US4826285A
Expired / Lapsed
US
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Method of enhancing the signal to noise ratio of an image recognition correlator
Assignee: United States Department of the Air Force
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Filing: 1987-09-24
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Granted: 1989-05-02
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Expires: 2007-09-24
Abstract
Abstract Method of producing an enhanced output correlation signal from an image matching correlator includes the steps of further transforming data representing an input image to produce a transformed image, multiplying the transformed image by at least one reference filter function representing a reference image to be compared with the input image to produce a product signal, inverse fourier transforming the product signal to product the output correlation signal, and introducing phase distortions within the reference filter function, sufficient to greatly enhance peak values and narrow the area of the correlation peak of the output correlation signal. The method may utilize optical or digital electronic correlation and transformation.
Inventors
- 👤 Joseph L. Horner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:08
CPC Classifications
G; G06; G06F; G06F17/00; G06F17/10; G06F17/15; G06F17/153; G06V; G06V10/00; G06V10/88; G06V10/89; G06V10/893; G06V10/895; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
102 words
A method of producing an enhanced output correlation signal from an image matching correlator comprising the steps of: (a) fourier transforming data representing an input image to produce data representing a transformed image; (b) multiplying said data representing a transformed image by a reference filter function representing a reference image to be compared with said input image, to produce a product signal; (c) inverse fourier transforming said product signal to produce said output correlation signal; and (d) introducing phase distortions within said reference filter function, before the performance of step (b), sufficient to substantially enhance peak values of said output correlation signal.
Claim 2
Independent Claim
102 words
A method of producing an enhanced output correlation signal from an image matching correlator comprising the steps of: (a) fourier transforming data representing an input image to produce data representing a transformed image; (b) multiplying said data representing a transformed image by a reference filter function representing a reference image to be compared with said input image, to produce a product signal; (c) inverse fourier transforming said product signal to produce said output correlation signal; and (d) introducing phase distortions within said reference filter function, before the performance of step (b), sufficient to substantially enhance peak values of said output correlation signal.
Claim 3
Dependent Claim
40 words
The method of claim 1 wherein step (d) is performed by utilizing phase distortion constant K 1 in the following equations: a(x,y)=A.sub.o s(x,y){exp i [s(x,y)]}, (2) φ=K.sub.1 πs+K.sub.2 πs.sup.2 +K.sub.3 πs.sup.3 +(3) having a value of between one and sixty.
Claim 4
Dependent Claim
14 words
The method of claim 1 wherein steps (a), (b), and (c) are performed optically.
Claim 5
Dependent Claim
14 words
The method of claim 2 wherein steps (a), (b), and (c) are performed optically.
Claim 6
Dependent Claim
17 words
The method of claim 1 wherein steps (a), (b), and (c) are performed by a digital computer.
Claim 7
Dependent Claim
17 words
The method of claim 2 wherein steps (a), (b), and (c) are performed by a digital computer.
Claim 8
Dependent Claim
20 words
The method of claim 1 wherein said reference filter function comprises a fast fourier transform of a reference image signal.
Claim 9
Dependent Claim
20 words
The method of claim 2 wherein said reference filter function comprises a fast fourier transform of a reference image signal.
Claim 10
Dependent Claim
20 words
The method of claim 5 wherein said reference filter function comprises a fast fourier transform of a reference image signal.
Claim 11
Dependent Claim
20 words
The method of claim 6 wherein said reference filter function comprises a fast fourier transform of a reference image signal.
Claim 12
Independent Claim
185 words
A method of improving the signal to noise ratio of an output correlation signal from an optical correlator employing a first spatial light modulator, having signal dependent phase distortions, for producing an input image, a second spatial light modulator, means for producing the fourier transform of said input image, as phase distorted by the first spatial light modulator, in the plane of said second spatial light modulator, reference filter function generating means for also applying a reference filter function to said second spatial light modulator to produce the product of the fourier transform of said input image as distorted by said first spatial light modulator, and said reference filter function, and means for generating the inverse fourier transform of said product, thus producing said output correlation signal, indicative of the degree of similarity between said input image and said filter reference function, said method comprising the step of: deliberately producing phase distortions within said reference filter function substantially equal to the phase distortions of said first spatial light modulator, to enhance the signal to noise ratio of the output correlation signal of said optical correlator.
Claim 13
Independent Claim
185 words
A method of improving the signal to noise ratio of an output correlation signal from an optical correlator employing a first spatial light modulator, having signal dependent phase distortions, for producing an input image, a second spatial light modulator, means for producing the fourier transform of said input image, as phase distorted by the first spatial light modulator, in the plane of said second spatial light modulator, reference filter function generating means for also applying a reference filter function to said second spatial light modulator to produce the product of the fourier transform of said input image as distorted by said first spatial light modulator, and said reference filter function, and means for generating the inverse fourier transform of said product, thus producing said output correlation signal, indicative of the degree of similarity between said input image and said filter reference function, said method comprising the step of: deliberately producing phase distortions within said reference filter function substantially equal to the phase distortions of said first spatial light modulator, to enhance the signal to noise ratio of the output correlation signal of said optical correlator.
Claim 14
Dependent Claim
24 words
The method of claim 11 including the step of utilizing a first spatial light modulator having a maximum degree of phase distortions associated therewith.
Claim 15
Dependent Claim
17 words
The method of claim 11 including utilizing a second spatial light modulator having substantially no phase distortion.
Claim 16
Dependent Claim
17 words
The method of claim 12 including utilizing a second spatial light modulator having substantially no phase distortion.
Claim 17
Independent Claim
203 words
A method of improving the signal to noise ratio of an output correlation signal from an optical correlator employing a first spatial light modulator, having signal dependent phase distortions, for producing an input image, a second spatial light modulator, means for producing the fourier transform of said input image, as phase distorted by the first spatial light modulator, in the plane of said second spatial light modulator, reference filter function generating means for also applying a reference filter function to said second spatial light modulator to produce the product of the fourier transform of said input image as distorted by said first spatial light modulator, and said reference filter function, and means for generating the inverse fourier transform of said product, thus producing said output correlation signal, indicative of the degree of similarity between said input image and said filter reference function, said method comprising the steps of: (a) determining the degree of the signal dependent phase distortions of said first spatial light modulator; and (b) deliberately producing phase distortions within said reference filter function substantially equal to the phase distortions of said first spatial light modulator, to enhance the signal to noise ratio of the output correlation signal of said optical correlator.
Claim 18
Independent Claim
203 words
A method of improving the signal to noise ratio of an output correlation signal from an optical correlator employing a first spatial light modulator, having signal dependent phase distortions, for producing an input image, a second spatial light modulator, means for producing the fourier transform of said input image, as phase distorted by the first spatial light modulator, in the plane of said second spatial light modulator, reference filter function generating means for also applying a reference filter function to said second spatial light modulator to produce the product of the fourier transform of said input image as distorted by said first spatial light modulator, and said reference filter function, and means for generating the inverse fourier transform of said product, thus producing said output correlation signal, indicative of the degree of similarity between said input image and said filter reference function, said method comprising the steps of: (a) determining the degree of the signal dependent phase distortions of said first spatial light modulator; and (b) deliberately producing phase distortions within said reference filter function substantially equal to the phase distortions of said first spatial light modulator, to enhance the signal to noise ratio of the output correlation signal of said optical correlator.
Claim 19
Dependent Claim
24 words
The method of claim 15 including the step of utilizing a first spatial light modulator having a maximum degree of phase distortions associated therewith.
Claim 20
Dependent Claim
17 words
The method of claim 15 including utilizing a second spatial light modulator having substantially no phase distortion.
Claim 21
Dependent Claim
17 words
The method of claim 16 including utilizing a second spatial light modulator having substantially no phase distortion.
References Cited (Backward Citations)
US4275454A
Cited
US4588260A
Cited
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