GB2314661A

GB2314661A - Fingerprint capture system

Info

Publication number: GB2314661A
Application number: GB9613128A
Authority: GB
Inventors: Douglas Halsall
Original assignee: ADVANCED INTEGRATION SYSTEMS L
Current assignee: ADVANCED INTEGRATION SYSTEMS L
Priority date: 1996-06-21
Filing date: 1996-06-21
Publication date: 1998-01-07
Anticipated expiration: 2016-06-21
Also published as: GB9613128D0; GB2314661B

Abstract

A fingerprint capture system includes two imaging devices (1, 2), preferably a digital fingerprint scanner and a digital camera, positioned respectively below and above a finger locating means (4), which is preferably the lens of the scanner. In use, after initiation of the image capture process, images are automatically captured from the two imaging devices (1, 2). The first imaging device (1) produces an image of the fingerprint of a finger of a person's hand located by the finger locating means (4) and the second imaging device (2) produces an image of the hand from which the finger used can be determined.

Description

A FINGERPRINT CAPTURE SYSTEM AND A METHOD OF FINGERPRINT CAPTURE This invention relates to a fingerprint capture system and a method of fingerprint capture for which the system can be used. In particular, the invention relates to a system and method for fingerprint capture suitable for use in the capture of an image of a fingerprint for enrollment in an Automatic Fingerprint Identification System (AFIS).

In known fingerprint capture systems, such as those used for enrollment in an AFIS, a digital fingerprint reader is used to capture a digital image of a fingerprint, which is stored and can later be accessed by the AFIS. With this known system, however, it is relatively easy for an individual to acquire multiple registrations on the AFIS. This is done by initially enrolling using one finger from one hand and subsequently enrolling a second third or even more times using a different finger for each enrollment. These actions may be noticed and stopped by the operator of the system.

However, in the case where the operator is inattentive or even in collusion with the individual, there is no way to prevent such multiple registrations.

The present invention has been developed to address the above problem by providing an audited fingerprint capture system and method, which can be used to check that the correct finger has been used during the fingerprint capture operation.

Accordingly, in a first aspect, the present invention provides a fingerprint capture system comprising finger locating means for locating a finger of a person's hand, a first imaging device below the finger locating means for producing an image of a fingerprint from the finger located by the locating means , a second imaging device above the locating means for producing an image of at least a portion of the person's hand, said portion including the or a part of said one finger, means for capturing and storing the images produced from the first and second imaging means, and control means for controlling the system automatically to capture the images from both the first and second imaging means.

The use of "above" and "below" herein is intended to express a relative relationship between the components of the system, which may of course assume any orientation in space. Furthermore, the term "images" is not limited to those which can be viewed by the human eye and includes, for example, digital data representing such an image.

Using a system in accordance with the present invention the validity of the captured fingerprint can be assessed, and in particular the finger from which the fingerprint was captured can be determined, by viewing the image produced by the second imaging device. Because the two images are captured automatically, there is a single imaging operation, so that the possibility of an operator intervening is greatly reduced or even eliminated.

It is possible to capture both images simultaneously.

However, for ease of data handling, the images are preferably captured sequentially with substantially no delay between capture of the respective images, ie the image from the second imaging device can be captured immediately after capture of the image from the first imaging device, or vice versa. With such sequential or simultaneous capture, since the image of the hand is captured at substantially the same time as the image of the fingerprint itself it will necessarily show the finger from which the fingerprint was captured. In this way, the likelihood of multiple registrations can be greatly reduced.

The first imaging device is preferably a digital fingerprint reader or scanner, for instance of the type used in known fingerprint capture systems. The lens of the fingerprint reader or scanner can conveniently serve as the finger locating means, the finger being placed face down on the lens as in the known system.

Likewise, the second imaging device is preferably a digital camera, most preferably a colour digital camera.

Although in principle other imaging devices may be used, it is particularly preferred that both the devices are digital devices. This can greatly simplify the capture and storage and any further processing of the images, for example for use with an AFIS.

In practical embodiments of the system of the invention, to allow an operator to ensure that a finger is correctly positioned for capture of the fingerprint, a preview image from the first imaging device may be displayed. The preview image may, for instance, using appropriate software, be displayed on the monitor of a computer used to control the system. Using the preview image, the operator can correctly align the finger before initiating capture of the fingerprint.

It is also possible to provide a preview image from the second imaging device. However, to discourage tampering, it is preferred that the preview image from the second device is by default not shown, but is available for use by a technician when initially setting up the system to ensure that correct focus is achieved.

The captured images may be stored in any suitable form, but the images associated with a single capture operation are preferably stored as a single entry in a record structure so that they can be easily retrieved together. For instance, the images may be stored in two files associated with one another by, for example, the construction of the file names.

Additional information, for example, demographic information, relating to the person from whom the image of the fingerprint is taken may also be stored by the system. Any such information is preferably stored in a file which is associated, for example by filename, with the respective image files. This additional information may be entered by the operator before, after, or even during the image capture operation.

In a second aspect, the present invention provides a method of fingerprint capture using a system having first and second imaging devices for producing images, the method comprising the steps of initiating the capture method, capturing an image from the first imaging device of a fingerprint from a finger of a person's hand, and capturing a separate image from the second imaging device of at least a portion of the hand, said portion including the or a part of said finger, wherein after initiation of the capture method the images from both the first and second imaging devices are captured automatically.

The image may be captured simultaneously or, more preferably, sequentially as discussed above.

The captured images are preferably stored in an associated manner as a single entry in a record structure, for instance by using associated file names, e.g. file names sharing a common text string unique to the associated group of files. In this way, the two images may be easily retrieved later by a scrutineer who can use the image from the second imaging device to check that the correct finger was used for the fingerprint capture operation.

A preferred embodiment of the present invention will now be described, by way of example, with reference to the accompanying figure which is a schematic illustration of an embodiment of the fingerprint capturing system of the present invention.

Shown in the figure is an audited print capture system including a digital fingerprint scanner 1 and a digital camera 2 (which will be referred to as the "audit camera"). The audit camera 2 is mounted above the scanner 1 on a stand 3 which rigidly holds the camera 2 at a fixed distance from the scanner 1. The audit camera 2 is focused on the lens 4 of the scanner 1. In use, the finger from which the fingerprint is to be taken is placed on the lens 4 which therefore acts to locate the finger. Both the scanner 1 and the audit camera 2 are connected to a personal computer (PC) 5 via a frame grabber card 6 installed in the PC 5. Software is installed on the PC 5 to control the capture and storage of images from the scanner 1 and audit camera 2 along with demographic information concerning the person from whom the fingerprint is being taken.

The scanner 1 and audit camera 2 both have composite outputs and the frame grabber card should be based on the ISA, EISA, PCI or PCMCIA architecture with dual channel input able to accept composite input. A suitable digital fingerprint scanner is the "Identicator DFR90", a suitable digital camera is the "JVC TK 1270", and a suitable frame grabber card is the "MRT VideoPort Professional". Any PC having an 80386 processor or later, at least 8 MB of RAM, and 100 megabytes of disk space or more can in principle be used. With the frame grabber card 6 installed in the PC along with the necessary software, including the driver for the frame grabber card 6 and the software to control the operation of the system, the scanner 1 and audit camera 2 are connected to respective composite inputs of the frame grabber card 6 in the normal way.

To initially set up the system, the control software provides an audit camera preview mode in which the audit camera's channel is opened and the image from the audit camera 2 is displayed on the monitor of the PC. Using this mode, the focus of the audit camera 2 can be adjusted to provide a clear image of a hand placed on the lens 4 of the scanner 1. Likewise, the software provides a scanner preview mode in which the scanner's channel is opened and which can be used to ensure that the scanner 1 is operating correctly.

In normal operation, the operator is first prompted to enter demographic details for the person whose fingerprint is to be recorded, such as name, address, etc. This data is written to disk with a file name including a number which is unique to the particular fingerprint capture operation and which number can later be used to identify all of the files associated with that operation. By way of example, we will take the file name to be 200-l.dmg, "200-1" being the unique identifier number.

The finger from which the fingerprint is to be taken is then placed on the lens 4 of the scanner 1. Using the scanner preview mode, the operator can ensure that the finger is correctly placed. In this preview mode, images are preferably transmitted to the monitor of the PC at a rate of at least ten frames per second.

To minimise the likelihood of tampering, the audit camera preview mode is not made available to the operator during normal operations.

When the operator is satisfied with the image of the fingerprint, they initiate the image capture operation, for example by pressing a predetermined key on the PC's keyboard. After initiation of the image capture, the system automatically captures images from both the scanner 1 and the audit camera 2 in the following manner.

The audit camera's 2 channel is opened and an image is captured of the hand as it is currently positioned on the fingerprint scanner 1. The system then switches to the fingerprint scanner's 1 channel and captures an image of the fingerprint from the selected finger on the scanner 1. This switching and capturing takes place over a very short time, such that the time delay between capture of the respective images is no more than a few milliseconds to render impossible the possibility of the person switching fingers between capture of the respective images. Additionally, with this automatic operation, since one action by the operator triggers the capture of both images, it is extremely difficult (if not impossible) for anyone to falsify the image data at the time of capture.

On capture of the images, they are stored to disk under file names associated with that of the demographic data by the unique identifying number for the capture operation. Following the example above, suitable file names for the scanner image and the camera image respectively are 200-l.fpr and 200-l.aud. In this embodiment, the images are initially stored as a Windows Bit Map (256 shades of grey) and can later be converted to any format required, for instance for use with an AFIS. Of course, the images may however be stored using other file formats.

The operation can then be repeated for the next person or even for a further finger of the same person.

In the latter case, it is of course not necessary to repeat the step of entering the demographic data.

Additionally, it is preferable that all of the finger print images for one person are associated with each other by a suitable file naming regime. For instance, in the example given above, images relating to a second fingerprint image could be stored under the file names 200-2.fpr and 200-2.aud.

On completion of the capture operation, the image of the fingerprint can be checked using suitable software to ensure its acceptability for the purpose it is to be used, for example an Automatic Fingerprint Identification System (AFIS). The captured image files can also be checked by a scrutineer who will view the image from the audit camera, and only accept records which satisfy predetermined criteria for finger placement. This scrutineering may take place locally, or, more preferably, the necessary data is transmitted to a central system for scrutineering. Following scrutineering all of the data can then be passed to the AFIS.

Claims

1. A fingerprint capture system comprising finger locating means for locating a finger of a person's hand, a first imaging device below the finger locating means for producing an image of a fingerprint from the finger located by the locating means , a second imaging device above the locating means for producing an image of at least a portion of the person's hand, said portion including the or a part of said one finger, means for capturing and storing the images produced from the first and second imaging means, and control means for controlling the system automatically to capture the images from both the first and second imaging means.

2. A fingerprinting capture system according to claim 1, wherein the control means is arranged to simultaneously capture images from the first and second imaging means.

3. A fingerprinting capture system according to claim 1, wherein the control means is arranged to sequentially capture images from the two imaging means immediately one after the other.

4. A fingerprinting capture system according to any one of claims 1 to 3 wherein the first imaging device is a digital finger print reader.

5. A fingerprint capture system according to claim 4, wherein the lens of the fingerprint reader provides the finger locating means.

6. A fingerprint capture system according to any one of the preceding claims wherein the second imaging device is a digital camera.

7. A fingerprint capture system according to any one of the preceding claims, wherein the control means is arranged to provide a preview image from the first imaging device prior to capture of the images.

8. A fingerprint capture system according to any one of the preceding claims, wherein the control means is arranged to provide a preview image from the second imaging device prior to capture of the images.

9. A fingerprint capture system according to any one of the preceding claims wherein the means for capturing and storing images is arranged for storing data representing the images from the first and second imaging means as a single entry in a record structure.

10. A fingerprint capture system according to claim 9, wherein said single entry in the record structure comprises two or more associated files.

11. A fingerprint capture systems according to claim 10, wherein said single entry in the record structure includes at least one further associated file for storing data other than image data.

12. A method of fingerprint capture using a system having first and second imaging devices for producing images, the method comprising the steps of initiating the capture method, capturing an image from the first imaging device of a fingerprint from a finger of a person's hand, and capturing a separate image from the second imaging device of at least a portion of the hand, said portion including the or a part of said finger, wherein after initiation of the capture method the images from both the first and second imaging devices are captured automatically.

13. A method of fingerprint capture according to claim 12, wherein the images are simultaneously captured.

14. A method of fingerprint capture according to claim 12, wherein the images are sequentially captured immediately one after the other.

15. A method according to any one of claims 12 to 14, wherein the two images are stored such that they are associated with one another as a single entry in a record structure.

16. A method according to claim 15, further comprising the steps of capturing demographic information relating to the person and storing the information such that it is associated with the stored images.

17. A method according to any one of claims 12 to 16, wherein subsequent to capture, the image from the second imaging device is checked to determine which finger of the person's hand the captured fingerprint is from.