Method and apparatus with fingerprint verification

A fingerprint verification method and apparatus is disclosed. The fingerprint verification method may include obtaining an input fingerprint image, determining a matching region between the input fingerprint image and a registered fingerprint image, determining a similarity corresponding to the matching region, representing a determined indication of similarities between the input fingerprint image and the registered fingerprint image, relating the determined similarity to the matching region as represented in a matching region-based similarity, determining a result of a verification of the input fingerprint image based on the matching region-based similarity, and indicating the result of the verification.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 USC § 119(a) of Korean Patent Application No. 10-2017-0031889 filed on Mar. 14, 2017 and Korean Patent Application No. 10-2017-0097033 filed on Jul. 31, 2017 in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference for all purposes.

BACKGROUND

The following description relates to fingerprint verification technology.

2. Description of Related Art

Automated biometrics-based verification technologies may be used to verify a user, for example, through analyses of a fingerprint, an iris, a voice, a face, and/or blood vessels. Such biological characteristics used for user authentication differ from individual to individual, rarely change during a user's lifetime, and have a low risk of being stolen or copied. In addition, because individuals always carry such characteristic information, the individuals do not need to remember to or intentionally carry any corresponding identification materials, and thus may not suffer an inconvenience when performing verifications with the biological characteristics. Currently, fingerprint verification approaches has been used for the user authentication, e.g., due to their high level of convenience, security, and economic efficiency.

SUMMARY

In one general aspect, a processor implemented fingerprint verification method includes obtaining an input fingerprint image, determining a matching region between the input fingerprint image and a registered fingerprint image, determining a similarity corresponding to the matching region, representing a determined indication of similarities between the input fingerprint image and the registered fingerprint image, relating the determined similarity to the matching region as represented in a matching region-based similarity, determining a result of a verification of the input fingerprint image based on the matching region-based similarity, and indicating the result of the verification.

The relating of the determined similarity to the matching region as represented in the matching region-based similarity may include determining the matching region-based similarity based on the matching region and the determined similarity.

The method may further include generating the matching region-based similarity to include default similarity values and without representing a matching region, where the determining of the matching region-based similarity may include representing the matching region in the matching region-based similarity and changing, from the default similarity values, similarity values corresponding to the matching region represented in the matching region-based similarity to be the determined similarity.

The determining of the result of the verification may include determining a score for the determined matching region-based similarity, and determining whether the verification is successful based on whether the score satisfies a predetermined fingerprint verification condition.

The determining of the similarity corresponding to the matching region may include determining a first similarity corresponding to a first matching region between the input fingerprint image and a first registered fingerprint image, the relating of the determined similarity to the matching region as represented in the matching region-based similarity may include determining the matching region-based similarity based on the first similarity and the first matching region, and, in response to a score determined based on the determined matching region-based similarity not satisfying a fingerprint verification condition, the fingerprint verification method may further include determining a second similarity corresponding to a determined second matching region between the input fingerprint image and a second registered fingerprint image.

The determining of the matching region-based similarity based on the first similarity and the first matching region may include allocating the first similarity to the first matching region as represented in the determined matching region-based similarity.

In response to the score determined based on the determined matching region-based similarity not satisfying the fingerprint verification condition, the fingerprint verification method may further include updating the determined matching region-based similarity based on the second matching region and the second similarity.

The updating of the determined matching region-based similarity based on the second matching region and the second similarity may include, in response to an overlapping region being present between the first matching region and the second matching region, allocating or maintaining a greatest similarity between the first similarity and the second similarity to the overlapping region as represented in the updated matching region-based similarity.

The updating of the determined matching region-based similarity based on the second matching region and the second similarity may further include allocating the second similarity to a remaining region of the second matching region, in which the overlapping region is not reflected, as represented in the updated matching region-based similarity.

The determining of the result of the verification may include determining a score for the matching region-based similarity, and, in response to the score satisfying a predetermined fingerprint verification condition, determining that the verification of the input fingerprint image is successful.

The determining of the result of the verification may include determining whether a total size of one or more matching regions, each having similarities meeting a predetermined threshold value, meets a predetermined threshold size using a matching region-based similarity representing plural matching regions with respect to plural registered fingerprint images, and determining whether the verification of the input fingerprint image is successful based on a result of the determining of whether the total size meets the predetermined threshold size.

The determining of the result of the verification may include, in response to an average similarity value, of similarity values respectively related to at least some of plural matching regions represented in a matching region-based similarity with respect to plural registered fingerprint images, meeting a predetermined threshold value, determining that the verification of the input fingerprint image is successful.

The at least some of the plural matching regions may be less than all of the plural matching regions represented in the matching region-based similarity.

The determining of the result of the verification may further include, in response to a score determined based on the matching region-based similarity determined with respect to all registered fingerprint images not satisfying the predetermined fingerprint verification condition, determining that the verification of the input fingerprint image is unsuccessful.

In one general aspect, provided is a non-transitory computer-readable medium storing instructions, which when executed by a processor, cause the processor to perform one or more or all processes or methods described herein.

In one general aspect, a processor implemented fingerprint verification method includes obtaining an input fingerprint image, determining a first similarity corresponding to a first matching region between the input fingerprint image and a first registered fingerprint image, determining a matching region-based similarity based on the first similarity and the first matching region, determining a score based on the matching region-based similarity, in response to the score not satisfying a predetermined fingerprint verification condition, determining a second similarity corresponding to a second matching region between the input fingerprint image and a second registered fingerprint image and updating the matching region-based similarity based on the second similarity and the second matching region, and determining a result of a verification of the input fingerprint image based on the matching region-based similarity or the updated matching region-based similarity.

The updating of the matching region-based similarity may include, in response to an overlapping region being present between the first matching region and the second matching region, allocating or maintaining a greatest similarity between the first similarity and the second similarity to the overlapping region represented in the updated matching region-based similarity.

The updating of the matching region-based similarity may further include allocating the second similarity to a remaining region, of the second matching region in which the overlapping region is not reflected, as represented in the updated the updated matching region-based similarity.

The determining of the result of the verification may include determining whether a total size of one or more matching regions, each having a similarity meeting a predetermined threshold value, meets a predetermined threshold size using a matching region-based similarity representing plural matching regions with respect to plural registered fingerprint images including the first registered fingerprint image and the second registered fingerprint image, and determining whether the verification of the input fingerprint image is successful based on a result of the determining of whether the total size meets the predetermined threshold size.

The determining of the result of the verification may include, in response to an similarity average value, of similarity values respectively related to at least some of plural matching regions represented in a matching region-based similarity with respect to plural registered fingerprint images including the first registered fingerprint image and the second registered fingerprint image, meeting a predetermined threshold value, determining that the verification of the input fingerprint image is successful.

In one general aspect, a processor implemented fingerprint verification method includes obtaining an input fingerprint image, determining a first matching region between the input fingerprint image and a first registered fingerprint image, determining a first similarity corresponding to the first matching region, determining a matching region-based similarity based on the first similarity and the first matching region, determining a second matching region between the input fingerprint image and a second registered fingerprint image, determining a second similarity corresponding to the second matching region, updating the matching region-based similarity based on the second similarity and the second matching region, determining a score based on a finally updated matching region-based similarity representing plural matching regions with respect to plural registered fingerprint images including the first registered fingerprint image and the second registered fingerprint image, and determining a result of a verification of the input fingerprint image based whether on the score meets a predetermined verification condition.

The updating of the matching region-based similarity may include, in response to an overlapping region being present between the first matching region and the second matching region, allocating or maintaining a greatest similarity, between the first similarity corresponding to the first matching region and the second similarity corresponding to the second matching region, to the overlapping region represented in the updated matching region-based similarity.

The updating of the matching region-based similarity may further include allocating the second similarity to a remaining region, of the second matching region in which the overlapping region is not reflected, as represented in the updated matching region-based similarity.

The determining of the result of the verification may include determining whether a total size of one or more matching regions, each having a similarity meeting a predetermined threshold value, meets a predetermined threshold size using the finally updated matching region-based similarity, and determining whether the verification of the input fingerprint image is successful based on a result of the determining of whether the total size meets the predetermined threshold size.

The determining of the result of the verification may include, in response to a similarity average value, of similarity values respectively related to at least some of the plural matching regions represented in the finally updated matching region-based similarity, meeting a predetermined threshold value, determining that the verification of the input fingerprint image is successful.

In one general aspect, a processor implemented fingerprint verification method includes obtaining an input fingerprint image, incrementally updating a matching region-based similarity respectively based on determined similarities for respectively determined matching regions between the input fingerprint image and each of plural registered fingerprint images, determining respective scores with respect to each of one or more of the incremental updatings of the matching region-based similarity, or a final score based on a finally updated matching region-based similarity representing plural matching regions with respect to at least a multiple of the plural registered fingerprint images, determining a result of a verification of the input fingerprint image based whether any of the respective scores or the final score meets a predetermined verification condition, and indicating the determined result of the verification.

The determining of the respective scores with respect to each of one or more of the incremental updatings of the matching region-based similarity may cease when a corresponding score, of the respective scores, is determined in the determining of the result of the verification as meeting the predetermined verification condition.

In one general aspect, a fingerprint verification apparatus includes a processor configured to determine a matching region between an input fingerprint image and a registered fingerprint image, determine a similarity corresponding to the matching region, representing a determined indication of similarities between the input fingerprint image and the registered fingerprint image, relate the determined similarity to the matching region as represented in a matching region-based similarity, determine a result of a verification of the input fingerprint image based on the matching region-based similarity, and indicate the result of the verification.

The processor may be further configured to determine the matching region-based similarity based on the matching region between the input fingerprint image and the registered fingerprint image and the similarity corresponding to the matching region between the input fingerprint image and the registered fingerprint image.

The processor may be further configured to determine a score based on the updated matching region-based similarity, and determine the result of the verification based on whether the score satisfies a predetermined fingerprint verification condition.

Throughout the drawings and the detailed description, unless otherwise described or provided, the same drawing reference numerals will be understood to refer to the same or like elements, features, and structures. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

It should be noted that if it is described in the specification that one component is “connected,” “coupled,” or “joined” to another component, a third component may be “connected,” “coupled,” and “joined” between the first and second components, although the first component may be directly connected, coupled or joined to the second component. In addition, it should be noted that if it is described in the specification that one component is “directly connected” or “directly joined” to another component, a third component may not be present therebetween. Likewise, expressions, for example, “between” and “immediately between” and “adjacent to” and “immediately adjacent to” may also be construed as described in the foregoing.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, operations, elements, and/or components in an example embodiment, but do not preclude the presence or addition of one or more other features, integers, operations, elements, components, and/or groups thereof in alternative embodiments, nor the lack of such stated features, integers, operations, elements, components, and/or combinations/groups thereof in further alternative embodiments unless the context and understanding of the present disclosure indicates otherwise. The use of the term ‘may’ herein with respect to an example or embodiment, e.g., as to what an example or embodiment may include or implement, means that at least one example or embodiment exists where such a feature is included or implemented while all examples and embodiments are not limited thereto.

FIG. 1is a diagram illustrating an example of a fingerprint verification method.

A fingerprint verification refers to a verification method used to determine whether a user attempting at a verification using a fingerprint is a valid user or not in user log-in, payment systems, and/or access control, as non-limiting examples. Referring toFIG. 1, a fingerprint verification apparatus configured to perform such a fingerprint verification is also represented by, or included in, a computing apparatus100. The computing apparatus100includes, for example, a smartphone, a wearable device, a tablet computer, a netbook, a laptop computer, a desktop computer, a personal digital assistant (PDA), a set-top box, a home appliance, a biometrics-based door lock, a security device, and a vehicle start device. One or more processors of the computing apparatus100may be configured to perform the fingerprint verification. As another example,FIGS. 12 and 13also demonstrate such computing apparatus examples.

For example, the computing apparatus100may determine whether a user attempting to gain access or a greater access to the computing apparatus100is a valid user by analyzing a fingerprint pattern of a fingerprint image120sensed through a fingerprint sensor110of the computing apparatus100. For example, in a case in which the user inputs a fingerprint to the fingerprint sensor110to cancel a lock state of the computing apparatus100, e.g., to ‘unlock’ the computing apparatus100, the computing apparatus100compares the fingerprint image120obtained through the fingerprint sensor110to at least one of registered fingerprint images142,144, and146stored in a database (DB)130, and determines whether to cancel the lock state of the computing apparatus100based on a result of the comparing. The DB130may store registered fingerprint images of at least one finger, and may be included in the computing apparatus100and/or may be included in a separate computing apparatus or remote cloud or server, for example.

In an example, a valid user may register, in advance, fingerprint information of the valid user in the computing apparatus100, and the computing apparatus100may store the fingerprint information registered by the valid user in the DB130or the example cloud or other server storage. The fingerprint information of the valid user may also be entered through another computing apparatus100, and transferred to or requested by the computing apparatus100ofFIG. 1, or otherwise acquired and stored in the DB130. The registered fingerprint information may be stored in a form of a registered fingerprint image, for example, as color, gray scale, intensity, depth, or black and white images. In another example, the registered fingerprint information of the registered fingerprint images142,144, or146may be stored as magnitude images, such representative of image information after having been frequency domain transformed or Fourier-Mellin transformed, as non-limiting example, from such color, gray scale, intensity, depth, or black and white images, while noting that the registered fingerprint information may still be stored and later utilized in still other forms. In a fingerprint registration process, a user may register various fingerprint images, for example, the registered fingerprint images142,144, and146. In a fingerprint verification process, the computing apparatus100may compare the fingerprint image120obtained through the fingerprint sensor110to the registered fingerprint images142,144, and146. Here, sizes of the fingerprint image120and the registered fingerprint images142,144, and146may be determined by a recognition region of the fingerprint sensor110, such as when the fingerprint image120and the registered fingerprint images142,144, and146are acquired by the same or like fingerprint sensor110, noting that examples are not limited thereto. In an example, due to a limited size of the recognition region of the fingerprint sensor110, the fingerprint image120obtained through the fingerprint sensor110and the registered fingerprint images142,144, and146may include information associated with partial fingerprint regions, i.e., only a partial portion or partial region of a full fingerprint or full fingerprint region. Thus, the fingerprint image120and the registered fingerprint images142,144, and146may each be obtained through the example fingerprint sensor110having such limited recognition area or region, and thus, may not include sufficient features to be used to accurately verify the fingerprint image120based on the partial fingerprint region represented by the fingerprint image120and/or the partial fingerprint regions represented by the respective registered fingerprint images142,144, and146. For example, if an independent fingerprint verification is performed based on a one-to-one comparison of such a partial fingerprint image and a partial registered fingerprint image, which both may have not sufficient differentiating or identifying features, an undesirable result, such as, for example, a false rejection or a false acceptance, may be obtained. An example of such an undesirable result will be described hereinafter with reference toFIGS. 2A and 2B.

FIG. 2Ais a diagram illustrating an example of occurrence of a false rejection.

Referring toFIG. 2A, in a case in which a size of a matching region, i.e., the region where a match occurs, between a fingerprint image210obtained through a fingerprint sensor and a registered fingerprint image220is small or of limited area, also corresponding to there being limited differentiatable or identifiable features in either of the fingerprint image210and registered fingerprint image220, it is possible that the fingerprint image210may be rejected from being a verified fingerprint due to the small size of the matching region even if the respective fingerprint patterns in the matching region are the same or substantially similar to each other. For example, to prevent false acceptances that may occur when partial fingerprint regions, from which a fingerprint may be less identifiable, are matched between a captured fingerprint and a registered fingerprint, verification methods may require a size of the matching region to be greater than or equal to a preset size before the captured fingerprint can be considered to correspond to a fingerprint verification condition for a determination that the fingerprint verification is successful.

Thus, in the example ofFIG. 2A, even though the fingerprint image210is of a same finger as the registered fingerprint image, i.e., with the same or substantial similarities in patterns, the fingerprint image210may be rejected, and thus a false rejection.

FIG. 2Bis a diagram illustrating an example of occurrence of a false acceptance.

Referring toFIG. 2B, in a case in which a fingerprint pattern of a fingerprint image230obtained through a fingerprint sensor and a fingerprint pattern of a registered fingerprint image240of different fingerprints are each less distinguishable, a matching region between the fingerprint image230and the registered fingerprint image240may be determined to be large due to respective simple fingerprint patterns of the fingerprint image230and the registered fingerprint image240, and thus, the similarity between the fingerprint image230and the registered fingerprint image240may be determined to be high and a typical verification method may verify the fingerprint image230as a valid fingerprint. However, because the fingerprint patters have such respective simple fingerprint patterns, even when the fingerprints are of different individuals the fingerprint image230may be validated due to the large similarity and large matching region, and thus it is highly possible that such false acceptances may occurs.

Such typical false rejections and false acceptances ofFIGS. 2A and 2Bmay adversely affect an accuracy or a recognition rate in the technological implementations of fingerprint verification, and thus represent technological problems, found herein desiring of technological solutions to prevent or more minimize such false rejections and false acceptances from occurring. One or more examples to be described hereinafter may, for example, present verification methods and implementing apparatuses that may resolve such issues described in such typical technological approaches and provide technological approaches for fingerprint verification with greater accurately and/or with greater verification speed, as only examples.

FIG. 3is a diagram illustrating an example of a fingerprint verification method.

Referring toFIG. 3, a fingerprint verification apparatus performs a fingerprint verification based on determined similarities between a fingerprint image310input for the fingerprint verification and each of a plurality of registered fingerprint images322,324,326, and328. The fingerprint verification apparatus performs the fingerprint verification based on determined respective matching regions between the input fingerprint image310and each of the registered fingerprint images322,324,326, and328, in addition to the determined similarities between the input fingerprint image310and each of the registered fingerprint images322,324,326, and328. For example, a determined matching region may correspond to a determined area or relative size of a matching portion or area between the input fingerprint image and a registered fingerprint image. The fingerprint verification apparatus determines a matching region-based similarity with respect to the input fingerprint image310. For example, the matching region-based similarity includes similarity information associated with a similarity between the input fingerprint image310and one or more registered fingerprint images, and may be related to a region corresponding to the input fingerprint image310represented in the matching region-based similarity, e.g., the similarity information may be allocated to a matching region included the matching region-based similarity, such as when the matching region-based similarity is represented as an image. The fingerprint verification apparatus respectively determines similarities and matching regions, or respective overlapping regions, between fingerprint patterns, for each comparing of the input fingerprint image310to each of the registered fingerprint images322,324,326, and328, and with each comparison the fingerprint verification apparatus updates the example matching region-based similarity based on each determined matching region and determined similarities corresponding to the determined matching regions.

For example, inFIG. 3, the reference numeral330indicates a visual representation of such a matching region-based similarity. The matching region-based similarity is represented as an integration of respective similarities or respective similarity information between the input fingerprint image310and each of registered fingerprint images322,324,326, and328. The matching region-based similarity includes information associated with the respective matching or overlapping regions and determined respective similarities or similarity information between the input fingerprint image310and each of the registered fingerprint images322,324,326, and328for the matching regions.

For example, to determine such a matching region-based similarity, the fingerprint verification apparatus determines an example matching region332and a corresponding similarity S1between the input fingerprint image310and the registered fingerprint image322. The fingerprint verification apparatus then updates a matching region-based similarity by allocating the similarity S1to the matching region332, of an entire region corresponding to the input fingerprint image310in the matching region-based similarity. The matching region-based similarity may be generated or set, e.g., based on an entire region corresponding to the input fingerprint image310, before, during, or after the determining of the matching region332and similarity S1, e.g., with the fingerprint verification apparatus updating the generated or set matching region-based similarity based on the determined matching region332and correspondingly determined similarity S1. Here, as an example of the matching region-based similarity being generated or set based on an entire region corresponding to the input fingerprint image310(or any of the registered fingerprint images), reference330inFIG. 3illustrates that the matching region-based similarity may have a size or area the same as, or related or relative to, the input fingerprint image310, with the example matching region332being illustrated as occupying or covering the illustrated portion of the whole of the matching region-based similarity, e.g., occupying or covering an illustrated portion of an area corresponding to a whole area of the input fingerprint image310. In operation340, the fingerprint verification apparatus may then determine a score for the matching region-based similarity and determine whether that score satisfies a fingerprint verification condition. In response to the score not satisfying the fingerprint verification condition, the fingerprint verification apparatus may proceed to compare the input fingerprint image310and the registered fingerprint image324, i.e., subsequent to the previous comparison with respect to the registered fingerprint image322. The determined score in operation340refers to value, as only an example, that may be used to determine whether the fingerprint verification is successful or not, e.g., based on whether the example value meets a predetermined reference value. With the comparing of the input fingerprint image310and the registered fingerprint image324, the fingerprint verification apparatus determines a matching region334and a similarity S2between the input fingerprint image310and the registered fingerprint image324, and updates the previously determined/updated matching region-based similarity based on the matching region334and the similarity S2. For example, the illustrated matching region-based similarity illustrates a bound region (full and dashed lines) that is illustrated as including the similarity S2. As will be discussed in greater detail further below, though there may be additional matching portions between the input fingerprint image310and the registered fingerprint image324outside the example bound region of matching region334, e.g., which could overlap with the illustrated bound region of matching region332illustrated as including the similarity S2and/or bound region of matching region336illustrated as including the similarity S3, these additional matching portions may not be updated or reflected in the matching region-based similarity with respect to the comparison of the input fingerprint image310and the registered fingerprint image324if either of the similarity S1and/or similarity S3indicate greater similarities than similarity S2. Thus, operation340may be repeated again with respect to the matching region-based similarity that has been updated with respect to the matching region334and a similarity S2, with the fingerprint verification apparatus determining whether a score determined based on the latest updated matching region-based similarity satisfies the fingerprint verification condition. In response to the score not satisfying the fingerprint verification condition, the fingerprint verification apparatus then performs similarly the forgoing on the next registered fingerprint image326. In such a case, the matching region-based similarity is again updated again based on a matching region336and a similarity S3between the input fingerprint image310and the registered fingerprint image326. Thus, the fingerprint verification apparatus repeatedly updates the matching region-based similarity by comparing the input fingerprint image310and each of the registered fingerprint images322,324,326, through the n-th registered fingerprint image328in sequential order until the fingerprint verification condition is satisfied or all registered fingerprint images have been considered. In the above example, due to the sequential determination of whether the fingerprint verification condition is satisfied based on each sequentially determined score corresponding to each updating of the matching region-based similarity, only some of the registered fingerprint images322,324,326, through328may ultimately need to be compared to the input fingerprint image310before the verification condition is met, e.g., instead of having compare all the registered fingerprint images322,324,326, through328to the input fingerprint image310before ultimately determining whether the verification condition is met, and thus the fingerprint verification may be terminated more rapidly and faster processing may be enabled if the verification condition is met earlier in the example sequential performances of operation340.

As noted, in the example ofFIG. 3, a determination of whether a fingerprint verification condition is satisfied may be made each time the matching region-based similarity is updated. However, in an example, the initial determination of whether fingerprint verification condition is satisfied may alternatively be determined after a number of updates have been performed or lastly after a final updating of the matching region-based similarity based on the n-th registered fingerprint image328. For example, all the matching regions and similarities between the input fingerprint image310and the registered fingerprint images322,324,326, through328may be determined, and the determination of whether the fingerprint verification condition is satisfied may then be made after the matching region-based similarity is finally updated. In another example, all the matching regions and similarities between the input fingerprint image310and the registered fingerprint images322,324,326, through328may be determined, then the matching region-based similarity may be generated or set based on analyses of all of the determined matching regions and similarities, and then the example operation340ofFIG. 3may be performed to determine whether the fingerprint verification condition is satisfied. In another example, an initial fast determination may be made to discern which registered fingerprint images to consider, and in which order, such as based on results of an initial fast, e.g., phase-only correlation (PoC), similarity determination operation with respect to the input fingerprint image310and each of the registered fingerprint images, prior to more detailed similarity comparisons being performed, such as the example Fourier-Mellin method described in greater detail with reference toFIGS. 7 through 9. In addition, in the above, examples are discussed where determination of whether a fingerprint verification condition is satisfied, based on a correspondingly determined score, is made each time the matching region-based similarity is updated, sequentially performed after each of a predetermined or set number or all of the matching region-based similarity updates are performed, examples also exist where respective determinations of whether a fingerprint verification condition is satisfied, based on a correspondingly determined score, may be made each time the matching region-based similarity is updated for each of a predetermined or set number of registered fingerprint images, and thereafter the next determining of whether the fingerprint verification condition is satisfied, based on a correspondingly determined score, delayed until a further predetermined or set number, or all, of remaining registered fingerprint images have been considered in respective the matching region-based similarity updates.

Thus, in one or more examples, a result of the fingerprint verification may not be determined based solely on an independently determined similarity between an input fingerprint image and a single registered fingerprint image, but may be determined based on a matching region-based similarity, which may be representative of incrementally combined results of respective comparisons of the input fingerprint image and plural registered fingerprint images, e.g., representative of incrementally combined results of respective comparisons of the input fingerprint image and plural registered fingerprint images in sequential order. Thus, in an example, a probability of occurrence of a false rejection or a false acceptance may be reduced compared to independent verification operations between an input fingerprint and each of two or more registered fingerprints, and thus an accuracy in the fingerprint verification and a recognition rate may be improved in an example.

FIGS. 4 and 5are flowcharts illustrating an example of a fingerprint verification method. It should be noted that in alternative implementations, the functions/acts noted may occur in other orders, e.g., including operations being performed in a reverse order, than noted in the flowcharts. In addition, for example, two steps or operations illustrated in succession in the examples ofFIGS. 4 and 5may alternatively be executed substantially concurrently, depending upon the functionality/acts involved in such various alternative examples.

Referring toFIG. 4, in operation410, a fingerprint verification apparatus obtains, e.g., by capturing, reading from a memory, and/or receiving, an input fingerprint image. The input fingerprint image refers to a fingerprint image, e.g., a target on which a fingerprint verification is to be performed, and may be obtained through a fingerprint sensor of the fingerprint verification apparatus, for example, or by a separate or even remote fingerprint sensor. In an example, the fingerprint sensor is configured to sense or capture only an image or features of only a portion of the whole of a finger that positioned relative to or applied to the fingerprint sensor. In addition, in an example, the fingerprint verification apparatus performs a preprocessing operation on the obtained input fingerprint image. The preprocessing operation may be performed to process the input fingerprint image to be in a form, shape, or orientation more suitable for the fingerprint verification by, for example, improving a quality of the input fingerprint image and adjusting a size of the input fingerprint image. The preprocessing operation may include removing noise from the input fingerprint image, increasing a contrast of the input fingerprint image, deblurring the input fingerprint image, performing warping to correct a distortion in the input fingerprint image, binarizing the input fingerprint image, normalizing the size of the input fingerprint image, and/or cropping the input fingerprint image, as only non-limiting examples.

In operation420, the fingerprint verification apparatus determines a matching region-based similarity based on a determined matching region between the input fingerprint image and at least one registered fingerprint image. The fingerprint verification apparatus selects a registered fingerprint image to be compared to the input fingerprint image from a plurality of registered fingerprint images stored in a DB, and calculates a similarity that indicates how similar the fingerprint pattern of the selected registered fingerprint image is to the fingerprint pattern of the input fingerprint image. Here, a determined high similarity indicates that the fingerprint pattern of the input fingerprint image is relatively considerably similar to the fingerprint pattern of the registered fingerprint image. Likewise, a determined low similarity indicates that the fingerprint pattern of the input fingerprint image is relatively dis-similar to the fingerprint pattern of the registered fingerprint image.

In one example, the fingerprint verification apparatus determines the matching region between the input fingerprint image and the registered fingerprint image using rotation information and translation information determined between the input fingerprint image and the registered fingerprint image, and calculates the similarity between the fingerprint patterns in/for the matching region. The rotation and translation information may correspond to the rotation and translation of either or both of the input fingerprint image and the registered fingerprint image that thereby aligns individual patterns, for example, of the respective fingerprint patterns, such as discussed in greater detail further below with respect toFIG. 6. Thus, the matching region refers to a fingerprint region, corresponding to both the input fingerprint image and the registered fingerprint image, where it is estimated that the input fingerprint image and the registered fingerprint image have a most same or similar fingerprint patterns. A method of determining the matching region-based similarity may include calculating the similarity between the input fingerprint image and the registered fingerprint image, which may be represented numerically, and allocating the calculated similarity to the determined matching region between the input fingerprint image and the registered fingerprint image. For example, in the above example ofFIG. 3, the matching region332may be determined and the calculated similarity S1allocated to that matching region332in/of the accordingly generated or set matching region-based similarity for the current verification operation with respect to the input fingerprint image and the one or more registered fingerprint images.

In one example, the fingerprint verification apparatus uses, as the similarity between the input fingerprint image and the registered fingerprint image, a feature value obtained by the fingerprint verification apparatus performing a fast Fourier transform (FFT) on the input fingerprint image and the registered fingerprint image. For example, the fingerprint verification apparatus calculates the similarity using an image frequency information-based matching method, such as, for example, a Fourier-Mellin method performed by the fingerprint verification apparatus. The similarity may be determined based on phase correlation information obtained by the fingerprint verification apparatus using the Fourier-Mellin method, or determined by the fingerprint verification apparatus based on the rotation information and the translation information between the input fingerprint image and the registered fingerprint image, in addition to the phase correlation information, as determined by the fingerprint verification apparatus. An example of a method of determining the similarity based on the Fourier-Mellin method will be described in greater detail with reference toFIGS. 7 through 9, noting that the method of determining the similarity between the input fingerprint image and the registered fingerprint image is not limited to the example Fourier-Mellin method, and in various examples various other methods may be used to determine a similarity between the fingerprint patterns of the input fingerprint image and the registered fingerprint image. For example, the similarity may be determined by the fingerprint verification apparatus based on a distribution or a form of feature points extracted by the fingerprint verification apparatus from the fingerprint patterns of the input fingerprint image and the registered fingerprint image. Another method, other than the example, Fourier-Mellin method, may include a method of discovering minutiae, as major feature(s) of a fingerprint, and performing aligning, matching, and similarity determinations based on a determined relationship between the minutiae.

The fingerprint verification apparatus updates the matching region-based similarity based on the calculated similarity. The matching region-based similarity may be initially set to have default values, for example, 0 for an allocated similarity of an entirety of the matching region-based similarity. Thus, the fingerprint verification apparatus may record or update the calculated similarity in a corresponding indicated region of the matching region-based similarity corresponding to the matching region between the input fingerprint image and the registered fingerprint image. A score may be determined for the matching region-based similarity, and in response to the score not satisfying a preset fingerprint verification condition, the fingerprint verification apparatus may proceed to calculate a similarity between the input fingerprint image and another registered fingerprint image, may then update the matching region-based similarity based on the result of that calculated similarity, and may again determine whether a score of the matching region-based similarity satisfies the preset fingerprint condition.

In one example, the fingerprint verification apparatus determines a first similarity corresponding to a first matching region between the input fingerprint image and a first registered fingerprint image. The fingerprint verification apparatus may thus update the matching region-based similarity based on the first similarity and the first matching region. In response to a score determined based on the updated matching region-based similarity not satisfying the fingerprint verification condition, the fingerprint verification apparatus determines a second similarity corresponding to a second matching region between the input fingerprint image and a second registered fingerprint image. Here, the previous updating of the matching region-based similarity based on the first similarity and the first matching region may include allocating the first similarity to a region of the matching region-based similarity representing the first matching region. For example, when the matching region-based similarity has a same area, form, or size as the input fingerprint image, the region of the matching region-based similarity representing the first matching region may merely be an indication of the first matching region in or with respect to the matching region-based similarity, such as demonstrated above with respect toFIG. 3and the matching region332being in/of the accordingly generated or set matching region-based similarity indicated by the reference numeral330. Thus, with the fingerprint verification apparatus having determined the second similarity corresponding to the second matching region, the fingerprint verification apparatus may update the matching region-based similarity based on the second similarity and the second matching region. The fingerprint verification apparatus updates the matching region-based similarity by allocating the second similarity to a region of the matching region-based similarity representing the second matching region. Here, when an overlap occurs between the first matching region and the second matching region, e.g., they overlap each other with respect to the input fingerprint image, when the second similarity and second matching region are allocated to the matching region-based similarity the fingerprint verification apparatus selectively allocates the greater of the first similarity and the second similarity to the region of the matching region-based similarity corresponding to the overlapping region. The fingerprint verification apparatus further allocates the second similarity to a remaining region of the matching region-based similarity representing the remaining portion of the second matching region in which the overlapping region is not included. According to such an example, for each remaining registered fingerprint that has not been yet been compared to the input fingerprint image, respective comparisons between the input fingerprint image and each of the remaining registered fingerprint images may be performed in sequential order, with the matching region-based similarity being incrementally or continuously updated based on the result of each respective comparison, until the fingerprint verification condition is satisfied or all registered fingerprints have been considered and the fingerprint verification condition is still not met. For example, when the fingerprint verification condition is satisfied after only half of the registered fingerprints have been considered, the fingerprint verification apparatus may cease operations and indicate the verification success in operation430without having to perform all such comparisons with all registered fingerprint images in the fingerprint verification process.

In another example, the fingerprint verification apparatus may first determine the respective similarities between the input fingerprint image and each of all of the registered fingerprint images, and may determine a matching region-based similarity based on the determined respective similarities. In this example, the fingerprint verification apparatus determines the respective matching regions and the similarities between the input fingerprint image and each of the registered fingerprint images, and then updates the matching region-based similarity based on the determined matching regions and the determined similarities. Here, in response to any overlapping regions being present between any of the matching regions, the fingerprint verification apparatus selectively allocates, to an example overlapping region, a greatest similarity among similarities corresponding to the corresponding matching regions that overlap each other. Similarities for each of such overlapping regions may similarly be selectively allocated. According to such an example, the respective similarities between the input fingerprint image and each of all of the registered fingerprint images are calculated, and whether the fingerprint verification condition is satisfied is then determined after the matching region-based similarity is finally determined based on the calculated similarities, determined matching regions, and any determined overlapping regions.

In operation430, the fingerprint verification apparatus determines a result of the fingerprint verification of the input fingerprint image based on the matching region-based similarity. For example, operation430may correspond to operation340ofFIG. 3, and thus discussions above with respect to operation430are not repeated here merely for brevity purposes. As noted, in response to the score determined based on the matching region-based similarity satisfying the fingerprint verification condition, the fingerprint verification apparatus determines that the fingerprint verification of the input fingerprint image is successful.

In one example, the fingerprint verification apparatus determines whether the fingerprint verification is successful based on whether a score determined based on the most recent updated matching region-based similarity, e.g., each time the matching region-based similarity is updated, satisfies the fingerprint verification condition. For example, the fingerprint verification apparatus may determine and indicate whether the fingerprint verification is successful or may determine and indicate whether the verification is unsuccessful.

In one example, the fingerprint verification apparatus determines whether a total size of matching regions, represented in the matching region-based similarity, having similarities greater than a threshold value is greater than a threshold size based on the matching region-based similarity, and determines whether the fingerprint verification of the input fingerprint image is successful based on a result of the determining. In response to the total size of the matching regions having similarities greater than the threshold value being greater than the threshold size, the fingerprint verification apparatus determines that the fingerprint verification of the input fingerprint image is successful. In another example, in response to an average value of the allocated similarities of the matching region-based similarity being greater than a threshold value, the fingerprint verification apparatus determines that the fingerprint verification of the input fingerprint image is successful. The fingerprint verification apparatus may indicate the result of the fingerprint verification process either explicitly or implicitly. For example, an explicit indication may include a display or audible announcement of the success of the fingerprint verification process and an implicit indication may include the fingerprint verification apparatus selectively performing or ceasing to perform additional operations of the fingerprint verification apparatus. For example, in response to the fingerprint verification being determined to be successful, the fingerprint verification apparatus may perform the implicit indication by cancelling a lock state of a computing apparatus represented by, connected to, or including the fingerprint verification apparatus, or by assigning, to a user, a right or authority to access one or more functions or features of the example computing apparatus or fingerprint verification apparatus. In a case in which a score, determined based on a matching region-based similarity determined with respect to all registered fingerprint images, does not satisfy the fingerprint verification condition, the fingerprint verification apparatus may determine that the fingerprint verification of the input fingerprint image is unsuccessful. In response to the fingerprint verification being determined to be unsuccessful, the fingerprint verification apparatus may similarly indicate the unsuccessful either explicitly or implicitly, e.g., with an implicit indication being the computing apparatus or verification apparatus maintaining the example lock state or restricting the right or authority of the user for the access to the one or more functions or features of the computing apparatus or fingerprint verification apparatus. Such and/or further examples of methods of determining whether the fingerprint verification is successful and/or unsuccessful will be described in greater detail below with reference toFIG. 11A.

FIG. 5is a flowchart illustrating an example of a fingerprint verification method. As only an example,FIG. 5may be a more detailed example of the method described with reference toFIG. 4. Thus, as an example, the above descriptions provided with reference toFIG. 4are also applicable to corresponding operations of the description provided hereinafter with reference toFIG. 5, and thus repeated descriptions thereof will be omitted here merely for brevity purposes.

Referring toFIG. 5, in operation510, a fingerprint verification apparatus obtains, e.g., captures, reading, and/or receives, an input fingerprint image. In operation520, the fingerprint verification apparatus performs a matching operation of the input fingerprint image to a registered fingerprint image. The matching may include rotating and/or translating at least one of the input fingerprint image and the registered fingerprint image, and determining a matching region between the input fingerprint image and the registered fingerprint image.

In operation530, the fingerprint verification apparatus determines a similarity, based on the matching region determined in operation520, between the input fingerprint image and the registered fingerprint image. For example, the fingerprint verification apparatus determines a first similarity corresponding to a first matching region between the input fingerprint image and a first registered fingerprint image.

In operation540, the fingerprint verification apparatus generates, sets, or updates a matching region-based similarity based on the similarity determined in operation530. For example, the fingerprint verification apparatus may update the generated or set matching region-based similarity based on the matching region between the input fingerprint image and the registered fingerprint image, and based on the determined similarity corresponding to the matching region between the input fingerprint image and the registered fingerprint image. For example, the fingerprint verification apparatus may apply the similarity determined in operation530to a previously determined matching region-based similarity with respect to a region of the previously determined matching region-based similarity corresponding to the matching region. Here, in an example where the matching region-based similarity has previously had a previously determined similarly applied to a region of the matching region-based similarity that overlaps with the matching region determined in operation520, i.e., a corresponding overlapping region, the greater similarity between the previously allocated similarity and the newly determined similarity may be allocated to the corresponding overlapping region.

In operation550, the fingerprint verification apparatus determines whether a score determined based on the matching region-based similarity satisfies a fingerprint verification condition. For example, the fingerprint verification apparatus calculates a score to determine whether a fingerprint verification is successful based on the matching region-based similarity determined based on the first similarity, and determines whether the calculated score satisfies the fingerprint verification condition. In operation560, in response to the fingerprint verification condition being satisfied, the fingerprint verification apparatus determines that the fingerprint verification is successful and terminates a fingerprint verification process. Conversely, in operation570, in response to the fingerprint verification condition not being satisfied, the fingerprint verification apparatus may determine whether similarities of all registered fingerprint images have been determined.

In operation580, in response to the similarities of all the registered fingerprint images having been determined, the fingerprint verification apparatus determines that the fingerprint verification is unsuccessful and terminates the fingerprint verification process. In operation590, in response to the determination that the similarities of all the registered fingerprint images have not been determined, the fingerprint verification apparatus selects another or subsequent registered fingerprint image from the registered fingerprint images and then repeats operations520,530,540,550, and570on the selected registered fingerprint image.

For example, the fingerprint verification apparatus calculates a score using the matching region-based similarity determined based on the first similarity. In response to the calculated score not satisfying the fingerprint verification condition, the fingerprint verification apparatus selects a second registered fingerprint image subsequent to the first registered fingerprint image in operation590. The fingerprint verification apparatus then matches the input fingerprint image to the second registered fingerprint image in operation520, and determines a second similarity corresponding to a second matching region between the input fingerprint image and the second registered fingerprint image in operation530. The fingerprint verification apparatus then updates the matching region-based similarity based on the second similarity in operation540. Here, in response to an overlapping region being determined to be present between the first matching region and the second matching region, the fingerprint verification apparatus allocates the greater similarity between the first similarity and the second similarity to the overlapping region. The fingerprint verification apparatus also allocates the second similarity to the remaining region of the second matching region in which the overlapping region is not included, to complete the updating of the matching region-based similarity. The fingerprint verification apparatus determines whether a score determined by the matching region-based similarity updated based on the second similarity satisfies the fingerprint verification condition in operation550. In response to the fingerprint verification condition not being satisfied and there still being available registered fingerprint image(s) remaining, the fingerprint verification apparatus selects another or next registered fingerprint image in operation590, and again performs the operations described above on the selected registered fingerprint image.

FIG. 6is a diagram illustrating an example of matching between an input fingerprint image and a registered fingerprint image.

Referring toFIG. 6, a fingerprint verification apparatus estimates rotation information and translation information of an input fingerprint image610and a registered fingerprint image620, and determines a matching region630between the input fingerprint image610and the registered fingerprint image620using the estimated rotation information and the estimated translation information. In one example, for the matching between the input fingerprint image610and the registered fingerprint image620, a method of matching patterns or features of a pixel intensity of an image in a space, or a method of determining a parameter needed for matching between two images in a frequency domain of the images may be used.

FIG. 7is a flowchart illustrating an example of a method of determining a similarity between an input fingerprint image and a registered fingerprint image based on a Fourier-Mellin method.

Referring toFIG. 7, in operation710, a fingerprint verification apparatus transforms information of a spatial domain included in an input fingerprint image to information of a frequency domain using an FFT. In operation730, the fingerprint verification apparatus transforms information of a spatial domain included in a registered fingerprint image to information of a frequency domain using an FFT. As only an example, the information of the frequency domain may be based on an orthogonal coordinates system that represents information using, for example, two-dimensional (2D) (x, y) coordinates.

In operation715, the fingerprint verification apparatus transforms a coordinates system of the information of the frequency domain included in the input fingerprint image to a polar coordinates system, for example, such as by using a log-polar transform (LPT). For example, the LPT may be performed on a magnitude value of a pixel in an FFT image obtained through the FFT. In the polar coordinates system, information may be represented by a radius, an angle, or a combination thereof. In operation735, the fingerprint verification apparatus applies an LPT to the information of the frequency domain included in the registered fingerprint image. The LPT will be described in greater detail with reference toFIG. 8.

FIG. 8is a diagram illustrating an example of an LPT. Referring toFIG. 8, in an orthogonal coordinates system, concentric circles are set based on a central point810. The concentric circles are divided into a plurality of regions based on a radius, an angle, or a combination thereof. For example, an LPT maps the plurality of regions in the orthogonal coordinates system to a plurality of regions in a polar coordinates system represented by a radius and an angle. In such an example, the central point810in the orthogonal coordinates system may be mapped by the verification apparatus to a region815corresponding to (0, 0°) in the polar coordinates system. Similarly, a first region820, a second region830, a third region840, and a fourth region850in the orthogonal coordinates system may be mapped by the verification apparatus to a first region825, a second region835, a third region845, and a fourth region855, respectively, in the polar coordinates system.

The LPT may map a plurality of regions in the orthogonal coordinates system to a plurality of regions in the polar coordinates system represented based on an angle. In such a case, the first region820in the orthogonal coordinates system may be mapped by the verification apparatus to a (0°) region in the polar coordinates system. The second region830and the third region840in the orthogonal coordinates system may be mapped by the verification apparatus to a (36°) region in the polar coordinates system, and the fourth region840in the orthogonal coordinates system may be mapped by the verification apparatus to a (324°) region in the polar coordinates system, as only examples.

Referring back toFIG. 7, in operation720, the fingerprint verification apparatus applies an FFT to the input fingerprint image to which the LPT is applied. In operation740, the fingerprint verification apparatus applies an FFT to the registered fingerprint image to which the LPT is applied. In operation750, the fingerprint verification apparatus performs a phase correlation based on a result obtained through the FFT, and detects a peak as a result of performing the phase correlation. A location of the detected peak indicates rotation information between the input fingerprint image and the registered fingerprint image.

In another example, the location of the detected peak may indicate scale information between the input fingerprint image and the registered fingerprint image. For example, one axis of an image obtained through the LPT may correspond to an angle, and the other axis of the image may correspond to a radius, and thus the location of the peak detected through the phase correlation may be indicated by a (a coordinate of the axis corresponding to an angle, a coordinate of the axis corresponding to a radius). The coordinate of the axis corresponding to an angle may indicate the rotation information, and the coordinate of the axis corresponding to a radius may indicate the scale information.

In an example, the fingerprint verification apparatus may not adjust or change a scale of the fingerprint image, or otherwise the fingerprint image may not have a change in scale, and thus a radius may be fixed to a preset value, for example, 1. In such an example, the location of the peak detected through the phase correlation may be represented by the coordinate of the axis corresponding to an angle, and the coordinate of the axis corresponding to an angle may indicate the rotation information.

In one example, the fingerprint verification apparatus detects a peak value by performing the phase correlation, and determines a similarity between the input fingerprint image and the registered fingerprint image based on the peak value. As a size of a region, for example, an overlapping region, in which a fingerprint pattern of the input fingerprint image and a fingerprint pattern of the registered fingerprint image are the same or similar to each other increases, or as similarity between the fingerprint pattern of the input fingerprint image and the fingerprint pattern of the registered fingerprint image increases, the peak value may tend to increase. Based on such a tendency, the fingerprint verification apparatus may determine the similarity between the input fingerprint image and the registered fingerprint image based on the peak value detected through the phase correlation.

The fingerprint verification apparatus rotates the input fingerprint image based on the rotation information θ in operation760, and applies an FFT on the rotated input fingerprint image in operation770. In operation780, the fingerprint verification apparatus performs a phase correlation based on the input fingerprint image to which the FFT is applied in operation770and the registered fingerprint image to which the FFT is applied in operation730. As a result of performing the phase correlation, a peak is detected, and a location of the detected peak indicates translation information (Tx, Ty) between the input fingerprint image and the registered fingerprint image. In operation790, the fingerprint verification apparatus translates the input fingerprint image rotated in operation760based on the translation information (Tx, Ty).

The fingerprint verification apparatus then matches the input fingerprint image and the registered fingerprint image by rotating and translating the input fingerprint image based on the rotation information and the translation information obtained through the example Fourier-Mellin method. In one example, the fingerprint verification apparatus determines a similarity based on a matching region determined by the matching between the rotated and translated input fingerprint image and the registered fingerprint image. The fingerprint verification apparatus may determine the similarity using various methods. For example, in one example, the fingerprint verification apparatus determines the similarity based on a brightness value-based normalized cross correlation method. For example, the fingerprint verification apparatus may determine the similarity based on a correlation obtained through the below Equation 1, for example.

In Equation 1, W denotes a matching region between an image I1and an image I2, and ncc(I1, I2) denotes a normalized cross correlation in the matching region W between the image I1and the image I2. For example, the image I1may be a rotated and translated input fingerprint image, and the image I2may be a registered fingerprint image. i denotes an x-axis coordinate of a pixel in the matching region W, and j denotes a y-axis coordinate of the pixel in the matching region W. x denotes translation information Tx in an x-axis direction, and y denotes translation information Ty in a y-axis direction. I1(i, j) denotes a pixel value on (i, j) coordinates of the image I1, and I2(x+i, y+j) denotes a pixel value on (x+i, y+j) coordinates of the image I2. Thus, the correlation ncc(I1, I2) in the matching region W that is calculated through Equation 1 above may be used as a similarity between the input fingerprint image and the registered fingerprint image. In such an example, extents of the matching region W may also be determined based on the number of pixels for which a resulting ncc value is greater than a threshold value.

Although rotating and translating an input fingerprint image is described with reference toFIG. 7, the rotating and translating may be performed on a registered fingerprint image based on a result of a phase correlation without the rotating and translating of the input fingerprint image. Alternatively, rotating and translating may be performed on both the input fingerprint image and the registered fingerprint image.

FIG. 9is a diagram illustrating an example of a method of determining a similarity between an input fingerprint image and a registered fingerprint image based on a Fourier-Mellin method performed by a verification apparatus.

Referring toFIG. 9, a registered fingerprint image910is transformed by the verification apparatus to a first LPT image915through an FFT and an LPT. An input fingerprint image920is transformed by the verification apparatus to a second LPT image925through an FFT and an LPT.

Through a phase correlation930between the first LPT image915and the second LPT image925by the verification apparatus, rotation information θ between the registered fingerprint image910and the input fingerprint image920is determined by the verification apparatus. In one example, a similarity between the registered fingerprint image910and the input fingerprint image920is determined by the verification apparatus based on a peak value detected by the verification apparatus through the phase correlation930.

The input fingerprint image920is rotated by the verification apparatus based on the rotation information θ determined through the phase correlation930. In addition, translation information (Tx, Ty) between the registered fingerprint image910and the input fingerprint image920is determined by the verification apparatus through a phase correlation950between an FFT image, which is an image obtained as a result of performing an FFT on the registered fingerprint image910by the verification apparatus, and an FFT image, which is an image obtained as a result of performing an FFT on a rotated input fingerprint image940by the verification apparatus.

Matching between the registered fingerprint image910and the input fingerprint image920is performed by the verification apparatus based on the rotation information θ and the translation information (Tx, Ty), and a matching region970between the registered fingerprint image910and the input fingerprint image920is thereby determined by the verification apparatus. In one example, a correlation corresponding to the matching region970in a matching image960between the registered fingerprint image910and the input fingerprint image920is calculated by the verification apparatus based on Equation 1 above, and the calculated correlation is determined to be the similarity between the registered fingerprint image910and the input fingerprint image920by the verification apparatus.

In a matching region-based similarity, the similarity determined based on the peak value detected through the phase correlation930or on the correlation calculated through Equation 1 is allocated by the verification apparatus to the matching region970.

FIG. 10is a diagram illustrating an example of a method of updating a matching region-based similarity.

Referring toFIG. 10, in operation1010, a fingerprint verification apparatus compares an input fingerprint image1000and a first registered fingerprint image1022, among a plurality of registered fingerprint images, determines a first matching region1032and a first similarity between the input fingerprint image1000and the first registered fingerprint image1022, and updates a matching region-based similarity based on the first matching region1032and the first similarity. The reference numeral1015inFIG. 10indicates a visualization of the matching region-based similarity determined in operation1010. Here, in an example where the first similarity is determined to be 0.97, the fingerprint verification apparatus allocates the first similarity 0.97 to the illustrated region A1corresponding to the first matching region1032in the matching region-based similarity1015. As illustrated inFIG. 10, a default value 0.0 may be allocated to another or remaining region, for example, A2. In an example, the default value 0.0 may have initially been allocated or set for all portions of the matching region-based similarity1015, so after the updating of the first similarity 0.97 to the illustrated region A1, the remainder of the matching region-based similarity1015may still have the default value 0.0.

In one example, the fingerprint verification apparatus determines a score based on the matching region-based similarity1015, and the fingerprint verification apparatus then determines whether the fingerprint verification is successful based on whether the score satisfies a predetermined fingerprint verification condition. The fingerprint verification condition may include, for example, a requirement that an average value of similarities in one or more regions of the matching region-based similarity1015, e.g., representing an area equal to or greater than a set 80% of the entire matching region-based similarity1015or the entire area of the input fingerprint image1000, needs to be equal to or greater than a set 0.9. Such fingerprint verification condition requirements may be preset and/or updated by a manufacturer and/or set or selected by a user, such as by the user selecting from different levels or required similarities and areas before verification is considered a success.

In response to the score determined based on the matching region-based similarity1015satisfying the fingerprint verification condition, the fingerprint verification apparatus determines that the fingerprint verification is successful and terminates the fingerprint verification process without comparing the input fingerprint image1000to another registered fingerprint image. Conversely, in response to the score determined based on the matching region-based similarity1015not satisfying the fingerprint verification condition, the fingerprint verification apparatus compares the input fingerprint image1000to a second registered fingerprint image1024, which is different from the first registered fingerprint image1022, and determines a second matching region1034and a second similarity between the input fingerprint image1000and the second registered fingerprint image1024in operation1040. In one example, the fingerprint verification condition may be determined based on of the size of the matching region(s), a similarity or similarities indicated in the matching region-based similarity1015, or a combination of the size of the matching region(s) and the similarity or similarities indicated in the matching region-based similarity1015.

With respect to determined second matching region and second similarity, the fingerprint verification apparatus updates the matching region-based similarity1015based on the determined second matching region1034and the determined second similarity. A reference numeral1045indicates a visualization of the matching region-based similarity that is updated based on the second matching region1034and the second similarity, after having been previously updated with respect to the first matching region1032and the first similarity. Here, in an example where the second similarity is determined to be 0.83, the fingerprint verification apparatus thus allocates the second similarity 0.83 to the illustrated region B2of a region corresponding to the second matching region1034in the matching region-based similarity1045. The illustrated region B3of the corresponding region is a region matched to both the first registered fingerprint image1022and the second registered fingerprint image1024, and thus corresponds to an overlapping region between the first matching region1032and the second matching region1034. In such a case, the similarity corresponding to the region B3is determined to be 0.97, which is the greater similarity between the previously allocated similarity 0.97 and the second similarity 0.83. For example, the similarity corresponding to the region B3may be maintained to be the previously allocated 0.97, i.e., previously allocated based on the first similarity 0.97, without being updated based on the determination that the second similarity is less than the first similarity 0.97. The example default value 0.0 may be maintained for illustrated regions B4and B5, which have not yet been determined to correspond to matching regions with any registered fingerprint image. The illustrated region B1, corresponding to the previously allocated first similarity 0.97 and the first matching region1032, is also maintained to have the allocated 0.97 distinct from the allocated second similarity 0.83 allocated for the second matching region1034.

Similarly, in response to a score determined based on the matching region-based similarity1045not satisfying the fingerprint verification condition, the fingerprint verification apparatus compares the input fingerprint image1000to a third registered fingerprint image1026, determines a third matching region1036and a third similarity between the input fingerprint image1000and the third registered fingerprint image1026, and updates the matching region-based similarity1045based on the third matching region1036and the third similarity in operation1050. Here, the third similarity is determined to be 0.92. The illustrated reference numeral1055is a visualization of this latest matching region-based similarity that has been updated based on the third matching region1036and the third similarity.

The fingerprint verification apparatus thus allocates the third similarity 0.92 to regions C3, C4, and C5of a region corresponding to the third matching region1036in the matching region-based similarity1055. Previous allocated similarities corresponding to the regions C3and C4were the example default 0.0, and thus are updated to be 0.92, which is a greater value than the default 0.0. The region C5is a region that is matched to both the second registered fingerprint image1024and the third registered fingerprint image1026, and thus corresponds to an overlapping region between the second matching region1034and the third matching region1036. In such a case, a similarity corresponding to the region C5is updated to be 0.92, which is the greater value between the previously allocated similarity 0.83 and the third similarity 0.92. The example default value 0.0 is thus maintained for the region C6, which has not yet been determined to correspond to matching regions with any registered fingerprint image. The illustrated region C1, corresponding to the previously allocated first similarity 0.97 and the first matching region1032, is also maintained to have the allocated 0.97 distinct from the allocated third similarity 0.92 allocated for the third matching region1036.

As described above, in a matching region-based similarity, respective similarities between an input fingerprint image and each of the registered fingerprint images may be determined with respect to each matching region between the input fingerprint image and each of the registered fingerprint images. Further, each time the input fingerprint image is compared to each of different registered fingerprint images and a corresponding additional matching region is determined, a total matching region of the matching region-based similarity may be incrementally expanded with each matching region-based similarity update.

Thus, when the updating of the matching region-based similarity1045is completed based on the third matching region1036and the third similarity, the fingerprint verification apparatus determines a score based on an updated matching region similarity1055, and determines whether the score satisfies the fingerprint verification condition. In response to the score satisfying the fingerprint verification condition, the fingerprint verification apparatus determines that the fingerprint verification process of the input fingerprint image is successful and the fingerprint verification apparatus may indicate the success of the fingerprint verification process. In response to the score not satisfying the fingerprint verification condition, the fingerprint verification apparatus may sequentially perform the same operations described in the foregoing on each remaining registered fingerprint images until the fingerprint verification condition is satisfied. The fingerprint verification apparatus may determine that the fingerprint verification process is unsuccessful when a final score determined based on a finally updated matching region-based similarity, e.g., obtained as a result of having performed such operations on all the registered fingerprint images, does not satisfy the fingerprint verification condition.

FIGS. 11A and 11Bare diagrams illustrating an example of a method of performing a fingerprint verification based on a matching region-based similarity.

Referring toFIG. 11A, a matching region-based similarity1120may be embodied as an image having a same resolution as a resolution of an input fingerprint image1100. For example, in a case in which the resolution of the input fingerprint image1100is n×m, in which n denotes a number of pixels in width and m denotes a number of pixels in length, the resolution of the matching region-based similarity1120may also be n×m. Here, each of illustrated similarities included in the matching region-based similarity1120inFIG. 11A, for example, corresponds to a similarity between the input fingerprint image1100and each of the multiple registered fingerprint images. As only an example, each of the registered fingerprint images may also have an n×m resolution.

Here, an input fingerprint image may be provided in the example illustrated rectangular shape, for example, the input fingerprint image1100as illustrated inFIG. 11A, or in an oval shape, for example, an input fingerprint image1130as illustrated inFIG. 11B. In one example, in a case in which an image of a fingerprint of a user is captured by a fingerprint sensor, integrated in a display, while a finger of the user is touching the display, the resultant input fingerprint image1130in the oval shape may be captured as illustrated inFIG. 11B. Alternatively or additionally, a sensing region of the fingerprint sensor may have an oval shape, and the resultant input fingerprint image captured by the fingerprint sensor may have an oval shape. After the aforementioned operations described above to respectively determine the matching region-based similarities ofFIGS. 1-10, for example, the matching region-based similarity corresponding to such an oval-shaped input fingerprint image, for example, the input fingerprint image1130, may be visualized as a matching region-based similarity1140illustrated inFIG. 11B, and the fingerprint verification determined based on considerations of the similarities and matching areas represented in the matching region-based similarity1140, as also discussed above.

Referring back toFIG. 11A, and as an example, determining whether a fingerprint verification condition is satisfied based on the matching region-based similarity1120will be described in greater detail below.

In the matching region-based similarity1120, a first region1122is a region associated with a matching region between the input fingerprint image1100and a first registered fingerprint image, and 0.97 is the similarity allocated to the first region1122. Similarities 0.83, 0.0, and 0.92 are similarity values allocated to a second region1124, a third region1126, and a fourth region1128, respectively. The similarity 0.0 may be a default value allocated to the third region1126because the third region1126does not include a region matched to any of all registered fingerprint images, or due to a determined considerably low similarity to a registered fingerprint image resulting in such a matching region not being determined or resulting in a determination to not adjust the default value because of the considerably low similarity, e.g., when the correspondingly determined similarity fails to meet a predetermined minimum similarity.

In one example, the fingerprint verification apparatus determines whether a fingerprint verification is successful based on whether a size of total of all matching regions, which have similarities that meet a threshold value (e.g., is greater than or equal to the threshold value), meets a threshold size (e.g., is greater than or equal to the threshold size) using the matching region-based similarity. For example, in a case in which the threshold value is 0.90 and the threshold size is A, for example, 4000, the fingerprint verification apparatus determines that the first region1122and the fourth region1128are the only matching regions whose similarities meet the threshold value, and then determines that the fingerprint verification is successful when a sum of a size of the first region1122and a size of the fourth region1128meets A. In a case of the matching region-based similarity1120is provided as an image, or representable by an image, the sum of the sizes may be determined to be the total number of pixels in the image to which a similarity meeting 0.90 has been allocated.

In another example, the fingerprint verification apparatus determines whether the fingerprint verification is successful based on whether an average value of the top or greatest value N similarities in the matching region-based similarity1120meets, e.g., is greater than or equal to, a threshold value. For example, in a case in which N is 100 and the threshold value is 0.95, the fingerprint verification apparatus arranges or considers similarities in the matching region-based similarity1120in a descending order and extracts the top 100 similarities in order, and determines that the fingerprint verification is successful when an average value of the extracted 100 similarities meets, e.g., is greater than or equal to, a predetermined threshold value of 0.95.

In still another example, the fingerprint verification apparatus determines whether the fingerprint verification is successful by arranging similarities in the matching region-based similarity1120in a descending order and determining whether a top M-th similarity is greater than or equal to a threshold value. For example, in a case in which M is 200 and the threshold value is 0.9, the fingerprint verification apparatus arranges the similarities in the matching region-based similarity1120in a descending order, and determines that the fingerprint verification is successful when a top 200th similarity in the order of similarities meets, e.g., is greater than or equal to, 0.9.

In these examples, values of N and M may be predetermined and/or set, adjusted, or updated by a manufacturer, service provider, and/or user, for example. Similarly, such thresholds herein may also be predetermined, such as by a manufacturer, and/or set, adjusted, or updated by the manufacturer, service provider, and/or user.

The fingerprint verification apparatus may determine whether the fingerprint verification is successful and/or may determine whether the fingerprint verification is unsuccessful using various fingerprint verification conditions, and a scope of examples is not limited by the examples described in the foregoing.

FIG. 12is a diagram illustrating an example of a fingerprint verification apparatus.

Referring toFIG. 12, a fingerprint sensor1210obtains, e.g., captures, reads, and/or receives, fingerprint information of a user, e.g., a user attempting at a fingerprint verification, and generates an input fingerprint image. The input fingerprint image may be transferred or transmitted to a fingerprint verification apparatus1220, and the fingerprint verification apparatus1220is configured to perform the fingerprint verification by comparing the input fingerprint image to at least one registered fingerprint image stored in a registered image DB1230. The verification process may further include a fingerprint registration process, where the user may register fingerprint images of each of at least one finger, and the registered fingerprint image DB1230may be generated and store the registered fingerprint images. The fingerprint registration process may be performed by another fingerprint verification apparatus or another device that is connected to the fingerprint sensor1210or another fingerprint sensor for capturing one or more fingerprints to generate and store the registered fingerprint images. The registered fingerprint image DB1230may alternatively be included in the fingerprint verification apparatus1220, just as examples exist where the fingerprint sensor1210is included or separate from the fingerprint verification apparatus1220. The fingerprint verification apparatus1220may respectively request or access registered fingerprint images from the registered fingerprint image DB1230, e.g., during the verification process, or the registered fingerprint image DB1230may automatically provide the registered fingerprint images to the fingerprint verification apparatus1220based on a command of the fingerprint verification apparatus1220. Here, though examples are presented for various embodiments, examples are not limited thereto.

The fingerprint verification apparatus1220may be configured to perform any one, combination, or all processes, stages, or operations of any one, combination, or all fingerprint verification methods described herein, such as discussed above with respect toFIGS. 1-11B, and provide a result of the fingerprint verification to the user or another server or device, such as through the aforementioned explicit or implicit indications of the results, as non-limiting examples. As a further example, the fingerprint verification apparatus1220may provide an example explicit indication of the result of the fingerprint verification through, for example, an output voice, vibration, displayed written character, displayed illustration, or displayed video. However, the indicating of the result is not limited to the examples described in the foregoing, and the fingerprint verification apparatus1220may indicate the result in various forms.

The fingerprint verification apparatus1220includes at least one processor1222and a memory1224. The memory1224is connected to the processor1222, and stores instructions implementable by the processor1222, data to be operated by the processor1222, and/or data processed by the processor1222for, during, or as a result of any, any combination, or all of the fingerprint verification processes, stages, operations, and/or methods described herein. The memory1224may include, for example, a non-transitory computer-readable medium, for example, a high-speed random access memory and/or a nonvolatile computer-readable storage medium (e.g., at least one disk storage device, a flash memory device, and other nonvolatile solid-state memory devices).

The processor1222executes such instructions to control the processor1222to perform any one, combination, or all processes, stages, operations, and/or methods described with reference toFIGS. 1 through 11B. Either through such executed instructions or through other hardware implementation, the processor1222may be configured to determine a matching region-based similarity based on a determined matching region between the input fingerprint image and the at least one registered fingerprint image, and determines a result of the fingerprint verification performed on the input fingerprint image based on the matching region-based similarity. The processor1222may be configured to generate, set, or update the matching region-based similarity based on the matching region between the input fingerprint image and the registered fingerprint image and a similarity corresponding to the matching region between the input fingerprint image and the registered fingerprint image. The processor1222determines whether the fingerprint verification is successful based on whether a score determined based on the updated matching region-based similarity satisfies a fingerprint verification condition.

FIG. 13is a diagram illustrating an example of a computing apparatus.

A computing apparatus1300performs a fingerprint verification process by obtaining a fingerprint image of a user and comparing the obtained fingerprint image to a registered fingerprint image. The computing apparatus1300may be configured to include or implement the functionalities of the fingerprint verification apparatus1220illustrated inFIG. 12, and thus the descriptions above are applicable to the operation of the computing apparatus1300, and may not be repeated in full below merely for brevity purposes. In addition, in an example, the computing apparatus1300corresponds to the fingerprint verification apparatus1220. Referring toFIG. 13, the computing apparatus1300includes a processor1310, a memory1320, a fingerprint sensor1330, a storage device1340, an input device1350, an output device1360, and a network interface1370. The processor1310of the computing apparatus1300, as well as the processor1222ofFIG. 12, may respectively be representative of a single processor, multiple processors, or networked processors or computing devices that share implementations of operations between such processors. Thus, a reference to a processor herein also refers to an example of one or more processors. The processor1310, the memory1320, the fingerprint sensor1330, the storage device1340, the input device1350, the output device1360, and the network interface1370may further communicate with one another through an example communication bus1380.

The processor1310is configured to implement functions and instructions in the computing apparatus1300. For example, the processor1310may be configured to execute instructions stored in the memory1320or the storage device1340. Thus, through such instructions and/or through alternative hardware implementations, the processor1310is configured to perform any one, combination, or all processes, stages, or operations described with reference toFIGS. 1 through 12.

The memory1320stores information to be used for the fingerprint verification process implemented by the computing apparatus1300. The memory1320includes a computer-readable storage medium or a computer-readable storage device. For example, the memory1320includes a random access memory (RAM), a dynamic RAM (DRAM), a static RAM (SRAM), or nonvolatile memories in other forms in the technical field to which the present disclosure pertains after an understanding of the present disclosure. The memory1320may store the aforementioned instructions to be implemented or executed by the processor1310and may store related information generated or relied upon during execution of any software or application being further implemented by the computing apparatus1300. For example, the memory1320may store software or applications whose execution is indicative of success of the fingerprint verification process, such as a mobile banking application or a process of the mobile banking application being executed or authorized upon a successful fingerprint verification.

The fingerprint sensor1330may obtain, e.g., capture, read, or receive, an input fingerprint image, e.g., in response to a detection or determination that a fingerprint is being input or provided from a user. The inputting of a fingerprint may include all actions or manipulations performed by the user from which the fingerprint may be obtained. For example, in a case in which a finger of the user comes into contact with a sensing region or the user performs a swipe motion on the sensing region using a finger, the fingerprint sensor1330may be configured to sense the fingerprint of the user. In another example, in a case in which the fingerprint sensor1330is integrated in a display example, a surface of the display may be embodied as the sensing region and the fingerprint sensor1330may be configured to sense a fingerprint from a finger being determined to be in contact with the display. The fingerprint sensor1330may be configured to perform various fingerprint information obtaining, e.g., capturing, reading, and/or receiving, methods, for example, an ultrasonic method, a mutual capacitance method, and an infrared image capturing method, as only examples. The fingerprint sensor1330may capture, as a fingerprint image, a fingerprint region corresponding to the sensing region of the fingerprint sensor1330, for example.

The storage device1340includes a computer-readable storage medium or a computer-readable storage device. The storage device1340stores a DB including registered fingerprint images. In one example, the storage device1340stores a greater amount of information than the memory1320, and stores the information for a long period of time. For example, the storage device1340may include, for example, a magnetic hard disk, an optical disc, a flash memory, an erasable programmable read-only memory (EPROM), a floppy disk, and nonvolatile memories in other forms that are well-known in the technical field to which the present disclosure pertains.

The input device1350is configured to obtain, e.g., capture, read, and/or receive, input from the user through a tactile, video, audio, and/or touch input. For example, the input device1350may include one or more of a keyboard, a mouse, a touchscreen, a microphone, a fingerprint reader, a retinal scanner, and other devices configured to detect an input from a user and transfer the detected input to the computing apparatus1300.

The output device1360is configured to provide the user with an output of the computing apparatus through a visual, auditory, and/or tactile channel. For example, the output device1360may provide the user with the output by visualizing information associated with a fingerprint verification. For example, the output device1360may include one or more of a liquid crystal display (LCD), a light-emitting diode (LED) display, a touchscreen, a speaker, a vibration generator, and other devices configured to provide an output to the user.

The network interface1370may be configured to and/or controlled to communicate with an external device through a wired or wireless network for which the network interface1370is configured to interact with. For example, the network interface1370may include one or more of an Ethernet card, an optical transceiver, a radio frequency transceiver, and other network interface cards configured to transmit and receive information. The network interface1370may wirelessly communicate with the external device through, for example, Bluetooth, WiFi, and a third generation (3G) or fourth generation (4G) communication method.

According to one or more example embodiments described herein, using a matching region-based similarity, a fingerprint verification may be performed based on an integrated matching region and similarity between an input fingerprint image and each of various registered fingerprint images. In addition, a false rejection and a false acceptance that may occur in the fingerprint verification when fingerprint image and registered fingerprint images are independently compared without such a matching region-based similarity consideration may be prevented, and thus an accuracy in the fingerprint verification or a recognition rate may be improved in an example.

The computing apparatus100, fingerprint sensor110, processors, fingerprint verification apparatuses, fingerprint sensor1210, fingerprint verification apparatus1220, processor1222, memory1224, processor1310, memory1320, computing apparatus1300, fingerprint sensor1330, storage device1340, input device1350, output device1360, network interface1370, and bus1380, as only examples, and other apparatuses, hardware modules, devices, and other components described herein with respect toFIGS. 1-13and that perform operations described in this application are implemented by hardware components. Examples of hardware components that may be used to perform the operations described in this application where appropriate include controllers, sensors, generators, drivers, memories, comparators, arithmetic logic units, adders, subtractors, multipliers, dividers, integrators, and any other electronic components configured to perform the operations described in this application. In other examples, one or more of the hardware components that perform the operations described in this application are implemented by computing hardware, for example, by one or more processors or computers. A processor or computer may be implemented by one or more processing elements, such as an array of logic gates, a controller and an arithmetic logic unit, a digital signal processor, a microcomputer, a programmable logic controller, a field-programmable gate array, a programmable logic array, a microprocessor, or any other device or combination of devices that is configured to respond to and execute instructions in a defined manner to achieve a desired result. In one example, a processor or computer includes, or is connected to, one or more memories storing instructions or software that are executed by the processor or computer. Hardware components implemented by a processor or computer may execute instructions or software, such as an operating system (OS) and one or more software applications that run on the OS, to perform the operations described in this application. The hardware components may also access, manipulate, process, create, and store data in response to execution of the instructions or software. For simplicity, the singular term “processor” or “computer” may be used in the description of the examples described in this application, but in other examples multiple processors or computers may be used, or a processor or computer may include multiple processing elements, or multiple types of processing elements, or both. For example, a single hardware component or two or more hardware components may be implemented by a single processor, or two or more processors, or a processor and a controller. One or more hardware components may be implemented by one or more processors, or a processor and a controller, and one or more other hardware components may be implemented by one or more other processors, or another processor and another controller. One or more processors, or a processor and a controller, may implement a single hardware component, or two or more hardware components. A hardware component may have any one or more of different processing configurations, examples of which include a single processor, independent processors, parallel processors, single-instruction single-data (SISD) multiprocessing, single-instruction multiple-data (SIMD) multiprocessing, multiple-instruction single-data (MISD) multiprocessing, and multiple-instruction multiple-data (MIMD) multiprocessing.