SEQUENTIAL IMAGE ALIGNMENT

• US 20110182486A1
• Filed: 05/13/2008
• Published: 07/28/2011
• Est. Priority Date: 05/16/2007
• Status: Active Grant

• Current Assignee: Precise Biometrics AB (Precise Biometrics Incorporated)
• Original Assignee: Precise Biometrics AB (Precise Biometrics Incorporated)
• Inventors: Nordin, Björn, Valfridsson, Krister
• Granted Patent: US 8,634,605 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement

Abstract

A method for reading fingerprints is disclosed. The method comprises acquiring images of a fingerprint from a finger upon relative movement between the finger and an image sensor; selecting lines from said acquired images representing a new area of said fingerprint; determining composition parameters for each selected line: and storing said composition parameters and said selected lines such that a composite image comprising said selected lines is composabte. A corresponding fingerprint reading apparatus, a device, and a computer program are also disclosed.

Claims

1. A method comprising acquiring images of a fingerprint from a finger upon relative movement between the finger and an image sensor;

selecting fines from said acquired images representing a new area of said fingerprint;

determining composition parameters for each selected line; and

storing said composition parameters and said selected lines such that a composite image comprising said selected lines is composable.

2. The method according to claim 1, wherein said composition parameters comprises an offset value for each selected line.

3. The method according to claim 1, further comprising deleting image lines of said acquired images that is not selected for said composite image.

4. The method according to claim 1, further comprising enabling overwriting of image lines of said acquired images that is not selected for said composite image.

5. The method according to claim 1, further comprising forming a sub-image comprising a set of said selected lines when said selected lines reach a predetermined amount;

comparing said sub-image with a reference image; and

deleting said lines of said set after said comparison is performed.

6. The method according to claim 5, wherein said forming of said sub-image is based on said stored composition parameters and said set and comprises aligning said lines of said set in accordance with said composition parameters.

7. The method according to claim 5, wherein said comparing comprises extracting features from said sub-image;

and comparing said extracted features with features of said reference image.

8. The method according to claim 1, further comprising forming said composite image when all images are acquired;

and comparing said composite image with a reference image.

9. The method according to claim 8, wherein said forming of said composite image is based on said stored composition parameters and said selected lines and comprises aligning said lines of said set in accordance with said composition parameters.

10. The method according to claim 8, wherein said comparing comprises extracting features from said composite image;

and comparing said extracted features with features of said reference image.

11. The method according to claim 1, wherein selecting a line of said lines comprises selecting at least a first acquired line representing said new area of said fingerprint

12. The method according to claim 1, wherein selecting a line of said lines comprises averaging at least two acquired lines representing said new area of said fingerprint, and determining an average of said lines to be said selected line.

13. The method according to claim 1, wherein selecting a line of said lines comprises determining one of at least two acquired lines representing said new area of said fingerprint best representing said new area, and selecting said one acquired line best representing said new area to be said selected line.

14. The method according to claim 1, wherein said relative movement between the finger and the image sensor is enabled in any direction.

30. A computer program comprising program code means adapted to perform any actions of claim 1 when the program is run on a processor

15. A fingerprint reading apparatus comprising a sensor arranged to acquire images of a fingerprint from a finger upon relative movement between the finger and said image sensor;

a processor arranged to select, from said acquired images, lines representing a new area of said fingerprint such that a composite image is composable, and the processor is further arranged to determine composition parameters for each selected line; and

a memory arranged to store said composition parameters and said selected lines.

16. The apparatus according to claim 15, wherein said composition parameters comprises an offset value for each selected line.

17. The apparatus according to claim 15, wherein said processor is arranged to provide a control signal causing deletion of image lines of said acquired images that is not selected for said composite image.

18. The apparatus according to claim 15, wherein said processor is arranged to enable overwriting of image lines of said acquired images that is not selected for said composite image.

19. The apparatus according to claim 15, further comprising a sub-image generator arranged to form a sub-image comprising a set of said selected lines when said selected lines reach a predetermined amount;

and a comparator arranged to compare said sub-image with a reference image, wherein said lines of said set are deletable after said comparison is performed.

20. The apparatus according to claim 19, wherein said stored composition parameters and said lines of said set is input to said sub-image generator such that said sub-image generator is able to align said lines in accordance with said composition parameters to form said sub-image.

21. The apparatus according to claim 19, wherein said comparator comprises a feature extractor arranged to extract features from said sub-image to be comparable with features of said reference image.

22. The apparatus according to claim 15, further comprising a composite image generator arranged to form a composite image comprising said selected lines when all images are acquired;

a comparator arranged to compare said composite image with a reference image.

23. The apparatus according to claim 22, wherein said stored composition parameters and said lines of said set is input to said composite image generator such that said composite image generator is able to align said selected lines in accordance with said composition parameters to form said composite image.

24. The apparatus according to claim 22, wherein said comparator comprises a feature extractor arranged to extract features from said composite image to be comparable with features of said reference image.

25. The apparatus according to claim 15, wherein at least one of said selected lines are each first acquired line representing a new area of said fingerprint.

26. The apparatus according to claim 15, wherein at least one of said selected lines comprises an average of at least two acquired lines representing a new area of said fingerprint

27. The apparatus according to claim 15, wherein at least one of said selected lines comprises one of at least two acquired lines determined to represent a new area of said fingerprint and determined to best represent said new area of said at least two lines.

28. The apparatus according to claim 15, wherein said relative movement between the finger and the image sensor is enabled in any direction.

29. A device comprising an apparatus according to claim 15, said device being any of a group comprising:

a door lock, a personal computer, a mobile phone, a personal digital assistant, a vehicle, a weapon, a toy, a smart card, a ticket, and a portable memory device.