Macro image processing system

• US 5,175,802 A
• Filed: 02/27/1989
• Issued: 12/29/1992
• Est. Priority Date: 08/28/1986
• Status: Expired due to Fees

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Crookshanks, Rex J.
• Primary Examiner(s): Harkcom, Gary V.
• Assistant Examiner(s): Zimmerman, Mark K.
• Application Number:
  US07/316,007
• Time in Patent Office: 1,401 Days
• Field of Search: 364/518, 382/42, 382/45, 395/100
• US Class Current: 382/278
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means

Abstract

An image processing system (10) includes an array (12) of detectors (14), each of which is designed to produce a current proportional to incident radiation. This system provides image processing at a viable sampling rate even for very large arrays and permits very efficient determination of single element detections. The modulation functions are supplied from a weighted summer (18). The weighted summer applies an invertible matrix of weights to a series of orthogonal Walsh functions defined over a predetermined sampling interval, the Walsh functions being generated by a function generator (16). The modulated outputs of the array are combined by summer 20 and distributed among parallel channels by a divider (22). Correlators (24) correlate the signal in each channel with a respective of the original Walsh functions. The correlated outputs are digitized by analog-to-digital converters for transmission and processing by a digital processor (28). The processor can at least partially reconstruct the detected spatial distribution for output to a display (30). The modulated detector output arrangement can be combined in a hierarchical manner to process groups of subarrays in the same manner that individual pixels are processed.

Claims

1. A signal detection and processing system, comprising:

a plurality of groups of detectors arranged to form an array and wherein each of said groups includes a plurality of said detectors arranged in a sub-array, each of said detectors providing an output signal representing the value of a phenomenon of interest incident said detector;

first modulation means for modulating the output signal of each detector in each of said sub-arrays by a plurality of first time varying signals which are mutually orthogonal over a first predetermined time interval;

first summing means for summing the modulated output signals of the detectors in each of said sub-arrays;

second modulation means for modulating the summed modulated output signals for each of said sub-arrays by a plurality of second time varying signals which are mutually orthogonal over a second predetermined time interval and for producing modulated output signals therefrom; and

,

second summing means, having an output signal, for summing the modulated output signals of said second modulation means,

whereby said output signal of said second summing means contains information on the spatial distribution of said phenomenon of interest incident said array.

2. The system of claim 1, including:

first correlator means, having an output signal, for correlating the output signal of said first summing means with respective ones of said first time-varying signals;

second correlator means, having an output signal, for correlating the output signal of said second summing means with respective ones of said second time-varying signals;

sampling means for sampling the output signal of said first correlator means over an interval over which said first time varying signals are orthogonal and for sampling the output signal of said second correlator means over an interval which said second time varying signals are orthogonal, said sampling means including signal processing means for processing the output signal of said second correlator means for providing information on the spatial distribution of said variable of interest incident said array.

3. The system of claim 2, wherein each of said first and second time varying signals are mutually orthonormal.

4. The system of claim 3, wherein:

the number of signals in said first time varying signals is equal to the number of detectors, and

the number of signals in said second time varying signals is equal to the number of sub-arrays.

5. The system of claim 3, wherein said array and said sub-arrays are each rectangular, the number of signals in said first time varying signals being equal to the number of rows of the groups in said array plus the number of columns of the groups in said array, and the number of signals in said second time varying signals is equal to the number of rows of the detectors in each sub-array plus the number of columns of the detectors in the sub-array.

6. The system of claim 2, wherein said signal processing means is further operative for determining when a change in intensity is detected by any detector in each sub-array and for determining when a change in intensity is detected by any group of detectors in said array.

7. The system of claim 2, wherein said signal processing means is further operative for determining which group of detectors of said array has detected a change in intensity when only one of said detectors detects such as change in a sampling interval and for determining which detector in a sub-array has detected a change in intensity when only one of said detectors detects such a change in a sampling interval.

8. The system of claim 1, wherein:

said first modulation means modulates the output signal of each detector in each of said sub-arrays by a respective weighted set of the respective first time varying signals associated with the detector,

said second modulation means modulates the output signals of each of sub-array by a respective weighted set of the respective second time varying signals associated with the sub-array,

the number of said first time varying signals is equal to the number of detectors,

the number of said second time varying signals is equal to the number of sub-arrays, and

the weights applied in summing said first and second time varying signals each constitute an invertible matrix.

9. A method of image processing, comprising the steps of:

(A) detecting a scene with an array of detectors, each detector having an output signal associated therewith and arranged in a plurality of groups thereof, wherein each group defines a sub-array of detectors;

(B) modulating the output signal of each detector in each of said sub-arrays by a first plurality of weighted time-varying signals that are orthogonal over a predetermined time period and thereafter producing a modulated output signal from each of said detectors;

(C) summing the modulated output signals of the detectors modulated in step (B) and thereafter producing a summed modulated output signal for each of said sub-arrays;

(D) modulating the summed, modulated output signal of each of said sub-arrays summed in step (C) by a second plurality of weighted time varying signals that are orthogonal over a predetermined time period and thereafter producing a modulated output signals for each of said sub-arrays; and

,

(E) summing the modulated output signal of each of said sub-arrays which are modulated in step (D).

10. The method of claim 9, including the step of:

(F) correlating the result of the summing performed in step (C) with respective ones of said first plurality of weighted time varying signals and thereafter producing a correlated output signal;

(G) sampling each correlated output signal of step (F) over a time interval over which said first time-varying signals are orthogonal;

(H) correlating the result of the summing performed in step (E) with respective ones of said second plurality of weighted time varying signals,

(I) sampling each result correlated in step (H) over a time interval over which said second time-varying signals are orthogonal; and

(J) processing the samples of steps (G) and (I) to obtain information regarding a spatial distribution of radiation incident on said detector array.

11. The method of claim 10, wherein said first and second time varying signals are each orthonormal.

12. The method of claim 11, wherein said first and second time varying signals are in the form of Walsh functions.

13. The method of claim 10, wherein the number of first time varying signals is equal to the number of detectors in each sub-array.

14. The method of claim 13, wherein the samples of step (G) are processed to determine an intensity of radiation incident to each detector in each sub-array.

15. The method of claim 10, wherein the number of second time varying signals is equal to the number of sub-arrays in said array.

16. The method of claim 15, wherein the samples of step (I) are processed to determine an intensity of radiation incident to each sub-array in said array.

17. The method of claim 10, wherein each of said sub-arrays is rectangular and the number of first time varying signals is the sum of the number of rows and the number of columns of each sub-array.

18. The method of claim 10, wherein said array is rectangular and the number of second time-varying signals is the sum of the number of rows and the number of columns of the array.

19. The method of claim 10 further comprising the steps of:

(K) applying weights to said first and to said second plurality of weighted time varying signals;

(L) summing said first plurality of time varying signals; and

(M) summing said second plurality of time varying signals.

20. The method of claim 19, wherein the weights applied to each of said first and said second plurality of time varying signals defines an invertible matrix.

21. The method of claim 19, wherein the weights applied to each of said first and said second plurality of time varying signals are defined by coefficients of a quantized Legendre polynomial.