Apparatus, method and system for screening receptacles and persons, having image distortion correction functionality

• US 7,991,242 B2
• Filed: 05/11/2006
• Issued: 08/02/2011
• Est. Priority Date: 05/11/2005
• Status: Expired due to Fees

• Current Assignee: Vanderlande APC Inc (Toyota Motor Corporation)
• Original Assignee: Optosecurity Inc. (Toyota Motor Corporation)
• Inventors: Bouchard, Michel R., Xu, Chen, Roy, Sébastien, Bergeron, Eric, Perron, Luc, Bergeron, Alain
• Primary Examiner(s): Werner; Brian P
• Assistant Examiner(s): Patel; Nirav G
• Application Number:
  US11/431,627
• Publication Number:
  US 20070041612A1
• Time in Patent Office: 1,909 Days
• Field of Search: 382/275
• US Class Current: 382/275
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• CPC Class Codes: G06V 10/898 combination of filters, e.g. phase-only filters
• CPC Class Codes: G06V 2201/05 Recognition of patterns representing particular kinds of hidden objects, e.g. weapons, explosives, drugs
• CPC Class Codes: G06V 30/144 using a slot moved over the image; using discrete sensing elements at predetermined points; using automatic curve following means

Abstract

A method and an apparatus suitable for screening a receptacle are provided. An image signal conveying an input image related to contents of the receptacle is received, the image signal having been produced by a device that is characterized by introducing distortion into the input image. A distortion correction process is applied to the image signal to remove at least part of the distortion from the input image, thereby to generate a corrected image signal conveying at least one corrected image. The corrected image signal is processed in combination with a plurality of data elements associated with a plurality of target objects in an attempt to detect a presence of at least one of the target objects in the receptacle. A detection signal is generated in response to detection of the presence of at least one target object in the receptacle.

Claims

1. An apparatus suitable for screening a receptacle, said apparatus comprising:

a) an input for receiving an image signal conveying an input image related to contents of the receptacle, the image signal having been produced by subjecting the receptacle to penetrating radiation using a device having a radiation source and radiation detectors, the device being characterized by introducing distortion into the input image so that the input image signal conveys a distorted representation of the receptacle and its contents, wherein part of the distortion introduced in the input image is dependent on a location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation;

b) a processing unit in communication with said input, said processing unit being programmed for;

applying a distortion correction process to the image signal to remove at least in part from the input image the part of the distortion dependent on the location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation, thereby to generate a corrected image signal related to contents of the receptacle, the corrected image signal conveying a modified representation of the receptacle and its contents, wherein applying the distortion correction process to the image signal includes;

selecting a candidate height from a range of possible heights, the possible heights in said range being related to respective locations relative to the radiation source and detectors of the device; and

using the selected candidate height to condition the distortion correction process applied to the image signal;

processing the corrected image signal in an attempt to detect a presence in the receptacle of a target object;

generating a detection signal in response to detection of the presence of the target object in the receptacle;

c) an output for releasing the detection signal.

2. The apparatus defined in claim 1, wherein the processing unit is programmed for applying the distortion correction process to the image signal multiple times, each application of the distortion correction process:

a) being associated with a respective candidate height; and

b) generating a respective corrected image signal conveying a corresponding corrected representation of the receptacle and its contents.

3. The apparatus defined in claim 1, wherein the input image signal is defined by intensity data for a set of observed coordinates, wherein the corrected image signal is defined by modified intensity data for a set of new coordinates, and wherein applying the distortion correction process comprises applying an image transformation to the intensity data for the set of observed coordinates to derive said modified intensity data for the new coordinates.

4. The apparatus defined in claim 3, wherein said image transformation involves processing of a data structure representative of an inferred spatial transformation applied by the device.

5. The apparatus defined in claim 3, wherein the processing unit is programmed for applying the image transformation to the input image signal multiple times, each application of the image transformation being associated with a respective candidate height and involving processing of a data structure representative of an inferred spatial transformation applied by the device for objects at the respective candidate height.

6. The apparatus defined in claim 4, wherein said inferred spatial transformation is two-dimensional.

7. The apparatus defined in claim 4, wherein said data structure is characterized by a set of parameters derived from registration of the observed coordinates with respect to a set of original coordinates.

8. The apparatus defined in claim 1, wherein the receptacle is a luggage item.

9. The apparatus defined in claim 1, wherein the receptacle is a cargo container.

10. The apparatus defined in claim 1, wherein the receptacle is a mail parcel.

11. The apparatus defined in claim 1, wherein processing the corrected image signal to detect the presence in the receptacle of the target object includes processing the corrected image signal in combination with an image of the target object.

12. The apparatus defined in claim 1, processing the corrected image signal to detect the presence in the receptacle of the target object includes processing the corrected image signal in combination with a Fourier transform of an image if the target object.

13. The apparatus defined in claim 1, wherein said image signal is an x-ray image.

14. The apparatus defined in claim 1, wherein the detection signal conveys the presence of the target object in the receptacle.

15. The apparatus defined in claim 1, wherein the detection signal enables identification of the target object whose presence in the receptacle was detected.

16. The apparatus defined in claim 1, wherein the detection signal conveys a data element identifying the target object whose presence in the receptacle was detected.

17. The apparatus defined in claim 1, wherein the detection signal conveys information describing at least one characteristic of the target object whose presence in the receptacle was detected.

18. The apparatus defined in claim 17, wherein the at least one characteristic comprises position information.

19. The apparatus defined in claim 1, wherein said detection signal is operative for causing a display unit to convey information related to the target object whose presence in the receptacle was detected.

20. The apparatus defined in claim 1, wherein said processing unit is responsive to detection of the presence the target object in the receptacle to:

a) generate log information elements conveying a presence of the target object whose presence in the receptacle was detected;

b) store said log information data elements on a computer readable storage medium.

21. The apparatus defined in claim 20, wherein said log information elements include a time stamp data element.

22. The apparatus defined in claim 1, wherein said processing unit performs a correlation operation between data derived from the corrected image signal and data derived from an image of the target object in order to detect the presence of the target object in the receptacle.

23. The apparatus defined in claim 22, wherein said processing unit comprises an optical correlator for effecting the correlation operation.

24. The apparatus defined in claim 22, wherein said processing unit comprises a digital correlator for effecting the correlation operation.

25. The apparatus defined in claim 1, wherein the input image related to the contents of the receptacle is two-dimensional.

26. The apparatus defined in claim 1, wherein the input image related to the contents of the receptacle is three-dimensional.

27. The apparatus defined in claim 1, wherein said image signal is in a format selected from the set consisting of VGA, SVGA and XGA.

28. The apparatus defined in claim 1, wherein said input image is in a format selected from the set consisting of JPEG, GIF, TIFF and bitmap.

29. The apparatus defined in claim 1, wherein the target object is a weapon.

30. A method for screening a receptacle, said method comprising:

a) receiving an image signal conveying an input image related to contents of the receptacle, the image signal having been produced by subjecting the receptacle to penetrating radiation using a device having a radiation source and radiation detectors, the device being characterized by introducing distortion into the input image, so that the input image signal conveys a distorted representation of the receptacle and its contents, wherein part of the distortion introduced in the input image is dependent on a location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation;

b) applying a distortion correction process to the image signal to remove at least in part from the input image the part of the distortion dependent on the location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation, thereby to generate a corrected image signal related to contents of the receptacle, the corrected image signal conveying a modified representation of the receptacle and its contents, wherein applying the distortion correction process to the image signal includes;

i. selecting a candidate height from a range of possible heights, the possible heights in said range being related to respective locations relative to the radiation source and detectors of the device; and

ii. using the selected candidate height to condition the distortion correction process applied to the image signal;

c) processing the corrected image signal in an attempt to detect a presence in the receptacle of a target object;

d) generating a detection signal in response to detection of the presence of the target object in the receptacle;

e) releasing the detection signal.

31. The method defined in claim 30, wherein said method comprises applying the distortion correction process to the image signal multiple times, each application of the distortion correction process:

a) being associated with a respective candidate height; and

b) generating a respective corrected image signal conveying a corresponding corrected representation of the receptacle and its contents.

32. The method defined in claim 30, wherein the input image is defined by intensity data for a set of observed coordinates, wherein the corrected image is defined by modified intensity data for a set of new coordinates, and wherein applying the distortion correction process comprises applying an image transformation to the intensity data for the set of observed coordinates to derive said modified intensity data for the new coordinates.

33. The method defined in claim 32, wherein said image transformation involves processing of a data structure representative of an inferred spatial transformation applied by the device.

34. The method defined in claim 32, wherein said method comprises applying the image transformation to the input image multiple times, each application of the image transformation being associated with a respective candidate height within the receptacle and involving processing of a data structure representative of an inferred spatial transformation applied by the device for objects at the respective candidate height.

35. The method defined in claim 33, wherein said inferred spatial transformation is two-dimensional.

36. The method defined in claim 33, wherein said data structure is characterized by a set of parameters derived from registration of the observed coordinates with respect to a set of original coordinates.

37. The method defined in claim 30, wherein processing the corrected image signal to detect the presence in the receptacle of the target object includes processing the corrected image signal in combination with an image of the target object.

38. The method defined in claim 30, processing the corrected image signal to detect the presence in the receptacle of the target object includes processing the corrected image signal in combination with a Fourier transform of an image of the target object.

39. The method defined in claim 30, wherein said image signal is an x-ray image.

40. The method defined in claim 30, wherein the detection signal conveys the presence of the target object in the receptacle.

41. The method defined in claim 30, wherein the detection signal enables identification of the target object whose presence in the receptacle was detected.

42. The method defined in claim 30, wherein the detection signal conveys a data element identifying the target object whose presence in the receptacle was detected.

43. The method defined in claim 30, wherein the detection signal conveys information describing at least one characteristic of the target object whose presence in the receptacle was detected.

44. The method defined in claim 43, wherein the at least one characteristic comprises position information.

45. The method defined in claim 30, further comprising causing a display unit to convey information related to the target object whose presence in the receptacle was detected.

46. The method defined in claim 30, further comprising, in response to detection of the presence of the target object in the receptacle:

a) generating log information elements conveying a presence of the target object whose presence in the receptacle was detected;

b) storing said log information data elements on a computer readable storage medium.

47. The method defined in claim 46, wherein said log information elements include a time stamp data element.

48. The method defined in claim 30, wherein said method comprises performing a correlation operation between data derived from the corrected image signal and data derived from an image of the target object in order to detect the presence of the target object in the receptacle.

49. The method defined in claim 48, wherein said correlation operation is effected by an optical correlator.

50. The method defined in claim 48, wherein said correlation operation is effected by a digital correlator.

51. The method defined in claim 30, wherein the input image related to the contents of the receptacle is two-dimensional.

52. The method defined in claim 30, wherein the input image related to the contents of the receptacle is three-dimensional.

53. The method defined in claim 30, wherein said image signal is in a format selected from the set consisting of VGA, SVGA and XGA.

54. The method defined in claim 30, wherein said input image is in a format selected from the set consisting of JPEG, GIF, TIFF and bitmap.

55. The method defined in claim 30, wherein the target object is a weapon.

56. A non-transitory computer-readable medium comprising computer-readable program code which, when interpreted by a computing apparatus, causes the computing apparatus to execute a method of screening a receptacle, the computer-readable program code comprising:

first computer-readable program code for causing the computing apparatus to be attentive to receipt of an image signal conveying an input image related to contents of the receptacle, the image signal having been produced by subjecting the receptacle to penetrating radiation using a device having a radiation source and radiation detectors, the device being characterized by introducing distortion into the input image so that the input image signal conveys a distorted representation of the receptacle and its contents, wherein part of the distortion introduced in the input image is dependent on a location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation;

second computer-readable program code for causing the computing apparatus to apply a distortion correction process to the image signal to remove at least in part from the second computer-readable program code for causing the computing apparatus to apply a distortion correction process to the image signal to remove at least in part from the input image the part of the distortion dependent on the location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation, thereby to generate a corrected image signal related to contents of the receptacle, the corrected image signal conveying a modified representation of the receptacle and its contents, wherein applying the distortion correction process to the image signal includes;

selecting a candidate height from a range of possible heights, the possible heights in said range being related to respective locations relative to the radiation source and detectors of the device; and

using the selected candidate height to condition the distortion correction process applied to the image signal;

third computer-readable program code for causing the computing apparatus to process the corrected image signal in an attempt to detect a presence of a target object in the receptacle;

fourth computer-readable program code for causing the computing apparatus to generate a detection signal in response to detection of the presence of the target object in the receptacle;

fifth computer-readable program code for causing the computing apparatus to release the detection signal.

57. An apparatus for screening a receptacle, comprising:

a) means for receiving an image signal conveying an input image related to contents of the receptacle, the image signal having been produced by subjecting the receptacle to penetrating radiation using a device having a radiation source and radiation detectors, the device being characterized by introducing distortion into the input image so that the input image signal conveys a distorted representation of the receptacle and its contents, wherein part of the distortion introduced in the input image is dependent on a location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation;

b) means for applying a distortion correction process to the image signal to remove at least in part from the input image the part of the distortion dependent on the location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation, thereby to generate a corrected image signal related to contents of the receptacle, the corrected image signal conveying a modified representation of the receptacle and its contents, said means for applying the distortion correction process being configured for;

i. selecting a candidate height from a range of possible heights, the possible heights in said range being related to respective locations relative to the radiation source and detectors of the device; and

ii. using the selected candidate height to condition the distortion correction process applied to the image signal;

c) means for processing the corrected image signal in an attempt to detect a presence of a target object in the receptacle;

d) means for generating a detection signal in response to detection of the presence of the target object in the receptacle;

e) means for releasing the detection signal.

58. A system for screening a receptacle, comprising:

a) an image generation device having a radiation source and radiation detectors and operable to generate an image signal conveying an input image related to contents of the receptacle subjecting the receptacle to penetrating radiation, the input image containing distortion introduced by said image generation device so that the input image signal conveys a distorted representation of the receptacle and its contents, wherein part of the distortion introduced in the input image is dependent on a location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation;

b) an apparatus in communication with said image generation device, said apparatus including a processor programmed for;

applying a distortion correction process to the image signal to remove at least in part from the input image the part of the distortion dependent on the location of the receptacle relative to the radiation source and radiation detectors while the receptacle was being subjected to penetrating radiation, thereby to generate a corrected image signal related to contents of the receptacle, the corrected image signal conveying a modified representation the receptacle and its contents, wherein applying the distortion correction process to the image signal includes;

selecting a candidate height from a range of possible heights, the possible heights in said range being related to respective locations relative to the radiation source and detectors of the device; and

using the selected candidate height to condition the distortion correction process applied to the image signal;

processing the corrected image signal in an attempt to detect a presence of a target object in the receptacle;

generating a detection signal in response to detection of the presence of the target object in the receptacle;

c) an output module for conveying information derived at least in part on the basis of said detection signal to a user of the system.

59. A system as defined in claim 58, wherein the image generation device uses penetrating radiation to generate said image signal.

60. A system as defined in claim 59, wherein the penetrating radiation is selected from the set consisting of x-ray, gamma-ray, computed tomography (CT scans) and millimeter wave.

61. An apparatus for screening a suitcase to determine if the suitcase contains a concealed firearm, the apparatus comprising:

a) an input for receiving an X-ray image signal, the X-ray image signal conveying an image of the suitcase being produced by subjecting the suitcase to penetrating radiation using an X-ray imaging device having a radiation source and radiation detectors, wherein objects in the suitcase have distorted shapes in the image and wherein part of the distortion introduced in the input image is dependent on a location of the suitcase relative to the radiation source and the radiation detectors while the suitcase was being subjected to penetrating radiation;

b) a computer based processing unit in communication with said input, said processing unit being programmed for;

i. applying a distortion correction process to the X-ray image signal to generate a corrected X-ray image signal, the corrected X-ray image signal conveying an image of the suitcase in which a correction has been applied to the distorted shapes, the correction applied removing at least in part the part of the distortion dependent on the location of the suitcase relative to the radiation source and the radiation detectors while the suitcase was being subjected to penetrating radiation, wherein applying the distortion correction process to the X-ray image signal includes;

(i) selecting a candidate height from a range of possible heights, the possible heights in said range being related to respective locations relative to the radiation source and detectors of the device; and

(ii) using the selected candidate height to condition the distortion correction process applied to the X-ray image signal;

ii. processing the corrected X-ray image signal with a shape matching algorithm to determine if an object in the image matches anyone of a plurality of firearm shapes stored in a database of shapes;

iii. generating a detection signal when a firearm shape is detected in the image;

c) an output for releasing the detection signal.