Image registration system and method

• US 20050271300A1
• Filed: 06/02/2004
• Published: 12/08/2005
• Est. Priority Date: 06/02/2004
• Status: Abandoned Application

• Current Assignee: Photon Research Associates, Inc. (Rtx Corporation)
• Original Assignee: Photon Research Associates, Inc. (Rtx Corporation)
• Inventors: Pina, Robert K.
• Application Number:
  US10/858,773
• Publication Number:
  US 20050271300A1
• Time in Patent Office: Days
• US Class Current: 382/294
• CPC Class Codes: G06V 10/431 Frequency domain transformation; Autocorrelation
• CPC Class Codes: G06V 10/507 Summing image-intensity values; Histogram projection analysis
• CPC Class Codes: G06V 10/758 Involving statistics of pixels or of feature values, e.g. histogram matching

Abstract

A method of characterizing alignment between two images includes receiving a first data set representative of a reference image, receiving a second data set representative of a target image, processing the first and second data sets that includes calculating an autocorrelation of the first data set to obtain a third data set that is substantially absent information representative of a relative shift between the reference image and the target image, and processing the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a fourth data set that includes information representative of a relative rotational difference between the reference image and the target image.

Claims

1. A method of characterizing alignment between two images comprising:

receiving a first data set representative of a reference image;

receiving a second data set representative of a target image;

processing the first and second data sets that includes calculating an autocorrelation of the first data set to obtain a third data set that is substantially absent information representative of a relative shift between the reference image and the target image; and

processing the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a fourth data set that includes information representative of a relative rotational difference between the reference image and the target image.

2. The method of claim 1 further comprising:

processing the first and second data sets to obtain a fifth data set that includes information representative of the relative shift between the reference image and the target image and substantially no information representative of the relative rotational difference between the reference image and the target image.

3. The method of claim 1 wherein the fourth data set includes information representative of a relative scaling difference between the reference image and the target image.

4. The method of claim 1 wherein processing includes calculating an autocorrelation of the second data set.

5. The method of claim 4 wherein processing includes calculating a Radon transform of the autocorrelation of the second data set.

6. The method of claim 1 wherein processing includes summing values included in the Radon transform of the autocorrelation of the first data set.

7. The method of claim 1 further comprising:

processing the first and second data sets to obtain a residual estimate of relative rotational difference between the reference image and the target image.

8. A method of aligning two images comprising:

receiving a first data set representative of a reference image;

receiving a second data set representative of a target image;

processing the first data set and the second data set that includes calculating an autocorrelation of the first data set to obtain a third data set that substantially includes no information representative of a relative shift between the reference image and the target image;

processing the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a relative rotational difference and a relative scaling difference between the reference image and the target image;

compensating the second data set for the relative rotational difference and relative scaling difference;

processing the first data set and the scaled and rotationally compensated second data set to obtain a fourth data set that includes information representative of the relative shift between the reference image and the target image; and

compensating the scaled and rotationally compensated second data set for the relative shift.

9. The method of claim 8 wherein processing the first data set and the second data set to obtain the third data set includes calculating an autocorrelation of the second data set.

10. The method of claim 9 wherein processing the third data set includes calculating a Radon transform of the autocorrelation of the second data set.

11. The method of claim 8 wherein processing the first data set and the second data set includes applying an edge filter.

12. The method of claim 8 wherein processing the third data set includes summing values included in the Radon transform.

13. A computer program product residing on a computer readable medium having a plurality of instructions stored thereon which, when executed by the processor, cause that processor to:

receive a first data set representative of a reference image;

receive a second data set representative of a target image;

process the first and second data sets that includes calculating an autocorrelation of the first data set to obtain a third data set that is substantially absent information representative of a relative shift between the reference image and the target image; and

process the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a fourth data set that includes information representative of a relative rotational difference between the reference image and the target image.

14. The computer program product of claim 13 further comprising instructions for:

processing the first and second data sets to obtain a fifth data set that includes information representative of the relative shift between the reference image and the target image and substantially no information representative of the relative rotational difference between the reference image and the target image.

15. The computer program product of claim 13 wherein the fourth data set includes information representative of a relative scaling difference between the reference image and the target image.

16. The computer program product of claim 13 wherein the instructions to process the first and second data sets include instructions for:

calculating an autocorrelation of the second data set.

17. The computer program product of claim 16 wherein the instructions to process the first and second data sets include instructions for:

calculating a Radon transform of the autocorrelation of the second data set.

18. The computer program product of claim 13 wherein the instructions to process the first and second data sets include instructions for:

summing values included in the Radon transform of the autocorrelation of the first data set.

19. The computer program product of claim 13 further comprising instructions for:

processing the first and second data sets to obtain a residual estimate of relative rotational difference between the reference image and the target image.

20. A computer program product residing on a computer readable medium having a plurality of instructions stored thereon which, when executed by the processor, cause that processor to:

receive a first data set representative of a reference image;

receive a second data set representative of a target image;

process the first data set and the second data set that includes calculating an autocorrelation of the first data set to obtain a third data set that substantially includes no information representative of a relative shift between the reference image and the target image;

process the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a relative rotational difference and a relative scaling difference between the reference image and the target image;

compensate the second data set for the relative rotational difference and relative scaling difference;

process the first data set and the scaled and rotationally compensated second data set to obtain a fourth data set that includes information representative of the relative shift between the reference image and the target image; and

compensate the scaled and rotationally compensated second data set for the relative shift.

21. The computer program product of claim 20 wherein the instructions to process the first data set and the second data set to obtain the third data set include instructions for:

calculating an autocorrelation of the second data set.

22. The computer program product of claim 21 wherein the instructions to process the third data set include instructions for:

calculating a Radon transform of the autocorrelation of the second data set.

23. The computer program product of claim 20 wherein the instructions to process the first data set and the second data set include instructions for:

applying an edge filter.

24. The computer program product of claim 22 wherein the instructions to process the third data set include instructions for:

summing values included in the Radon transform of the autocorrelation of the second data set.

25. An image registration system comprising:

means for receiving a first data set representative of a reference image;

means for receiving a second data set representative of a target image;

means for processing the first and second data sets that includes calculating an autocorrelation of the first data set to obtain a third data set that is substantially absent information representative of a relative shift between the reference image and the target image; and

means for processing the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a fourth data set that includes information representative of a relative rotational difference between the reference image and the target image and substantially no information representative of a relative shift between the reference image and the target image.

26. The image registration system of claim 25 further comprising:

means for processing the first and second data sets to obtain a fifth data set that includes information representative of the relative shift between the reference image and the target image and substantially no information representative of the relative rotational difference between the reference image and the target image.

27. The image registration system of claim 25 wherein the fourth data set includes information representative of a relative scaling difference between the reference image and the target image.

28. The image registration system of claim 25 wherein processing includes calculating an autocorrelation of the second data set.

29. The image registration system of claim 28 wherein processing includes calculating a Radon transform of the autocorrelation of the second data set.

30. The image registration system of claim 25 wherein processing includes summing values included in the Radon transform of the autocorrelation of the first data set.

31. The image registration system of claim 25 further comprising:

means for processing the first and second data sets to obtain a residual estimate of relative rotational difference between the reference image and the target image.

33. The image registration system of claim 31 wherein processing the first data set and the second data set to obtain the third data set includes calculating an autocorrelation of the second data set.

34. The image registration system of claim 33 wherein processing the third data set includes calculating a Radon transform of the autocorrelation of the second data set.

32. An image registration system comprising:

means for receiving a first data set representative of a reference image;

means for receiving a second data set representative of a target image;

means for processing the first data set and the second data set that includes calculating an autocorrelation of the first data set to obtain a third data set that substantially includes no information representative of a relative shift between the reference image and the target image;

means for processing the third data set that includes calculating a Radon transform of the autocorrelation of the first data set to obtain a relative rotational difference and a relative scaling difference between the reference image and the target image;

means for compensating the second data set for the relative rotational difference and relative scaling difference;

means for processing the first data set and the scaled and rotationally compensated second data set to obtain a fourth data set that includes information representative of the relative shift between the reference image and the target image; and

means for compensating the scaled and rotationally compensated second data set for the relative shift.

35. The image registration system of claim 32 wherein processing the first data set and the second data set includes applying an edge filter.

36. The image registration system of claim 32 wherein processing the third data set includes summing values included in the Radon transform of the autocorrelation of the first data set.

37. A method of characterizing alignment between two images comprising:

receiving a first data set representative of a reference image;

receiving a second data set representative of a target image;

transforming the first data set and the second data set from the spatial domain into the Fourier domain;

filtering the Fourier transform of the first data set and the Fourier transform of the second data set;

transforming the filtered Fourier transform of the first data set to obtain a third data set in the spatial domain and the filtered Fourier transform of the second data set to obtain a fourth data set in the spatial domain; and

processing the third data set and the fourth data set to obtain a data set that is substantially absent information representative of a relative shift between the reference image and the target image.

38. The method of claim 37 wherein processing the third data set and the fourth data set includes calculating the autocorrelation of the third data set.

39. The method of claim 38 further comprising:

processing the data set that is substantially absent information representative of a relative shift between the reference image and the target image that includes calculating a Radon transform of the autocorrelation of the third data set to obtain a data set that includes information representative of a relative rotational difference between the reference image and the target image.