Method and device for preventing false acceptance of latent finger print images

Abstract

Disclosed is a method for detecting a latent fingerprint image provided to a biometric input device of a fingerprint based security system. First and second images of the fingerprint are captured during a time period interval Δt. At least one of the first and second images are analyzed to identify an extractable feature within a global reference frame, the extractable feature useable for authenticating an individual. The first and second images are compared one with the other to determine differences indicative of motion about the identified extractable feature within a local reference frame during the time period interval Δt. Absent motion about the identified extractable feature being detected, the fingerprint is registered as a latent fingerprint and cannot be used to authenticate the individual who is seeking authorization.

Description

FIELD OF THE INVENTION [0001] This invention relates generally to imaging devices and more particularly to contact imaging devices for imaging fingerprints and the like. BACKGROUND OF THE INVENTION [0002] Computer security is fast becoming an important issue. With the proliferation of computers and computer networks into all aspects of business and daily life—financial, medical, education, government, and communications - the concern over secure file access is growing. Using passwords is a common method of providing security. Password protection and / or combination type locks are employed for computer network security, automatic teller machines, telephone banking, calling cards, telephone answering services, houses, and safes. These systems generally require knowledge of an entry code that has been selected by a user or has been configured in advance. [0003] Pre-set codes are often forgotten, as users have no reliable method of remembering them. Writing down the codes and storing the...

AI Technical Summary

Benefits of technology

[0015] Thus, in an attempt to overcome these and other limitations of known prior art devices, it is an object of this invention to provide a contact imaging device that is relatively inexpensive and practicable to manufacture that prevents user authorization based on latent fingerprints.

Problems solved by technology

Computer security is fast becoming an important issue.

Pre-set codes are often forgotten, as users have no reliable method of remembering them.

Writing down the codes and storing them in close proximity to an access control device (i.e. a combination lock) results in a secure access control system with a very insecure code.

Alternatively, the nuisance of trying several code variations renders the access control system more of a problem than a solution.

Password systems are known to suffer from other disadvantages.

Most users, being unsophisticated users of security systems, choose passwords which are relatively insecure.

One of the problems associated with fingerprint sensors concerns the reliable and accurate transformation of the ridge-and-valley pattern of the fingertip into electrical or optical signals to be stored in a digital format.

Optical systems as described above, for example using a prism, require sophisticated equipment and tend to be bulky and costly.

It is a disadvantage of prior art fingerprint sensing devices that when used, the user leaves a latent fingerprint, similar to the type of fingerprints used by police to identify suspects at crime scenes.

Thus, it is a problem that an unauthorized person can place a piece of paper over, for example, an optical fingerprint imager and the device will image the latent fingerprint and falsely identify the unauthorized person.

Unfortunately, an unauthorized individual could simply replace an existing biometric input device with a different biometric input device having a latent fingerprint image on a platen surface thereof.

It is a further limitation of the prior art that, by altering a latent fingerprint slightly and in a manner that does not affect authentication, an unauthorized user will be falsely authenticated.

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