JP2006318374A - Glasses determination device, authentication device, and glasses determination method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glasses determination device and the like capable of precisely determining reflection light, which is reflected in an eye image by glasses, with a few restrictions on lighting light. <P>SOLUTION: A glasses determination part 31 is provided with a histogram generation part 311 generating a histogram about a luminance value of the eye image, a histogram memory 312 storing the generated histogram, a first comparison part 313 finding a difference between a frequency of each luminance value and a frequency of a luminance value smaller than that by one about the generated histogram for comparing dimension relationship between the difference and a first threshold value, a second comparison part 314 finding a difference between a frequency of each luminance value and a frequency of a luminance value smaller than that by one about the generated histogram for comparing dimension relationship between the difference and a second threshold value, and a determination part 315 determining whether the reflection light by the glasses is included in the eye image or not from the comparison result by the first and second comparison parts 313 and 314. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spectacles discrimination device, an authentication device, and a spectacles discrimination method.

  In recent years, as a method of personal authentication at the time of access in devices that require high security such as entry / exit management devices and information devices storing important information such as personal information, human fingerprints, irises, fundus blood vessels, facial Various authentication methods using so-called biometric information unique to a subject, such as features, blood vessel patterns such as arms and hands, have been put into practical use.

  As one of them, an authentication method using the difference in eyelid pattern of the iris portion of the eye (hereinafter, this authentication method is referred to as “iris authentication method”) has been proposed and put into practical use.

  In this iris authentication method, the eye of the subject and its surroundings are illuminated with near-infrared illumination or the like, and an image of an area including the eye of the subject (hereinafter referred to as “eye image”) is captured using a camera. Then, extract the iris region from the obtained eye image and create authentication information that is coded so that the difference in the eyelid pattern of the iris part is expressed as numerical information, and this authentication information is pre-registered authentication information (Hereinafter referred to as “registered authentication information”) and comparison. As a result of the comparison and collation, when it is determined that they match each other, the subject is authenticated as a person who has been registered in advance (see, for example, Patent Document 1). In addition, since the iris image can obtain the clearest image in the near-infrared wavelength region, many of the devices that capture the eye image used at this time have a visible light cut filter attached to the lens.

  This iris authentication method has been widely put into practical use as an authentication method in places where high reliability such as a low identity rejection rate and a low acceptance rate for others and high security is required, and has demonstrated excellent effects.

  On the other hand, in an authentication apparatus that performs personal authentication by the iris authentication method as described above, an eye image that can be authenticated by the authentication apparatus, that is, an eye image in which the iris of the subject is clearly captured at an appropriate position and in an appropriate size is obtained. Must be incorporated into the authentication device. For example, when a subject wears glasses, illumination light or external light is reflected on the surface of the glasses and reflected in the eye image, and part or all of the iris in the eye image is hidden by the reflected light. In such a case, a clear iris image may not be obtained, and the iris may not be encoded properly.

  Therefore, the luminance value in the photographed eye image is compared with the threshold value, and if the area of the luminance value larger than the threshold value is equal to or larger than the predetermined value, it is determined that the reflected light from the glasses is reflected in the eye image. Have been proposed (see, for example, Patent Document 2 and Patent Document 3).

  As the reflected light reflected in the eye image, there is light reflected by the surface of the subject's skin, in addition to that by the glasses. Since the reflected light from the skin surface varies greatly depending on the state of the skin, the reflected light from the skin may be reflected in the eye image as reflected light having a high luminance value depending on the subject. Such reflected light from the skin surface is not a problem because it does not hide the iris unlike reflected light from glasses.

  However, in the above-described method, since the area of the luminance value larger than the threshold value is detected and the determination of the spectacle reflection is performed, when the luminance value of the reflected light by the skin is high, Even an eye image that cannot be discriminated and actually has no problem may be erroneously discriminated as an eye image that cannot be used for authentication.

  Therefore, in Patent Document 3 (paragraph numbers 0025 to 0029, FIG. 8), in addition to the above-described method, the luminance greater than the threshold value in the eye image taken to distinguish the reflection from the glasses and the reflection from the skin is further disclosed. A method of detecting the area of the value, detecting a histogram of luminance in the Y-axis direction of the photographed eye image, and analyzing it is also disclosed.

Note that the histogram is a graph representing the distribution of image brightness. Generally, the X-axis is the luminance value, and the Y-axis is the cumulative frequency (the number of appearances of the pixel. ")". Hereinafter, in this specification, a histogram is used as this general histogram. However, in the histogram described in Patent Document 3, the Y axis has a Y axis in an eye image, and the X axis has a luminance value equal to or greater than a threshold value. This represents the number of appearances of a pixel, which is slightly different from a general histogram.
Japanese Patent No. 3307936 JP 2003-308522 A JP 2001-167284 A

  However, in the method described in Patent Document 3, the determination result may vary greatly depending on the shape of the reflected light on the spectacle surface. For example, if the shape of the reflected light on the spectacle surface is a specific shape such as a rectangle, the distribution of the luminance histogram in the Y-axis direction in the photographed eye image changes sharply, so that the spectacle reflection and the skin reflection are distinguished. And get the expected results. However, if the shape of the reflected light on the spectacle surface is a shape other than those described above, for example, a circle or the like, the distribution of the luminance histogram in the Y-axis direction of the photographed eye image does not change steeply. The skin reflex cannot be distinguished well.

  And in order to make the shape of the reflected light on the spectacle surface rectangular, it is necessary to illuminate the illumination light by making the shape of the light source light rectangular, etc. It cannot be used as it is as a light source.

  The present invention has been made in view of such problems, and there are few restrictions on illumination light, and it is possible to discriminate reflected light from glasses reflected in an eye image with high accuracy, and reflected light from glasses and glasses. It is an object of the present invention to provide a spectacle discriminating device, an authentication device, and a spectacle discriminating method capable of discriminating and discriminating the reflected light from the eye.

  The glasses discriminating apparatus according to the present invention obtains a histogram relating to a luminance value of an eye image photographed in the photographing unit, an illuminating unit that irradiates illumination light to a region including the subject's eyes, a photographing unit that photographs the eye image of the subject. A histogram unit, a first comparison unit that obtains a difference between a frequency at each luminance value of the histogram and a frequency at a luminance value that is one less than the luminance value, and compares the difference with a first threshold value; A second comparison unit that obtains a difference between the frequency in the luminance value compared in the one comparison unit and the frequency in the luminance value that is one greater than the luminance value, and compares the difference with a second threshold value; And a determination unit for determining whether or not reflected light from the glasses is reflected in the photographed eye image based on the comparison result of the first comparison unit and the comparison result of the second comparison unit. Features.

  With this configuration, it is possible to determine whether or not the reflected light from the glasses is reflected in the eye image from the histogram relating to the luminance value of the photographed eye image.

  In the first comparison unit, a value obtained by subtracting the frequency at a luminance value 1 smaller than the luminance value from the frequency at an arbitrary luminance value in the histogram is larger than the first threshold value, and the second comparison unit. In this case, when the value obtained by subtracting the frequency at the luminance value 1 larger than the luminance value from the frequency at the arbitrary luminance value is larger than the second threshold value, the determination unit includes the glasses in the photographed eye image. It is good also as a structure which judges that the reflected light by is reflected. According to this configuration, with respect to each luminance value of the histogram of the photographed eye image, whether or not the reflected light from the glasses is reflected in the eye image based on the relationship between the respective frequencies and the luminance values before and after that. Can be determined.

  In addition, when the luminance value to be compared in the first comparison unit is the maximum luminance value, the determination unit determines that the reflected light from the glasses is included in the photographed eye image based only on the comparison result of the first comparison unit. It is good also as a structure which judges whether it is reflected. According to this configuration, whether or not the reflected light from the glasses is reflected in the photographed eye image even if the brightness value of the reflected light from the glasses reflected in the photographed eye image is the maximum brightness value. Can be determined.

  In addition, the first comparison unit and the second comparison unit may be configured to perform comparisons for all luminance values that are equal to or greater than the arbitrarily set comparison minimum luminance value. According to this configuration, since the luminance value of the reflected light generated by the glasses is high, the first comparison unit and the second comparison unit perform comparison with a luminance value equal to or higher than the comparison minimum luminance value. The range of luminance values to be performed can be narrowed, and it can be efficiently determined whether or not the reflected light from the spectacles is reflected in the photographed eye image.

  Further, the comparative minimum luminance value may be a value set based on a proportional relationship with the brightness of the illumination light of the illumination unit. According to this configuration, since the comparative minimum luminance value is set based on the brightness of the illumination light of the illumination unit, the value of the comparative minimum luminance value is increased when the brightness of the illumination light of the illumination unit becomes bright. Thus, it is possible to accurately determine whether or not the reflected light from the glasses is reflected in the photographed eye image.

  Further, the authentication device of the present invention performs the authentication process using the iris part of the eye image determined by the eyeglass determination device and the eyeglass determination device that the reflected light from the eyeglasses is not reflected in the photographed eye image. And an authentication processing unit for performing the processing. According to this configuration, it is determined whether or not the reflected light from the glasses is reflected in the photographed eye image, and an authentication process is performed using only the iris portion of the eye image in which the reflected light from the glasses is not reflected. Therefore, it is possible to accurately perform iris authentication.

  Further, the glasses discriminating apparatus may be configured to include a registration unit that registers information relating to the iris of the eye image determined that the reflected light from the glasses is not reflected in the photographed eye image. According to this configuration, it is determined whether or not the reflected light from the glasses is reflected in the photographed eye image, and information about the iris is registered only for the eye image in which the reflected light from the glasses is not reflected. Can do.

  In the eyeglass discrimination method of the present invention, the first step of irradiating illumination light to an area including the subject's eye, the second step of photographing the eye image of the subject, and the luminance of the eye image photographed in the second step A third step for obtaining a histogram relating to the value, a difference between the frequency at each luminance value of the histogram obtained at the third step and the frequency at a luminance value one smaller than the luminance value, and the frequency at the luminance value and the luminance value The fourth step of sequentially obtaining the difference between the frequency at a luminance value that is 1 greater, the difference between the frequency at each luminance value of the histogram obtained at the fourth step and the frequency at a luminance value that is 1 smaller than the luminance value, and the first The frequency at each luminance value of the histogram obtained in the fifth step and the fourth step for comparing the threshold value and the luminance value thereof Based on the sixth step of comparing the difference between the frequency at the luminance value of 1 greater than the second threshold and the second threshold, the comparison result in the fifth step and the comparison result in the sixth step are included in the photographed eye image. And a seventh step of determining whether or not the reflected light from the glasses is reflected.

  According to this method, it is possible to determine whether or not the reflected light from the glasses is reflected in the eye image from the histogram relating to the luminance value of the photographed eye image.

  According to the present invention, there are few restrictions on illumination light, and it is possible to discriminate between reflected light from spectacles reflected in an eye image with high accuracy, and discriminate discrimination between reflected light from skin and reflected light from glasses. It is possible to provide a spectacle discriminating device, an authentication device, and a spectacle discriminating method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
An authentication apparatus according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is an external view showing an outline of an authentication device 1 according to Embodiment 1 of the present invention.

  The authentication device 1 shown in FIG. 1 is for illumination comprising a guide mirror 13 that confirms the position of an eye by a reflected image when a subject captures an eye image of the subject, and a known light emitting element that emits near infrared light. The LED 12 and a lens 21 disposed behind the guiding mirror 13 are provided. The illumination LED 12 includes three pairs of LEDs (light emitting diodes) arranged symmetrically with respect to the optical axis of the lens 21, and the three pairs can be switched to emit light. Then, the authentication device 1 captures an image of an area including the subject's eyes, that is, an eye image by causing any one of the LEDs for illumination 12 to emit light. At this time, in the authentication device 1, it is determined by the glasses discriminating unit 31 described later whether or not the reflected light from the glasses is reflected in the photographed eye image. And when it determines with the reflected light by spectacles being reflected in the image | photographed eye image, the authentication apparatus 1 light-emits LED different from the LED currently light-emitted at that time, and is the illumination light. The eye image is taken again by changing the irradiation angle with respect to the subject. Further, for an eye image that is determined not to have reflected light from the glasses, the authentication apparatus 1 performs iris authentication using the iris portion of the photographed eye image, and determines whether the subject has been registered in advance. And outputs the result as an electrical signal. Alternatively, information regarding the iris portion of the photographed eye image is registered as registration authentication information.

  FIG. 2 is a block diagram showing a configuration of authentication apparatus 1 according to Embodiment 1 of the present invention.

  As shown in FIG. 2, the authentication device 1 uses an eye image capturing device 50 that captures an eye image of a subject, and performs iris authentication processing or iris information registration using the eye image captured by the eye image capturing device 50. And an iris information processing unit 40 to perform.

  The eye image capturing device 50 includes a guide mirror 13, an illumination unit 10 that illuminates a subject, an image capturing unit 20 that captures an eye image, and an image signal processing unit 30 that performs signal processing on an eye image captured by the image capturing unit 20. It has.

  The guide mirror 13 installed in front of the lens 21 is used for a subject to confirm the position of his / her eyes by viewing the reflected image. The guide mirror 13 is formed of a generally known semi-transparent material, and reflects and transmits light at the same time, and part of the transmitted light is input to the photographing unit 20.

  The illumination unit 10 includes an illumination LED 12 made of a known light emitting element such as a light emitting diode that emits near infrared light, and an illumination control unit 11 that performs illumination control of the illumination LED 12. The illumination LED 12 is composed of three pairs of LEDs arranged at different distances from the center of the lens 21 symmetrically with respect to the optical axis of the lens 21, and the irradiation angle to the subject with respect to the optical axis of the lens 21 is different from each other. The illumination light is irradiated so as to illuminate an area including the subject's eyes. The illumination control unit 11 selects any one of the three pairs of LEDs to emit light, and emits light so that the illumination light from the pair of LEDs has a light amount suitable for eye image acquisition. To control. Furthermore, it is possible to switch the LED to emit light.

  The photographing unit 20 includes a lens 21 configured by a generally used fixed focus lens, an imaging element 22 configured by a known element such as a CCD, and a preprocessing unit 23. Near-infrared light emitted from the illumination LED 12 is reflected by the subject's eye and its surroundings, and the reflected light is input to the image sensor 22 through the lens 21. The input incident light is photoelectrically converted by the image sensor 22 and input to the preprocessing unit 23 as an electrical signal. The pre-processing unit 23 extracts an image signal component from the electrical signal input from the image sensor 22 and performs image quality determination regarding contrast, focus, and the like, and performs necessary processing as an image signal such as gain adjustment and the like. The signal is output to the signal processing unit 30. The lens 21 or the image sensor 22 preferably has a configuration having a filter that transmits near-infrared light and cuts visible light.

  The image signal processing unit 30 is configured to determine whether or not the eye image captured by the imaging unit 20 includes reflected light from the glasses, and the position of the pupil is determined from the eye image captured by the imaging unit 20. A pupil detection unit 32 to detect, an eye position determination unit 33 to determine whether or not the pupil detected by the pupil detection unit 32 is in an appropriate position in the eye image, and a result of the eye position determination unit 33 to be photographed And an authentication image acquisition unit 34 that acquires an eye image photographed by the unit 20 as an eye image for authentication or registration.

  The glasses discriminating unit 31 creates a histogram related to the luminance value from the eye image signal output from the preprocessing unit 23. Then, for each luminance value of the histogram, a difference between each frequency and the frequency at a luminance value that is one smaller than the luminance value is obtained, and the difference is compared with a first threshold value. Further, a difference from the frequency at a luminance value that is one greater than the luminance value is obtained, and the difference is compared with a second threshold value. When the difference between them is larger than the first threshold value and the second threshold value, it is determined that the reflected light from the glasses is included in the photographed eye image. The details of this operation will be described later together with a block diagram of the glasses discriminating unit 31. And when it determines with the spectacles discrimination | determination part 31 including the reflected light by spectacles in the image | photographed eye image, it instructs the illumination control part 11 to switch LED to light-emit. In this way, the eye image is captured again by changing the irradiation angle of the illumination light to the subject. In this way, the glasses discriminating unit 31 can determine whether or not the reflected light from the glasses is included in the photographed eye image. The first threshold value and the second threshold value are preferably determined in advance by experiments or the like.

  The pupil detection unit 32 determines the pupil from the eye image signal output from the preprocessing unit 23 when it is determined that the reflected light from the spectacles is not included in the eye image captured by the spectacles determination unit 31. Detect position. As a method for detecting the pupil position from the signal of the eye image, a generally known technique such as a method using template matching or a method using circular integration (Japanese Patent Publication No. 8-504979) may be used. it can.

  The eye position determination unit 33 determines whether or not the position of the pupil detected by the pupil detection unit 32 is at the center position of the eye image, and keeps the pupil at the center position of the eye image for a certain time (for example, 0.5 seconds). About) When a stable detection is possible, a signal to the effect that the eye is placed at an appropriate position is output to the authentication image acquisition unit 34.

  The authentication image acquisition unit 34 receives the signal from the eye position determination unit 33, takes in the signal of the eye image output from the preprocessing unit 23, and uses it as an authentication or registration eye image to the iris information processing unit 40. Output.

  The iris information processing unit 40 registers an iris authentication processing unit 41 that performs iris authentication processing using the eye image captured by the eye image capturing device 50 and iris information of the eye image captured by the eye image capturing device 50. An iris information registration unit 42 for performing the above and a storage unit 43.

  The iris authentication processing unit 41 cuts out the image of the iris region from the authentication eye image output from the image signal processing unit 30, and creates authentication information based on the iris pattern of the iris part. Then, the registered authentication information registered in advance and the authentication information are compared and collated to determine whether or not they match each other, thereby determining whether or not the subject is a registrant.

  The iris information registration unit 42 cuts out an iris region image from the authentication eye image output from the image signal processing unit 30 and creates authentication information based on the iris pattern of the iris part. Then, the authentication information is registered in the storage unit 43 as registration authentication information.

  The storage unit 43 includes a generally known recording device such as a recording device that records information using magnetism or light, or a recording device that uses a semiconductor memory, and stores registration authentication information and the like.

  Note that the iris information processing unit 40 cuts out an iris region image from the authentication eye image output from the image signal processing unit 30, for example, common processing in the iris authentication processing unit 41 and the iris information registration unit 42. A process for creating the authentication information based on the pattern of the wrinkles of the portions may be performed in common. The function of the iris information processing unit 40 can be realized by using a method known so far as described in Patent Document 1 described above, for example.

  As described above, in the authentication device 1 according to Embodiment 1 of the present invention, a histogram relating to the luminance value is obtained from the photographed eye image, and the reflected light from the glasses is not included in the photographed eye image from the histogram. To determine. If it is determined that the reflected light from the glasses is not included in the photographed eye image, authentication information is created from the iris pattern in the photographed eye image and registered as registration authentication information. Or verifying the authentication information with registered authentication information registered in advance to authenticate whether or not the subject is a previously registered person.

  The functions of the image signal processing unit 30, the preprocessing unit 23, the illumination control unit 11, and the iris information processing unit 40 may be realized by hardware, or each function can be realized by software. It may be described and executed by an arithmetic device or the like. When each function is realized by software, it is possible to configure the eye image capturing device 50 and the iris information processing unit 40 using a computer loaded with a program for realizing each of the above functional blocks in the arithmetic device. It becomes.

  Next, a description will be given of differences in histograms regarding luminance values obtained from eye images taken when the subject is wearing glasses and when the subject is not wearing glasses.

  FIG. 3 is a diagram showing a histogram relating to an eye image photographed by the authentication device 1 according to Embodiment 1 of the present invention and a luminance value obtained from the eye image. In FIG. 3, eye images 70 a to 70 c are eye images taken by the authentication device 1, and a graph shown beside the eye images 70 a to 70 c is an accumulation in the luminance value on the X axis and the luminance value on the Y axis. It is a histogram in each eye image expressed as frequency.

  FIG. 3A is a diagram showing an eye image in which the subject is not wearing glasses and the reflected light from the skin surface is not reflected and its histogram, and FIG. FIG. 3C is a diagram showing an eye image in which the reflected light from the skin surface is reflected and a histogram thereof without wearing glasses, and FIG. 3C is a diagram in which the subject wears glasses and the reflected light from the glasses is reflected. It is the figure which showed the eye image and its histogram.

  As shown in FIG. 3A, when no reflected light is reflected in the eye image, even in a histogram obtained therefrom, in a high luminance value region (region indicated by a dotted circle in the drawing). Frequency distribution does not occur.

  On the other hand, as shown in FIG. 3 (b), even if the subject is not wearing glasses, if the reflected light is generated on the skin surface around the subject's eye and is reflected in the eye image, the eye image is displayed. In the histogram obtained from the above, a frequency distribution occurs in a high luminance value region.

  In addition, as shown in FIG. 3C, in an eye image in which the subject is wearing glasses and the reflected light on the surface of the glasses is reflected, the frequency distribution in the high luminance value region is displayed in the histogram obtained from the eye image. Occurs.

  As described above, in FIGS. 3B and 3C in which the reflected light from the glasses and the reflected light from the skin are reflected, a frequency distribution is generated in a high luminance value region in the histogram obtained from the eye image. However, the shape of the frequency distribution differs between an eye image in which reflected light from glasses is reflected and an eye image in which reflected light from skin is reflected.

  As shown in FIG. 3C, in the histogram of the eye image in which the reflected light from the glasses is reflected, an impulse waveform having a peak locally in the high luminance value region and having no frequency distribution in the surrounding luminance values. The distribution waveform is as follows. This is presumably because the spectacle surface is uniform and the illumination light is reflected on the spectacle surface as if it were specularly reflected and reflected in the eye image. On the other hand, as shown in FIG. 3B, the histogram in the eye image in which the reflected light from the skin is reflected has a local peak in the high luminance value region, but a distribution waveform such as an impulse waveform. Rather, the distribution waveform has a smooth continuous frequency distribution in the luminance values around it. This is presumably because the surface of the skin is not uniform like the eyeglass surface and has some irregularities, and the reflected light of the illumination light on the surface contains some irregular reflection components.

  In the present invention, paying attention to the difference in the distribution waveform of the histogram generated by the difference in reflected light, the frequency distribution generated in the high luminance value region has no local peak, and the local peak If the frequency distribution of the surrounding luminance values is not a gentle continuous change, whether the reflected light from the glasses is included in the captured eye image Determine.

  FIG. 4 is an enlarged view of the luminance distribution of the high luminance value region in the histogram relating to the luminance value obtained from the eye image captured by the authentication device 1 according to Embodiment 1 of the present invention. 4A is an enlarged view of a histogram of an eye image in which reflected light from the skin surface is reflected (an enlarged view of a portion surrounded by a broken line in the histogram of FIG. 3B), and FIG. FIG. 4 is an enlarged view of a histogram of an eye image in which light reflected by glasses is reflected (an enlarged view of a portion surrounded by a broken line in the histogram of FIG. 3C). In the luminance value shown on the X axis, the luminance value n is the maximum luminance value.

  As shown in FIGS. 4A and 4B, both the histogram of the eye image in which the reflected light from the skin surface is reflected and the histogram of the eye image in which the reflected light from the glasses are reflected are the frequencies at the luminance value n-3. Has become a peak. As shown in FIG. 4B, in the histogram of the eye image in which the reflected light from the glasses is reflected, the frequency at the luminance value n-2 and the frequency at the luminance value n-4 are small. The value obtained by subtracting the frequency at the luminance value n−2 from the frequency at the luminance value n−2 and the value obtained by subtracting the frequency at the luminance value n−4 from the frequency at the luminance value n−3 are both substantially equal to the frequency at the luminance value n−3. It has become.

  On the other hand, as shown in FIG. 4A, in the histogram of the eye image in which the reflected light from the skin is reflected, the frequency at the luminance value n-2 and the frequency at the luminance value n-4 are shown in FIG. It is larger than the histogram of the eye image in which the reflected light from the glasses is reflected. Therefore, the value obtained by subtracting the frequency at the luminance value n-2 from the frequency at the luminance value n-3 and the value obtained by subtracting the frequency at the luminance value n-4 from the frequency at the luminance value n-3 are both reflected by the spectacles. The value is smaller than the histogram of the reflected eye image.

  That is, the difference between the frequency at one luminance value and the frequency at a luminance value that is 1 smaller than the luminance value, and the difference between the frequency at the luminance value and the frequency at a luminance value that is 1 larger than the luminance value are represented by each luminance of the histogram. If each value is obtained and the obtained difference is compared with each threshold value, if a frequency distribution exists in the high luminance value region of the histogram, it is possible to determine whether it is due to the reflected light from the glasses. It becomes possible. Therefore, in the first embodiment of the present invention, the distribution shape of the frequency distribution in the high luminance value region of the histogram is obtained, and the frequency difference between the luminance values before and after each luminance value is obtained and compared with the threshold value. The determination is made to determine whether the subject is wearing glasses.

  FIG. 5 is a block diagram showing a configuration of the eyeglass determination unit 31 included in the authentication device 1 according to Embodiment 1 of the present invention.

  As shown in FIG. 5, the glasses discriminating unit 31 according to Embodiment 1 of the present invention creates a histogram from the eye image data sent from the preprocessing unit 23, and a histogram creating unit 311 creates the histogram. A histogram memory 312 for storing the histogram data, a first comparison unit 313, a second comparison unit 314, and a determination unit 315.

  The histogram creation unit 311 creates a histogram related to the luminance value based on the eye image data sent from the preprocessing unit 23. At this time, the histogram creating unit 311 may be configured to create the histogram by calculating the frequencies for all the brightness values from the brightness value 0 to the maximum brightness value, but the brightness value of the reflected light from the glasses is high. A configuration may be adopted in which a minimum luminance value is arbitrarily determined and a histogram is created for luminance values equal to or greater than the comparative minimum luminance value. With this configuration, for example, it is possible to reduce the storage capacity of the histogram memory 312 and to shorten the time required for the comparison processing in the first comparison unit 313 and the second comparison unit 314.

  The histogram memory 312 includes a storage device configured by a generally known semiconductor memory, and stores a histogram created by the histogram creation unit 311. Further, the histogram stored in the histogram memory 312 is periodically reset, and then a new histogram is stored. The reset period may be arbitrary, but may be reset at a timing when a new eye image is acquired.

  The first comparison unit 313 calculates a difference between the frequency at each luminance value and the frequency at a luminance value 1 smaller than the luminance value after the histogram generation unit 311 generates a histogram regarding the luminance value of the photographed eye image. The magnitude relationship between the difference and the first threshold value is obtained.

  The second comparison unit 314 calculates the difference between the frequency at each luminance value and the frequency at a luminance value that is one greater than the luminance value after the histogram generation unit 311 generates a histogram regarding the luminance value of the photographed eye image. The magnitude relationship between the difference and the second threshold value is obtained.

  The first comparison unit 313 and the second comparison unit 314 increase the luminance value one by one from the lowest luminance value in the created histogram, and perform the above-described comparison for each luminance value. However, since the luminance value of the reflected light from the glasses is high, a comparative minimum luminance value may be arbitrarily determined, and the above-described comparison may be performed for luminance values that are equal to or higher than the comparative minimum luminance value. By doing so, it is possible to reduce the amount of memory used and the time required for processing. Further, if the comparative minimum luminance value is a variable value that can be changed based on the emission luminance of the illumination light, the accuracy of the processing at this time can be further improved.

  The determination unit 315 determines whether reflected light from the glasses is included in the photographed eye image from the comparison results in the first comparison unit 313 and the second comparison unit 314. If a difference is larger than the first threshold value in the comparison by the first comparison unit 313 and the difference is larger than the second threshold value in the comparison by the second comparison unit 314 at a certain luminance value. The determination unit 315 determines that the reflected light from the glasses is included in the photographed eye image. Note that the determination unit 315 determines only by the result of the first comparison unit 313 because there is no luminance value larger than the luminance value at the maximum luminance value.

  FIG. 6 is a flowchart showing the operation of the authentication device 1 according to the first embodiment of the present invention. First, the subject positions the face in front of the authentication device 1 and performs eye alignment while looking at the guide mirror 13, and then the authentication operation or registration operation is performed by inputting an authentication start instruction or a registration start instruction. Is started (S11). Then, the illumination control unit 11 causes any one of the LEDs for illumination 12 to emit light, and the imaging unit 20 captures an eye image of the subject irradiated with illumination light from the illumination LED 12 (S12).

  The pre-processing unit 23 determines whether the image quality such as focus, brightness, and contrast of the acquired eye image is appropriate. If the image quality is not appropriate, the pre-processing unit 23 performs necessary processing such as an instruction to the subject and captures the eye image again (S13 ). For the eye image for which the image quality is determined to be appropriate by the pre-processing unit 23, the histogram creation unit 311 creates a histogram relating to the luminance value (S20).

  The first comparison unit 313 obtains, for each luminance value of the generated histogram, a difference between each frequency and the frequency at a luminance value that is one smaller than the luminance value (S21), and the difference and the first threshold value are obtained. The magnitude relation with the value is compared (S22). In addition, the second comparison unit 314 obtains a difference between each frequency described above and the frequency at a luminance value that is one greater than the luminance value (S23), and determines the magnitude relationship between the difference and the second threshold value. Compare (S24).

  The determination unit 315 determines whether reflected light from the glasses is included in the photographed eye image based on the comparison in step S22 and the comparison in step S24. At this time, when the comparison is made with respect to the maximum luminance value, since there is no luminance value larger than the luminance value, the comparison result in step S24 is ignored, and the determination is made based only on the comparison result in step S22 (S25). .

  Then, if the result of the comparison in the first comparison unit 313 in step S22 is large and the result of the comparison in the second comparison unit 314 in step S24 is large, the determination unit 315 is photographed. It is determined that the reflected light from the glasses is included in the eye image, the illumination unit is instructed to switch illumination (S26), and the eye image is captured again by returning to step S12.

  If the comparison result of either the comparison in step S22 or the comparison in step S24 is not large, it is determined whether the luminance value being compared is the maximum luminance value (S27) and must be the maximum luminance value. For example, preparation is made for comparison with respect to the frequency of the luminance value one greater than the luminance value (S28), and the comparison is performed again by returning to step S21 and step S23.

  If the luminance value being compared is the maximum luminance value, the pupil detection unit 32 detects the pupil position and its radius from the photographed eye image. Then, the eye position determination unit 33 determines whether or not the eye is captured at an appropriate size in an appropriate position in the photographed eye image based on the position of the pupil detected by the pupil detection unit 32 and its radius ( S30). If it is determined that it is not appropriate, the process returns to step S12 to capture the eye image again.

  About the eye image judged to be suitable in step S30, the authentication image acquisition part 34 outputs it to the iris information processing part 40 as an eye image for authentication or registration (S40). The iris information processing unit 40 cuts out an iris image from the eye image data based on the center coordinates of the pupil (S41). Then, the iris image is converted into unique authentication information indicating the iris pattern as a numerical value (S42), and if it is set to perform an authentication operation on the photographed eye image (S43), it is registered. An authentication operation is executed by comparing with the registered authentication information (S44). If it is set to perform a registration operation on the photographed eye image, an operation of registering the authentication information obtained in step S42 in the storage unit 43 as registration authentication information is executed (S45).

  As described above, in the first embodiment of the present invention, a histogram relating to the luminance value of the photographed eye image is created, and the reflected light from the glasses is applied to the photographed eye image from the frequency distribution waveform obtained from the histogram. Whether or not is included.

  Thereby, the reflected light from the glasses can be detected with high accuracy. For example, when it is determined that the captured eye image includes reflected light from the glasses, the eye image is captured again by changing the irradiation angle of the illumination light that illuminates the subject from the illumination unit 10. For example, it is possible to capture an eye image in which the reflected light from the glasses is not reflected in the eye image, and it is possible to obtain highly accurate authentication information regarding the iris.

  In the first embodiment of the present invention, the illumination LED 12 is described as being composed of one LED. However, the present invention is not limited to this configuration. For example, you may comprise each of LED12 for illumination with several LED. As described above, when each of the illumination LEDs 12 is composed of a plurality of LEDs, each LED may be an LED having a relatively low light emission luminance, and the subject can be changed by changing the number of LEDs to emit light. The amount of light when irradiating the eyes can be controlled.

  In the first embodiment of the present invention, the illumination LED 12 is described as being composed of three pairs of LEDs. This is for increasing the number of combinations of illumination light irradiation angles with respect to the subject's eyes. However, the present embodiment is not limited to this configuration. For example, the illumination LED 12 may be composed of three or more pairs of illumination LEDs, or may be composed of three or less pairs of illumination LEDs. .

  Or it is good also as a structure provided with the movable part which can comprise LED12 for illumination by a pair of LED, and can move the LED. With such a configuration, the illumination LED 12 can be moved to a position close to and far from the lens 21 by the movable portion, and eye images with different illumination light irradiation angles on the subject's eyes can be taken. it can. In addition to physically moving the LED 12 for illumination, generally known means for performing reflection, refraction, spectroscopy, etc. of lenses, prisms, mirrors, etc. are used, or combinations thereof are used to utilize light refraction and reflection. Then, it is possible to change the irradiation angle of the illumination light with respect to the subject's eye by changing the optical path of the illumination light from the illumination LED 12.

  In the embodiment of the present invention, the configuration in which the illumination light from the illumination LED 12 is near infrared light has been described. This is because the iris has a characteristic of easily reflecting infrared light, so that the contrast of the photographed eye image is increased and the accuracy of the discrimination is improved. The same configuration can also be achieved by covering the illumination LED 12 with a generally known filter or the like that blocks visible light and transmits near-infrared light.

  In the embodiment of the present invention, the configuration in which the illumination LEDs 12 are arranged on the left and right sides of the guide mirror has been described. However, for example, a configuration in which the illumination LEDs 12 are arranged above and below the guide mirror may be used. . In any case, it is desirable that the illumination LED 12 be disposed at an optimal position so that illumination light can be appropriately irradiated onto the subject at an appropriate irradiation angle.

  Various values such as threshold values described in the embodiments of the present invention vary depending on the environment where the eye image capturing apparatus is installed and the photographing conditions such as the luminance and light quantity of illumination light. It is desirable to obtain and set as appropriate.

  Note that the authentication device described in the embodiment of the present invention may include a display unit (not shown) using a liquid crystal, an EL, or the like that displays an eye image captured by the eye image capturing device. At this time, when the display unit is used for confirmation by an administrator or the like of the authentication device, it is desirable that the display unit can be installed away from the authentication device.

  Further, in the embodiment of the present invention, the configuration in which the guide mirror is disposed on the front surface of the lens has been described. It does not matter. Further, in the embodiment of the present invention, the guide mirror is merely used for grasping the horizontal position of the eye and the distance between the eye and the lens unit. It is also possible to adopt a configuration that does not use a guiding mirror by configuring the eye so that it can be guided to an appropriate position.

  In the embodiment of the present invention, the configuration in which the image quality of the captured eye image is determined first and then the presence / absence of the reflected light by the glasses is described has been described. A configuration may be adopted in which the presence / absence of light is determined, and then the image quality of the photographed eye image is determined.

  Further, in the authentication device according to the embodiment of the present invention, the configuration in which the eye image capturing device and the iris information processing unit are integrated has been described, but the configuration is not limited to this configuration, and the eye image capturing device, Each component such as an iris information processing unit may be configured as a separate device, or the eye image capturing device alone may be used only for capturing an eye image.

  According to the spectacles discriminating device, the authentication device, and the spectacles discriminating method according to the present invention, there are few restrictions on the illumination light, the reflected light from the spectacles reflected in the eye image can be discriminated with high accuracy, and the reflection by the skin Since light and reflected light from spectacles can be distinguished and discriminated, it is useful as a spectacle discriminating device, an authentication device, and a spectacle discriminating method.

1 is an external view showing an outline of an authentication device according to Embodiment 1 of the present invention. Block diagram showing the configuration of the authentication device The figure which showed the histogram regarding the luminance value obtained from the eye image image | photographed with the authentication apparatus, and the eye image The figure which expanded the luminance distribution of the high luminance value area among the histograms concerning the luminance value obtained from the eye image photographed by the authentication device The block diagram which shows the structure of the spectacles discrimination | determination part contained in the authentication apparatus Flow chart showing operation of the authentication device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Authentication apparatus 10 Illumination part 11 Illumination control part 12 LED for illumination
DESCRIPTION OF SYMBOLS 13 Guide mirror 20 Image pick-up part 21 Lens 22 Image pick-up element 23 Pre-processing part 30 Image signal processing part 31 Eyeglass discrimination | determination part 32 Pupil detection part 33 Eye position determination part 34 Authentication image acquisition part 40 Iris information processing part 41 Iris authentication process part 42 Iris Information registration unit 43 Storage unit 50 Eye image capturing device 70a, 70b, 70c Eye image 311 Histogram creation unit 312 Memory for histogram 313 First comparison unit 314 Second comparison unit 315 Determination unit

Claims (8)

An illumination unit that emits illumination light to a region including the subject's eyes;
A photographing unit for photographing an eye image of the subject;
A histogram portion for obtaining a histogram relating to a luminance value of an eye image photographed in the photographing portion;
A first comparison unit that obtains a difference between a frequency at each luminance value of the histogram and a frequency at a luminance value that is one smaller than the luminance value, and compares the difference with a first threshold value;
A second comparison for obtaining a difference between the frequency in the luminance value compared in the first comparison unit and the frequency in the luminance value one greater than the luminance value, and comparing the difference with a second threshold value. And
A determination unit that determines whether reflected light from the glasses is reflected in the photographed eye image based on the comparison result of the first comparison unit and the comparison result of the second comparison unit; An eyeglass discrimination device characterized by the above. In the first comparison unit, a value obtained by subtracting the frequency at a luminance value 1 smaller than the luminance value from the frequency at an arbitrary luminance value in the histogram is greater than a first threshold value, and the second comparison is performed. When the value obtained by subtracting the frequency at the luminance value 1 larger than the luminance value from the frequency at the arbitrary luminance value is larger than a second threshold value, the determination unit 2. The glasses discriminating apparatus according to claim 1, wherein it is determined that reflected light from the glasses is reflected on the screen. When the luminance value to be compared in the first comparison unit is the maximum luminance value, the determination unit is based on only the comparison result of the first comparison unit, and the reflected light from the glasses is captured in the photographed eye image. 3. The glasses discriminating apparatus according to claim 2, wherein it is determined whether or not the image is reflected. 4. The glasses discriminating apparatus according to claim 3, wherein the first comparison unit and the second comparison unit perform comparison for all luminance values that are equal to or greater than a comparative comparison luminance value that is arbitrarily set. 5. The glasses discriminating apparatus according to claim 4, wherein the comparative minimum luminance value is a value set based on a proportional relationship with the brightness of illumination light of the illumination unit. The glasses discriminating device according to any one of claims 1 to 5,
The glasses discriminating apparatus includes an authentication processing unit that performs an authentication process using an iris portion of an eye image that has been determined that reflected light from the glasses is not reflected in the photographed eye image. Authentication device. The said spectacles discrimination | determination apparatus was provided with the registration part which registers the information regarding the iris of the eye image determined that the reflected light by spectacles is not reflected in the image | photographed eye image. Authentication device. A first step of irradiating illumination light to a region including the subject's eyes;
A second step of taking an eye image of the subject;
A third step for obtaining a histogram relating to a luminance value of the eye image photographed in the second step;
The difference between the frequency at each luminance value of the histogram determined in the third step and the frequency at a luminance value that is one smaller than the luminance value, and the frequency at the luminance value and the frequency at a luminance value that is one greater than the luminance value, A fourth step for sequentially determining the difference between
A fifth step of comparing a first threshold value with a difference between the frequency at each luminance value of the histogram obtained at the fourth step and the frequency at a luminance value one smaller than the luminance value;
A sixth step of comparing a difference between a frequency at each luminance value of the histogram obtained in the fourth step and a frequency at a luminance value one greater than the luminance value with a second threshold value;
And a seventh step of determining whether or not the reflected light from the glasses is reflected in the photographed eye image based on the comparison result in the fifth step and the comparison result in the sixth step. To discriminate glasses.

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