Depth-based surveillance image reconstruction
A subject may be interrogated with electromagnetic radiation for producing image data representative of an image of the subject. First and second image data, produced based on reflectivity in first and second frequency ranges, may be related. In some examples, image data for one picture element may be produced based at least in part on reflectivity of the radiation at a depth selected based at least in part on a depth of another picture element. In some examples, plural images may be produced based on reflectivity at different depths. In some examples, a value of reflectivity may be determined for an intermediate depth between two adjacent depths of image data based at least in part on reflectivity of the radiation for a plurality of spaced-apart depths.
1. A method of surveilling a subject comprising:
irradiating at least a portion of the subject with electromagnetic radiation having one or more frequencies between about 100 MHz and about 2 THz;
receiving the irradiated electromagnetic radiation reflected from the subject;
producing, from the received electromagnetic radiation, at least first image data representative of at least the portion of the subject based at least in part on reflectivity of the electromagnetic radiation for a plurality of depths for each of a plurality of picture elements;
selecting a first depth for each of the plurality of picture elements based at least in part on the reflectivity of the electromagnetic radiation at at least the first depth;
selecting a second depth for each of the plurality of picture elements based at least in part on the first depth of at least another one of the picture elements; and
producing at least second image data representative of at least a first image of at least the portion of the subject based at least in part on reflectivity of the electromagnetic radiation at the second depth.
2. The method of claim 1 , in which selecting a first depth includes selecting a first depth corresponding to a depth at which the reflectivity is a maximum for the corresponding picture element.
3. The method of claim 1 , in which selecting a second depth includes selecting a second depth from a plurality of depths including the first depth.
4. The method of claim 1 , in which selecting a second depth of one picture element is based at least in part on the first depth of each of a group of picture elements including the one picture element.
5. The method of claim 4 , in which the group is an m×n kernel of adjacent picture elements, where m and n are integers.
6. The method of claim 4 , in which selecting a second depth of one picture element includes performing a numerical function on the depths of the picture elements in the group.
7. The method of claim 6 , in which performing a numerical function includes computing at least one of a median, a mode, and a mean.
8. The method of claim 1 , in which selecting a second depth includes selecting a second depth in a manner tending to make the second depths have reduced variability between adjacent picture elements compared to the first depths.
9. An imaging system comprising:
an interrogating apparatus configured to transmit toward and receive from a subject in a subject position, electromagnetic radiation having one or more frequencies between about 100 MHz and about 2 THz, the interrogating apparatus producing an image signal representative of the received radiation; and
a controller adapted to produce, from the received electromagnetic radiation, at least first image data representative of at least the portion of the subject based at least in part on reflectivity of the electromagnetic radiation for a plurality of depths for each of a plurality of picture elements, to select a first depth for each of the plurality of picture elements based at least in part on the reflectivity of the electromagnetic radiation at at least the first depth, to select a second depth for each of the plurality of picture elements based at least in part on the first depth of at least another one of the picture elements, and to produce at least second image data representative of at least a first image of at least the portion of the subject based at least in part on reflectivity of the electromagnetic radiation at the second depth.
10. The system of claim 9 , in which the controller is further adapted to select a first depth corresponding to a depth at which the reflectivity is a maximum for the corresponding picture element.
11. The system of claim 9 , in which the controller is further adapted to select a second depth from a plurality of depths including the first depth.
12. The system of claim 9 , in which the controller is further adapted to select a second depth of one picture element based at least in part on the first depth of each of a group of picture elements including the one picture element.
13. The system of claim 12 , in which the group is an m×n kernel of adjacent picture elements, where m and n are integers.
14. The system of claim 12 , in which the controller is further adapted to perform a numerical function on the depths of the picture elements in the group.
15. The system of claim 14 , in which the controller is further adapted to compute at least one of a median, a mode, and a mean.
16. The system of claim 9 , in which the controller is further adapted to select a second depth in a manner tending to make the second depths have reduced variability between adjacent picture elements compared to the first depths.
17. The system of claim 9 , in which the controller is further adapted to produce image data corresponding to a three-dimensional holographic image of at least a portion of the subject.
18. One or more storage media having embodied therein a program of commands adapted to be executed by a computer processor to:
irradiate at least a portion of the subject with electromagnetic radiation having one or more frequencies between about 100 MHz and about 2 THz;
receive the irradiated electromagnetic radiation reflected from the subject;
produce, from the received electromagnetic radiation, at least first image data representative of at least the portion of the subject based at least in part on reflectivity of the electromagnetic radiation for a plurality of depths for each of a plurality of picture elements;
select a first depth for each of the plurality of picture elements based at least in part on the reflectivity of the electromagnetic radiation at at least the first depth;
select a second depth for each of the plurality of picture elements based at least in part on the first depth of at least another one of the picture elements; and
produce at least second image data representative of at least a first image of at least the portion of the subject based at least in part on reflectivity of the electromagnetic radiation at the second depth.