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Title:
A SYSTEM AND METHOD FOR CAPTURING AN IRIS OF A SUBJECT
Document Type and Number:
WIPO Patent Application WO/2018/185744
Kind Code:
A1
Abstract:
The present invention discloses a technique for imaging/capturing an iris of a subject. The method comprises illuminating at least one eye region to thereby reduce a size of a pupil; focusing an imaging device onto an illuminated inner ring of the iris; turning off illumination; activating an imaging device and a flash generating a flash light after a certain time period after the turning off the illumination and capturing an image of the iris; and obtaining an image being indicative of a structure of the iris. The system comprises an LED arrangement configured for emitting an illumination light beam towards an inner ring of the iris causing reduction of a size of a pupil; an imaging device being configured and operable for focusing onto the illuminated inner ring of the iris, capturing an image data of the iris and generating an image being indicative of a structure of the iris; a flash unit configured for producing a flash light; a diffuser arrangement configured for collecting the flash light and directing the flash light towards a region of the iris at a certain projection angle; and a control unit being connected to the imaging device, the flash light, and to the LED arrangement, and being configured and operable for turning off the illumination produced by said LED arrangement and activating the imaging device together with the flash light after a certain period of time after the turn off.

Inventors:
KOCH ROBIN (DE)
MUELLER TOBIAS (DE)
HARISH GALYA (IL)
Application Number:
PCT/IL2018/050358
Publication Date:
October 11, 2018
Filing Date:
March 28, 2018
Export Citation:
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Assignee:
KOCH ROBIN (DE)
MUELLER TOBIAS (DE)
HARISH GALYA (IL)
International Classes:
G03B15/05; A61B3/00; G06K9/00
Domestic Patent References:
WO2016080031A12016-05-26
Foreign References:
US20050152583A12005-07-14
US20050249385A12005-11-10
US6247813B12001-06-19
US20050270386A12005-12-08
Attorney, Agent or Firm:
SCHNUR, Myriam (IL)
Download PDF:
Claims:
CLAIMS:

1. A method for capturing an iris comprising:

illuminating at least one eye region to thereby reduce a size of a pupil;

focusing an imaging device onto an illuminated inner ring of the iris ;

turning off illumination;

activating an imaging device and a flash generating a flash light after a certain time period after the turning off the illumination and capturing an image of the iris; and obtaining an image being indicative of a structure of the iris.

2. The method of claim 1, wherein said activating of the imaging device and the flash is performed substantially simultaneously.

3. The method of claim 1 and claim 2, wherein said certain period of time is less than 1 second.

4. The method of any one of claims 1 to claim 3, comprising aligning the flash light with respect to the iris, and focusing and collecting the flash light to obtain a certain angle of projection of the flash light on the iris .

5. A system for imaging an iris of a subject comprising:

an LED arrangement configured for emitting an illumination light beam towards an inner ring of the iris causing reduction of a size of a pupil;

an imaging device being configured and operable for focusing onto the illuminated inner ring of the iris, capturing an image data of the iris and generating an image being indicative of a structure of the iris;

a flash unit configured for producing a flash light;

a diffuser arrangement configured for collecting said flash light and directing said flash light towards a region of the iris at a certain projection angle; and

a control unit being connected to said imaging device, said flash light, and to said LED arrangement, and being configured and operable for turning off said illumination produced by said LED arrangement and activating said imaging device together with said flash light after a certain period of time after the turn off.

6. The system of claim 5, wherein said LED arrangement is distributed in a vicinity of a subject's face.

7. The system of claim 5 or claim 6, wherein said imaging device comprises said flash unit.

8. The system of any of the preceding claims, wherein said period of time includes a time after afterglow of said flash light.

9. The system of any of the preceding claims, wherein said control unit comprises a switch connected via a wired or wireless connection to a remote release of said imaging device.

10. The system of any of the preceding claims, wherein said imaging device is disposed at a distance of less than 30cm from the eye.

11. The system of any of the preceding claims, comprising a headrest for supporting a subject's face such that the distance between said imaging device and the subject is fixed.

12. The system of any of the preceding claims, wherein said imaging device comprises a still camera.

13. The system of any of the preceding claims, wherein said LED arrangement, said flash, said diffuser arrangement and said imaging device are enclosed in a certain volume.

Description:
A SYSTEM AND METHOD FOR CAPTURING AN IRIS OF A SUBJECT

TECHNOLOGICAL FIELD

The present invention relates to the field of image capturing. BACKGROUND ART

References considered to be relevant as background to the presently disclosed subject matter are listed below:

Japanese Patent Application No. JP 2001215109;

PCT application No. WO 2008/131201 ;

- US patent application No. US 2013/250,087;

US patent application No. US 2011/304,721 ;

Chinese patent application No. CN 201310573650.0;

Russian patent application No. Ru 2012139646/14

PCT application No. WO 2014/087425;

- Korean patent application No. KR1020130075954

Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter. BACKGROUND

Though some techniques for iris capturing are available on the market, the underlying technology is not without its drawbacks. It is extremely challenging to collect a high quality image of the iris. Usually, a major pre- and post- processing of the iris image is required. Iris recognition uses camera technology, typically employing near infrared (NIR) illumination to see through the iris coloration, to create images of the detail-rich, intricate structures of the iris. One problem with iris recognition is that focusing is extremely difficult when accurately capturing near infrared (NIR) iris images. In order to obtain iris features with dark eyes, NIR illumination and sensors are used. Due to NIR, the sensor is not as efficient compared to that which is visible by a human, so an increase in illumination is necessary. Even with intense illumination, the camera aperture setting is often such that the depth of field is short, which is a major factor in capturing images that are not in focus. Autofocusing is not feasible, because the iris can be located anywhere within the operating range of the iris camera, and also because the camera lens has a very small depth of field. GENERAL DESCRIPTION

Accordingly, there exists a long-felt need to develop an image capturing device for human iris patterns, which utilizes accurate focus, high speed, provides accurate and fast iris segmentation, and also produces high quality images. The present invention meets the above mentioned needs by providing an improved image capturing device for iris patterns of humans, which is accurate, fast, devoid of the defects and distortions mentioned earlier, and also provides some advantageous aspects hitherto not known in this field, as described hereinafter in this complete specification.

All throughout this specification including the claims, the words "iris", "image", "LED", "light" and "imaging device" are to be interpreted in the broadest sense of these respective terms, and include all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/Limitation if any, referred to in the specification, is solely by way of example and understanding of the present invention.

The technique of the present invention enables to obtain three dimensional structures of an iris of a subject, and comprises illuminating the eye in a manner to reduce the size of the pupil, focusing illumination onto the inner ring of the iris, turning off the illumination, and activating an imaging device and a flash after a certain delay. In this way a maximal illumination, leading to a maximal size of the iris, combined with a minimal reflection from such illumination, is provided. It should be understood that the main problem with iris capturing is that the eye requires a certain illumination to be photographed. The illumination should keep the pupil small in size so that the iris can be shown in maximal dimensions. However, at the same time, any light source in the vicinity of the subject's face is always visible on the final picture due to the form and wet surface structure of the human eye. The inventors have found that by using the technique of the present invention in which inter alia LED lights are distributed very close on the left and right of the subject's face, gives the advantage of keeping the pupil minimal in size, as well as giving the operator the ability to easily focus on the illuminated iris. When the iris is sufficiently sharp, the operator turns off illumination of the LEDs and activates the imaging device for a certain period of time after illumination is turned off. This certain period of time is selected as the required optimal time to make sure the LEDs are completely dark (including the afterglow), yet the pupil has not yet adjusted its size. It should be noted that pupils start to expand rapidly after illumination is removed. The inventors have found that pupils start to expand not earlier than ½ of a second after turning off illumination.

According to one broad aspect of the present invention there is provided a system for imaging an iris of a subject, which comprises an LED arrangement configured for emitting an illumination light beam towards an inner ring of the iris causing reduction of a size of a pupil; an imaging device being configured and operable for focusing onto the illuminated inner ring of the iris, capturing an image of the iris and generating an image being indicative of a structure of the iris; a flash configured for producing a flash light; a diffuser arrangement configured for collecting the flash light and directing the flash towards a region of the iris at a certain projection angle; and a control unit being connected to the imaging device, the flash light and to the LED arrangement and being configured and operable for turning off the illumination and activating the imaging device after a certain period of time after the turn off.

It should be noted that the inner ring of the iris is defined as the boundary between the iris and the pupil.

It should be understood that the technique of the present invention causes reduction of a size of a pupil to a minimal size for the specific subject. The size of the pupil can be reduced to 1/20 of the entire iris area depending on the individual, his/her physical state, and light sensitivity. The projection angle is defined as the angle created between the direction of the center of the camera lens and the direction of the flash light beam.

In some embodiments, the LED arrangement is located in the vicinity of a subject's face e.g. at a distance not exceeding 30 cm from the subject's eye.

The flash may be an external flash unit or may be incorporated in the imaging device.

In some embodiments, the period of time includes a time after afterglow of the flash light. In some embodiments, the control unit comprises a switch (e.g. relay) connected via a wired or wireless connection to a remote release of the imaging device. The switch may be a relay wired to a remote release of the imaging device which is triggered a certain time after the lights are turned off.

In some embodiments, the imaging device (the front end of the camera lens) is disposed at a distance of less than 30 cm from the eye.

In some embodiments, the system comprises a headrest for supporting a subject's face such that the distance between said imaging device and the subject is fixed.

In some embodiments, the imaging device comprises a still imaging device. In some embodiments, the LED arrangement, the flash, the diffuser arrangement and the imaging device are enclosed in a certain volume.

According to another broad aspect of the present invention, there is provided a method for capturing an iris comprising illuminating at least one eye region to thereby reduce a size of a pupil; focusing an imaging device onto the illuminated inner ring of the iris; turning off the illumination; activating an imaging device and a flash generating a flash light after a certain time period after the turning off the illumination, and capturing an image of the iris; and obtaining an image being indicative of a structure of the iris. Generally one image of one iris is provided at each time.

In some embodiments, the activation of the imaging device and the flash is performed substantially simultaneously.

In some embodiments, the certain period of time is less than 1 second.

In some embodiments, the method comprises aligning the flash light with respect to the iris, and focusing and collecting the flash light to obtain a certain angle of projection of the flash light on the iris. This technique enables to reduce reflection of light on the iris.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 is a schematic illustration of a block diagram of the system according to some embodiments of the present invention;

Fig. 2 is a schematic illustration of a flow chart of the method according to some embodiments of the present invention;

Fig. 3 is a schematic illustration of another possible configuration of the system according to some embodiments of the present invention; and

Fig. 4 is a picture obtained by using the technique of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring to Fig. 1, there is illustrated, by way of a block diagram, the main structural and functional part of a capturing system 100 of the present invention. The system 100 is configured for imaging an iris of a subject. The system 100 includes such main constructional parts as an LED arrangement 102, an imaging device (e.g. camera) 104, a flash unit 106, a diffuser arrangement 110 and a control unit 108 .The LED arrangement 102 may be distributed in a vicinity (e.g. not exceeding 30cm) of a subject's face and is configured for emitting illumination light beam towards an inner ring of the iris causing reduction of the size of a pupil.

The imaging device 104 (e.g. camera) is configured and operable for focusing onto the illuminated inner ring of the iris, capturing an image of the iris, and generating an image being indicative of a three-dimensional structure of the iris. The front end of the camera lens may be disposed at a distance of less than 30 cm from the eye. The imaging device 104 may be a still camera. In a specific and non-limiting example, the imaging device 104 may be of the type Canon EOS 5d Mark II having extension rings of 56mm and a macro lens of the type Canon 100mm. The camera settings may be as follows: l/200s, aperture f/8, ISO 160. In this specific and non-limiting example, the camera is placed at a distance of about 10 cm from the eye. The connection between imaging device 104 and control unit 108 may be a fiber optics cable of about 9mm (45 single ropes each lmm). The system 100 of the present invention provides sufficient illumination for a SLR Camera to operate at ISO values as low as 160 which results in very high overall quality of the resulting image without noise or artefacts. The flash unit 106 is configured for producing a flash neutral (white) light. Although, as shown in the figure, the flash unit 106 is a device external to the imaging device 104, it may be a part of it. The optical diffuser arrangement 110 is configured for collecting the flash light and directing the flash light towards a region of the iris at a certain projection angle a. In a specific and non- limiting example the flash unit 106 may be of the type Canon 430 EX II. The flash settings may be as follows: ½, Zoom 105mm. The flash connection with the control unit 108 may be a fiber optics cable with a length of about 45cm. The optical diffuser arrangement 110 may be any device that diffuses or spreads out or scatters light in some manner. It may be a white surface, translucent objects, and can include ground glass diffusers, Teflon diffusers, holographic diffusers, opal glass diffusers, and greyed glass diffusers. In a specific and non-limiting example, the flash light is collected in an adjusted and darkened plastic diffuser, and are focused and piped through fiber optics wires which are contained in a pre-bent copper pipe which guarantees the optimum angle at which the flash hits the iris. The optimum angle of the flash pipe to hit the eye is in the range of about 40°-80° with respect to the center of the camera lens.

The control unit 108 is configured generally as a computing/electronic utility including inter alia such utilities as data input and output utilities 108A, 108B, memory 108C, and data processor and analyzer modules 108D, 108E. The control unit 108 is connected to imaging device 104, the flash 106 and to LED arrangement 102. In some embodiments, some or all data analysis modules of the control unit 108 may be incorporated in a personal electronic/communication device, such as a smart phone. To this end, such a communication device may be installed with a specific software application. Such a communication device may typically be located in the vicinity of the imaging device 104 during image acquisition, and the communication between them may be via Bluetooth, Wi-Fi based or other communication methods. The control unit 104 is configured to turn off illumination and activate imaging device 104 after a certain period of time after the turn off. The period of time may include a time after glow. In some embodiments the control unit 108 comprises a switch 108G connected via a wired or wireless connection to a remote release of imaging device 104. In some embodiments, when the iris is sufficiently sharp, the operator activates imaging device 104 (e.g. pushes a foot switch which acts as the light switch and includes a relay as well). Alternatively, the process may be automated, and upon detection of a certain sharpness of the iris by the data analyzer 108E of the control unit, the switch 108G may activate imaging device 104. The switch 108G is connected (wired or wireless) to the remote release of imaging device 104 which can be triggered after less than 1 second of a second after the lights are turned off. The inventors have found about 0.1 of a second enables to make sure the LEDs are completely dark (including the afterglow) but the pupils have not yet adjusted their sizes (they start to expand rapidly after the source of light is removed, but not earlier than ½ of a second). In this way, the size of the pupil is minimal, and the maximum size of the iris is thus portrayed. This leads to a very detailed and clear imaging of the human iris with a magnification of up to x200. The shadows (on the iris) created by the flashlight allow for portrayal of the three-dimensional structures of the iris. The typical reflections of state of the art technology are heavily reduced or fully eliminated. Furthermore, only minimum lighting distortion is present (0% - ½% of the iris size) depending on several factors such as curvature, and the size to which the pupil contracts.

Referring to Fig. 2, there is illustrated, by way of a flow chart, the main steps of an iris capturing method of the present invention. The method 200 comprises in step 210 illuminating at least one eye region to thereby reduce the size of a pupil; focusing an imaging device onto the illuminated inner ring of the iris (step 220); turning off the illumination (step 230); activating an imaging device and a flash light after a certain time period T after turning off illumination (step 240); capturing an image of the iris (step 250), and obtaining an image being indicative of a structure of the iris. Step 210 may be performed by using a LED arrangement emitting light in the visible range. The illumination spot of the LED arrangement is selected to cover at least the pupil's region of the eye. Step 220 may be performed by adjusting the focal length of the camera lens such that the iris plane is at the focal point of the camera lens. Step 230 may be performed automatically or manually by using a switch connected to the LED arrangement. The period of time T may be less than 1 second after turning off the illumination. The period of time T is appropriately selected to, on the one hand, capture the image when the iris has an optimal size, and, on the other hand, to reduce light reflections induced by the illumination which generate shade on regions of the picture. The inventors have found that, by using a specific and non-limiting system, the optimal period of time T may be about 0.1 second. In some embodiments, activation of the imaging device and the flash light is performed substantially simultaneously, but a difference of a few tenths of seconds may exist between their activation. It should be noted that the proposed iris capturing method is very fast and takes about two minutes to perform all the steps 210-250 mentioned above.

In some embodiments, the method comprises aligning the flash light with the iris, and focusing and collecting the flash to obtain a certain angle of projection of the flash light on the iris (step 260) to enable reduction of reflection of flash light on the iris. In a specific and non-limiting example, the flash light is laterally aligned with respect to the iris at a projection angle of about 65°. The technique provides color fidelity of the image, as well as singularisation of three dimensional structures through high levels of contrast of light and shade. This can be further emphasized during a post processing stage.

Referring to Fig. 3, there is illustrated, by way of a block diagram, a possible configuration of the system 300 of the present invention. In this specific and non-limiting example, the front end of the camera lens of the imaging device 104 is disposed at a distance of less than 10cm (from the eye). The system 300 comprises inter alia a headrest 310 for supporting a subject's face such that the distance between imaging device 104 and the subject is fixed. In this configuration the LED arrangement 102, the imaging device 104 the flash unit 106 and the diffuser arrangement 110 are enclosed in a certain volume (housing). This configuration enables to provide a small and portable system, easily operable. The imaging device 104 may slide on a mounting device such as a tripod (not shown) and can be easily placed at the required distance from the eye. The switch activating the imaging device 104 and the flash may be a foot switch.

The following is a specific and non-limiting example of the procedure using the technique of the present invention. (1) The subject places his/her head on the photo box's head rest. (2) The forehead is kept in place by a metal bar cushioned by foam. The chin rests on a plastic pillow (easily cleanable) which is filled with soft foam to allow for various face sizes. (3) The head is placed immediately in front of the imaging device. The head rest serves also as a movement limiter for the imaging device which prevents the imaging device lens from touching the subject's eye. (4) One or both LED/s are switched on by the operator (depending on ambient lighting, the subject's individual pupil size etc.). The size of the pupil is reduced. (5) The operator focuses the inner ring of the iris with the imaging device's internal live view mode. (6) The foot switch is pressed. (7) The LED/s are turned off and the imaging device and the flash are activated. (8) The picture is transferred in RAW format to a computer via a USB cable. Fig. 4 shows an image 40 obtained by using the technique of the present invention. The three-dimensional structure and the high quality of the image are clearly shown. In a specific and non-limiting example, this image showing a three-dimensional structure of an individual iris, may be used as a personalized means to create art that includes a unique aspect of a subject's body. As each subject has a unique pair of eyes, while a fingerprint has 40 unique identification features, the iris has 256. It can be used as a unique and innovative approach to personalized art, and can relate to the field of creating unique works of art. The image can be printed on any material of any size and may include photographs, logos, prints, or other indicia as a means for enhancing aesthetics and/or providing an opportunity for promotional marketing or advertising of a business, event, or for personal enhancement and customization. For example, the image can be printed on any textile to create personalized iris fashion items. The entire process may be performed in a store to enable customers to spend more time in the store and to create a unique buzz and motivate customers to visit stores. This can also enhance customer engagement and brand loyalty. An online "follow-up" personalized merchandize purchase may thus have long term effects. Other items such as jewelry, watches, phonecases, and bags may be personalized in the same way. Digital merchandizing may also be created by using the technique of the present invention. Items such as a smartphone Screensaver, smart watch background, social media marketing and branding assets may also be personalized. The novel technique of the present invention enables fast transformation of an iris photo into a uniquely personalized piece of art showing colors and 3D structures of the iris, not seen to the observer. The image obtained by using the technique of the present invention is not limited to any use and the proposed technique may be applied to various technological fields.