CN103440483B - A kind of iris image acquiring device of initiative focusing - Google Patents

Abstract

The invention discloses an active focusing iris image acquisition device. The device is mainly composed of an iris acquisition lens, an infrared light emitting diode, a computer and an opaque cylinder (4), and the iris acquisition lens (8) is fixed on the opaque cylinder (4) On the rear side, the infrared light-emitting diodes are evenly distributed around the iris collection lens (8), rings are fixed up and down on the front side of the opaque cylinder (4), and the rear of the opaque cylinder (4) The upper and lower sides are also fixed with cuboids as scales, and eye-catching rectangular marks are painted on the two scales respectively. The computer (10) is connected to the iris acquisition lens (8), trigger switch (9) and buzzer ( 11) Connected. The invention can effectively overcome the problems of hidden dangers in sanitation, high equipment price, difficulty in positioning the iris within the optimal imaging distance range of the lens, and long time for obtaining clear iris images.

Description

An active focusing iris image acquisition device

technical field

The invention relates to an iris image acquisition device, more specifically, the invention relates to an iris image acquisition device with active and fast focusing.

Background technique

As one of the biometric technologies for identification, iris recognition technology has been widely recognized by scholars from all over the world for its stability, non-contact, security and uniqueness. The clarity of the iris image directly affects the effects of iris positioning, feature matching, and feature recognition, and is a key factor affecting the use of iris features for identity recognition. In order to ensure the collection of clear iris images, various iris image acquisition systems have emerged at home and abroad. According to the types of positioning aids, there are mainly contact positioning aids and non-contact positioning aids.

The contact positioning aid only needs to fix a cylindrical cavity in front of the lens, where the length of the cylindrical cavity is the optimal imaging distance of the lens. The contact positioning auxiliary device is low in cost, simple in method, and accurate in positioning. However, every time the iris is collected, the collector needs to be in contact with the auxiliary device, especially when the iris is collected by multiple people, which brings hidden dangers in hygiene. The non-contact positioning auxiliary device avoids the deficiencies in health hazards, is convenient to use, and has accurate positioning. However, the existing non-contact positioning auxiliary device has high equipment prices, and it is difficult to position the iris within the optimal imaging distance of the lens. Deficiencies in obtaining a clear iris image for a long time and so on. The non-contact positioning aids that have appeared mainly include:

1. Use ranging sensors, stepping motors and other equipment to realize the autofocus function of the lens on the iris. This type of device first measures the distance between the lens and the captured eye through the ranging sensor. If the distance is not the optimal imaging distance of the lens, then the distance between the lens and the captured eye is adjusted by using the forward and backward movement of the stepping motor. The distance is finally realized as the optimal imaging distance of the lens. When collecting iris each time, it must be ensured that the distance measured by the ranging sensor is the distance between the lens and the eye to be collected. This type of device can realize automatic positioning function and is easy to use. However, during the collection process, the position of the collected eyes of the collector is very high, and the collector needs to rely on experience or under the guidance of others to ensure that the collected eyes can be detected by the distance sensor. Measure the distance to the lens; due to the lack of subjective control of the device by the collector, during the collection process, the collector is prone to blink, close the eyes, tilt the head and other situations that are not conducive to collecting a complete iris image; high-precision The price of distance measuring sensor and stepper motor is expensive, which is also the shortcoming of this type of device.

2. Use monitors and other equipment to realize the feedback function, provide users with real-time collected iris image information, and prompt users whether to collect iris images that meet the requirements of location and clarity. This type of device ensures that the collector can see the position and clarity of the collected eyes in real time. When the eye position is correct and the iris clarity meets the requirements, the iris collection will start. Since the collector has subjective control over the device, it is possible to avoid blinking, closing eyes, tilting the head and other situations that are not conducive to the collection of a complete iris image. However, only using monitors and other equipment to determine the optimal imaging distance of a lens cannot Realizing the determination of the imaging distance range of the lens increases the difficulty for the collector to determine the position of the captured eye; when the collector determines the position of the captured eye through monitors and other equipment, due to the lack of reference objects, it is necessary to constantly adjust the position of the captured eye until It is displayed on the monitor, and then adjusted accordingly through the feedback of the collected eye position information in the monitor, which increases the iris acquisition time; the display and other equipment also increase the cost of the iris image acquisition device.

3. Use the lens motor to drive the lens to move forward and backward or the collector to move by itself, collect a series of iris images in real time, and use the quality evaluation algorithm to evaluate the quality of the collected iris images until the iris image that meets the definition requirements is found until. This type of device can ensure that clear iris images that meet the requirements are collected, but it is necessary to evaluate the quality of a series of collected iris images separately, and finally select the iris images that meet the requirements, which is time-consuming.

The different combinations of the above different types of non-contact positioning auxiliary devices constitute new auxiliary devices that fail to offset the deficiencies of the original respective auxiliary devices.

Contents of the invention

The invention utilizes an opaque cylinder, a ring, a ruler, a lens, an infrared light-emitting diode, a trigger switch, a buzzer and a computer to form an iris collection device. Use the ring and ruler to realize the initiative of the collected eyes of the collector to find the best imaging range of the lens, press the trigger switch by the collector to start the iris image collection work, and store the image in the computer, and use the buzzer to realize Notify the collector that the iris image has been collected. The active focusing iris image acquisition device and method of the present invention realizes no health and safety hazards, low equipment cost, simple method, high focusing accuracy, short iris acquisition time, and the collector can actively control the iris Collect time to avoid blinking and other behaviors, easy to implement and other advantages.

The technical problem to be solved by the present invention is to overcome the hidden dangers of sanitation existing in the prior art, the high price of auxiliary equipment, the difficulty in finding the imaging distance range of the lens, and the long iris collection time, and provide an iris image collection with active focus device.

In order to solve the above-mentioned technical problems, the present invention is realized by adopting the following technical solutions, which are described as follows in conjunction with the accompanying drawings:

An active focusing iris image acquisition device, mainly composed of an iris acquisition lens, an infrared light-emitting diode, a computer and an opaque cylinder 4, the iris acquisition lens 8 is fixed on the rear side of the opaque cylinder 4, and the iris acquisition lens 8 has an optical axis It coincides with the center line of the opaque cylinder 4; the infrared light-emitting diodes are evenly distributed around the iris collection lens 8 according to the actual iris collection situation, and the number of infrared light-emitting diodes is at least 4; above the front side of the opaque cylinder 4 A ring I2 and a ring II3 are respectively fixed at the fixed point p and the lower fixed point k, |pk|=2R, and the planes of the two rings are on the same plane as the front side of the opaque cylinder 4; the opaque cylinder The upper and lower sides of the rear side of 4 are respectively fixed with cuboids as scale I6 and scale II13, and the two scales are parallel to the straight line pk, which is the connection line between the upper and lower points p and k on the front side of the opaque cylinder 4. The two scales Eye-catching mark I5 and mark II14 are respectively painted on it to ensure that the mark is easy to be seen by the collector through the ring; the computer 10 is connected to the iris collection lens 8, the trigger switch 9 and the buzzer 11 respectively through USB cables, The iris acquisition lens 8 is triggered by the trigger switch 9 to start taking pictures, and the lens sends the captured eye image to the computer and the buzzer sounds.

The length L of the opaque cylinder 4 should satisfy the relational expression, L<m to avoid contact between the eyes and the opaque cylinder 4, where m is the distance between the optical center o of the iris collection lens 8 and point b, where b is the distance between the lens and the iris The closest point in the imaging distance range.

In order to prevent the iris collection lens 8 from capturing the inner wall of the opaque cylinder 4 and increase the calculation amount of the subsequent iris recognition algorithm, the radius R of the opaque cylinder 4 should satisfy the relation It is the angle between the central axis 1 and the straight line od or straight line oc.

According to the iris image collected by the lens between the optical centers o and b of the iris acquisition lens 8, the recognition rate requirement of the follow-up iris recognition algorithm cannot be satisfied, and the closest point b of the imaging distance range of the lens to the iris is determined; The distance between the optical center o of the acquisition lens 8 is greater than the distance between the optical center and point a. The iris image collected by the iris acquisition lens 8 cannot meet the recognition rate requirements of the subsequent iris recognition algorithm. It is determined that the imaging distance range of the lens for the iris is the farthest Point a: According to the parameters given by the lens, determine the wide angle of the iris acquisition lens as , the distance between the lens optical center o and the closest point b is measured as m, and the distance from the farthest point a is m+2n.

The radius r of the ring I2 and the ring II3 and the length of the mark I5 are determined by the following formula:

Point z is the midpoint of line segment ab and line segment cd, cd⊥ab, |ob|=m, |bz|=n, therefore, in Δcoz, The intersection point of straight line acq and scale I6 is e, the intersection point of straight line dbp and scale I6 is f, the intersection point of straight line adt and scale II13 is h, the intersection point of straight line cbk and scale II13 is g, because |cz|=|zd|, |az|=| zb|, so the straight line ac is parallel to the straight line db, so |qp|=|ef|=|cd|, since |qp|=2r, find Therefore, according to the calculation formula Calculate the ring radius r, according to the calculation formula Calculate the length of marker I5.

The position of the mark I5 from the optical center o of the iris collection lens 8 is determined by the following formula:

In Δeao, since |oe|=|oa|×tan∠caz, tan∠caz=|cz|/|az|, |oa|=m+2n,

|az|=n, get Therefore, according to this formula, calculate the position of mark I5 from the optical center o of iris collection lens 8;

The position of the mark II14 from the optical center o of the lens and the length of the mark II14 are determined by the following formula:

In the same way, find out Therefore, according to the formula Find the position of mark Ⅱ14 from the optical center o of the lens; according to the formula Find the length of marker II14.

According to the size of each component, the radius r of the ring I2 and the ring II3 is determined, and a mark I5 is drawn with a striking color at the position oe on the scale I6, and the length is ef, and it is used at the position oh on the scale II13. Draw a mark Ⅱ14 in eye-catching color, the length is gh; the intersection point of straight line eqa and straight line gkb is c, the intersection point of straight line hta and straight line fpb is d, and the area acbd is the imaging distance range of the lens for the iris.

The iris collection device of the present invention connects the lens with the computer through the first USB connection line, connects the trigger switch with the computer through the second USB connection line, and connects the buzzer with the computer through the third USB connection line , consists of an opaque cylinder, two rings, two rulers, two marks, lens, a group of infrared light-emitting diodes, a trigger switch, a computer and a buzzer to form an iris collection device. Using software programming, the trigger switch can be used to trigger the lens to start taking pictures. After the lens transmits the captured eye image to the computer, the buzzer sounds and the sound lasts for three seconds.

Compared with prior art, the beneficial effects of the present invention are:

1. Compared with the existing contact device, the active focusing iris image acquisition device and method of the present invention has the characteristics of no sanitary hazards.

2. Compared with the existing non-contact device that utilizes the distance measuring sensor to realize the fixed focus between the lens and the eyes, the iris image acquisition device and method of a kind of active focusing of the present invention has the advantages of simple device, low cost, Accurate focusing, fast focusing speed, easy to implement, and less unqualified conditions such as acquisition and closed eyes.

3. The iris image acquisition device and method of a kind of active focusing of the present invention have the advantages of low device cost and high success rate of focusing compared with existing devices that utilize display screens and the like to actively position and fix the focus of the eyes. High and fast fixed focus.

4. The iris image acquisition device and method of a kind of active focusing of the present invention are compared with the existing devices that need to take a series of iris images and evaluate the iris image quality by iris quality evaluation algorithm, the device of the present invention can The clear iris image can be collected permanently, and it has the characteristics of fast fixed focus.

5. Compared with the existing automatic focusing iris image acquisition device and method of the present invention and the existing method of automatically collecting iris and using voice prompts to prompt the completion of the collection, the method of the present invention triggers the iris collection lens actively The switch device avoids blinking, closing eyes, and tilting the head during iris collection, which is not conducive to the collection of complete iris images, which is conducive to subsequent iris image processing and speeds up the iris matching speed.

6. According to the present invention, an active focusing iris image collection device and method according to the present invention has low device cost, simple structure, accurate focus, and the process of collecting iris pictures is simple, convenient, fast and clear in steps , saves time and effort, and has a high success rate of collecting clear and complete iris images at one time.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

Fig. 1 is the structural representation of the iris acquisition device adopted in a kind of active focusing iris image acquisition device and method of the present invention;

Fig. 2 is a schematic diagram of auxiliary lines for determining the size of each part of the iris image acquisition device and method in an active focusing iris image acquisition device according to the present invention;

FIG. 3 is a flow chart of the iris image acquisition process in an active focusing iris image acquisition device and method according to the present invention.

In the figure: 1-central axis, 2-circle Ⅰ, 3-circle Ⅱ, 4-opaque cylinder, 5-mark Ⅰ, 6-scale Ⅰ, 7-infrared light-emitting diode Ⅰ, 8-iris collection lens, 9 -trigger switch, 10-computer, 11-buzzer, 12-infrared light-emitting diode Ⅱ, 13-scale Ⅱ, 14-marker Ⅱ

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

1. Build an iris collection device

Referring to Fig. 1, the iris image acquisition device consists of an opaque cylinder, ring 1 and ring 2 with the same radius, scale 1 and scale 2 with equal length, mark 1 on scale 1, mark 2 on scale 2, six Composed of infrared light-emitting diodes, an iris collection lens, a trigger switch, a computer, and a buzzer, the lens is placed on one side of the cylinder, the optical axis of the lens coincides with the central axis of the cylinder, and the other side of the cylinder is used for collection iris image. Six infrared light-emitting diodes with a wavelength of 850nm are used to evenly surround the lens. An opaque white scale is used. The marking color on the scale is red. The opaque cylinder and ring are made of black plastic material to increase the aiming mark through the ring. Comfortable, the width of the inner and outer edges of the ring is 1cm, the lens, buzzer, and trigger switch in the iris collection device are connected to the computer through USB, and the module for controlling the USB port is written using VC++, which can realize the receiving of lens collection Iris image, control buzzer, receive trigger switch status.

2. Determine the size of opaque cylinders, rings, markers, rulers and the effective imaging range of the collected eyes

The length of the opaque cylinder is L and the radius of the cylinder is R. In order to ensure that the eyes are not in contact with the opaque cylinder, the relationship L<m should be satisfied.

In order to prevent the iris acquisition lens from capturing the inner wall of the opaque cylinder and increase the calculation amount of subsequent iris positioning, the relationship should be satisfied

See Figure 2, Wide Angle of Lens Between point a and point b is the clear iris image range that can be collected by the lens, |ob|=m=19cm, |ab|=2n=2cm. The radius of the circle is r, the point p is the fixed point between the circle 1 and the opaque cylinder, the point k is the fixed point between the circle 2 and the opaque cylinder, |pq|=2r, |kt=2r. Point z is the midpoint of line segment ab and line segment cd, cd⊥ab, |ob|=m, |bz|=n, so in Δcoz, The intersection point of straight line acq and scale 1 is e, the intersection point of straight line dbp and scale 1 is f, the intersection point of straight line adt and scale 2 is h, the intersection point of straight line cbk and scale 2 is g, because |cz|=|zd|, |az|=| zb|, so the straight line ac is parallel to the straight line db, so |qp|=|ef|=|cd|, and |qp|=2r, we can get In Δeao,

Since |oe|=|oa|×tan∠caz, tan∠caz=|cz/|az|, |oa|=m+2n, |az|＝n, can find out Similarly, it can be obtained Since R=(mL)×tan(∠pbo), ∠pbo=∠caz, we can find |ef| is the length of marker 1, |gh| is the length of marker 2, H1 is the length of scale 1, and H2 is the length of scale 2.

Let m=19cm, n=1cm, The following results can be obtained:

|gh|=16.56cm, |oh|=173.88cm, H1=174cm, H2=174cm.

The area where the lens can capture the effective iris image, that is, the area of the rhombus acbd is

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 16.56</span>}{\mathrm{<span\; class="notranslate">\; cm</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; .</span>$

Since L should satisfy the relation: L<m, R should satisfy the relation: That is, R≥0.414L,

combine Available

L≤18.095, R, L value relationship is shown in Table 1.

Table 1 Corresponding relationship between R value and L value Unit: cm

The larger the value of L, the closer the eyes are to the opaque cylinder during iris collection. If the distance is too close, it will increase people's discomfort. Since m=19cm, we set the maximum value of L to be 15cm. In this embodiment, L is randomly selected. =13cm, the radius R=49.68cm of the opaque cylinder can be drawn from Table 1.

In order to increase the degree of recognition, the color of scale 1 and scale 2 is selected as white, and the color of mark 1 and mark 2 is selected as red. In the area composed of point a, point c, point b, and point d, the collector can see mark 1 through ring 1 and mark 2 through ring 2 through the collected eyes. At the same time, in this area , the lens can capture a clear iris image that meets the requirements, that is, as long as the collector sees the marks 1 and 2 through the collected eyes through the ring 1 and the ring 2 at the same time, it indicates that the tested eye is in the area acbd, and it can be A clear iris picture that meets the requirements is collected by the lens.

In summary, the dimensions of the components of the iris collection device are as follows: the radius of the opaque cylinder is 49.68cm, and the length is 13cm; the radius of the ring is 8.28cm, and the width of the inner and outer edges is 1cm; The distance from the highest point to the optical center is 173.88cm.

3. Iris collection process.

Referring to Figure 3, the collector adjusts the position between the iris collection device and the collected eye according to his own height and the comfort of aiming at the mark through the ring. When seeing mark 1 and mark 2 at the same time, it indicates that the eye is in the best area Inside, prepare to press the trigger switch. At this time, the collector should ensure the stability of the iris collection device, and at the same time, be careful not to blink, close the eyes, tilt the head and other actions that affect the iris image collection. After pressing the trigger switch, wait for the iris image Collecting, when the buzzer sounds, it reminds the collector that after the iris image collection is completed, the collector can leave. The process of collecting iris images by the lens is at the millisecond level, so the process from when the collector presses the trigger switch to when the iris image is collected is very short and will not bring discomfort to the collector.

Claims (1)

1. An active focusing iris image acquisition device, mainly composed of an iris acquisition lens, an infrared light emitting diode, a computer and an opaque cylinder (4), the optical axis of the iris acquisition lens (8) and the opaque cylinder (4) The center lines coincide; the infrared light-emitting diodes are evenly distributed around the iris collection lens (8) according to the actual iris collection situation, and the number of infrared light-emitting diodes is at least 4; the computer (10) is connected to the iris via a USB connection line The acquisition lens (8), the trigger switch (9) and the buzzer (11) are connected, the iris acquisition lens (8) is triggered by the trigger switch (9) to start taking pictures, the lens transmits the captured eye image to the computer and the buzzer sounds The device sounds; it is characterized in that: The iris collection lens (8) is fixed on the rear side of the opaque cylinder (4), and the upper fixed point p and the lower fixed point k on the front side of the opaque cylinder (4) are respectively fixed with a ring I (2) and ring II (3), |pk|=2R, the planes of the two rings are on the same plane as the front side of the opaque cylinder (4); the upper and lower sides of the opaque cylinder (4) are respectively A cuboid is fixed as the scale I (6) and scale II (13), and the two scales are parallel to the straight line pk, the straight line pk is the line connecting the upper and lower points p and k on the front side of the opaque cylinder (4), on the two scales Eye-catching marks I (5) and marks II (14) are respectively painted to ensure that marks I (5) and marks II (14) are easily seen by collectors through rings I (2) and rings II (3); The length L of the opaque cylinder (4) should satisfy the relational expression, L<m to avoid contact between the eyes and the opaque cylinder (4), where m is the distance between the optical center o of the iris collection lens (8) and point b, wherein b is the closest point of the imaging distance range of the lens to the iris; In order to prevent the iris acquisition lens (8) from photographing the inner wall of the opaque cylinder (4) and increase the calculation amount of the subsequent iris recognition algorithm, the radius R of the opaque cylinder (4) should satisfy the relation is the angle between the central axis (1) and the straight line od or straight line oc; According to the iris image collected by the lens between the optical center o and b of the iris acquisition lens (8), the recognition rate requirement of the follow-up iris recognition algorithm cannot be satisfied, and the closest point b of the imaging distance range of the iris is determined by the lens; If the distance from the optical center o of the iris acquisition lens (8) is greater than the distance between the optical center and point a, the iris image collected by the iris acquisition lens (8) cannot meet the recognition rate requirements of the subsequent iris recognition algorithm. The farthest point a of the imaging distance range; according to the parameters given by the lens, determine the wide angle of the iris acquisition lens as Measure the distance between the lens optical center o and the closest point b as m, and the distance from the farthest point a as m+2n; The radius r of the ring I (2) and the ring II (3) and the length of the mark I (5) are determined by the following formula: Point z is the midpoint of line segment ab and line segment cd, cd⊥ab, |ob|=m, |bz|=n, therefore, in Δcoz, The intersection point of straight line acq and scale I (6) is e, the intersection point of straight line dbp and scale I (6) is f, the intersection point of straight line adt and scale II (13) is h, the intersection point of straight line cbk and scale II (13) is g, because| cz|=|zd|, |az|=|zb|, so the straight line ac is parallel to the straight line db, so |qp|=|ef|=|cd|, since |qp|=2r, find Therefore, according to the calculation formula Calculate the ring radius r, according to the calculation formula Calculate the length of mark I (5); The position of the mark I (5) from the optical center o of the iris collection lens (8) is determined by the following formula: In Δeao, since |oe|=|oa|×tan∠caz, tan∠caz=|cz|/|az|, |oa|=m+2n, |az|=n, get Therefore, according to this formula, the position of mark I (5) from the optical center o of the iris collection lens (8) is obtained; The position of the mark II (14) from the optical center o of the lens and the length of the mark II (14) are determined by the following formula: In the same way, find out Therefore, according to the formula Find the position of mark II (14) from the optical center o of the lens; according to the formula Find the length of mark II(14); According to the size of each component, the radius r of the ring I (2) and the ring II (3) is determined, and a mark I (5) is drawn with a striking color at the position oe on the scale I (6), and the length is ef, draw a mark II (14) with an eye-catching color at the position oh on the scale II (13), and the length is gh; the intersection point of straight line eqa and straight line gkb is c, the intersection point of straight line hta and straight line fpb is d, and the area acbd is The imaging distance range of the lens for the iris.