Hand-held fingerprint scanner with on-board image normalization data storage

• US 6,744,910 B1
• Filed: 10/29/1999
• Issued: 06/01/2004
• Est. Priority Date: 06/25/1999
• Status: Expired due to Term

• Current Assignee: Sonavation, Inc.
• Original Assignee: Cross Match Technologies Incorporated (Assa Abloy AB)
• Inventors: McClurg, George William, Brunell, David, Scott, Walter Guy
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): CARTER, AARON W
• Application Number:
  US09/430,296
• Time in Patent Office: 1,677 Days
• Field of Search: 382/124-127, 382/274, 382/306, 340/5.53, 340/5.83, 340/5.52, 348/241, 348/248, 348/222.1, 358/504, 358/406, 358/463
• US Class Current: 382/124
• CPC Class Codes: G06V 10/30 Noise filtering
• CPC Class Codes: G06V 40/13 Sensors therefor

Abstract

A hand-held fingerprint scanner having local storage of image normalization data is disclosed, as well as a method of manufacturing such a scanner. The image normalization data is representative of fixed pattern noise associated with the image sensor used in the fingerprint scanner. This data may be combined with the raw image data resulting in normalized image data. The image normalization data is stored in non-volatile memory where it can be transmitted to a host processor. Alternatively, the fingerprint scanner may include a normalization processor, allowing transmission of normalized fingerprint images to a host processor. Also disclosed is a fingerprint scanning system having remote fingerprint scanners with local storage of image normalization data.

Claims

1. A remote fingerprint scanner comprising:

an image sensor; and

image normalization data stored in a non-volatile memory, wherein said image normalization data is specific to the image sensor and is representative of image sensor sensitivity at a pixel level;

wherein the remote fingerprint scanner is capable of being detachably coupled with a docking station that is coupled to a host processor;

wherein said image sensor is capable of detecting at least one fingerprint image when the remote fingerprint scanner is not coupled with the docking station; and

wherein said image normalization data and fingerprint image data corresponding to said at least one fingerprint image are transmitted to the host processor through the docking station when the remote fingerprint scanner is detachably coupled with the docking station.

2. The remote fingerprint scanner of claim 1, wherein said fingerprint scanner is a mobile, hand-held fingerprint scanner.

3. The remote fingerprint scanner of claim 1, further comprising:

a data communications interface that couples said fingerprint image data and said image normalization data between the remote fingerprint scanner and the docking station.

4. The remote fingerprint scanner of claim 3, wherein said data communications interface is selected from the group consisting of a universal serial bus (USB) and an IEEE 1394 compatible interface.

5. The remote fingerprint scanner of claim 1, further comprising:

a camera board;

wherein said image sensor and said non-volatile memory are disposed on said camera board.

6. The remote fingerprint scanner of claim 1, wherein said image normalization data is representative of non-uniform sensitivity among pixels, rows of pixels, or columns of pixels within said image sensor.

7. The remote fingerprint scanner of claim 6, wherein said image normalization data is representative of non-uniform sensitivity among columns of pixels within said image sensor, said image normalization data comprising an image normalization coefficient for each column within said image sensor, wherein an image normalization coefficient for a particular column, x, within said sensor is defined according to the following equation:

 

NORM(x)=AVERAGE IMAGE INTENSITY−

AVERAGE COLUMN INTENSITY(x);

where;

NORM(x) is the image normalization coefficient for a particular column, x;

AVERAGE IMAGE INTENSITY is defined according to the following equation;

$\mathrm{AVERAGE}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{IMAGE}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{INTENSITY}=\frac{\underset{\mathrm{col}=0}{\overset{x}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{\mathrm{row}=n}{\overset{n^{\mathrm{\prime <br><br>}}}{\sum <br><br>}}<br><br>\mathrm{IMAGE}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\mathrm{col},\mathrm{row}\right)<br><br>\text{\hspace{1em}<br><br>}}{\left(X+1\right)\times <br><br>\left(n^{\mathrm{\prime <br><br>}}-n+1\right)};<br><br>$

where X+1 is the total number of columns in said image sensor, and where n and n′

are integers such that 0≦

n<

Y and 0<

n′

≦

Y (where Y is the maximum row ordinate value in said image sensor), such that n′

-n+1 represents the number of rows within each column from which individual column intensity is determined; and

where AVERAGE COLUMN INTENSITY(x) is the average intensity for a particular column, x, within said image sensor and is defined by the following equation;

$\mathrm{AVERAGE}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{COLUMN}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{INTENSITY}\left(x\right)=\frac{\underset{\mathrm{row}=n}{\overset{n^{\mathrm{\prime <br><br>}}}{\sum <br><br>}}<br><br>\mathrm{IMAGE}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(x,\mathrm{row}\right)<br><br>\text{\hspace{1em}<br><br>}}{\left(n^{\mathrm{\prime <br><br>}}-n+1\right)};<br><br>$

where n and n′

are integers such that 0≦

n<

Y and 0<

n′

≦

Y (where Y is the maximum row ordinate value in said image sensor), such that n′

-n+1 represents the number of rows within each column from which average column intensity is determined.

8. The mobile, hand-held fingerprint scanner of claim 1, further comprising:

a normalization processor that, with said image normalization data, normalizes raw image data from said image sensor.

17. The remote fingerprint scanner of claim 1, wherein said fingerprint image data includes raw fingerprint image data.

18. The remote fingerprint scanner of claim 1, wherein said fingerprint image data includes normalized fingerprint image data.

9. A fingerprint scanning system comprising:

at least one remote fingerprint scanner, each said at least one remote fingerprint scanner including;

an image sensor, and

image normalization data stored in a non-volatile memory, wherein said image normalization data is specific to the image sensor and is representative of image sensor sensitivity at a pixel level;

at least one host processor; and

a docking station corresponding to each said at least one host processor;

wherein said image sensor of a first remote fingerprint scanner is capable of detecting at least one fingerprint image when said first remote fingerprint scanner is not coupled with any docking station; and

wherein a first host processor receives data from said first remote fingerprint scanner when said first remote fingerprint scanner is detachably coupled to a docking station corresponding to said first host processor.

10. The fingerprint scanning system of claim 9, wherein each said at least one remote fingerprint scanner is a mobile, hand-held fingerprint scanner.

11. The fingerprint scanning system of claim 9, wherein each said at least one remote fingerprint scanner further includes a data communications interface;

wherein said data communications interface of said first remote fingerprint scanner couples data between said first remote fingerprint scanner and a first docking station when said first remote fingerprint scanner is coupled to said first docking station.

12. The fingerprint scanning system of claim 11, wherein each said data communications interface is selected from the group consisting of a universal serial bus (USB) and an IEEE1394 compatible interface.

13. The remote fingerprint scanning system of claim 9, wherein each said at least one remote fingerprint scanner further comprises:

a camera board;

wherein said image sensor and said non-volatile memory are disposed on said camera board.

14. The remote fingerprint scanning system as in claim 9, wherein said image normalization data is representative of non-uniform sensitivity among pixels, rows of pixels, or columns of pixels within said image sensor.

15. The remote fingerprint scanner of claim 14, wherein said image normalization data is representative of non-uniform sensitivity among columns of pixels within said image sensor, said image normalization data comprising an image normalization coefficient for each column within said image sensor, wherein an image normalization coefficient for a particular column, x, within said sensor is defined according to the following equation:

16. The fingerprint scanning system of claim 9, wherein said at least one mobile, hand-held fingerprint scanner further comprises:

a normalization processor that, with said image normalization data, normalizes raw image data from said image sensor.

19. The fingerprint scanning system of claim 9, wherein said data includes said image normalization data corresponding to said first remote fingerprint scanner and fingerprint image data.

20. The fingerprint scanning system of claim 19, wherein said fingerprint image data includes raw fingerprint image data.

21. The fingerprint scanning system of claim 19, wherein said fingerprint image data includes normalized fingerprint image data.

22. A fingerprint scanning system comprising:

a remote fingerprint scanner, said remote fingerprint scanner including;

an image sensor, and

image normalization data stored in a non-volatile memory, wherein said image normalization data is specific to the image sensor and is representative of image sensor sensitivity at a pixel level;

a docking station; and

a host processor that receives at least one fingerprint image signal from said remote fingerprint scanner when said remote fingerprint scanner is detachably coupled to said docking station; and

wherein said image sensor detects said at least one fingerprint image signal when said at least one remote fingerprint scanner is not coupled with said docking station.

23. The fingerprint scanning system of claim 22, wherein said at least one remote fingerprint scanner is a mobile, hand-held fingerprint scanner.

24. The fingerprint scanning system of claim 22, wherein said remote fingerprint scanner further includes a data communications interface that couples data between said remote fingerprint scanner and said docking station.

25. The fingerprint scanning system of claim 24, wherein said data communications interface is selected from the group consisting of a universal serial bus (USB) and an IEEE1394 compatible interface.

26. The remote fingerprint scanning system of claim 22, wherein said remote fingerprint scanner further comprises:

a camera board;

wherein said image sensor and said non-volatile memory are disposed on said camera board.

27. The remote fingerprint scanning system as in claim 22, wherein said image normalization data is representative of non-uniform sensitivity among pixels, rows of pixels, or columns of pixels within said image sensor.

28. The remote fingerprint scanner of claim 27, wherein said image normalization data is representative of non-uniform sensitivity among columns of pixels within said image sensor, said image normalization data comprising an image normalization coefficient for each column within said image sensor, wherein an image normalization coefficient for a particular column, x, within said sensor is defined according to the following equation:

29. A method for capturing at least one fingerprint using a remote fingerprint scanner comprising:

(A) detecting the at least one fingerprint with an image sensor of the remote fingerprint scanner;

(B) detachably coupling the remote fingerprint scanner with a docking station so that a host processor and the remote fingerprint scanner can communicate;

(C) transmitting image normalization data stored in a non-volatile memory of the remote fingerprint scanner to the host processor, wherein said image normalization data is specific to the image sensor and is representative of image sensor sensitivity at a pixel level; and

(D) transmitting fingerprint image data corresponding to the detected at least one fingerprint image to the host processor.

30. The method of claim 29, further comprising:

(E) decoupling the remote fingerprint scanner and docking station.

31. The method of claim 29, wherein step (D) comprises:

transmitting raw fingerprint image data corresponding to the detected at least one fingerprint image to the host processor.

32. The method of claim 29, further comprising the step of:

normalizing raw fingerprint image data corresponding to the detected at least one fingerprint image using the stored image normalization data.

33. The method of claim 32, wherein step (D) comprises:

transmitting the normalized fingerprint image data corresponding to the detected at least one fingerprint image to the host processor.

34. A remote fingerprint scanner comprising:

an image sensor; and

image normalization data stored in a non-volatile memory;

wherein said image normalization data is specific to said image sensor and is representative of non-uniform sensitivity among pixels, rows of pixels, or columns of pixels within said image sensor;

wherein said image normalization data is representative of non-uniform sensitivity among columns of pixels within said image sensor, said image normalization data comprising an image normalization coefficient for each column within said image sensor, wherein an image normalization coefficient for a particular column, x, within said sensor is defined according to the following equation;

35. A fingerprint scanning system comprising:

at least one remote fingerprint scanner, said at least one remote fingerprint scanner including;

an image sensor, and

image normalization data stored in a non-volatile memory; and

at least one host processor that receives image signals from said at least one remote fingerprint scanner;

wherein said image normalization data is specific to said image sensor and is representative of non-uniform sensitivity among pixels, rows of pixels, or columns of pixels within said image sensor;

wherein said image normalization data is representative of non-uniform sensitivity among columns of pixels within said image sensor, said image normalization data comprising an image normalization coefficient for each column within said image sensor, wherein an image normalization coefficient for a particular column, x, within said sensor is defined according to the following equation;

36. A method of manufacturing a remote fingerprint scanner having local storage of image normalization data comprising the steps of:

(a) exciting an image sensor with a light source;

(b) determining a set of normalization coefficients; and

(c) storing said normalization coefficients in a non-volatile memory, said non-volatile memory disposed locally with said image sensor;

wherein step (b) includes comparing an average column intensity for each column to an average image intensity, said comparison resulting in a normalization coefficient for each column.

37. The method of claim 36, wherein said comparison is performed according to the following equation: