and a fourth step(S11, S12, and S13) of determining again whether is the iris is a falsification if the iris is really recognized in the above steps and informing the system of the fact if the iris is a falsification or informing the system of the confirmation of a living iris if the iris is not a falsification.

[0018] FIG. 1 is a block diagram of an iris recognition system to which a falsification discrimination method in accordance with the present invention is applied. As shown therein, the iris recognition system comprises a camera 2 for imaging the eye 1 of a person attempting to be recognized; an iris image processing unit 3 for capturing the image of the iris and pupil by processing an output image signal of the camera 2, outputting a lighting control signal of light emitting diodes LED_L and LED_R while confirming whether a LED image is presented on a corresponding image in the pupil image, and determining whether the iris image is true or false; a light emitting diode drive unit 4 for lighting the light emitting diodes LED_L and LED_R for lighting installed at the right and left sides of the camera 1 from the eye 1 according to the lighting control signal; a distance measurement unit 5 for measuring the distance from the camera 2 to the eye 1 utilizing infrared light; an iris recognition unit 6 for performing an iris recognition process using a database when it is confirmed that the iris is imaged as the result of the comparison; and an informing unit 7 for informing the system of iris recognition and falsification.

[0019] The operation of the present invention thusly constructed will be described in detail as follows with reference to FIGS. 2 and 3.

[0020] The distance measurement unit 5 transmits infrared light to the front of the camera 2, and determining whether the user approaches the field of view on the basis of the infrared light incident which is reflected by the user. S1

[0021] In the above step, if it 1 confirmed that the user approaches the field of view, the eye 1 of the user is imaged by performing the zooming or focus control function while measuring the distance between the user and the camera 2 by the distance measurement unit 5. S2

[0022] The iris image processing unit 3 captures the image of the iris and pupil by processing the output image signal of the camera 2. At this time, as an example of light emitting diode at one side, the light emitting diode (e.g., LED_L) installed at the left side of the camera 2 from the eye 1 is lighted by the light emitting drive unit 4, and the reflected image of the light emitting diode LED_L is confirmed in the image of the iris and pupil. S3-S5

[0023] Similarly, the light emitting diode LED_R installed at the opposite side of the light emitting diode LED_L is lighted, and the reflected image of the light emitting diode LED_R is confirmed in the image of the iris and pupil. S6-S8

[0024] The reason why the light emitting diodes LED_L and LED_R are lighted and the reflected images of the same are detected is in order to determine the iris of a living eye 1 is imaged when the image captured by the iris image processing unit 3 as shown in FIG. 2,

[0025] That is, the reflected image of the light emitting diode LED_L at the left side and the light emitting diode LED_R at the right side in the image captured by the iris image processing unit 3 are presented on the pupil 9, respectively.

[0026] However, in the case that a photograph is taken or a dynamic image is utilized for falsification purposes, the reflected images of the light emitting diodes LED_L and LED_R are not presented on the pupil 9.

[0027] Therefore, the iris image processing unit 3 lights the left side light emitting diode LED_L, the right side light emitting diode LED_R, or both diodes as described in the above. At this time, it is determined whether the iris is true or false by confirming if the reflected image is presented on a corresponding position as above. If the iris is proven to be false, the fact is informed by the informing unit 7. S9-S10

[0028] And, it is determined whether the iris is one registered in a database in step 11, the confirmation of a living iris is informed by the informing unit 7 in the case that the iris is proven to be really recognized in step 13, and if the iris is not really recognized, it is determined that the iris is not one registered in the database, whereby an admission rejection is informed by the informing unit 7.

[0029] FIG. 4 has the same steps from S1 to S8 as FIG. 3, and comprises the steps of determining whether the iris is one registered in the database in step 9, informing the system of the rejection if the iris is really recognized in step 10, determining again whether the iris is a falsification if the iris is not really recognized in step 11, and informing the system of the fact if it is a falsification in step 12 or informing the system of the confirmation if it is not a falsification in step 13.

[0030] As explained above in detail, the present invention has the effect of preventing an illegal intrusion using a photograph or dynamic image without fail by determining whether the iris is true or false based on the reflected position of the light source by analyzing the iris image while changing the position of the light source.