US4827528A
Expired / Lapsed
US
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Error-minimizing noise-reduction system
Assignee: Leland Stanford Junior University
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Filing: 1985-11-15
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Granted: 1989-05-02
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Expires: 2005-11-15
Abstract
Abstract In a multiple-measurement system, a weighted sum of the measurements is used to provide a selective image. An additional weighted sum is used to provide an increased signal-to-noise ratio image. An improved selective image is formed by combining the low frequency portions of the selective image and the correct high frequency componenets from the increased signal-to-noise ratio image. To provide the correct high frequency components the error between the selective image and the improved selective image is minimized. The low-noise high-frequency image is weighted by the ration of the cross correlation of the selective andlow noise images divided by the autocorrelation of thelow noise image.
Inventors
- 👤 Albert Macovski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 00:12
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/70
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
124 words
In a method for forming a selective image of improved signal-to-noise ratio from an array of measurements the steps of: forming a first combination of the measurements to provide a selective image signal; low-pass filtering the selective image signal to form a low frequency image signal; forming a high-pass filtered second comgination of the measurements to provide a low noise high frequency image signal; and combining the low frequency image signal with a controlled amount of the high frequency image signal to form an improved selective image with the control adjusted to minimize the average error between the improved selective image and the selective image and to minimize the squared error between the high frequency portions of the selective image and the improved image.
Claim 2
Dependent Claim
124 words
In a method for forming a selective image of improved signal-to-noise ratio from an array of measurements the steps of: forming a first combination of the measurements to provide a selective image signal; low-pass filtering the selective image signal to form a low frequency image signal; forming a high-pass filtered second comgination of the measurements to provide a low noise high frequency image signal; and combining the low frequency image signal with a controlled amount of the high frequency image signal to form an improved selective image with the control adjusted to minimize the average error between the improved selective image and the selective image and to minimize the squared error between the high frequency portions of the selective image and the improved image.
Claim 3
Dependent Claim
55 words
The method as recited in claim 1 where the step of minimizing the squared error includes the step of multiplying the high frequency image by the quotient of the cross-correlation of the high frequency portions of the selective image and the low noise, high frequency image and the autocorrelation of the low-noise high frequency image.
Claim 4
Dependent Claim
121 words
Apparatus for forming a selective image of improved signal-to-noise ratio from an array of measurements comprising: means for providing a first combination of the measurements to provide a selective image; means for providing a low-pass filtered selective image; means for providing a second combination of the measurements to provide a low-noise image; means for providing a high-pass filtered low-noise image; and means for combining the low-pass filtered selective image with a controlled amount of the high-pass filtered low-noise image to form an improved selective image with the control determined by minimizing the error between the selective image and the improved selective image and minimizing the squared error between the high frequency portions of the selective image and the improved selective image.
Claim 5
Dependent Claim
121 words
Apparatus for forming a selective image of improved signal-to-noise ratio from an array of measurements comprising: means for providing a first combination of the measurements to provide a selective image; means for providing a low-pass filtered selective image; means for providing a second combination of the measurements to provide a low-noise image; means for providing a high-pass filtered low-noise image; and means for combining the low-pass filtered selective image with a controlled amount of the high-pass filtered low-noise image to form an improved selective image with the control determined by minimizing the error between the selective image and the improved selective image and minimizing the squared error between the high frequency portions of the selective image and the improved selective image.
Claim 6
Dependent Claim
29 words
Apparatus as recited in claim 3 where the selective image is a projection image of a volume and the measurements are projection measurements of different components of the volume.
Claim 7
Dependent Claim
17 words
Apparatus as recited in claim 3 where the selective image is a cross-sectional image of a volume.
Claim 8
Dependent Claim
53 words
Apparatus as recited in claim 3 where the means for minimizing the squared error includes means for multiplying the high frequency image by the quotient of the cross correlation of the high frequency portions of the selective image and the low noise image and the autocorrelation of the low noise high frequency image.
Claim 9
Dependent Claim
27 words
Apparatus as recited in claim 6 where the cross correlation and autocorrelation are formed using a square group of picture elements surrounding the picture element being processed.
Claim 10
Dependent Claim
15 words
Apparatus as recited in claim 3 including means for forming a plurality of selective images.
Claim 11
Dependent Claim
27 words
Apparatus as recited in claim 8 where the plurality of selective images are used as basis images which are subsequently combined to enhance or eliminate specific materials.
Claim 12
Dependent Claim
37 words
Apparatus as recited in claim 3 where the measurements used to process the selective image are chosen so as to provide zero added high-pass filtered signal in the absence of signals whereby the background noise is minimized.
Claim 13
Dependent Claim
20 words
Apparatus as recited in claim 3 where the noise components of the selective image and the low-noise image are orthogonal.
Claim 14
Dependent Claim
15 words
Apparatus as recited in claim 3 where the low-pass filter and high-pass filter are complimentary.
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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) | 1992-05-01 | 1992-10-31 | 1993-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-01 | 1996-10-31 | 1997-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-01 | 2000-10-31 | 2001-05-02 | $7700.00 | Window Closed / Lapsed |