System and method for improved forensic analysis

• US 20110033082A1
• Filed: 08/04/2010
• Published: 02/10/2011
• Est. Priority Date: 08/04/2009
• Status: Abandoned Application

• Current Assignee: Chemimage Corporation
• Original Assignee: Chemimage Corporation
• Inventors: Beckstead, Jeffrey, Bangalore, Arjun
• Application Number:
  US12/806,039
• Publication Number:
  US 20110033082A1
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0248 using a sighting port, e.g. camera or human eye
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/32 Investigating bands of a spectrum in sequence by a single detector
• CPC Class Codes: G01N 2021/6423 Spectral mapping, video display
• CPC Class Codes: G01N 2021/6493 by alternating fluorescence/transmission or fluorescence/reflection
• CPC Class Codes: G01N 21/27 using photo-electric detection G01N21/31 takes precedence; circuits for computing concentration logarithmic circuits G06G7/24; photometric circuits in general G01J
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 21/6456 Spatial resolved fluorescence measurements; Imaging
• CPC Class Codes: G06V 10/56 relating to colour

Abstract

The present disclosure provides for a system and method for analyzing questioned documents. A sample document is illuminated to thereby generate a first plurality of interacted photons. The first plurality of interacted photons are detected at a first detector to thereby generate a digital image. The digital image is analyzed to thereby identify at least one region of interest of the sample document. This region of interest is illuminated to thereby generate a second plurality of interacted photons. This second plurality of interacted photons are passed through a tunable filter and detected at a second detector to thereby generate a hyperspectral image representative of the region of interest. The hyperpsectral image may then be analyzed to evaluate changes to or differentiate different inks present in the sample document. Chemometric techniques such as k-means clustering, PCA, and/or PLSDA may also be applied.

Claims

1. A system comprising:

a surface for placing a sample document;

an illumination source for illuminating said sample document to thereby generate a first plurality of interacted photons and a second plurality of interacted photons wherein said first and second plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample, photons absorbed by said sample, photons scattered by said sample, photons emitted by said sample, and combinations thereof;

a collection optics for collecting said first plurality of interacted photons and said second plurality of interacted photons;

a first detector for detecting said first plurality of interacted photons and generating a digital image representative of said sample;

at least one tunable filter through which said second plurality of interacted photons are passed to thereby generate a plurality of filtered photons;

a second detector for detecting said plurality of filtered photons and generating a hyperspectral image representative of said sample.

2. The system of claim 1 wherein said hyperspectral image comprises an image and a fully resolved spectrum unique to the material for each pixel location in said image.

3. The system of claim 1 wherein said hyperspectral image comprises a visible hyperspectral image.

4. The system of claim 1 wherein said first detector comprises a RGB camera.

5. The system of claim 1 wherein said second detector comprises a spectral camera.

6. The system of claim 5 wherein said spectral camera comprises at least one of:

a charge coupled device, a complementary metal-oxide-semiconductor, an intensified charge coupled device, and combinations thereof.

7. The system of claim 1 wherein said illumination source comprises a broadband white light source.

8. The system of claim 1 wherein said collection optics comprises a zoom lens.

9. The system of claim 1 wherein said tunable filter is selected from the group consisting of:

a multi-conjugate tunable filter, a liquid crystal tunable filter, acousto-optical tunable filters, Lyot liquid crystal tunable filter, Evans Split-Element liquid crystal tunable filter, Solc liquid crystal tunable filter, Ferroelectric liquid crystal tunable filter, Fabry Perot liquid crystal tunable filter, and combinations thereof.

10. The system of claim 1 further comprising a means for directing said first plurality of interacted photons to said first detector and directing said second plurality of interacted photons through said tunable filter and to said second detector.

11. The system of claim 1 wherein said illumination source may be configured to illuminate said sample at a plurality of different angles.

12. The system of claim 1 further comprising a reference database wherein said reference database comprises a plurality of reference data sets wherein each reference data set is associated with a known ink type.

13. A method comprising:

illuminating a sample document to thereby generate a first plurality of interacted photons wherein said first plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample, photons absorbed by said sample, photons scattered by said sample, photons emitted by said sample, and combinations thereof;

directing said first plurality of interacted photons to a first detector;

detecting said first plurality of interacted photons at said first detector to thereby generate a digital image representative of said sample;

analyzing said digital image to thereby identify at least one region of interest of said sample;

illuminating said region of interest to thereby generate a second plurality of interacted photons wherein said second plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample, photons absorbed by said sample, photons scattered by said sample, photons emitted by said sample, and combinations thereof;

passing said second plurality of interacted photons through a tunable filter to thereby generate a plurality of filtered photons;

directing said plurality of filtered photons to a second detector; and

detecting said plurality of filtered photons at said second detector to thereby generate a hyperspectral image representative of said region of interest.

14. The method of claim 13 wherein said second detector comprises a spectral detector.

15. The method of claim 14 wherein said spectral detector is selected from the group consisting of:

a charge coupled device, a complementary metal-oxide-semiconductor, an intensified charge coupled device, and combinations thereof.

16. The method of claim 13 further comprising:

analyzing said hyperspectral image to thereby determine if two or more ink types are distinguishable in said region of interest.

17. The method of claim 16 wherein said analysis comprises visual inspection by a user.

18. The method of claim 16 wherein said analyzing comprises evaluating at least one spectra associated with at least one ink present in said region of interest.

19. The method of claim 16 further comprising:

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, applying one or more chemometric techniques to said hyperspectral image.

20. The method of claim 19 wherein said chemometric technique is selected from the group consisting of:

k-means clustering, partial least squares discriminate analysis, principal component analysis, and combinations thereof.

21. The method of claim 13 further comprising:

analyzing said hyperspectral image to thereby determine at least one of;

an alteration has been made to said region of interest and an alteration has not been made to said region of interest.

22. The method of claim 13 wherein said illuminating of at least one of said sample of document and said region of interest is accomplished using broadband white light.

23. The method of claim 13 wherein said digital image comprises a RBG image.

24. The method of claim 13 wherein said hyperspectral image comprises an image and a fully resolved spectrum unique to the material for each pixel location in said image.

25. The method of claim 13 wherein said hyperspectral image comprises a visible hyperspectral image.

26. A method comprising:

identifying at least one region of interest of a sample document wherein said region of interest comprises at least one ink type;

obtaining a hyperspectral image representative of said region of interest;

analyzing said hyperspectral image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, applying a first chemometric technique to said hyperspectral image to thereby generate a first processed image, wherein said chemometric technique comprises k-means clustering;

analyzing said first processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, applying a second chemometric technique to thereby generate a second processed image, wherein said chemometric technique comprises principal component analysis;

analyzing said second processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more inks types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, reporting a result.

27. The method of claim 26 further comprising:

if two or more inks are not distinguishable in said region of interest of said second processed image, applying partial least squares discriminate analysis.

28. The method of claim 27 wherein partial least squares discriminate analysis is applied to only ink pixels.

29. The method of claim 26 wherein analyzing said hyperspectral image comprises the steps of:

automatically identifying at least one of;

background pixels, ink pixels, and combinations thereof, and

applying at least one of said first chemometric technique and said second chemometric technique to only ink pixels.

30. The method of claim 26 wherein said analysis is performed semi-automatically.

31. The method of claim 26 wherein said region of interest is identified by:

providing a sample document;

illuminating said sample document to thereby generate a first plurality of interacted photons wherein said first plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample document, photons absorbed by said sample document, photons scattered by said sample document, photons emitted by said sample document, and combinations thereof;

detecting said first plurality of interacted photons to thereby generate a digital image representative of said sample document;

analyzing said digital image to thereby identify at least one region of interest of said sample document.

32. The method of claim 26 wherein said hyperspectral image comprises a visible hyperspectral image.

33. The method of claim 26 wherein said analyzing comprises visual inspection by a user.

34. The method of claim 26 wherein said analyzing comprises evaluating at least one spectra associated with at least one ink present in said region of interest.

35. The method of claim 26 further comprising:

repeating the method of claim 26 for at least one other region of interest identified in said sample document.

41. The method of claim 36 further comprising:

repeating the method of claim 33 for at least one other region of interest identified in said sample document.

36. A method comprising:

identifying at least one region of interest of a sample document wherein said region of interest comprises at least one ink type;

obtaining a hyperspectral image representative of said region of interest;

analyzing said hyperspectral image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, applying a first chemometric technique to said hyperspectral image to thereby generate a first processed image, wherein said chemometric technique comprises k-means clustering;

analyzing said first processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, applying a second chemometric technique to thereby generate a second processed image, wherein said chemometric technique comprises partial least squares discriminate analysis;

analyzing said second processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more inks types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, reporting a result.

37. The method of claim 36 wherein said region of interest is identified by:

providing a sample document;

illuminating said sample document to thereby generate a first plurality of interacted photons wherein said first plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample document, photons absorbed by said sample document, photons scattered by said sample document, photons emitted by said sample document, and combinations thereof;

detecting said first plurality of interacted photons to thereby generate a digital image representative of said sample document;

analyzing said digital image to thereby identify at least one region of interest of said sample document.

38. The method of claim 36 wherein said hyperspectral image comprises a visible hyperspectral image.

39. The method of claim 36 wherein said analyzing comprises visual inspection by a user.

40. The method of claim 36 wherein said analyzing comprises evaluating at least one spectra associated with at least one ink present in said region of interest.

42. The method of claim 36 wherein analyzing said hyperspectral image comprises the steps of:

automatically identifying at least one of;

background pixels, ink pixels, and combinations thereof, and

applying at least one of said first chemometric technique and said second chemometric technique to only ink pixels.

43. The method of claim 36 wherein said analysis is performed semi-automatically.

44. A method comprising:

illuminating a sample document to thereby generate a first plurality of interacted photons wherein said first plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample, photons absorbed by said sample, photons scattered by said sample, photons emitted by said sample, and combinations thereof;

detecting said first plurality of interacted photons at a first detector to thereby generate a digital image representative of a sample document;

analyzing said digital image to thereby identify at least one region of interest of said sample document;

illuminating said region of interest to thereby generate a second plurality of interacted photons wherein said second plurality of interacted photons are selected from the group consisting of;

photons reflected by said sample, photons absorbed by said sample, photons scattered by said sample, photons emitted by said sample, and combinations thereof;

detecting said second plurality of interacted photons to thereby generate a hyperspectral image representative of said region of interest;

analyzing said hyperspectral image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable, applying a first chemometric technique to thereby generate a first processed image;

analyzing said first processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable, applying a second chemometric technique to thereby generate a second processed image;

analyzing said second processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, applying a third chemometric technique to said second processed image to thereby generate a third processed image;

analyzing said third processed image to thereby determine if two or more ink types are distinguishable in said region of interest;

if two or more ink types are distinguishable in said region of interest, reporting a result, and

if two or more ink types are not distinguishable in said region of interest, reporting a result.

45. The method of claim 44 wherein said hyperspectral image comprises a visible hyperspectral image.

46. The method of claim 44 wherein said first chemometric technique is a technique selected from the group consisting of:

principle component analysis, partial least squares discriminate analysis, cosine correlation analysis, Euclidian distance analysis, k-means clustering, multivariate curve resolution, band t. entropy method, mahalanobis distance, adaptive subspace detector, spectral mixture resolution, and combinations thereof.

47. The method of claim 44 wherein said second chemometric technique is selected from the group consisting of:

principle component analysis, partial least squares discriminate analysis, cosine correlation analysis, Euclidian distance analysis, k-means clustering, multivariate curve resolution, band t. entropy method, mahalanobis distance, adaptive subspace detector, spectral mixture resolution, and combinations thereof.

48. The method of claim 44 wherein said third chemometric technique is selected from the group consisting of:

principle component analysis, partial least squares discriminate analysis, cosine correlation analysis, Euclidian distance analysis, k-means clustering, multivariate curve resolution, band t. entropy method, mahalanobis distance, adaptive subspace detector, spectral mixture resolution, and combinations thereof.

49. The method of claim 44 further comprising:

automatically identifying at least one of;

background pixels, ink pixels, and combinations thereof; and

applying at least one of said first chemometric technique, said second chemometric technique, said third chemometric, and combinations thereof to only said ink pixels.

50. The method of claim 44 wherein said analyzing comprises evaluating at least one spectra associated with at least one ink present in said region of interest.

51. The method of claim 44 wherein said analyzing comprises visual inspection by a user.