Patent US6711293B1 successfully refreshed from Google Patents.
US6711293B1
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Method and apparatus for identifying scale invariant features in an image and use of same for locating an object in an image
Assignee: University of British Columbia
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Filing: 2000-03-06
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Granted: 2004-03-23
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Expires: 2020-03-06
Abstract
Abstract A method and apparatus for identifying scale invariant features in an image and a further method and apparatus for using such scale invariant features to locate an object in an image are disclosed. The method and apparatus for identifying scale invariant features may involve the use of a processor circuit for producing a plurality of component subregion descriptors for each subregion of a pixel region about pixel amplitude extrema in a plurality of difference images produced from the image. This may involve producing a plurality of difference images by blurring an initial image to produce a blurred image and by subtracting the blurred image from the initial image to produce the difference image. For each difference image, pixel amplitude extrema are located and a corresponding pixel region is defined about each pixel amplitude extremum. Each pixel region is divided into subregions and a plurality of component subregion descriptors are produced for each subregion. These component subregion descriptors are correlated with component subregion descriptors of an image under consideration and an object is indicated as being detected when a sufficient number of component subregion descriptors (scale invariant features) define an aggregate correlation exceeding a threshold correlation with component subregion descriptors (scale invariant features) associated with the object.
Inventors
- 👤 David G. Lowe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:57
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/70; G06T7/73; G06V; G06V10/00; G06V10/40; G06V10/46; G06V10/462
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
167 words
A method of identifying scale invariant features in an image defined by a plurality of pixels, the method comprising: locating pixel amplitude extrema in a plurality of difference images produced from said image by: comparing the amplitude of each pixel in an image under consideration with the amplitudes of pixels in an area about said each pixel in said image under consideration to identify local maximal and minimal amplitude pixels; comparing the amplitudes of said local maximal and minimal amplitude pixels with the amplitudes of pixels in a predecessor image to the image under consideration to identify possible maximal and minimal amplitude pixels and comparing the amplitudes of said possible maximal and minimal amplitude pixels with the amplitudes of pixels in a successor image to the image under consideration to identify actual maximal and minimal amplitude pixels; and producing a plurality of component subregion descriptors for each subregion of a pixel region about said pixel amplitude extrema in said plurality of difference images produced from said image.
Claim 2
Independent Claim
167 words
A method of identifying scale invariant features in an image defined by a plurality of pixels, the method comprising: locating pixel amplitude extrema in a plurality of difference images produced from said image by: comparing the amplitude of each pixel in an image under consideration with the amplitudes of pixels in an area about said each pixel in said image under consideration to identify local maximal and minimal amplitude pixels; comparing the amplitudes of said local maximal and minimal amplitude pixels with the amplitudes of pixels in a predecessor image to the image under consideration to identify possible maximal and minimal amplitude pixels and comparing the amplitudes of said possible maximal and minimal amplitude pixels with the amplitudes of pixels in a successor image to the image under consideration to identify actual maximal and minimal amplitude pixels; and producing a plurality of component subregion descriptors for each subregion of a pixel region about said pixel amplitude extrema in said plurality of difference images produced from said image.
Claim 3
Dependent Claim
12 words
The method claimed in claim 1 further comprising producing said difference images.
Claim 4
Dependent Claim
35 words
The method claimed in claim 2 wherein producing a difference image comprises blurring an initial image to produce a blurred image and subtracting said blurred image from said initial image to produce a difference image.
Claim 5
Dependent Claim
41 words
The method claimed in claim 3 wherein producing said difference images comprises successively blurring and subtracting as recited in claim 3 where said initial image used in a successive blurring function includes a blurred image produced in a predecessor blurring function.
Claim 6
Dependent Claim
20 words
The method claimed in claim 1 further comprising producing a pixel gradient vector for each pixel in each difference image.
Claim 7
Dependent Claim
24 words
The method claimed in claim 5 further comprising associating vector orientations with respective actual maximal and minimal amplitude pixels associated with each difference image.
Claim 8
Dependent Claim
35 words
The method claimed in claim 6 wherein producing a plurality of component subregion descriptors comprises producing subregion descriptors for each respective subregion in response to pixel gradient vectors of pixels within said each respective subregion.
Claim 9
Dependent Claim
31 words
The method claimed in claim 7 wherein producing each of said subregion descriptors comprises determining the number of pixel vectors at orientations within a predefined range of orientations in said subregion.
Claim 10
Dependent Claim
41 words
The method claimed in claim 7 wherein producing a plurality of subregion descriptors comprises associating with each of said descriptors a plurality of orientation ranges and determining the number of pixel vectors at orientations within respective orientation ranges, for each subregion.
Claim 11
Independent Claim
160 words
An apparatus for identifying scale invariant features in an image defined by a plurality of pixels, the apparatus comprising a processor circuit configured to: locate said pixel amplitude extrema in difference images by: comparing the amplitude of each pixel in an image under consideration, with the amplitudes of pixels in an area about said each pixel in said image under consideration to identify local maximal and minimal amplitude pixels; comparing the amplitudes of said local maximal and minimal amplitude pixels with the amplitudes of pixels in a predecessor image to the image under consideration to identify possible maximal and minimal amplitude pixels; comparing the amplitudes of said possible maximal and minimal amplitude pixels with the amplitudes of pixels in a successor image to the image under consideration to identify actual maximal and minimal amplitude pixels; and produce a plurality of component subregion descriptors for each subregion of a pixel region about pixel amplitude extrema in said plurality of difference images.
Claim 12
Independent Claim
160 words
An apparatus for identifying scale invariant features in an image defined by a plurality of pixels, the apparatus comprising a processor circuit configured to: locate said pixel amplitude extrema in difference images by: comparing the amplitude of each pixel in an image under consideration, with the amplitudes of pixels in an area about said each pixel in said image under consideration to identify local maximal and minimal amplitude pixels; comparing the amplitudes of said local maximal and minimal amplitude pixels with the amplitudes of pixels in a predecessor image to the image under consideration to identify possible maximal and minimal amplitude pixels; comparing the amplitudes of said possible maximal and minimal amplitude pixels with the amplitudes of pixels in a successor image to the image under consideration to identify actual maximal and minimal amplitude pixels; and produce a plurality of component subregion descriptors for each subregion of a pixel region about pixel amplitude extrema in said plurality of difference images.
Claim 13
Dependent Claim
17 words
The apparatus claimed in claim 10 wherein said processor circuit is configured to produce said difference images.
Claim 14
Dependent Claim
37 words
The apparatus claimed in claim 11 wherein said processor circuit is configured to blur an initial image to produce a blurred image and to subtract said blurred image from said initial image to produce a difference image.
Claim 15
Dependent Claim
45 words
The apparatus claimed in claim 12 wherein said processor circuit is configured to successively blur and subtract as recited in claim 12 and is configured to use a blurred image produced in a predecessor blurring function as said initial image, in a successive blurring function.
Claim 16
Dependent Claim
25 words
The apparatus claimed in claim 10 wherein said processor circuit is configured to produce a pixel gradient vector for each pixel in each difference image.
Claim 17
Dependent Claim
29 words
The apparatus claimed in claim 14 wherein said processor circuit is configured to associate vector orientations with respective actual maximal and minimal amplitude pixels associated with each difference image.
Claim 18
Dependent Claim
33 words
The apparatus claimed in claim 15 wherein said processor circuit is configured to produce subregion descriptors for each respective subregion in response to pixel gradient vectors of pixels within said each respective subregion.
Claim 19
Dependent Claim
30 words
The apparatus claimed in claim 16 wherein said processor circuit is configured to determine the number of pixel vectors at orientations within a predefined range of orientations in said subregion.
Claim 20
Dependent Claim
41 words
The apparatus claimed in claim 16 wherein said processor circuit is configured to associate with each of said descriptors a plurality of orientation ranges and to determine the number of pixel vectors at orientations within respective orientation ranges, for each subregion.
Claim 21
Independent Claim
177 words
An apparatus for identifying scale invariant features in an image defined by a plurality of pixels, the apparatus comprising: means for locating pixel amplitude extrema in a plurality of difference images produced from said image, said means for locating comprising: means for comparing the amplitude of each pixel in an image under consideration, with the amplitudes of pixels in an area about said each pixel in said image under consideration to identify local maximal and minimal amplitude pixels; means for comparing the amplitudes of said local maximal and minimal amplitude pixels with the amplitudes of pixels in a predecessor image to the image under consideration to identify possible maximal and minimal amplitude pixels and means for comparing the amplitudes of said possible maximal and minimal amplitude pixels with the amplitudes of pixels in a successor image to the image under consideration to identify actual maximal and minimal amplitude pixels; and means for producing a plurality of component subregion descriptors for each subregion of a pixel region about said pixel amplitude extrema in said plurality of difference images.
Claim 22
Independent Claim
177 words
An apparatus for identifying scale invariant features in an image defined by a plurality of pixels, the apparatus comprising: means for locating pixel amplitude extrema in a plurality of difference images produced from said image, said means for locating comprising: means for comparing the amplitude of each pixel in an image under consideration, with the amplitudes of pixels in an area about said each pixel in said image under consideration to identify local maximal and minimal amplitude pixels; means for comparing the amplitudes of said local maximal and minimal amplitude pixels with the amplitudes of pixels in a predecessor image to the image under consideration to identify possible maximal and minimal amplitude pixels and means for comparing the amplitudes of said possible maximal and minimal amplitude pixels with the amplitudes of pixels in a successor image to the image under consideration to identify actual maximal and minimal amplitude pixels; and means for producing a plurality of component subregion descriptors for each subregion of a pixel region about said pixel amplitude extrema in said plurality of difference images.
Claim 23
Dependent Claim
19 words
A computer readable medium comprising codes for directing a processor circuit to execute the method of claim 1 .
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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) | 2007-03-23 | 2007-09-22 | 2008-03-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-03-23 | 2011-09-22 | 2012-03-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-03-23 | 2015-09-22 | 2016-03-23 | $7700.00 | Window Closed / Lapsed |