Radiometric imaging device and corresponding method

• US 8,692,708 B2
• Filed: 03/22/2011
• Issued: 04/08/2014
• Est. Priority Date: 03/30/2010
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nogueira-Nine, Juan
• Primary Examiner(s): Phan, Dao
• Application Number:
  US13/053,808
• Publication Number:
  US 20110273320A1
• Time in Patent Office: 1,113 Days
• Field of Search: 342/27, 342/179, 342/185, 342/191, 342/192, 356/317, 356/451, 356/479, 250/332, 250/334
• US Class Current: 342/179
• CPC Class Codes: G01K 11/006 using measurement of the effect of a material on microwaves or longer electromagnetic waves, e.g. measuring temperature via microwaves emitted by the object G01K17/003, G01J5/00 take precedence; measuring the effect of a material on X-, gamma- or particle radiation G01K11/30
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01S 13/904 SAR modes

Abstract

Radiometric imaging for scanning a scene includes a radiometer for detecting radiation emitted in a predetermined spectral range from a spot of the scene and for generating a radiation signal from the detected radiation. Spot movement circuitry effects a movement of the spot, from which the radiation is detected, to various positions. Control circuitry controls the spot movement circuit to effect the movement of the spot from one position to another position so that radiation is detected at a number of spots distributed over the scene. The number is lower than the number of pattern signals of the high-density signal pattern and the radiation signals generated from the radiation detected at the number of spots form a low-density signal pattern. Processing circuitry processes the radiation signals of the low-density signal pattern and generates the high-density signal pattern by applying compressive sensing to the low-density signal pattern.

Claims

1. A radiometric imaging device for scanning a scene and generating a high-density signal pattern representing said scene, said device comprising:

a radiometer to detect radiation emitted in a predetermined spectral range from a spot of said scene and for generating a radiation signal from said detected radiation,

a spot mover to effect a movement of the spot, from which the radiation is detected, to various positions,

control circuitry to control said spot mover to effect the movement of the spot from one position to another position so that radiation is detected at a number of spots distributed over the scene, wherein said number is lower than a number of pattern signals of said high-density signal pattern and radiation signals generated from the radiation detected at said number of spots form a low-density signal pattern, and

processing circuitry to process the radiation signals of said low-density signal pattern and to generate said high-density signal pattern by applying compressive sensing to said low-density signal pattern, wherein

said control circuitry is adapted to effect, after said high-density signal pattern representing said scene has been generated, a movement of the spot, from which the radiation is detected, to various positions in a reduced field of view, which is smaller than the whole scene and contains an object of interest, so that radiation is detected at a reduced number of spots distributed over the reduced field of view,

said reduced number is lower than a number of pattern signals of a high-density signal pattern representing said reduced field of view and radiation signals generated from the radiation detected at said reduced number of spots form a low-density signal pattern of said reduced field of view, and

said processing circuitry is adapted to process the radiation signals of said low-density signal pattern of said reduced field of view and to generate said high-density signal pattern of said reduced field of view by applying compressive sensing to said low-density signal pattern of said reduced field of view.

2. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover so that the number of radiation signals of said low-density signal pattern is by a factor in the range from 10% to 90% lower than the number of pattern signals of said high-density pattern.

3. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover so that the spots, from which radiation is detected, are substantially equally distributed over the scene.

4. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover to effect a continuous movement of said spot over the scene.

5. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover to effect a movement along a pre-determined trajectory over the scene, along a zig-zag trajectory, a meandering trajectory that includes scans over the scene line by line or column by column, or a spiral trajectory.

6. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover in dependence on a desired resolution of an image of the scene, a distribution of an object to be scanned within the scene, and/or a sparsity of an image of said scene.

7. The radiometric imaging device as claimed claim 1, wherein said control circuitry is adapted to randomly determine the direction of movement of the spot from one position to the next position.

8. The radiometric imaging device as claimed in claim 1, wherein said spot mover includes a mechanical spot movement device to effect a relative movement of the radiometer with respect to the scene for effecting a movement of said spot to mechanically move the radiometer for effecting a movement of said spot.

9. The radiometric imaging device as claimed in claim 1, wherein said spot mover comprises electronic spot movement circuitry to electronically move the sensitivity profile of said radiometer for effecting a movement of said spot by an electronic beam positioner or an electronic beam former.

10. The radiometric imaging device as claimed in claim 1, wherein said processing circuitry is adapted to reconstruct an image by applying a l1-norm minimization algorithm to said radiation signals.

11. The radiometric imaging device as claimed in claim 1, wherein the radiation signals of said scene have a sparse representation in a known domain, a total variation domain, Fourier domain, wavelets domain, or curvelets domain.

12. The radiometric imaging device as claimed in claim 1, further comprising a memory to store one or more lists of positions of spots, from which radiation shall be detected, wherein said control circuitry is adapted for selecting the positions of said plurality of distributed spots from one of said lists.

13. The radiometric imaging device as claimed in claim 1, further comprising position generation circuitry to determine the positions of said plurality of distributed spots by use of a predetermined function or distribution by a uniform Bernoulli or Gaussian distribution.

14. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover to effect a movement so that radiation is detected at a number of spots irregularly distributed over the scene.

15. The radiometric imaging device as claimed in claim 1, wherein said radiometer comprises a single radiometer unit to detect radiation emitted from a spot representing a single pixel.

16. The radiometric imaging device as claimed in claim 1, wherein said radiometer comprises a line or array of radiometer units to detect radiation emitted from a spot representing a line or array of pixels.

17. The radiometric imaging device as claimed in claim 1, wherein said radiometer is adapted to detect radiation emitted in a millimeter wavelength range, in a wavelength range from 0.1 to 100 mm or from 1 to 10 mm.

18. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to divide said scene into blocks of a number of pixels, select at least one pixel from each block and connect said selected pixels forming a trajectory, along which the spot is moved over the scene.

19. The radiometric imaging device as claimed in claim 1, wherein said radiometric imaging device is an active radiometric imaging device further comprising a radio transmitter to emit radiation onto said scene, wherein said radiometer is adapted to detect radiation reflected from said scene.

20. The radiometric imaging device as claimed in claim 1, wherein said radiometric imaging device is a passive radiometric imaging device.

21. The radiometric imaging device as claimed in claim 1,

wherein said control circuitry is adapted to further stepwise reduce the field of view and to effect a movement of the spot, from which the radiation is detected, to various positions in a further reduced field of view, and

wherein said processing circuitry is adapted to process the radiation signals of said low-density signal pattern of said further reduced field of view and to generate a high-density signal pattern of said further reduced field of view.

22. The radiometric imaging device as claimed in claim 1,

wherein said control circuitry is adapted to effect a movement of the spot, from which the radiation is detected, to various positions in a reduced field of view, which is smaller than the whole scene and contains an object of interest, so that radiation is detected at a high number of spots of the reduced field of view, wherein said high number corresponds to the number of pattern signals of a high-density signal pattern representing said reduced field of view and the radiation signals generated from the radiation detected at said high number of spots form a high-density signal pattern of said reduced field of view, and

wherein said processing circuitry is adapted to process the radiation signals of said high-density signal pattern of said reduced field of view.

23. The radiometric imaging device as claimed in claim 1, further comprising:

detection circuitry to detect an object of interest in a high-density signal pattern and to provide object information about a detected object of interest, including a position and size of an object of interest, to said control circuitry.

24. The radiometric imaging device as claimed in claim 1, further comprising:

a user interface circuit to input and provide information about a detected object of interest, including a position and size of an object of interest, and/or field of view information about the position and size of a reduced field of view to said control circuitry.

28. The radiometric imaging device as claimed in claim 1, wherein said control circuitry is adapted to control said spot mover so that the number of radiation signals of said low-density signal pattern is by a factor in the range from 25% to 75% lower than the number of pattern signals of said high-density pattern.

25. A radiometric imaging method for scanning a scene and generating a high-density signal pattern representing said scene, said method comprising the steps of:

detecting radiation emitted in a predetermined spectral range from a spot of said scene and for generating a radiation signal from said detected radiation,

moving of the spot, from which the radiation is detected, to various positions,

controlling a spot movement device to effect the movement of the spot from one position to another position so that radiation is detected at a number of spots distributed over the scene, wherein said number is lower than the number of pattern signals of said high-density signal pattern and the radiation signals generated from the radiation detected at said number of spots form a low-density signal pattern,

processing the radiation signals of said low-density signal pattern and for generating said high-density signal pattern by applying compressive sensing to said low-density signal pattern,

controlling, after said high-density signal pattern representing said scene has been generated, a movement of the spot, from which the radiation is detected, to various positions in a reduced field of view, which is smaller than the whole scene and contains an object of interest, so that radiation is detected at a reduced number of spots distributed over the reduced field of view, wherein said reduced number is lower than a number of pattern signals of a high-density signal pattern representing said reduced field of view and radiation signals generated from the radiation detected at said reduced number of spots form a low-density signal pattern of said reduced field of view, and

processing the radiation signals of said low-density signal pattern of said reduced field of view and generating said high-density signal pattern of said reduced field of view by applying compressive sensing to said low-density signal pattern of said reduced field of view.

26. Computer readable non-transitory medium having instructions stored thereon which, when carried out on a computer, cause the computer to perform the steps of processing and reconstructing of the method as claimed in claim 25.

27. A radiometric imaging device that scans a scene and generates a high-density signal pattern representing said scene, said device comprising:

a radiometer that detects radiation emitted in a predetermined spectral range from a spot of said scene and generates a radiation signal from said detected ra-diation,

spot moving means for effecting a movement of the spot, from which the radiation is detected, to various positions,

control means for controlling said spot moving means to effect the movement of the spot from one position to another position so that radiation is detected at a number of spots distributed over the scene, wherein said number is lower than the number of pattern signals of said high-density signal pattern and the radiation signals generated from the radiation detected at said number of spots form a low-density signal pattern, and

processing means for processing the radiation signals of said low-density signal pattern and generates said high-density signal pattern by applying compressive sensing to said low-density signal pattern, wherein

said control means effects, after said high-density signal pattern representing said scene has been generated, a movement of the spot, from which the radiation is detected, to various positions in a reduced field of view, which is smaller than the whole scene and contains an object of interest, so that radiation is detected at a reduced number of spots distributed over the reduced field of view,

said reduced number is lower than a number of pattern signals of a high-density signal pattern representing said reduced field of view and radiation signals generated from the radiation detected at said reduced number of spots form a low-density signal pattern of said reduced field of view, and

said processing means processes the radiation signals of said low-density signal pattern of said reduced field of view and generates said high-density signal pattern of said reduced field of view by applying compressive sensing to said low-density signal pattern of said reduced field of view.