CN101137997A - Systems and methods for improved biometric feature definition - Google Patents

Abstract

Methods and systems are provided for performing a biometric function. A purported skin site of an individual is illuminated under distinct optical conditions during a single illumination session for a fixed position of the purported skin site. Light from the purported skin site is received for each of the optical conditions. Images of the purported skin site are generated from the received light. The images are analyzed to identify a biometric feature as a characteristic in a portion of at least one of the images. The biometric function is implemented in accordance with an identification of the biometric feature.

Description

Be used to improve the System and method for of determining of biometric characteristic

The cross reference of associated documents

The application to be on January 7th, 2005 submitted to by Robert K.Rowe., Application No. is 60/641,991, denomination of invention is the non-provisional application of " SYSTEMS AND METHODS FOR IMPROVEDBIOMETRIC FEATURE DEFINITION ", and requires its right of priority.

The application was submitted to by people such as Robert K.Rowe. on April 5th, 2004, Application No. is 10/818,698, denomination of invention is the part continuation application of " MULTISPECTRAL BIOMETRIC SENSOR ", this application is that the Application No. of submitting on April 4th, 2003 is 60/460,247 application, the Application No. that on June 27th, 2003 submitted to is 60/483,281 application, the Application No. that on September 18th, 2003 submitted to is 60/504,594 application and on March 10th, 2004 submit to, Application No. is the non-provisional application of each application in 60/552,662 the application.

The application was submitted to by Robert K.Rowe. on April 25th, 2005, Application No. is 11/115,100, denomination of invention is the part continuation application of " MULTISPECTRAL IMAGINGBIOMETRICS ", this application is that the Application No. of submitting on June 1st, 2004 is 60/576,364 application, the Application No. that on August 11st, 2004 submitted to is 60/600,867 application, the Application No. that on September 17th, 2004 submitted to is 60/610,802 application, on February 18th, 2005 submitted to, Application No. is 60/654,354 application and on March 4th, 2005 submit to, Application No. is the non-provisional application of each application in 60/659,024 the application.

The application was submitted to by Robert K.Rowe. and Stephen P.Corcoran on April 25th, 2005, Application No. is 11/115,101, denomination of invention is the part continuation application of " MULTISPECTRALBIOMETRICS IMAGING ", this application is that the Application No. of submitting on June 1st, 2004 is 60/576,364 application, the Application No. that on August 11st, 2004 submitted to is 60/600,867 application, the Application No. that on September 17th, 2004 submitted to is 60/610,802 application, the Application No. that on February 18th, 2005 submitted to is 60/654, the Application No. of submitting in 354 application and on March 4th, 2005 is the non-provisional application of each application in 60/659,024 the application.

The application was submitted to by Robert K.Rowe. on April 25th, 2005, Application No. is 11/115,075, denomination of invention is the part continuation application of " MULTISPECTRAL LIVENESSDETERMINATION ", this application is that the Application No. of submitting on June 1st, 2004 is 60/576,364 application, the Application No. that on August 11st, 2004 submitted to is 60/600,867 application, the Application No. that on September 17th, 2004 submitted to is 60/610,802 application, the Application No. that on February 18th, 2005 submitted to is 60/654, the Application No. of submitting in 354 application and on March 4th, 2005 is the non-provisional application of each application in 60/659,024 the application.

The application relates to application following pending trial, that be commonly assigned: on September 17th, 2004 was 60/610 by the Application No. that RobertK.Rowe submits to, 802, denomination of invention is 11/015 for application and on Dec 17th, 2004 of " FINGERPRINT SPOOF DETECTION USING MULTISPECTRALIMAGING " by the Application No. that Robert K.Rowe submits to, 732, denomination of invention is the application of " COMBINEDTOTAL-INTERNAL-REFLECTANCE AND TISSUE IMAGING SYSTEMSAND METHODS ".

Above-mentioned each that mention applies for that in fact all integral body is incorporated herein by reference.This merging of carrying out by reference comprises that Application No. is the appendix of 60/641,991 application.

Technical field

The present invention relates in general to field of biometrics.Particularly, the present invention relates to be used to improve the system and method for determining of biometric characteristic.

Background technology

By biometric system obtain required performance depend on substantially with biometric characteristic in the data acquisition and the other parts in the data acquisition isolate ability---biometric characteristic may be used for discerning people's identity, the identification then general and people of the other parts in the data acquisition has nothing to do.For example, consider the situation of fingerprint sensor.When each fingerprint image is gathered, the unique various phenomenon of image is influenced.Even when identical fingerprint also is such during by imaging.For example, finger is placed on that the different piece that all can make finger on the sensor contacts with sensor and by imaging at every turn.The direction of finger and the difference of pressure can cause the distortion of skin, change and other pseudomorphism that influences fingerprint image characteristics of picture contrast.Sensor self also may be introduced pseudomorphism in the image, and pseudomorphism changes between image and the image.The pseudomorphism that these sensors cause may comprise and pass through fixed pattern noise that the plane of delineation changes in a certain way and many high frequency imaging noise sources that it comprises shot noise and dark noise among the noise source that is in other type.

Because the existence in the abiotic statistics source of these kinds variation, usually, two width of cloth fingerprint images can not directly compare by shirtsleeve operation, determine that as adopting the image subtraction whether they are from same individual.On the contrary, be used for adding up the image of registered database or at the image that is used for testing, the prominent feature of image is discernible no matter be.Relatively these features, determining in two width of cloth images, whether having abundant feature, and whether on essentially identical correlation space position.If like this, then this two width of cloth image is called coupling; Otherwise this two width of cloth image then is judged to be and does not match.

Many existing fingerprint sensors need be pointed with sensor and directly contact with images acquired.When finger when insufficient with contacting of sensor, finger reduces with the direct area that contacts between sensor, and understands the disappearance that cause biometric information in collection.Usually, from this image area that reduces, can only extract less biometric characteristic, so that the correct decline of judging the ability of fingerprint image matching.

For the fingerprint characteristic with suitably definition solves some shortcomings in these shortcomings, many systems need the user more than one sample is provided, in system database, to register.By this way, may need the multiple image of same finger, and the common trait that will analyze multiple image, pass through each registration image with detection.But the ability whether definite real biometric characteristic exists still relates to finger orientation, translation, rotation, twists and spreads all over the difference of the aspects such as other image artifacts of registered image set.In addition, gathering and compare several fingerprint images mostly just is to be feasible in registration procedure.In the implementation of normal biometrics function, in identification or verification process, most applicable cases needs biometric sensor to adopt the single fingerprint image that is acquired rapidly to operate.In such scene, have no chance by adopting multiple image to improve the feature detection of test sample book.

Generally, fingerprint sensor also can be gathered the image of the surface that is derived from finger skin.But these surfaces will experience the variation that the difference of wearing and tearing, dirt or environmental baseline is brought, and perhaps all these can further have influence on determining of fingerprint characteristic.And these character of surface based on the indistinct finger mark on the plane of staying smooth atresia, just can be relatively easy to duplicate.Therefore, only relying on, traditional fingerprint sensor of energy measurement finger surface feature has many negative results.At first, number and quality that can detected biometric characteristic be limited to those features that exist on the surface skin, but these features may wear and tear or lack.The second, depend on the imagineering of the fingerprint pattern that the sensor that is present in the feature on the appearance skin adopt to authorize specially, be easy to generate potential safety hazard.

Because finger approximate circle cylinder, so, the trend that skin has the edge from sensor surface towards imaging region to break away from.Therefore, the fingerprint image of gathering for the requirement of enforcement generally adopts rolling process collection.In such process, finger is when sensor surface rolls, and finger-image is obtained, so that finger more partly can contact with sensor, to allow them by imaging.This process is time-consuming, and has caused certain trouble to the user, wants correct these data of collection all to need skilled operating personnel to help just can finish usually.So although on principle, the increase of image-region can improve performance, this fingerprint image acquisition method can not be used by automatic or unattended biometric sensor usually.

In view of the above, in the art, exist a kind of method and system to carry out improved technical need to the collection biological statistics that can determine biometric characteristic.

Summary of the invention

Embodiments of the invention provide the method that realizes the biometrics function.Under multiple different optical condition, in single illumination in the period, at the fixing substantially position irradiation people's of skin part specific skin part.For in a plurality of different optical conditions each, can receive light from this specific skin part.Receive light by these, just can form the multiple image of this specific skin part.Analyze described multiple image, with identification biometric characteristic, as the feature in the part of at least one image in the described image.This biometrics function realizes according to the identification of this biometric characteristic.

In certain embodiments, biometric characteristic is the total feature of various piece of a plurality of images in the described multiple image.In certain embodiments, described biometric characteristic also can comprise a lot of biometric characteristics.In this case, described a plurality of image can be analyzed by the spatial coherence between the identification multiple image under for the identical condition of the placement location at each image in a plurality of images, described particular skin position, allows described a plurality of biometric characteristic to be discerned according to the spatial coherence of being discerned.The realization of biometrics function in these embodiments, also can comprise with described a plurality of biometric characteristics be stored in database in, the one group biometric characteristic relevant with the set of identified person's biometric characteristic gather and compare.

In one embodiment, this specific skin part can comprise people's a finger, and described a plurality of images comprise fingerprint image, and described biometric characteristic comprises the minutiae point of fingerprint image.In other embodiments, this biometric characteristic is included in ridge on the skin part and the expression of paddy.In a further embodiment, this biometric characteristic comprises the feature that the subsurface blood vessel of this specific skin part exists.The example of a plurality of different optical conditions comprises different illumination wavelength, different polarization conditions, different irradiation or imaging direction, different focal plane and other.The example of implementing the biometrics function comprises the identity of discerning the people or examining the people.In certain embodiments, the light that receives from the particular skin position may comprise from this subsurface scattered light in particular skin position.Described multiple image can comprise total internal reflection (" the TIR ") image and the non-total internal reflection images of this skin part.

In one embodiment, this particular skin position comprises people's finger, and contacts with platen.Described a plurality of image comprises finger-image, and biometric characteristic is included in the people's who is identified outside this particular skin position and the platen contact point biometric characteristic.

Described multiple image can allow this biometric characteristic being identified in the piece image at least of skeletonizing in described image by the boneization of piece image at least in the described image is analyzed in some cases.In another embodiment, described a plurality of images can resolve into one group of basic function by the part with the piece image at least in the described image to be analyzed, and wherein said biometric characteristic comprises by the one group of coefficient that is decomposed to form.

The method of realization biometric characteristic function can be implemented in biometric system.This biometric system comprises platen, irradiation source, imaging system and controller.This platen is suitable for placing people's particular skin position.This irradiation source is set for when this particular skin position is placed on the platen it is shone.This imaging system is set for the light of reception from this particular skin position.This controller comprises the instruction that is used for implementing based on biometric system said method.

Description of drawings

Can further understand essence of the present invention and advantage with reference to hereinafter detailed description part and accompanying drawing, wherein, identical Reference numeral is indicated similar parts in the text.In some cases, Reference numeral comprises the numerical portion that has Latin alphabet suffix; Only the numerical portion of quoted figures mark represents to quote together the Reference numeral that contains this numerical portion but have different Latin alphabet suffix.

Fig. 1 is the process flow diagram of summarizing the various aspects of a plurality of embodiment of the present invention;

Fig. 2 is the functional structure schematic diagram according to the biometric system of the embodiment of the invention;

Fig. 3 A-3C be used to illustrate according to the different embodiment that different illumination wavelength and/or different polarization condition be provided of the present invention, can gather the biometric sensor of multiline data;

Fig. 4 is used for illustrating at of the present invention another provides the embodiment at many irradiation sources and detection angle can gather the biometric sensor of multiline data;

Fig. 5 A and 5B provide the side view and the front view of biometric sensor among another embodiment of poly focal plane, that can gather the multiline data respectively;

Fig. 6 is used to illustrate the biometric sensor that has made up the described biometric sensor each side of Fig. 3 A-5B, to allow utilizing a plurality of illumination wavelength, the adjusting of a plurality of polarization, a plurality of illumination angle, a plurality of detections angle and a plurality of plane of delineation to gather the multiline data;

Fig. 7 represents to carry out untreated image and the treated image that three kinds of different optical configurations of imaging obtain by the finger with dry skin on the platen that is used to be opposite to biometric sensor of the present invention; And

Fig. 8 represents by being used for carrying out untreated image and the treated image that three different optical configurations of imaging obtain with minimum contact takes place for the platen of biometric sensor of the present invention finger.

Embodiment

Embodiments of the invention provide the system and method for realizing the biometrics function by the multiple image that obtains a skin part in the single irradiation period under different optical conditions.Therefore, these images comprise the different information about this skin part, and these information can combine in every way to produce determining biometric characteristic reliably.The use of single irradiation period can make described image generate from the position of the almost fixed of skin part, has eliminated the uncertainty of feature aspect relative orientation between image, thereby has improved precision and reduced processing requirements.

Term " biostatistics " typically refers to the statistical study to the life entity feature.A branch of biostatistics comprises " biometric identification ", and it is usually with a kind of operation the in two kinds of patterns, provides people's automatic identification or examines people's identity.Arrive as used herein, " biometric characteristic ", or only be called " feature " sometimes, be meant to comprise and the biometrics task, such as a width of cloth of the relevant information of the judgement of biometric identification, identity verification, activity, sample reliability and other similar task or those parts of set of diagrams picture.Term " part " is meant the part of the object except the integral body of object; Therefore, " part " of image is meant and is not entire image but a part of image.In different certain embodiments, the part of image can refer to be less than in the image image area 10%, that be less than image area 5%, that be less than image area 2%, that be less than image area 1%, be less than image area 0.5%, be less than image surface circle 0.2%, that be less than image area 0.1% or become the part of other small scale with image area.

Comprise that at skin part under the situation of finger, biometric characteristic comprises " minutiae point ", these " minutiae point " are well known in fingerprint technique, and they are the local fingerprint ridge features that appear at ridge crotch and ridge termination.Comprise in other situations of finger the specific pattern that biometric characteristic forms in the part of fingerprint image for ridge and paddy by fingerprint at skin part.

Here the skin part that can be applicable to measure of Miao Shuing comprises all surfaces and whole joint, nail and all other outer surfaces of nail matrix, palm, the back of the hand, wrist and forearm, face, eye, ear and health of finger and thumb.Although following discussion is carried out at " finger " sometimes especially, should be appreciated that these embodiment only are used for demonstration, and other embodiment also can be used on the skin part at other part places of health in the certain embodiments that is provided.

Being integrated into of all images that collects in the single irradiation period, under much different optical conditions is meant what is called " multiline data " here.Described different optical condition can comprise the difference of polarization conditions, the difference of irradiating angle, the difference of imaging angle, the difference of illumination wavelength and the position difference of the skin part plane of delineation, and wherein said plane is referred to herein as " focal plane ".Under some optical conditions, the appearance of the total internal reflection at the interface between sample and platen (" TIR ") phenomenon and distribution are very obvious to the influence of the image of gained.These images are called as " total reflection image " here.Under some optical conditions, the image that obtains comes down to not to be subjected to the platen place whether to have the influence of TIR effect.These images are meant " direct projection image (direct image) " here.

Only for for example, be included among the embodiment of the image that obtains under the different illumination wavelength in the multiline data, wavelength may (UV-A be 320-400nm) to middle infrared (Mid-IR) (～5 μ m) near ultraviolet ray.Can be used on detectable wavelength in the embodiment of about 300nm in about 1100nm scope based on the imaging array of silicon.In these cases, illumination wavelength can advantageously selectedly be located in the detectable scope.In some cases, illumination wavelength is within the visible spectrum zone (400-700nm).Here used " discrete wavelength " is meant set of wavelengths or the wavestrip as single accomodating unit, and for each accomodating unit, information only extracts from accomodating unit on the whole, rather than extracts from the single wavelength subclass of accomodating unit.In some cases, described accomodating unit may be discontinuous, so that when multiple discrete wavelength was provided, certain wavelength between any two wavelength or wavestrip was not provided, but this not necessarily.

Wherein the multiline data embodiment that is included in the image that obtains under the different polarization conditions can be included in cross polarization attitude, parallel polarization attitude and/or not have the image that obtains under the polarization state.Polarisation of light may be linearity or oval.Under the situation of linear polarization, " intersection " means that the optical axis of polarizer roughly is a quadrature.Under the situation of elliptic polarization, " intersection " means that polarizer roughly is rightabout (dextrorotation is to left-handed).

Comprise for multiline data wherein and the embodiment of the image that obtains with different illumination angles can provide irradiates light to realize with different angles by the platen of placing with respect to skin part.In some cases, by forming described image with irradiates light roughly less than the angle incident of the skin one formed critical angle in platen interface.Under other situation, by forming described image with irradiates light roughly greater than the angle incident of the skin one formed critical angle in platen interface.

Comprise for multiline data wherein and the embodiment of the image that obtains with different imaging angles can realize with the detector array of different angles orientation by the platen that is placed on it with respect to skin part.In some cases, some images are by forming with the detector array of observing skin part less than the angle of the skin one formed critical angle in platen interface.In other situations, some images are by forming with the detector array of observing skin part greater than the angle of the skin one formed critical angle in platen interface.

Comprise the embodiment of the image that obtains with different focal planes for multiline data wherein, can by have can carry out the zoom adjustment so that not the imaging system of the sample areas imaging correctly that directly contacts with platen realize.For example, in the first such image, the focus of imaging system is set to be imaged on the interface between skin part and the platen.In the second such image, focus may be set again with on the plane that is imaged on (promptly in the sample side) a distance, platen top, or the like.In certain embodiments, the imaging system of corresponding this varifocal imaging device is configured to the heart far away, even a series of image that overlaps partly is set in out of focus.

Embodiment can be alternatively or is additionally adopted and have fixed-focus but the big relatively imaging system of depth of focus, promptly uses varifocal imaging system alternatively or additionally.In this case, imaging system can be arranged to: suitable focus area comprises the position surperficial and (promptly in the sample side) a distance above platen of platen, and making is enough to more most imaging samples.In some cases, this imager provides telecentric imaging, and this can guarantee that the outer zone of focus spatially aims at other focus inner plane.

Only in the mode of explanation, comprise at skin part under the situation of finger, the embodiment of corresponding different focal planes allows the feature except that fingerprint characteristic to be extracted from some or all planes of delineation.For example, can be detected by the one or more planes of delineation with the wavelength that is absorbed by blood level such as the features such as blood vessel of depths, it can comprise and roughly is positioned at the oxyhaemoglobin peak value of 540nm to 576nm.In some cases, analyzed with the corresponding many planes of delineation of many illumination wavelength, be used to discern and have the feature of forming corresponding spectral signal with blood or other skin.

Method of the present invention is generalized into the process flow diagram of Fig. 1.Although set some steps that can implement in certain embodiments among Fig. 1, the present invention also can comprise other embodiment.Especially, sequence of steps shown in the figure is not limited to this, and some particular step in the process flow diagram neither be necessary, and some steps can be canceled in further embodiments, and some additional steps that clearly do not provide also can increase implementation in further embodiments.

This method is from module 104, and the user is placed on skin part on the platen of biometric sensor.Although following description relates to " skin part ", but be to be appreciated that, because multiline technology described herein has the ability of distinguishing real biological tissue and various fakements, therefore, embodiments of the invention also can be used for the sensing and the analysis of any " being claimed " skin part more at large.Multiline is measured and is realized on skin part, manually or automatically triggers measuring sequence in different embodiment.Automatically triggering can realize by the mechanism that comprises photoswitch, capacitance switch, pressure switch, mechanical switch and other similar device, and can advantageously utilize one or more be suitable for locating, cameras, with the position of the described skin part of real-time detection with Flame Image Process.

Measuring sequence can be from module 108 by irradiation skin part under the multiline condition.Such irradiation is usually in the single illumination period, carry out at the almost fixed position of described skin part.One of ordinary skill in the art will appreciate that even if in single illumination in the period, the irradiation under the multiline condition also can be carried out simultaneously or order is carried out.Illumination is simultaneously or order depends in part on the special characteristic of multiline condition, and the different examples of following ad hoc structure are for example understood can realize the structure that throws light on simultaneously under the multiline condition of certain type.When illumination was carried out in proper order, the time that whole process continues will enough lack, and usually less than one second, in this process, the motion of skin part is minimum.

Then, in module 112, receive light from skin part.The light that receives may be included in the light of the surface reflection of this skin part, such as from platen one skin interface, and/or may comprise from the scattered light under the surface of this skin part.This subsurface scattering provides can not getable information in traditional fingerprint imaging technology.Especially, the ability of extracting biometric information under the surface provides a kind of mechanism that realizes that biometrics is judged, even if still can realize under the situation that surface characteristics lacks or damages.By this way, embodiments of the invention are for nonideal skin quality, as dry, humidity is excessive, lack flexibility, and/or the feature of wearing and tearing, typical as with old man, the people that is engaged in heavy physical labour, perhaps those skins are exposed to the people in the chemical substance, such as hairdresser or nurse etc., are durable.

In module 116, receive light and generate image with certain processing mode.Processing may comprise the different image of extraction from single composograph.Processing also can comprise image processing step, such as histogram equalization, contrast enhancing, edge enhancing, noise filtering and similar processing.Image segmentation can be used to remove image background, and only stays the zone that sample exists.Shown in module 120, processing also can comprise the conversion of enforcement to the one or more image, so that piece image spatially aligns with other images.Recognition of Spatial between image makes the existence that is identified biometric characteristic between multiple image present correlativity.

The image processing process that extracts these biometric characteristics carries out in module 124.For example, comprise among the embodiment of finger, on each width of cloth single image, can find minutiae point at skin part.Similarly, the whole pattern of ridge and paddy also can be determined, and perhaps specific interesting areas as the central area of fingerprint, also can be identified in image.In some cases, the combination of some image or image can the analyzed distinguishing characteristics of other spectrum to determine to exist in blood characteristics or the image.Described biometric characteristic can comprise one group of coefficient, and described one group of coefficient is by resolving into the fingerprint characteristic in regional area one group of basic function that is fit to, and as sinusoidal wave, gal uncle's wave filter or different wavelet etc., and is formed.The identification of this biometric characteristic can advantageously be avoided traditionally by the negative effect that pseudomorphism caused that exists in the image.Therefore, this identification is different from the identification of traditional fingerprint image, and in traditional fingerprint image identification, many factors (as dry skin) may cause the contrast of image very low, so that it is discontinuous that ridge is rendered as, and makes to be difficult to distinguish minutiae point from simple image artifacts.

In biometric characteristic was found in embodiment on a plurality of planes of delineation, those features can be carried out combination, shown in module 128.Because these images spatially are mutually related, and represent the position of identical skin part, so the position of these features can be defined between the image well.Thus, can be by appropriate mathematical operation, as ask average, perhaps as " with " or " or " these logical combination computings, or by these features are assessed or made up to the mode that exists the special characteristic of crossing over the plane of delineation to put to the vote individually.Combined feature set can comprise the Warning Mark which plane of delineation some indicate from single features sources, perhaps to some other designators of characteristic type or source indication.

For example, composite character can generate according to this rule in one embodiment: promptly, if composite character (for example, minutiae point) is present in the plane of delineation at least and in the position of being defined, shows that then this feature is present on this position.In another embodiment, if composite character is present in the plane of delineation of half (or certain other special ratios) at least in the described plane of delineation and in a position, then this feature is expressed as being present on this position.Another embodiment may need feature to be present in all images plane and in described position, can represent to exist composite character.In embodiment also, composite character can be generated by following rule: but only when composite character is present near all images plane that has recognition feature feature locations, represent that just this feature is present on the position of being defined.The rule that is used for existing at different embodiment expression composite characters is obvious for the those of ordinary skills that read this description.

In certain embodiments, the information that different stage place on stream is obtained from image can combine, especially before the characteristic extraction step of module 124.For example, raw video picture can combine in some way, and as suing for peace by pixel one pixel, perhaps pretreated image also can combine in some way.In other example, the numerical value that from image, obtains, as gal uncle's wavelet coefficient or gradient fields, can be by being combined as averaging, strengthen calculating such as average (robust mean), intermediate value.

In addition, in certain embodiments, feature can be identified by the check image combination.Only by way of example, in one embodiment, blood characteristics can be present in the blood volume of each pixel position in each width of cloth image in the set of diagrams picture by assessment and be found out, and wherein said set of diagrams picture is corresponding to a plurality of illumination wavelength based on known absorption spectra of blood.Mathematics manipulation can be used to carry out these analyses as the minimum variance estimate of classics and multiple other known method of estimation.

Characteristic set is can be under typical biometrics operation processed realizing the biometrics function, as register, examine, identification and/or fraud detection.For example, provide the people of skin part to be identified, perhaps his identity can be verified.These biometrics functions can be in certain embodiments compare by the combination of the biometric characteristic that will obtain and property data base and realize, shown in module 132.For example, database can comprise the detailed description of the combination of the biometric characteristic that obtains from a plurality of people, as the part of enrollment process, and by combination and the content in the database that generates in module 128 compared in module 132 these biometrics functions of realization.

The overall general picture of structure of biometric system that is suitable for realizing the method for Fig. 1 provides in the schematic diagram of Fig. 2.Fig. 2 expresses each system element roughly and realizes as how discrete or more integrated mode.Biometric system 200 illustrates and comprises the hardware element that is electrically connected through bus 226.Described hardware element comprises processor 202, input media 204, output unit 206, memory storage 208, computer-readable storage media reader 210a, communication system 214, handles accelerator module 216 (such as DSP or other application specific processors) and internal memory 218.Described computer-readable storage media reader 210a further is connected to computer-readable recording medium 210b, that this combination is represented all sidedly is long-range, local, fixing and/or movably memory storage add the storage medium that carries computer-readable information provisionally and/or more muchly.That described communication system 214 can comprise is wired, wireless, the connecting interface of modulator-demodular unit and/or other type, and allows data and external device (ED) to exchange.Gather the multiline data by biometric sensor 256, described biometric sensor 256 also can be electrically connected by bus 226.

Biometric system 200 comprises also and is depicted as the current software element that is sitting in the working storage (workingmemory) 220 that described software element comprises operating system 224, other code 222, for example the program for realizing that the inventive method designs.The change that system can carry out substantially according to specific needs is conspicuous to those skilled in the art.For example, the hardware of customization also can adopt, and/or specific element can be realized in hardware, software (comprising portable software, as Macintosh (applets)) or both.Further, also can be connected to other calculation element, as the network input/output device.

The multiple different structure that can be used for biometric sensor 25 among the different embodiment is provided in Fig. 3 A-6 for the purpose of description.For example, Fig. 3 A expresses under the multiline condition that is provided, combines the example of the biometric sensor 300 of many illumination wavelength.As the part of biometrics function, the multi-wavelength carries out different interactions with the different component of customer-furnished finger or other tissue usually.For example, absorbed consumingly by blood less than the wavelength of about 600nm, and because the existence of oxyhaemoglobin has strong peak value at about 540nm and 576nm place especially.Usually, it is darker that the long wavelength (for example, ruddiness or infrared light) of light infiltrates skin, and be subjected to the influence of darker structure; Short wavelength (as blue light or black light) infiltrates more shallow, is subjected to the strong influence of surface and nearly surface skin structure.

Skin part 304 rests on the platen 308 among Fig. 3 A, and described platen is transparent or semitransparent to the wavelength that is used to shine skin part 304.Photo-detector 312 as digital camera, is used for forming the image of the skin of skin part 304 by multiple lens, mirror and/or other optical element (Fig. 3 is not shown) with the near interface of platen 308.Detector 312 can be to wide wavelength coverage sensitivity.In some cases, detector 312 can combine with the digital imagery silicon chip.This camera based on silicon (silicon-based) can be " black and white " camera, can survey to cover the approximately wide wavelength coverage from 350nm to 1100nm.

Irradiation source 310 can be provided as the accurate monochromatic source of different wave length.The example of suitable sources 310 comprises light emitting diode (" LEDs "), laser, laser diode, quantum dot (quantum dots), the incandescent source that filters and other.In detector 312 comprised embodiment based on the sensor of silicon, the wavelength of light source 310 can be selected in the about scope between 350nm and the 1100nm.In one embodiment, light source is positioned at the visible range of about 400-700nm.Can blaze abroad in different ways and directly towards skin part 304 from the light in each source 310.For example, light can adopt the optical element as lens and/or mirror and be expanded or collimate.Can use scattering medium to make light diffusion, described scattering medium can be such as obscured glass material piece, opal, holographic diffuser, translucent plastic and other mechanism known in the art.

The sequence of operation of sensor 300 is with following sequential illumination: the light source 310-1 of specific wavelength is used for irradiation and obtains and memory image to allow detector 312.Then, the first light source 310-1 closes, and secondary light source 310-2 opens and shines.Afterwards, detector 312 obtains and stores down piece image.This order can repeat repeatedly in 310 continuation of all light sources.Alternately, each light source 310 can be modulated with well-determined frequency, and detector 312 with any one irradiation modulating frequency frequency all inequality under obtain a series of images.Next, the gained image can be analyzed, to adopt the method known in the art contribution of each illumination wavelength assessed.

Fig. 3 B expresses the multi-wavelength embodiment of another kind of form.In this case, biometric sensor 300 ' comprises the irradiation source 316 that is provided as wideband light source, such as unfiltered incandescent lamp or white light LEDs.Detector 312 in the embodiment of Fig. 3 A functional, detector 320 is equipped with to realize the optically filtering computing.A method of doing like this is that the color filter array (not shown) is attached on the imaging array surface, is similar to the Bayer pattern of often using on color camera (Bayer pattern).Another kind method is the color beam splitter in conjunction with a plurality of detecting devices that different coloured images is led.

The sequence of operation of the system shown in Fig. 3 B is after wideband light source 316 irradiations, gathers the one or more image.Under the situation of color filter array, single coloured image can be extracted as one group of sub-pixel, or single coloured image is read from single detector under the situation of color beam splitter.

Fig. 3 C has described in conjunction with the different polarization condition, with the biometric sensor 300 of the image of gathering multiple different skin part 304 ".Polarisation of light is subjected to appearing at the influence of the optical scattering of tissue or other scattering medium kind.For this reason, the linear polarization of intersection can resist surface reflection, and strengthens with tissue darker interactional light taking place.In a similar manner, parallel linear polarization can be used in the outstanding different characteristic of organizing with different elliptic polarization structure.In a kind of relevant mode, polarization, especially linear polarization, influence occurs in the volume reflection that passes through the Fresnel reflection phenomenon on the optical interface.Equally, different linear polarization can be used to strengthen or weaken reflected light from one or more interfaces.

In Fig. 3 C, skin part 304 is shone by platen 308 by light source 324, and by detector 328, to be similar in conjunction with Fig. 3 A and the described mode imaging of Fig. 3 B.Described light source 324 can be accurate monochrome or broadband, and detector 328 can be black and white or colour, adopts in conjunction with the described mode of those figure.Light from some (or whole) in the irradiation source 324 can be polarized element 332-1 polarization.Polarizer 332-1 can comprise linear polarizer or elliptical polarizers in different embodiment.Similarly, some in the detector 328 can be seen image by the second polarizer 332-2, and described second polarizer also can be linear polarization or elliptical polarizers in different embodiment.

In one embodiment, irradiation polarizer 332-1 and detecting polarization device 332-2 are arranged to linear polarization, make that the optical axis of these two polarizers 332 is roughly perpendicular.In other cases, polarizer 332 is configured to have the polarization of almost parallel.

Comprise under the situation of elliptical polarizers that at arbitrary polarizer 332 linear polarization (Fig. 3 C is not shown) that this elliptical polarizers can be orientated at an angle at the axis with respect to elliptical polarizers before.This angle can be selected to produce dextrorotation or left-handed rotation in known in the art mode.In one embodiment, be provided with the elliptical polarizers that is included among the polarizer 332, make two polarizers 332 produce left-handed rotations or two polarizers 332 produce right-handed rotations.In another embodiment, a polarizer 332 can produce left-handed rotation, and another polarizer 332 produces right-handed rotation simultaneously.

Shown in Fig. 3 C, unpolarized light source 324 also can exist, and produces to be polarized the observed illuminate condition of detector 328-1.Embodiment also can have the unpolarized camera 328-2 that observes the image that the light be used for from polarization light source 324-2 produces.

Illustrate the use of the multi-angle of irradiation and imaging in conjunction with biometric sensor shown in Figure 4.The change of illumination angle or search angle causes the transmitted light on the optical interface or the variation of catoptrical size and/or direction usually.On known special angle as critical angle, the interfacial energy between two kinds of media with different refractivity produces the total internal reflection effect.Observe the skin part that contacts with platen at the either side of platen one air critical angle and can produce visibly different image with significantly different information contents.The projection effect (shadow-casting effects) that also may exist corresponding non-rule feature (such as outer fingerprint pattern) to take place, and multiple polarization effect.All these effects change in different irradiations and survey the attributes of images that is produced by imager under the optical angle.

Fig. 4 expresses a plurality of irradiation sources 412 by being used as or comprising the prism 408 irradiation skin parts 404 of platen.Also have a plurality of detectors 416 of observing skin part 404 by prism 408.The use of prism has minimized the optical effect that occurs at the interface that light entered or left platen material institute warp.Other forms of platen can replacedly adopt, and comprise microprism array and simple plane window (simple planarwindow).In the drawings, the light from irradiation source 412 can be similar to collimation before irradiation skin part 404.When skin part 404 was shone by any or full illumination source 412, any or whole detectors 416 can acquisition of image data.In some cases, one or more light sources, as the source 412-1 among the figure, can be with angular orientation, to cause the total internal reflection effect on interface between skin part 404 and the platen greater than the critical angle that limits by platen one air interface.In some cases, one or more detectors, as the detector 416-1 among the figure, can be similarly with angular orientation greater than the critical angle that limits by platen one air interface, the image that makes detector produce is subjected to the influence of total internal reflection effect.

Fig. 5 A and Fig. 5 B express can be with the part of the biometric sensor 500 of a plurality of focal planes images acquired.Fig. 5 A is the side view of this biometric sensor 500, and Fig. 5 B is the front view of sensor 500.Skin part 504 is placed on the platen 508.The side view of Fig. 5 B shows a kind of trend: when skin part 504 is included in the bent body portion, as in finger, skin part 504 exists not and platen 508 contacted zones.Therefore, zoom detector 512 allows image acquisition to be caught by different focal planes.For example, first such image can be obtained by detector 512, and wherein focal point settings becomes to make image along the plane 524 and be optimum at the interface between skin part 504 and platen 508 roughly.The such image of next width of cloth may obtain with the focus of the detector 508 that resets, to image on the plane 520 that is positioned at platen 508 tops.Obtained when the such image of the 3rd width of cloth may be configured to image in another plane 516 in the focus of detector 512, by that analogy.

Be included in imaging systems in the detector 512 and can comprise that lens, mirror and other obtain the optical element (not shown among Fig. 5 A or the 5B) of the focus of expection, the mechanism that changes focus with this optical element comprises dynamo-electric assembly, adopt the liquid lens element that acts on the electrostatic force on the fluid filled element, the deformable mirror, based on the parts of MEMS, or the like.In certain embodiments, the imaging system that is included in the detector 512 can be configured to provide telecentric imaging (telecentric imaging), and feature maintenance alignment in the image of gathering down will be set at different focal lengths thus.

In certain embodiments, when the imaging system was designed to sufficiently long depth of focus is provided, the imaging system of fixed-focus can be used with detector 512.For example, the fixed-focus system can be used, and wherein focussing plane 516,520 and 524 can be focused with enough resolution and picture quality.Typically, fingerprint characteristic is by the system imaging of the resolution with 500 pixels of about per inch (ppi), but this need can wide region from about 100ppi to about 4000ppi in, change according to the needs of using.The imaging system design that remains on the ability of in the specific focus area, with required resolution feature being carried out imaging is for well known to those of ordinary skill in the art.In some cases, such imaging system also can be designed to provide the telecentric imaging characteristic.

Fig. 6 expresses by making up different mechanism and makes up mechanism that several different being used to gather the multiline data, under different optical conditions, to produce the embodiments of the invention of a plurality of images.Skin part 604 contacts with the platen of being made by prism 608.The right side faceted pebble of prism 608 has been coated light diffuse reflection coating 610 among the figure.From the light of source 612-2 and 612-3 before entering prism and irradiation skin part 604, respectively by polarizer 620-1 and 620-3.Light from source 612-1 does not at first pass through polarizer, but has fed prism.The light wavelength of being sent by different source 612 also differs from one another substantially.In certain embodiments, polarizer 620-1 and 620-. can be the roughly the same linear polarizations of direction.

Detector 616-2 observes skin part 604 by polarizer 620-2 and prism 608.Polarizer 620-2 can be direction and irradiation polarizer 620-1 and the vertical substantially linear polarization of 620-3.Detector 616-1 observes skin part 604 by prism 608, and does not insert polarizer.This detector 616-1 can be directed, makes it be subjected to the influence of the TIR at the interface between skin part 604 and the prism 608 fully.

Be included in the detector 616 one or all in imaging system can provide for obtaining image with the focussing plane that changes.In one embodiment, detector 616-2 is suitable for gathering a plurality of images with different focusing settings, carries out imaging fully with the part that does not contact with platen 608 for skin part 604.Alternatively, the imaging system of detector 616-2 can be the fixed-focus system with selected depth of focus, and what make skin part 604 can be with enough resolution imagings with platen 608 contacted desired amount.No matter under the zoom or the situation of fixed-focus, imaging system can further be adapted to provide the telecentric imaging ability.

Light from source 612-1 feeds prism 608, and coated 610 diffuse reflections are with the interface between irradiation skin part 604 and the platen 610.Skin part is by a plurality of detector 616 imagings.After image got access under the irradiation of source 612-1, this source was closed and source 612-2 opens.Any or all of detector 616 can obtain second group of image.Then, this order can repeat for source 612-3.

Expressed the light source and the detector of specific quantity and provide or receive source and detector through those specific quantities of the light of polarization although should be pointed out that Fig. 6, this only is for the purpose of description.More generally, embodiment can make up several arbitrarily in the many aspects that generate above-mentioned multiline data.For example, embodiment shown in Figure 6 can be modified, so that only adopt nonpolarized light or only adopt the monofocal plane.In addition, optional embodiment can adopt the source and the detector of any amount more generally, and can have an any amount those be set up source and the detector that light is provided or receives light by polarizer by polarizer.

Fig. 7 illustrates some data that system generated of constructing according to the structure of Fig. 6.Be before imaging, to be exposed to based on ten minutes very dry finger in the drying agent of clay by the skin part of imaging.The image in figure left side, with label 704,712 and 720 signs, be preliminary pretreated under the different optical condition image of the finger of observed drying.And they are corresponding to the image that produces in the module 116 of Fig. 1.

The image on Fig. 7 right side, identify by label 708,716 and 724, be to carry out the result that biometric characteristic extracts at above-mentioned left-side images respectively, promptly, image 708 is that the biometric characteristic of image 704 extracts the result, image 716 is that the biometric characteristic of image 712 extracts the result, and image 724 is that the biometric characteristic of image 720 extracts the result.In the image right 708,716 and 724 each is all expressed the image of bone form of its left-side images, and any minutiae point of being found out, and is for example identified by label 728.Have the image of the bone image of minutiae point 708,716 and 724 corresponding to the generation of 128 places of module among Fig. 1.

Compactly, the boneization of image is to reduce the processing with the remainder that becomes skeleton-type of foreground area in the image.This remainder has been protected the range and the connectivity of original area to a great extent, has removed most of original foreground pixels simultaneously.Typically, boneization is by a kind of realization among the dual mode.For a class technology, morphologic desaturation makes the line that can not carry out desaturation and centre again remain with the continuous edge ground corrosion pixel of so a kind of mode from every crestal line.The vestige that remains is similar to bone.For another kind of technology, the variable in distance of image is calculated, wherein the singular point of bone in the variable in distance.Under any situation, the image of resulting boneization can be processed, to adopt the known method in this area the end or the bifurcation of line defined.These are known as minutiae point, and their using also in the biometrics task are known by the people.Alternatively, these methods can be directly used in original grey lattice (not boneization) image, extract one group of similar minutiae point to adopt technology known in the art.

Use optical arrangement images acquired 704 corresponding to irradiation source 612-1 among Fig. 6 and detector 616-1.This is one and typically constructs based on the measurement of TIR.As shown in Figure 7, obviously, the TIR image is serious decline owing to the dry mass of observed finger.This deterioration is created in a spot of minutiae point of sign in the image 708, so caused the biometric system performance of being on duty mutually.

Employing is corresponding to the optical arrangement images acquired 712 of irradiation source 612-2 among Fig. 6 and detector 616-2.Linear polarization corresponding to polarizer 620-1 and 620-2 is arranged on vertical substantially direction.Employing is observed finger corresponding to the optical arrangement images acquired 72 of irradiation source 612-1 among Fig. 6 and detector 616-2 by polarizer 620-2.In this case, the wavelength of source 612-1 and 612-2 is similar, is the ruddiness of the approximate 635nm of wavelength.Resulting image 712 and 720 produces more and better biometric characteristic in the image 716 and 724 of corresponding boneization, shown in the contrast view of those images and image 708.

Fig. 8 expresses the one group of similar data that is produced by identical systems, but in this case, is to obtain with contacting of sensor data very light, that collected when making that contact area is very little according to the finger the people.Identical among the layout of image and Fig. 7.That is, image 804,812 is corresponding with the pretreated image of gathering respectively with the polarization form of intersecting with different irradiation/detection angles under the TIR condition with 820, and image 808,816 is corresponding with the result after the feature extraction with 824.Because contact is regional little, has the wherein descried zone that greatly is reduced of fingerprint characteristic energy by the irradiation of source 612-1 and the TIR image 804 that imaging produced of detector 616-1.Corresponding treated image 808 is also expressed the feature that can extract from this image quantity descends very big.

Image 812 and 820 contrast are very obvious, and they all use detector 616-2 to gather, and this detector 616-2 has sizable focal length.Although contact area is little, these images are still expressed whole finger-print region.Corresponding feature extraction image 816 and 824 is expressed said method and system extract biometric characteristic in the contact region that exceeds between skin part and the sensor ability.

Like this, described after several embodiment, it should be understood by one skilled in the art that different modifications, alternative structure and equivalent can adopt under the situation that does not break away from spirit of the present invention.Therefore, foregoing description should not limit protection scope of the present invention, and protection scope of the present invention limits in the claims.

Claims (30)

1. method that realizes the biometrics function, described method comprises:

Under multiple different optical condition, in single illumination in the period, at the fixing substantially position irradiation people's at particular skin position specific skin part;

Each optical condition in the corresponding multiple different optical condition receives the light from specific skin part;

Generation is from the multiple image of the specific skin part that receives light;

Analyze multiple image, with identification as the biometric characteristic of the feature in the part of piece image at least in the described image; And

Identification according to described biometric characteristic realizes described biometrics function.

2. method according to claim 1, wherein, described biometric characteristic is the various piece common characteristic of a plurality of images in the multiple image.

3. method according to claim 1, wherein, described biometric characteristic comprises a plurality of biometric characteristics.

4. method according to claim 3, wherein, analyze multiple image and comprise:

Under the position for the every width of cloth image in the multiple image, described specific skin part is identical condition, the spatial relationship between the identification multiple image; And

Discern a plurality of biometric characteristics according to the spatial relationship of being discerned.

5. method according to claim 3 wherein, realizes that described biometrics function comprises a plurality of biometric characteristics are stored in the relevant biometric characteristic of biometric characteristic in the database and people that be identified and compare with one group.

6. method according to claim 1, wherein, described specific skin part comprises people's finger; Described multiple image comprises fingerprint image; And described biometric characteristic comprises the minutiae point of described fingerprint image.

7. method according to claim 1, wherein, described multiple different optical condition comprises different illumination wavelength.

8. method according to claim 1, wherein, described multiple different optical condition comprises different polarization conditions.

9. method according to claim 1, wherein, described multiple different optical condition is included in the different direction of illumination of the described specific skin part of single irradiation period internal radiation.

10. method according to claim 1, wherein, described multiple different optical condition comprises different focussing planes.

11. method according to claim 1 wherein, realizes that described biometrics function comprises identification people or check people's identity.

12. method according to claim 1, wherein, described reception comprises the subsurface scattered light of reception from described particular skin position from the light of specific skin part.

13. method according to claim 1, wherein, described multiple image comprises total internal reflection (" the TIR ") image of described skin part and the non-total internal reflection images of described skin part.

14. method according to claim 1, wherein, described specific skin part comprises people's finger; Described specific skin part contacts with platen; Described multiple image comprises fingerprint image; And described biometric characteristic comprises the biometric characteristic of the people who is identified outside described specific skin part and the area that platen contacts.

15. method according to claim 1 wherein, is analyzed multiple image and is comprised:

At least one width of cloth in the described image of boneization; And

Discern in the described image by the biometric characteristic of the piece image at least of boneization.

16. method according to claim 1, wherein:

Described analysis multiple image comprises that the described part with the piece image at least in the described image resolves into one group of basic function; And

Described biometric characteristic comprises that a component separates the coefficient of formation.

17. method according to claim 1, wherein, described biometric characteristic comprises ridge on the skin part and the representative of paddy.

18. method according to claim 1, wherein, described biometric characteristic comprises the feature that the blood vessel under the described specific skin part exists.

19. a biometric system comprises:

Be adapted to place the platen of people's specific skin part;

Be set for and shine the irradiation source that is placed on the described specific skin part on the platen;

Be set for the imaging system of reception from described specific skin part; And

With the controller that irradiation source is connected with imaging system, described controller comprises:

Under multiple different optical condition, in single illumination in the period, for the position of the almost fixed at described particular skin position, shine the instruction of described specific skin part with irradiation source;

The instruction that the light that is received by imaging system produces the multiple image of specific skin part;

Analyze multiple image, with identification as the instruction of the biometric characteristic of the feature in the part of piece image at least in the described image; And

Realize the instruction of described biometrics function according to the identification of described biometric characteristic.

20. biometric system according to claim 19, wherein, described biometric characteristic is the common feature of the various piece of a plurality of images in the multiple image.

21. biometric system according to claim 19, wherein, described biometric characteristic comprises a plurality of biometric characteristics.

22. biometric system according to claim 21, wherein, the described instruction that is used to analyze multiple image comprises:

Under the position for the every width of cloth image in the multiple image, described specific skin part is identical condition, the instruction of the spatial relationship between the identification multiple image; And

Discern the instruction of a plurality of biometric characteristics according to the spatial relationship of being discerned.

23. biometric system according to claim 21, further comprise the database that links to each other with controller, described database is relevant with the people's who is identified biometric characteristic group, wherein, the instruction that realizes described biometrics function comprises a plurality of biometric characteristics and one group of instruction that the biometric characteristic that is stored in the database compares.

24. biometric system according to claim 19 further comprises being set for first polarizer that makes the light polarization that irradiation source provides, wherein:

Described imaging system comprises and is set for second polarizer that makes the light polarization that receives from described specific skin part; And

Described multiple different optical condition comprises different relevant polarization conditions.

25. biometric system according to claim 19 further comprises being set for first polarizer that makes the light polarization that irradiation source provides, wherein:

Described imaging system comprises and is set for second polarizer that makes the light polarization that receives from described specific skin part; And

Described first and second polarizers roughly become cross conformation.

26. biometric system according to claim 19, wherein:

Described imaging system comprises the color filter array with a plurality of distributed filter elements, and each filter element is suitable for the light of a wavelength in the specialized narrowband wavelength coverage that its wavelength of transmission is a limited amount; And

Described multiple different optical condition is included in the different wavelength of the irradiates light in the specific narrowband wavelength scope.

27. biometric system according to claim 26, wherein, described instruction of shining described specific skin part with irradiation source under multiple different optical condition comprises the instruction of sequentially shining described specific skin part with different wave length.

28. biometric system according to claim 19, wherein, described controller further comprises with than by the big angle of the critical angle of the interface definition between platen external environment condition and the platen, use instruction from the described particular skin of the rayed in platen position, wherein, the instruction of the multiple image of the described specific skin part of the described photogenerated that is received by imaging system comprises by at least one width of cloth in the photogenerated multiple image on the platen interface of inciding described specific skin part and platen contact position, as the instruction of the image of the surface structure of described specific skin part.

29. biometric system according to claim 19, wherein, the instruction of analyzing multiple image comprises:

The instruction of the piece image at least in the described image of boneization; And

Discern the instruction of biometric characteristic of the piece image at least of the boneization in the described image.

30. biometric system according to claim 19, wherein:

The instruction of described analysis multiple image comprises the instruction that the described part with the piece image at least in the described image resolves into one group of basic function; And

Described biometric characteristic comprises that a component separates the coefficient of formation.

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