WO2015108911A1

WO2015108911A1 - Method and apparatus for controlling intensity of illumination in eye based biometric systems

Info

Publication number: WO2015108911A1
Application number: PCT/US2015/011308
Authority: WO
Inventors: Salil Prabhakar
Original assignee: Delta ID Inc.
Priority date: 2014-01-16
Filing date: 2015-01-14
Publication date: 2015-07-23

Abstract

The invention provides an apparatus, method and computer program product for eye based biometric recognition. The invention comprises acquiring a first image frame of an image capture region under illumination of a first intensity and responding to a determination that the first image frame meets at least a first suitability criteria, by illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity. The invention may acquire a second image frame of the image capture region under illumination of the second intensity.

Description

Method and Apparatus for Controlling Intensity of Illumination

in Eye Based Biometric Systems

Field of the Invention

The invention relates to a method and apparatus for controlling intensity of illumination for achieving power efficiencies and for eye safety in biometric systems that rely on distinctive characteristics of the eye (such as iris based biometrics or retina based biometrics).

Background

Eye based biometric devices typically require a subject's eye to be positioned in a prescribed region (i.e. within a desired eye capture volume corresponding substantially to an object plane of an imaging apparatus such as a camera), whereafter the eye is illuminated by an illumination source (such as an LED, incandescent light or other light source), and an image of the subject's eye is acquired for further processing. The illumination source requires to be powered by a power source, such as a battery or other energy source. Prior art eye based biometric devices were typically large, immobile units with substantial power sources or reserves - and accordingly, powering an illumination source did not present difficulty. Presently however, eye based biometric systems are being implemented in mobile devices (e.g. cellular or mobile phones, smartphones, laptops, personal digital assistants (PDAs), tablets, phablets, watches and other wearable devices, or other similar devices), and rely on the mobile device battery for powering the illumination source. Given known limitations on mobile device battery size, and the importance of improving performance of mobile device batteries between charges, there is a need to provide power efficiencies in operation of illumination source(s) within eye based biometric devices. In addition, dissipating significant amounts of heat is a challenge in the compact mobile devices.

Additionally, it has been established that eye based biometric apparatuses perform better when images of the eye (particularly for iris based systems) are acquired in the infrared (IR) region of the electromagnetic spectrum, and particularly in the IR-A or near infrared region (NIR) of the electromagnetic spectrum i.e. when eye images are acquired using wavelengths falling between 700 nanometres (nm) and 1400 nm. Illumination sources presently used in eye based biometric apparatuses therefore include sources capable of illuminating the subject's eye with wavelengths falling within the IR or NIR spectrum.

It is however known that beyond certain pre-defined limits, exposure to IR and NIR spectrum wavelengths may cause retinal burns and cataractogenesis in eye tissue. This is a particular concern in biometric apparatuses which rely on simultaneous image capture and processing, wherein an illumination source continually illuminates the subject's eye while the camera acquires multiple images of the eye until either (a) the apparatus reaches a match or non-match decision or (ii) a predetermined termination event (such as a timeout) occurs. Continuous or pulsed illumination of the eye for an extended period of time during image capture and processing increases exposure to IR and NIR spectrum wavelengths, with a corresponding increase in the attendant risks. There is accordingly also a need to reduce the amount of IR or NIR radiation directed upon a subject's eye during image acquisition by a biometric device, without affecting the quality of image capture.

The present invention seeks to address the above issues. Summary

The invention provides an apparatus for eye based biometric recognition. The apparatus may comprise an imaging apparatus, at least one illumination source, and an illumination controller configured to control intensity of illumination generated by one or more illumination sources. The apparatus may be configured to acquire a first image frame of an image capture region under illumination of a first intensity, and respond to a determination that the first image frame meets at least a first suitability criteria, by illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity. The apparatus may acquire a second image frame of the image capture region under illumination of the second intensity.

In an embodiment of the invention, the apparatus may be configured to respond to a determination that the second image frame meets at least a second suitability criteria, by illuminating the image capture region with illumination of a third intensity, such that the third intensity is greater than the second intensity. The apparatus may thereafter acquire a third image frame of the image capture region.

The first suitability criteria may include any one or more of (i) presence of an eye or iris within the image capture region, (ii) eye or iris positioned wholly within the image capture region, (iii) minimum size of the eye image or iris image acquired by the imaging apparatus (iv) sufficient usable eye area or iris area within the image frame (v) sufficient image margin and (vi) suitable gaze angle. In an embodiment of the above invention, the first suitability criteria may include one or both of (i) an eye or iris positioned wholly inside the image capture region corresponding to the imaging apparatus, or (ii) an eye or iris positioned wholly within a depth of field corresponding to the imaging apparatus. The second suitability criteria may include any one or more of (i) minimum size of an eye image or iris image acquired by the imaging apparatus (ii) sufficient usable eye area or iris area within the image frame (iii) sufficient image margin and (iv) suitable gaze angle.

In a particular embodiment of the above invention, the apparatus may be configured to acquire the first image frame of the image capture region under illumination from a first illumination source and acquire the second image frame of the image capture region under illumination from a second illumination source.

The first illumination source may in a particular implementation be a display screen.

An embodiment of the apparatus may be configured to acquire the first image frame of the image capture region under ambient illumination and acquire the second image frame of the image capture region under illumination from the at least one illumination source. In accordance with one embodiment of the above invention, the magnitude of the illumination of first intensity may be (i) sufficient for assessment of an image frame against the first suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction. In a specific embodiment, the magnitude of the illumination of second intensity may be sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

In another embodiment, the magnitude of the illumination of second intensity may be (i) sufficient for assessment of an image frame against the second suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

The magnitude of the illumination of third intensity may be sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction. The invention also provides a method for illuminating an image capture region of an eye based biometric recognition. The method comprises acquiring a first image frame of an image capture region under illumination of a first intensity and responding to a determination that the first image frame meets at least a first suitability criteria, by illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity. The method may acquire a second image frame of the image capture region under illumination of the second intensity.

In an embodiment of the above method, the method may further comprise responding to a determination that the second image frame meets at least a second suitability criteria, by illuminating the image capture region with illumination of a third intensity, such that the third intensity is greater than the second intensity. The method may thereafter acquire a third image frame of the image capture region.

The first suitability criteria may include any one or more of (i) presence of an eye or iris within the image capture region, (ii) eye or iris positioned wholly within the image capture region, (iii) minimum size of the eye image or iris image acquired by the imaging apparatus (iv) sufficient usable eye area or iris area within the image frame (v) sufficient image margin and (vi) suitable gaze angle. In another embodiment, the first suitability criteria may include one or both of (i) an eye or iris positioned wholly inside the image capture region corresponding to the imaging apparatus, or (ii) an eye or iris positioned wholly within a depth of field corresponding to the imaging apparatus.

The second suitability criteria may include any one or more of (i) minimum size of an eye image or iris image acquired by the imaging apparatus (ii) sufficient usable eye area or iris area within the image frame (iii) sufficient image margin and (iv) suitable gaze angle. In a particular embodiment, the method may further comprise acquiring the first image frame of the image capture region under illumination from a first illumination source and acquiring the second image frame of the image capture region under illumination from a second illumination source. The first illumination source may in a particular implementation be a display screen.

In yet another embodiment, the method may comprise acquiring the first image frame of the image capture region under ambient illumination, and acquiring the second image frame of the image capture region under illumination from the at least one illumination source.

In accordance with a particular embodiment of the above method, the magnitude of the illumination of first intensity may be (i) sufficient for assessment of an image frame against the first suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

In a specific embodiment, the magnitude of the illumination of second intensity may be sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

In yet another embodiment, the magnitude of the illumination of second intensity may be (i) sufficient for assessment of an image frame against the second suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

The magnitude of the illumination of third intensity may be sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

The invention additionally provides computer program products configured to implement the apparatus and methods described above and in further detail throughout the specification.

An embodiment of the invention comprises a computer program product for illuminating an image capture region of an eye based biometric recognition, which computer program product comprises a computer usable medium having a computer readable program code embodied therein, the computer readable program code comprising instructions for acquiring a first image frame of an image capture region under illumination of a first intensity and responding to a determination that the first image frame meets at least a first suitability criteria, by illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity and acquiring a second image frame of the image capture region under illumination of the second intensity.

Brief Description of the Accompanying Drawings

Figure 1 is a functional block diagram of an apparatus for eye based biometric recognition.

Figure 2 and Figure 3 respectively comprise flowcharts illustrating methods for eye based biometric recognition according to the present invention. Figure 4 illustrates an exemplary computer system in which various embodiments of the invention may be implemented. Description of the Invention

The present invention includes methods, apparatuses and computer programs for controlling illumination generated by an illumination source provided in an eye based biometric system, for achieving one or both of power efficiencies and eye safety.

Figure 1 is a functional block diagram of a device 100 having an apparatus for eye based biometric recognition (e.g. iris or retina based biometric recognition), the device including an imaging apparatus 102 and an image processing apparatus 104. Imaging apparatus 102 acquires an image of the subject's eye and transmits the image to image processing apparatus 104. The image captured by imaging apparatus 102 may be a still image or a video image. Image processing apparatus 104 thereafter analyses and compares data extracted from the captured image of the subject's eye / iris against data extracted from previously acquired eye / iris images, to identify the subject, or to verify the identity of the subject. Device 100 may additionally include an illumination source 106 (for example an incandescent light source, an IR or NIR spectrum illumination source or any other illumination source) and a controller 108 configured to control intensity of illumination source 106. Although not illustrated in Figure 1, device 100 may include other components, including for extracting still frames from video images, for processing and digitizing image data, and for enabling communication between components of the apparatus.

Existing eye based biometric recognition methods and systems typically illuminate a predetermined image capture region (corresponding substantially to an object plane of the camera) by an illumination source, and simultaneously commence acquisition of image frame(s) corresponding to the illuminated image capture region. Each captured image frame may thereafter be subjected to extraction and comparison processes by the image processing apparatus to determine whether the captured image frame includes an eye / iris and whether that eye / iris is a match for any previously digitized eye / iris information stored in a database. The extraction and comparison steps may include (i) segmentation - locating inner and outer boundaries of the eye / iris within the acquired image, and cropping the portion of the image which corresponds to the eye / iris (ii) feature extraction -processing image data corresponding to the cropped image, to extract and encode salient and discriminatory features that represent an underlying biometric trait, into a feature set. (iii) image comparison - comparing the feature set corresponding to the acquired eye / iris image against previously stored image templates from a database, to generate scores that represent a difference (i.e. degree of similarity or dissimilarity) between the input image and the database templates. Results of the comparison step may be used to arrive at a decision (identity decision) regarding identity of the acquired eye / iris image.

The invention is premised on the discovery that every image frame (of the image capture region) that is acquired by an imaging apparatus is not necessarily suitable for segmentation, feature extraction or image comparison steps. An image frame of the image capture region may be found to be unsuitable for one or more of the subsequent processing steps on account of unsuitable positioning of the subject's eye / iris relative to the image capture region, including on occurrence of any one or more of the following events - (i) absence of an eye / iris within the image capture region, (ii) eye / iris being only partially positioned within the image capture region, (iii) small size of the eye / iris image acquired by the imaging apparatus, owing to distance at which the subject's eye is positioned (iv) limited usable eye / iris area within the image frame due to occlusions by eye-lids or other objects (v) margin size and (vi) unsuitable gaze angle. Each of these events is described briefly below:

• Absence of eye / iris within the image capture region - by disregarding images of the image capture region when an eye / iris is not positioned therewithin, irrelevant image frames may be eliminated.

• Eye / iris partially positioned within the image capture region - by disregarding images of the image capture region when an eye / iris is not entirely or sufficiently positioned therewithin, processing of image frames that do not include sufficient meaningful information may be eliminated.

• Iris size - by specifying a threshold eye / iris size for capture within an image frame, processing of image frames that do not offer sufficient textural information for accurate extraction and comparison may be eliminated.

• Occlusion of usable iris area - usable iris area is measured as the percentage of iris that is not occluded by eyelash(es), eyelid(s), specular reflects, ambient specular reflections or otherwise. Occlusion of the iris not only reduces the available iris textural information for comparison, but also decreases accuracy of the iris segmentation process, both of which increase recognition errors. Defining threshold values for usable iris area serves to eliminate image frames that are likely to result in recognition errors. · Margin size - Margin size refers to the distances of the outer iris boundary from the four image frame boundaries (top, bottom, left and right). Insufficient image margins present difficulties for feature extraction. Image margins may therefore be used a criterion for disregarding images without further processing. · Unsuitable gaze angle - gaze angle of an iris image is a measure of deviation between the optical axis of the subject's eye and the camera's chief ray going through the center of the pupil in the aforementioned eye. Imaging of the iris when off-axis is found to create a projective deformation of the iris, which affects accuracy of feature extraction and comparison operations. A predetermined threshold for permissible gaze angle serves to eliminate unsuitable image frames.

In the event positioning of the subject's eye within the image capture region is unsuitable for image processing on any one or more of the above criteria, a corresponding image frame of the subject's eye in such position would render non-optimal results. Accordingly, prior to acquiring an image frame of sufficient quality for further image processing steps, it is advantageous that the image capture region be examined for suitable positioning of the subject's eye there within.

Critically, it has been discovered that assessment of an image capture region to determine whether the subject's eye is optimally positioned there within may be achieved under illumination conditions of a lower intensity than the illumination conditions required when acquiring an eye / iris image intended for subsequent segmentation, feature extraction or image comparison operations. The invention utilizes this discovery to improve power efficiencies and eye safety by providing a multi stage eye illumination and image acquisition process prior before commencing subsequent segmentation, feature extraction or image comparison operations.

Figure 2 illustrates an embodiment of the method of the present invention. At step 202 the image capture region is subjected to illumination of a first intensity, and an image frame of the image capture region is acquired by the imaging apparatus. Illumination of the first intensity may be achieved either by an illumination source associated with the biometric apparatus, or by ambient light.

Step 204 thereafter checks whether the acquired image frame meets one or more predetermined criteria indicating unsuitability of position of the subject's eye / iris for further image processing. The one or more predetermined criteria may include any one or more of: (i) absence of an eye / iris within the image capture region, (ii) eye / iris being only partially positioned within the image capture region, (iii) small size of the eye / iris image acquired by the imaging apparatus, owing to distance at which the subject's eye is positioned (iv) limited usable eye / iris area within the image frame (v) insufficient image margin and (vi) unsuitable gaze angle, or (vii) any other predetermined criteria indicating unsuitable positioning of a subject's eye / iris within the image capture region.

If assessment under the one or more predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method reverts to step 202. If on the other hand, assessment under the predetermined criteria indicates suitability of position of the subject's eye / iris for further image processing, the method proceeds to step 206.

At step 206 the illumination source generates illumination sufficient to illuminate the image capture region (and the subject's eye / iris positioned therewith) with illumination of a second intensity, wherein said illumination of second intensity (i) is greater than the first illumination intensity and (ii) is preferably of sufficient magnitude to ensure acquisition of an image of adequate quality for the further steps of segmentation, feature extraction and (or) image comparison. At step 208 the imaging apparatus acquires an image of the image capture region (and the eye / iris positioned therewithin) and subjects the acquired image to one or more of the further steps of segmentation, feature extraction and image comparison.

At step 210 the method checks for a termination event (such as an identity decision, or a timeout instruction). If a termination event is not detected, the method may revert to step 206. If a termination event is detected, the method may terminate. It would be understood that instead of using predetermined criteria indicating unsuitability of position of a subject's eye / iris, step 204 may in an alternate embodiment check whether the acquired image frame meets one or more predetermined criteria indicating suitability of position of the subject's eye / iris for further image processing. The one or more predetermined criteria may include any one or more of: (i) presence of an eye / iris within the image capture region, (ii) eye / iris being fully positioned within the image capture region, (iii) sufficiently large size of the eye / iris image acquired by the imaging apparatus (iv) sufficient usable eye / iris area within the image frame (v) sufficient image margin and (vi) suitable gaze angle, or (vii) any other predetermined criteria indicating suitability of position of a subject's eye / iris within the image capture region.

If assessment under the one or more predetermined criteria indicates suitability of position of the subject's eye / iris for further image processing, the method proceeds to step 206. If on the other hand, assessment under the predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method reverts to step 202.

In an embodiment of the invention, magnitude of the illumination of first intensity is (i) sufficient for assessment of suitability or unsuitability of an image frame against the predetermined criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction. In this embodiment, magnitude of the illumination of second intensity is sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

Illumination of the image capture region by differing first and second illumination intensities may be achieved in any one of several ways. Illumination of the first intensity may be achieved by ambient light, or a first illumination source comprising any of, a visible light generating illumination source, a non- IR or non-NIR illumination source, or an IR or NIR illumination source. The field of illumination of the first illumination source may be configured to irradiate the image capture region with illumination of a first intensity. Illumination of a first intensity may be selected so as to be sufficient to enable image acquisition of the image capture region with sufficient detail to enable assessment whether the subject's eye / iris is suitably positioned within the image capture region. The illumination of the first intensity however need not be equal to (and preferably is significantly less than) intensity required to acquire eye / iris images of sufficient detail to enable the further steps of segmentation, feature extraction or image comparison.

Illumination of the second intensity may be achieve by any second illumination source comprising any of, a visible light generating source or an IR or NIR illumination source. The field of illumination of the second illumination source may be configured to irradiate the image capture region with illumination of a second intensity - wherein said illumination of second intensity (i) is greater than the first illumination intensity and (ii) is of sufficient magnitude to ensure capture of an image having adequate quality, texture information and detail to enable for the further steps of segmentation, feature extraction or image comparison for the purposes of biometric recognition.

It would be understood that in addition to the steps illustrated in Figure 2, in more particular embodiments, the invention may include additional steps. In one embodiment, if at step 204, assessment under the one or more predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method may first checks for occurrence of a termination event. The method terminates if a termination event has occurred, else the method may revert to step 202. In another embodiment of the method of Figure 2, subsequent to execution of either of steps 208 or 210, the method may revert to step 202. Reversion to step 202 may occur responsive to one or more of a predetermined set of events - for example, if it is found that the subject's eye no longer satisfies one or more suitability requirements previously tested for at step 204.

Figure 3 illustrates another embodiment of the method of the present invention. At step 302 the image capture region is subjected to illumination of a first intensity, and a first image frame of the image capture region is acquired by the imaging apparatus. Illumination of the first intensity may be achieved either by an illumination source associated with the biometric apparatus, or by ambient light. Step 304 thereafter checks whether the acquired first image frame meets a first set of predetermined criteria indicating unsuitability of position of the subject's eye / iris for further image processing. The first set of predetermined criteria may include (i) the subject's eye / iris being positioned partly or wholly outside the image capture region defined by the imaging apparatus, or (ii) the subject's eye being positioned partly or wholly outside of a depth of field defined in relation to the imaging apparatus, which depth of field is defined to enable capture of an image of the eye with detail sufficient for biometric purposes or (iii) both. If assessment of the first image frame under the first set of predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method reverts to step 302. If on the other hand, assessment of the first image frame under the first set of predetermined criteria does not indicate unsuitability, the method proceeds to step 306.

As in the embodiment discussed in connection with Figure 2, instead of checking against predetermined criteria indicating unsuitability of position of a subject's eye / iris, step 304 may in an alternate embodiment check whether the acquired image frame satisfies a first set of predetermined criteria indicating suitability of position of the subject's eye / iris for further image processing. In this alternate embodiment, the first set of predetermined criteria may include (i) the subject's eye / iris being wholly inside the image capture region defined by the imaging apparatus, or (ii) the subject's eye being positioned wholly within a depth of field defined in relation to the imaging apparatus, which depth of field is defined to enable capture of an image of the eye with detail sufficient for biometric purposes or (iii) both.

If assessment under the first set of predetermined criteria indicates suitability of position of the subject's eye / iris for further image processing, the method proceeds to step 306. If on the other hand, assessment under the predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method reverts to step 302.

At step 306 the image capture region is subjected to illumination of a second intensity, and a second image frame of the image capture region (and of the subject's eye / iris positioned therewithin) is acquired by the imaging apparatus. Illumination of the second intensity may be achieved by an illumination source associated with the biometric apparatus, wherein said illumination of second intensity (i) is greater than the first illumination intensity and (ii) is preferably of sufficient magnitude to ensure acquisition of a second image frame such that the second image frame is of adequate quality for evaluation according to a second set of predetermined criteria.

Step 308 thereafter checks whether the acquired second image frame meets a second set of predefined criteria indicating unsuitability of position of the subject's eye / iris for further image processing. The second set of predetermined criteria may include one or more of (i) small size of the eye / iris image acquired by the imaging apparatus, owing to distance at which the subject's eye is positioned (ii) limited usable eye / iris area within the image frame (iii) insufficient image margin (iv) unsuitable gaze angle, or (v) any other predetermined criteria indicating unsuitable positioning of a subject's eye / iris within the image capture region.

As in the case of step 304, instead of checking against predetermined criteria indicating unsuitability of position of a subject's eye / iris, step 308 may in an alternate embodiment check whether the acquired image frame satisfies a second set of predetermined criteria indicating suitability of position of the subject's eye / iris for further image processing. In this alternate embodiment, the second set of predetermined criteria may include one or more of (i) sufficiently large size of the eye / iris image acquired by the imaging apparatus (ii) sufficient usable eye / iris area within the image frame (iii) sufficient image margin (iv) suitable gaze angle, or (v) any other predetermined criteria indicating suitable positioning of a subject's eye / iris within the image capture region.

If assessment of the second image frame under the second set of predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method reverts to step 306. If on the other hand, assessment of the second image frame under the second set of predetermined criteria indicates suitability, the method proceeds to step 310.

At step 310 the image capture region is subjected to illumination of a third intensity, and a third image frame of the image capture region (and of the subject's eye / iris positioned there within) is acquired by the imaging apparatus. Illumination of the third intensity may be achieved by an illumination source associated with the biometric apparatus, wherein said illumination of third intensity (i) is greater than the second illumination intensity and (ii) is preferably of sufficient magnitude to ensure acquisition of an image of adequate quality for the further steps of segmentation, feature extraction and (or) image comparison. The third image frame may thereafter be subjected to one or more of the further steps of segmentation, feature extraction and image comparison.

At step 312 the method checks for a termination event (such as an identity decision, or a timeout instruction). If a termination event is not detected, the method may revert to step 310. If a termination event is detected, the method may terminate.

In an embodiment of the invention, magnitude of the illumination of first intensity is (i) sufficient for assessment of suitability or unsuitability of an image frame under the first set of predetermined criteria and (ii) insufficient for assessment of suitability or unsuitability of an image frame under the second set of predetermined criteria. In a further embodiment, magnitude of the illumination of second intensity is (i) sufficient for assessment of suitability or unsuitability of an image frame under the second set of predetermined criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction. In this embodiment, magnitude of the illumination of third intensity is sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

Illumination of the image capture region by differing first, second and third illumination intensities may be achieved in any one of several ways.

Illumination of the first intensity may be achieved by ambient light, or a first illumination source comprising any of, a visible light generating illumination source, a non- IR or non-NIR illumination source, or an IR or NIR illumination source. The field of illumination of the first illumination source may be configured to irradiate the image capture region with illumination of a first intensity. Illumination of a first intensity may be selected so as to be sufficient to enable image acquisition of the image capture region with sufficient detail to enable assessment according to the first set of predetermined criteria. The illumination of the first intensity however need not be equal to (and preferably is significantly less than) the second and third intensities of illumination. In an embodiment, illumination of the first intensity may be just sufficient to detect specular reflections received from a subject's eye. Illumination of the second and third intensities may be generated by any second illumination source and third illumination source respectively, which second and third illumination sources may comprise any of, a visible light generating source or an IR or NIR illumination source. The field of illumination of the second illumination source and of the third illumination source may be respectively configured to irradiate the image capture region with illumination of a second intensity and third intensity.

It would be understood that in addition to the steps illustrated in Figure 3, in particular embodiments, the invention may include certain additional steps. In an embodiment, if at step 304, assessment under the first set of predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method may check for occurrence of a termination event. The method may terminate if a termination event has occurred, else the method may revert to step 302. Similarly, if at step 308, assessment under the second set of predetermined criteria indicates unsuitability of position of the subject's eye / iris for further image processing, the method may check for occurrence of a termination event. The method may terminate if a termination event has occurred, else the method may revert to step 306.

In another embodiment of the method generally discussed in connection with Figure 3, subsequent to execution of step 308, the method may revert to step 302 wherein the image capture region is once again subjected to illumination of a first intensity, and an image frame of the image capture region is acquired by the imaging apparatus. Reversion to step 302 may occur responsive to one or more of a predetermined set of events - for example, if it is found that the subject's eye no longer satisfies one or more predetermined criteria previously tested for at step 304. Similarly, subsequent to execution of step 310, the method may revert to either step 302 or step 306, responsive to one or more of a predetermined set of events - for example, if it is found that the subject's eye no longer satisfies one or more predetermined criteria previously tested for at step 304 or at step 308 respectively. In embodiments of the invention as discussed in connections with Figures 2 and 3, illumination of at least two of the first, second and third intensities may be generated by a single illumination source that is controlled by an illumination controller configured to vary intensity of the generated illumination. In an embodiment, the respective fields of illumination of one or more of the first, second and third illumination sources may be configured to partially, substantially or entirely coincide with the image capture region of the biometric apparatus.

In embodiments of the invention as discussed in Figures 2 and 3, where the biometric apparatus is implemented within a mobile device, illumination of the first intensity may be generated by an illuminated display screen (such as an LCD or LED screen) of the mobile device, while illumination of one or more of the second and third intensities may be generated by an illumination source such as an incandescent light source, LED or other light source.

It would be understood that in implementing the embodiment of Figure 2, the biometric apparatus only requires to illuminate the image capture region with illumination of the second (higher) intensity subsequent to determining that a subject's eye / iris is suitably positioned within the image capture region. For the purpose of ascertaining whether the eye is suitably positioned within the image capture region, the apparatus relies on illumination of the first (lower) intensity - thereby achieving the objectives of (i) power conservation and (ii) reducing incidence of IR or NIR wavelengths upon a subject's eye / iris until it is determined that the eye / iris is correctly positioned within the image capture region of the imaging apparatus. Similarly, in implementing the embodiment of Figure 3, the tiered three stage increase in illumination, achieves both power conservation and reduction of incidence of IR or NIR wavelengths on a subject's eye / iris.

In an embodiment of the invention, the apparatus for controlling illumination intensity may include a controller for controlling power supplied to the illumination source(s) (and accordingly intensity of illumination generated at the illumination source). In one embodiment, the controller may be a processor implemented control (for example a control implemented by a processor located within a mobile device) capable of controlling intensity of the illumination source(s) to achieve a desired irradiance incident upon the image capture region. In another embodiment, the controller may comprise a sensor and control circuitry dedicated to control of the illumination source and that is independent of processors within the mobile device.

Figure 4 illustrates an exemplary system in which various embodiments of the invention may be implemented.

The system 402 comprises at-least one processor 404 and at-least one memory 406. The processor 404 executes program instructions and may be a real processor. The processor 404 may also be a virtual processor. The computer system 402 is not intended to suggest any limitation as to scope of use or functionality of described embodiments. For example, the computer system 402 may include, but not limited to, one or more of a general- purpose computer, a programmed microprocessor, a micro-controller, an integrated circuit, and other devices or arrangements of devices that are capable of implementing the steps that constitute the method of the present invention. In an embodiment of the present invention, the memory 406 may store software for implementing various embodiments of the present invention. The computer system 402 may have additional components. For example, the computer system 402 includes one or more communication channels 408, one or more input devices 410, one or more output devices 412, and storage 414. An interconnection mechanism (not shown) such as a bus, controller, or network, interconnects the components of the computer system 402. In various embodiments of the present invention, operating system software (not shown) provides an operating environment for various softwares executing in the computer system 402, and manages different functionalities of the components of the computer system 402. The communication channel(s) 408 allow communication over a communication medium to various other computing entities. The communication medium provides information such as program instructions, or other data in a communication media. The communication media includes, but not limited to, wired or wireless methodologies implemented with an electrical, optical, RF, infrared, acoustic, microwave, bluetooth or other transmission media.

The input device(s) 410 may include, but not limited to, a touch screen, a keyboard, mouse, pen, joystick, trackball, a voice device, a scanning device, or any another device that is capable of providing input to the computer system 402. In an embodiment of the present invention, the input device(s) 410 may be a sound card or similar device that accepts audio input in analog or digital form. The output device(s) 412 may include, but not limited to, a user interface on CRT or LCD, printer, speaker, CD/DVD writer, LED, actuator, or any other device that provides output from the computer system 402.

The storage 414 may include, but not limited to, magnetic disks, magnetic tapes, CD- ROMs, CD-RWs, DVDs, any types of computer memory, magnetic stipes, smart cards, printed barcodes or any other transitory or non-transitory medium which can be used to store information and can be accessed by the computer system 402. In various embodiments of the present invention, the storage 414 contains program instructions for implementing the described embodiments.

In an embodiment of the present invention, the computer system 402 is part of a distributed network where various embodiments of the present invention are implemented for rapidly developing end-to-end software applications.

The present invention may be implemented in numerous ways including as a system, a method, or a computer program product such as a computer readable storage medium or a computer network wherein programming instructions are communicated from a remote location.

The present invention may suitably be embodied as a computer program product for use with the computer system 402. The method described herein is typically implemented as a computer program product, comprising a set of program instructions which is executed by the computer system 402 or any other similar device. The set of program instructions may be a series of computer readable codes stored on a tangible medium, such as a computer readable storage medium (storage 414), for example, diskette, CD-ROM, ROM, flash drives or hard disk, or transmittable to the computer system 402, via a modem or other interface device, over either a tangible medium, including but not limited to optical or analogue communications channel(s) 408, or implemented in hardware such as in an integrated circuit. The implementation of the invention as a computer program product may be in an intangible form using wireless techniques, including but not limited to microwave, infrared, bluetooth or other transmission techniques. These instructions can be preloaded into a system or recorded on a storage medium such as a CD-ROM, or made available for downloading over a network such as the Internet or a mobile telephone network. The series of computer readable instructions may embody all or part of the functionality previously described herein.

While the exemplary embodiments of the present invention are described and illustrated herein, it will be appreciated that they are merely illustrative. It will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from or offending the spirit and scope of the invention as defined by the appended claims.

Claims

Claims:

1. An apparatus for eye based biometric recognition comprising: an imaging apparatus; at least one illumination source; and an illumination controller configured to control intensity of illumination generated by one or more illumination sources; wherein the apparatus is configured to: acquire a first image frame of an image capture region under illumination of a first intensity; and respond to a determination that the first image frame meets at least a first suitability criteria, by:

illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity; and

acquiring a second image frame of the image capture region under illumination of the second intensity.

2. The apparatus as claimed in claim 1, wherein the apparatus is configured to respond to a determination that the second image frame meets at least a second suitability criteria, by: illuminating the image capture region with illumination of a third intensity, such that the third intensity is greater than the second intensity; and acquiring a third image frame of the image capture region.

3. The apparatus as claimed in claim 1, wherein the first suitability criteria includes any one or more of (i) presence of an eye or iris within the image capture region, (ii) eye or iris positioned wholly within the image capture region, (iii) minimum size of the eye image or iris image acquired by the imaging apparatus (iv) sufficient usable eye area or iris area within the image frame (v) sufficient image margin and (vi) suitable gaze angle.

4. The apparatus as claimed in claim 2, wherein the first suitability criteria includes any one or more of (i) an eye or iris positioned wholly inside the image capture region corresponding to the imaging apparatus, or (ii) an eye or iris positioned wholly within a depth of field corresponding to the imaging apparatus.

5. The apparatus as claimed in claim 2, wherein the second suitability criteria includes any one or more of (i) minimum size of an eye image or iris image acquired by the imaging apparatus (ii) sufficient usable eye area or iris area within the image frame (iii) sufficient image margin and (iv) suitable gaze angle.

6. The apparatus as claimed in claim 1, wherein the apparatus is configured to: acquire the first image frame of the image capture region under illumination from a first illumination source; and acquire the second image frame of the image capture region under illumination from a second illumination source.

7. The apparatus as claimed in claim 6, wherein the first illumination source is a display screen.

8. The apparatus as claimed in claim 1, wherein the apparatus is configured to: acquire the first image frame of the image capture region under ambient illumination; and acquire the second image frame of the image capture region under illumination from the at least one illumination source.

9. The apparatus as claimed in claim 1, wherein magnitude of the illumination of first intensity is (i) sufficient for assessment of an image frame against the first suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

10. The apparatus as claimed in claim 9, wherein magnitude of the illumination of second intensity is sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

11. The apparatus as claimed in claim 2, wherein magnitude of the illumination of second intensity is (i) sufficient for assessment of an image frame against the second suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

12. The apparatus as claimed in claim 11, wherein magnitude of the illumination of third intensity is sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

13. A method for illuminating an image capture region of an eye based biometric recognition, the method comprising: acquiring a first image frame of an image capture region under illumination of a first intensity; and responding to a determination that the first image frame meets at least a first suitability criteria, by: illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity; and acquiring a second image frame of the image capture region under illumination of the second intensity.

14. The method as claimed in claim 13, further comprising responding to a determination that the second image frame meets at least a second suitability criteria, by: illuminating the image capture region with illumination of a third intensity, such that the third intensity is greater than the second intensity; and acquiring a third image frame of the image capture region.

15. The method as claimed in claim 13, wherein the first suitability criteria includes any one or more of (i) presence of an eye or iris within the image capture region, (ii) eye or iris positioned wholly within the image capture region, (iii) minimum size of the eye image or iris image acquired by the imaging apparatus (iv) sufficient usable eye area or iris area within the image frame (v) sufficient image margin and (vi) suitable gaze angle.

16. The method as claimed in claim 14, wherein the first suitability criteria includes any one or more of (i) an eye or iris positioned wholly inside the image capture region corresponding to the imaging apparatus, or (ii) an eye or iris positioned wholly within a depth of field corresponding to the imaging apparatus.

17. The method as claimed in claim 14, wherein the second suitability criteria includes any one or more of (i) minimum size of an eye image or iris image acquired by the imaging apparatus (ii) sufficient usable eye area or iris area within the image frame (iii) sufficient image margin and (iv) suitable gaze angle.

18. The method as claimed in claim 13, further comprising: acquiring the first image frame of the image capture region under illumination from a first illumination source; and acquiring the second image frame of the image capture region under illumination from a second illumination source.

19. The method as claimed in claim 18, wherein the first illumination source is a display screen.

20. The method as claimed in claim 13, further comprising: acquiring the first image frame of the image capture region under ambient illumination; and acquiring the second image frame of the image capture region under illumination from the at least one illumination source.

21. The method as claimed in claim 13, wherein magnitude of the illumination of first intensity is (i) sufficient for assessment of an image frame against the first suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

22. The method as claimed in claim 21, wherein magnitude of the illumination of second intensity is sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

23. The method as claimed in claim 14, wherein magnitude of the illumination of second intensity is (i) sufficient for assessment of an image frame against the second suitability criteria and (ii) insufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

24. The method as claimed in claim 23, wherein magnitude of the illumination of third intensity is sufficient for acquisition of an image frame having sufficient eye texture information or iris texture information to enable one or more of segmentation and feature extraction.

25. A computer program product for illuminating an image capture region of an eye based biometric recognition, comprising a computer usable medium having a computer readable program code embodied therein, the computer readable program code comprising instructions for: acquiring a first image frame of an image capture region under illumination of a first intensity; and responding to a determination that the first image frame meets at least a first suitability criteria, by: illuminating the image capture region with illumination of a second intensity, where the second intensity is greater than the first intensity; and acquiring a second image frame of the image capture region under illumination of the second intensity.