JP4182581B2 - Iris photography device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an iris photographing apparatus for photographing an iris (iris) of a human eye.
[0002]
[Background]
In recent years, security systems that perform individual recognition using an iris pattern of human eyes have attracted attention. In such a security system, first, an eye of a subject to be personally recognized is illuminated and photographed, and a portion corresponding to an iris is extracted from an eye image signal obtained by the photographing. Next, a feature extraction process is performed on the image signal corresponding to the iris by a Gabor filter or the like to obtain an iris pattern. Next, iris registration or iris collation is executed using the iris pattern.
[0003]
First, in the iris registration, the subject's iris pattern obtained as described above with a label (registrant name, ID number, date, etc.) attached is stored in a storage device. On the other hand, in the iris collation, an iris pattern that is substantially the same as the iris pattern of the subject obtained as described above is searched from the storage device. Here, when substantially the same iris is searched from the storage device, the label attached to the iris pattern is read from the storage device, so that the name of the subject and the personal information such as the ID number are stored. Get it.
[0004]
As described above, in the security system, personal recognition is performed based on the iris pattern obtained by photographing the human eye.
Therefore, it is desired that an iris photographing apparatus for photographing an iris is capable of photographing so that such personal recognition can be performed with high accuracy.
[0005]
[Problems to be solved by the invention]
An object of this invention is to provide the iris imaging device which can perform iris imaging | photography which can perform an individual recognition accurately.
[0006]
[Means for Solving the Problems]
Iris imaging apparatus according to the present invention includes a camera for obtaining an iris image signal by photographing a subject's iris, and a display device for displaying an iris image based on the iris image signal, the size of the pupil portion from within the iris image A means for obtaining, a luminance adjusting means for once decreasing the display luminance of the display device during display of the iris image and then increasing the luminance when the size of the pupil portion is larger than a predetermined value; Means for externally outputting the iris image signal when the size is smaller than a predetermined value.
[0007]
[Action]
In the present invention, when the diameter of the pupil portion of the subject obtained from the photographed iris image signal is larger than a predetermined value, the display brightness of the display device that performs image display based on the iris image signal is temporarily reduced. The diameter of the pupil part is forcibly reduced by increasing after the squeezing, and the iris image signal obtained by photographing as described above is externally output only when the diameter of the pupil part is smaller than a predetermined value. Since it is configured, an iris image larger than a predetermined area is always output to the outside, and an iris pattern with high recognition accuracy can be generated.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a configuration of an iris photographing apparatus according to the present invention.
In FIG. 1, the illumination unit 4 irradiates the iris 6 of the subject's eye with illumination light for photographing. The illumination unit 4 is formed by arranging a plurality of LED elements 4a having peak components in the near infrared region in a matrix. The iris image reflected from the iris 6 of the subject's eye by the illumination light from the illumination unit 4 is led to the half mirror 1 through the protective glass 7.
[0009]
The half mirror 1 reflects the iris image derived via the protective glass 7 and reflects it to the imaging lens (not shown) of the camera 3, while displaying on the display device 2 composed of, for example, a liquid crystal display device. The display image displayed on the surface 2 a is transmitted and led to the protective glass 7. The half mirror 1 is a so-called hot mirror having characteristics as shown in FIG. 2, that is, transmitting visible light, and reflecting 90% or more of light in the near infrared wavelength region (750 nm or more). Therefore, the iris image including a large amount of the near-infrared wavelength region is derived to the photographing lens of the camera 3 as a bright image.
[0010]
The photographing lens of the camera 3 condenses the iris image reflected by the half mirror 1 on a light receiving surface of an imaging element (not shown) of the camera 3. The imaging device generates an image signal corresponding to the iris image formed on the light receiving surface, and uses this as an iris image signal _{IV to each} of the iris photographing control circuit 10, the display device drive circuit 12, and the transmission circuit 13. Supply.
[0011]
In response to the transmission start command signal TX supplied from the iris imaging control circuit 10, the transmission circuit 13 uses, as a transmission iris image signal, one frame of the iris image signal I _V obtained by imaging with the camera 3 at that time. To an iris recognition device (not shown). The iris recognition device extracts the portion corresponding to the iris from the iris image signal _IV and further performs feature extraction processing using a Gabor filter or the like to obtain an iris pattern, which is registered or verified with a registered iris pattern. To do.
[0012]
On the other hand, the display device drive circuit 12 drives the display device 2 to display an image based on the iris image signal _IV supplied from the camera 3 on the display surface 2a. Further, the display device driving circuit 12 turns on or off the backlight 2b of the display device 2 in accordance with the backlight on / off control signal L _ON supplied from the iris photographing control circuit 10. For example, when the backlight on / off control signal L _ON having the logic level “0” is supplied, the display device driving circuit 12 turns off the backlight 2b, and the backlight on / off control signal L _{ON having the} logic level “1”. Is supplied, the backlight 2b is turned on. At this time, when the backlight 2b is turned on, an image corresponding to the iris image signal I _V is displayed on the display surface 2a, and the display image passes through the half mirror 1 and the protective glass 7 and reaches the subject's eyes. In other words, the iris image of the subject photographed by the camera 3 is displayed on the display surface 2 a of the display device 2, which passes through the half mirror 1 and the protective glass 7 and is reflected on the subject's eyes again. The subject monitors the iris image displayed on the display surface 2a of the display device 2 and adjusts the position by moving his / her face so that the iris image comes to the center of the screen. When this position adjustment is completed, the subject presses the switch 14 in order to transmit his / her iris image taken by adjusting the position to the iris recognition device. In response to the pressing operation, the switch 14 generates a transmission request signal _TRQ and supplies it to the iris imaging control circuit 10.
[0013]
The iris imaging control circuit 10 includes, for example, a ROM (Read Only Memory) in which a program that controls operation during iris imaging is stored, a CPU (Central Processing Unit) that executes iris imaging control according to the program, and a RAM (Random Access Memory).
Here, when the transmission request signal T _RQ is supplied from the switch 14, the CPU in the iris imaging control circuit 10 exits the currently executed main flow (not described) and performs the iris imaging shown in FIG. Move on to execution of control routine.
[0014]
In FIG. 3, first, the CPU executes a pupil size calculation routine (step S1). In this pupil size calculation routine, first, a pupil image corresponding to the pupil portion 8 of the subject is extracted from the iris image signal _IV supplied from the camera 3. Next, the size (diameter) of the pupil portion 8 is calculated based on the extracted pupil image, and this is stored in the RAM as the pupil size P _S. When the pupil size P _S is stored in the RAM, the CPU exits the pupil size calculation routine and proceeds to execution of step S2 described below to determine whether or not the pupil size P _S is larger than the predetermined size R. Is determined (step S2).
[0015]
If it is determined in step S2 that the pupil size P _S is larger than the predetermined size R, the CPU generates a backlight on / off control signal L _ON having a logic level “0”, which is displayed on the display device driving circuit 12. (Step S3). The display device drive circuit 12 turns off the backlight 2b of the display device 2 in accordance with the backlight on / off control signal L _ON having the logic level “0”, and lowers the display brightness. Thus, when the backlight 2b is turned off and the display brightness of the display device 2 decreases, the amount of light that reaches the eyes of the subject through the half mirror 1 and the protective glass 7 decreases. The size (diameter) of the pupil part 8 increases, and the area of the iris part 6 decreases accordingly. Next, the CPU supplies a backlight on / off control signal L _ON having a logic level “1” to the display device driving circuit 12 (step S4). The display device drive circuit 12 turns on the backlight 2b of the display device 2 again in response to the backlight on / off control signal L _ON having the logic level “1”, and increases the display brightness. When the backlight 2b of the display device 2 shifts from the off state to the on state and the display brightness increases, the amount of light reaching the eyes of the subject through the half mirror 1 and the protective glass 7 also increases, and this is followed. Thus, the size (diameter) of the pupil part 8 of the subject decreases, and the area of the iris part 6 increases accordingly.
[0016]
After completion of step S4, CPU returns again to the execution of step S1, in step S2 to pupil size P _S is determined not to be larger than a predetermined size R, repeatedly execute the operations as described above To do.
Here, in such a step S2, the pupil size P _S is determined not to be larger than a predetermined size R, CPU sends a transmission start instruction signal TX to the transmission circuit 13 (step S5). In response to the transmission start command signal TX, the transmission circuit 13 uses, as a transmission iris image signal, a still image for one frame of the iris image signal _IV obtained by photographing with the camera 3 at that time as an iris image signal (not shown). Send to the recognition device. That is, only when the pupil size P _S is smaller than the predetermined size R, that is, when the area of the iris portion 6 is larger than the predetermined, the photographed iris image is output to the iris recognition device.
[0017]
After completion of step S5, the CPU exits the iris photographing control routine as shown in FIG. 3 and returns to the execution of the main flow (not described).
Thus, in the iris photographing apparatus according to the present invention, when photographing the subject's iris and outputting it externally, first, the size (diameter) of the pupil portion 8 is obtained from the photographed subject's iris image. At this time, if the size of the pupil portion 8 is larger than the predetermined size R, the display brightness of the display device 2 is once lowered by turning off the backlight 2b, and then the backlight 2b is turned on. By increasing the display brightness, the size of the pupil portion 8 of the subject's eye is forcibly changed to a small size. This is an operation performed in view of the fact that the pupil of the human eye generally becomes smaller when the amount of light changes from a dark state to a bright state. According to such an operation, even when the size of the pupil portion 8 of the subject's eye is larger than the predetermined size R at the beginning of photographing, this can be forcibly reduced. Here, when the size of the pupil portion 8 becomes smaller than the predetermined size R, an iris image signal for one frame obtained by photographing at this time is externally output.
[0018]
That is, the present invention focuses on the fact that the smaller the pupil diameter of the subject's eye, the larger the area of the iris and the higher the recognition accuracy of the iris pattern can be generated. Only when it is small, the iris image signal obtained by photographing at this time is externally output. At this time, even if the diameter of the pupil of the subject's eye is larger than a predetermined value, the display brightness of the display device is once reduced and then increased to forcibly increase the diameter of the subject's eye pupil. I try to make it smaller.
[0019]
Therefore, according to the iris photographing apparatus according to the present invention, it is possible to always output only an iris image larger than a predetermined area (send to the iris recognition apparatus), so that it is possible to generate an iris pattern with high recognition accuracy. .
In the above embodiment, in order to forcibly reduce the pupil of the subject's eyes, the backlight 2b of the display device 2 is turned off and turned on in steps S3 and S4 to lower the display brightness of the display device 2. However, the operation is not limited to such an operation.
[0020]
FIG. 4 is a diagram showing another example of an iris photographing control routine made in view of such points. In FIG. 4, steps S1, S2 and S5 are the same as those shown in FIG.
In the iris imaging control routine shown in FIG. 4, when it is determined in step _S <b> 2 that the pupil size P _S is larger than the predetermined size R, the CPU issues an image signal supply stop command to the display device driving circuit 12. Send out (step S3 '). In response to the image signal supply stop command, the display device driving circuit 12 stops supplying the image signal to the display device 2. As described above, when the supply of the image signal is stopped, the display surface 2a of the display device 2 becomes a pure white screen state with only the backlight for a moment, and the pupil of the eye of the subject becomes small in response to this. Next, the CPU sends an image signal supply restart command to the display device drive circuit 12 (step S4 ′). In response to the image signal supply restart command, the display device drive circuit 12 restarts the supply of image signals to the display device 2 again.
[0021]
In this way, even when the supply of the iris image signal to the display device 2 is temporarily stopped and then restarted, the size of the pupil portion 8 of the subject's eyes can be reduced.
In steps S3 (S3 ′) and S4 (S4 ′), the pupil of the subject's eyes is forcibly changed small by changing the amount of light irradiated to the subject's eyes largely. It is known that the human pupil changes even with a slight change in the amount of light. In short, in steps S3 (S3 ′) and S4 (S4 ′), the display luminance of the display device 2 may be changed to such an extent that the pupil of the subject's eyes changes in the direction of decreasing.
[0022]
In the embodiment shown in FIG. 1, an example of an iris photographing apparatus in which the camera 3 and the display device 2 are integrated is shown. However, the display device 2 is a personal computer (hereinafter referred to as a PC). ) Display may be used.
FIG. 5 is a diagram showing a configuration of an iris photographing apparatus made in view of such points.
The configuration shown in FIG. 5 is not only the display device 2 but also a notebook personal computer (hereinafter referred to as a notebook PC) 20 having the function of the iris recognition device as described above, and a display unit housing of the notebook PC 20. The camera 3, the half mirror 1, the transmission cable 70, and the PC card 80 are attached to the detachable clip 30.
[0023]
A lighting unit 4 is provided on the front surface of the camera 3. Further, a half mirror 1 is attached to the front surface in parallel with the front surface and rotatable about J in the drawing. Here, when the subject views the screen 30a of the notebook PC 20 through the half mirror 1, the iris image of the subject's eye is photographed by the camera 3, and the iris image signal obtained by the photographing is the transmission cable 70 and the PC card. It is taken into the notebook PC 20 through 80. The notebook PC 20 displays an iris window 50 as shown in FIG. 4 on the screen 30a, and displays the iris image of the subject captured as described above in the display frame. That is, the screen 30a and the iris window 50 of the notebook PC 20 have the same function as the display device 2 shown in FIG. At this time, the operation of the iris photographing control routine and the iris recognition device shown in FIG. 3 may be executed by the CPU mounted on the notebook PC 20.
[0024]
In the above embodiment, a case where a liquid crystal display device is used as the display device 2 has been described. However, as the display device 2, any display device such as a cathode ray tube display, an electroluminescence display, or a plasma display may be used. good.
[0025]
【The invention's effect】
As described above, in the present invention, the diameter of the pupil portion is obtained from the iris image signal obtained by photographing the subject's iris, and when this is larger than a predetermined value, the display based on the iris image signal is performed. Iris image signal obtained by the above imaging only when the diameter of the pupil is forcibly reduced by decreasing the display brightness of the device and then increasing it, and the diameter of the pupil is smaller than a predetermined value Is output externally.
[0026]
Therefore, according to the iris photographing apparatus according to the present invention, since only the iris image signal including the iris image larger than the predetermined area is output from the photographed iris image signal, the iris having high recognition accuracy is output. Pattern generation is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an iris photographing apparatus according to the present invention.
FIG. 2 is a diagram showing reflection / transmission characteristics of a half mirror 1;
FIG. 3 is a diagram showing an iris photographing control routine.
FIG. 4 is a diagram showing another example of an iris photographing control routine.
FIG. 5 is a diagram showing a configuration when an iris photographing apparatus according to the present invention is combined with a personal computer.
[Brief description of symbols]
DESCRIPTION OF SYMBOLS 1 Half mirror 2 Display apparatus 2b Backlight 3 Camera 10 Iris photography control circuit 13 Transmission circuit

Claims (3)

A camera that captures the iris of the subject and obtains an iris image signal;
A display device for displaying an iris image based on the iris image signal ;
Means for determining the size of the pupil from the iris image;
A luminance adjusting means for once decreasing the display luminance of the display device during display of the iris image and then increasing it when the size of the pupil part is larger than a predetermined value;
Means for outputting the iris image signal externally when the size of the pupil portion is smaller than a predetermined size. The display device is a liquid crystal display device, and the brightness adjusting means turns off the backlight of the liquid crystal display device once and then turns it on again when the size of the pupil part is larger than a predetermined size. The iris photographing apparatus according to claim 1. A camera that captures the iris of the subject and obtains an iris image signal;
A display device for displaying an iris image based on the iris image signal ;
Means for determining the size of the pupil from the iris image;
Means for temporarily stopping the supply of the iris image signal to the display device when the size of the pupil part is larger than a predetermined value, and supplying the iris image signal again;
Means for outputting the iris image signal externally when the size of the pupil part is smaller than a predetermined size.

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