US3748644A
Expired / Lapsed
US
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Automatic registration of points in two separate images
Assignee: Westinghouse Electric Corp
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Filing: 1969-12-31
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Granted: 1973-07-24
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Expires: 1989-12-31
Abstract
Abstract Features are extracted from a two-dimensional image for subsequent comparison with features extracted from a further twodimensional image to determine whether the separate images have at least one area in common, and if so, to provide automatic registration of points of correspondence in the two images in the area or areas in common.
Inventors
- 👤 G Tisdale
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:18
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/80
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
136 words
A process for correlating two unknown images to determine whether they contain a common region, said process including: accepting at least two points of substantial information-bearing character within each image as image points for the extraction of features from the respective image, taking measurements, with respect to the accepted image points of each image and in relation to an imaginary line joining each such accepted image point and another accepted image point, of characteristics of the respective image which are invariant regardless of orientation and scale of the respective image, comparing the invariant measurements obtained from one of said images with the invariant measurements obtained from the other of said images, and if sufficient correspondence exists therebetween, correlating the image points of the two images with respect to which the corresponding invariant measurements have been obtained.
Claim 2
Dependent Claim
136 words
A process for correlating two unknown images to determine whether they contain a common region, said process including: accepting at least two points of substantial information-bearing character within each image as image points for the extraction of features from the respective image, taking measurements, with respect to the accepted image points of each image and in relation to an imaginary line joining each such accepted image point and another accepted image point, of characteristics of the respective image which are invariant regardless of orientation and scale of the respective image, comparing the invariant measurements obtained from one of said images with the invariant measurements obtained from the other of said images, and if sufficient correspondence exists therebetween, correlating the image points of the two images with respect to which the corresponding invariant measurements have been obtained.
Claim 3
Dependent Claim
17 words
The process of claim 1 wherein said acceptable image points lie on lines within the respective image.
Claim 4
Dependent Claim
24 words
The process of claim 1 wherein at least some of said acceptable image points lie along gray scale intensity gradients of the respective image.
Claim 5
Dependent Claim
29 words
The process of claim 1 wherein said invariant characteristics include the orientation of lines in the respective image relative to the imaginary line joining each said two image points.
Claim 6
Dependent Claim
18 words
The process of claim 1 wherein said invariant characteristics include gray scale intensity gradients about accepted image points.
Claim 7
Dependent Claim
64 words
The process of claim 1 further comprising, deriving from each image the geometric relationship between at least some of the accepted image points for the respective image, and wherein said geometric relationship between image points includes the distance between a pair of said image points and the orientation of an imaginary line joining said pair of image points relative to a preselected reference axis.
Claim 8
Dependent Claim
60 words
The process of claim 6 wherein said correlating of image points includes normalizing the derived geometrical relationships between said images, comparing the normalized values for a plurality of said geometrical relationships, and inter-relaTing points within said images as points of correspondence in a region common to said images on the basis of the extent of correspondence between said normalized values.
Claim 9
Dependent Claim
39 words
The process of claim 7 wherein said comparing of normalized values includes developing a cluster of points in the image plane, in which the magnitude of said cluster is representative of the extent of correspondence of said normalized values.
Claim 10
Dependent Claim
31 words
The process of claim 1 wherein said images have been derived by respective sensors responsive to distinct and different portions of the frequency spectrum and have a substantial region in common.
Claim 11
Dependent Claim
21 words
The process of claim 1 wherein said images are representative of phenomena contained in fields of view of different spectral content.
Claim 12
Dependent Claim
14 words
The process of claim 1 wherein said images have a substantial region in common.
Claim 13
Dependent Claim
13 words
The process of claim 11 wherein said images are of different chronological origin.
Claim 14
Dependent Claim
21 words
The process of claim 1 wherein said images are overlapping in subject matter and have only a relatively small common region.
Claim 15
Dependent Claim
126 words
Apparatus for comparing selected characteristics of first and second images to determine a relationship therebetween, said apparatus comprising: image means for providing first and second image electrical signals corresponding respectively to the first and second images; extracting means responsive to the first and second image signals for determining at least first and second image points within each of the first and second images; measuring means for measuring characteristics of the respective images, with respect to each said image point as defined by the corresponding image signal extracted therefrom, which characteristics are invariant regardless of orientation and scale of the respective images, and comparison means for comparing the invariant characteristics as measured for each of the first and second images, for determining correspondence therebetween within selected limits.
Claim 16
Dependent Claim
126 words
Apparatus for comparing selected characteristics of first and second images to determine a relationship therebetween, said apparatus comprising: image means for providing first and second image electrical signals corresponding respectively to the first and second images; extracting means responsive to the first and second image signals for determining at least first and second image points within each of the first and second images; measuring means for measuring characteristics of the respective images, with respect to each said image point as defined by the corresponding image signal extracted therefrom, which characteristics are invariant regardless of orientation and scale of the respective images, and comparison means for comparing the invariant characteristics as measured for each of the first and second images, for determining correspondence therebetween within selected limits.
Claim 17
Dependent Claim
38 words
Apparatus as claimed in claim 14, wherein said extracting means is responsive to the first and second image signals for identifying and for determining the image points therein as extremeties or points of intersection of the identified lines.
Claim 18
Dependent Claim
106 words
Apparatus as claimed in claim 14, wherein there is further included: second measuring means for measuring the distance between every pair of image points as determined by said extracting means, within each of the first and second images, third measuring means for measuring the angle between an imaginary line defined by each said pair of image points, within each of the first and second images, and preselected reference lines therein; means for normalizing the distance and angle measurements derived from the first and second images; and means for comparing the normalized distance and angular measurements to further establish a relationship between the first and second images.
Claim 19
Independent Claim
136 words
A method for registration of two images, comprising the steps of: extracting from each of said images at least first and second image points for measurement of representative features of the respective image, relative to the extracted image points, for comparison with features similarly measured from the other image, relating each such first image point to each such second image point extracted from the respective image, measuring feature characteristics of the respective image with respect to each said first image point as thus related to each such second image point, which characteristics are invariant regardless of orientation and scale of the respective image, comparing the measured invariant characteristics of the two images to determine the degree of correspondence therebetween, and establishing points of correspondence between the two images in accordance with the results of said comparison.
Claim 20
Independent Claim
136 words
A method for registration of two images, comprising the steps of: extracting from each of said images at least first and second image points for measurement of representative features of the respective image, relative to the extracted image points, for comparison with features similarly measured from the other image, relating each such first image point to each such second image point extracted from the respective image, measuring feature characteristics of the respective image with respect to each said first image point as thus related to each such second image point, which characteristics are invariant regardless of orientation and scale of the respective image, comparing the measured invariant characteristics of the two images to determine the degree of correspondence therebetween, and establishing points of correspondence between the two images in accordance with the results of said comparison.
Claim 21
Dependent Claim
90 words
The method of claim 17 wherein said features include characteristics which are variant, further comprising: upon establishing points of correspoNdence between the two images in accordance with the results of comparison of the measured, invariant characteristics, measuring at least selected ones of the variant characteristics of the extracted features, and comparing the measured variant characteristics of the extracted features, thereby to effect registration of the two images in accordance with correlation of the geometric retalionship of the image points of one image with corresponding image points of the other image.
Claim 22
Dependent Claim
41 words
The method of claim 18 further comprising normalizing the measured variant characteristics of the features of one image with respect to the measured variant characteristics of the features of the other image prior to comparison of the said measured variant characteristics.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |