Patent US5661818A successfully refreshed from Google Patents.
US5661818A
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Method and system for detecting grids in a digital image
Assignee: Carestream Health Inc
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Filing: 1995-01-27
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Granted: 1997-08-26
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Expires: 2015-01-27
Abstract
Abstract A method for detecting grids in a digital image having a plurality of pixels for capturing an image, comprises the steps of performing a high pass filter operation on a sample of pixels for filtering out the image from the sampled pixels; and performing a statistical F-test operation on the results of the high pass filter operation for determining when the digital image contains grids.
Inventors
- 👤 Roger S. Gaborski
- 👤 Thaddeus F. Pawlicki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:41
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/73; G06T5/75; G06V; G06V30/00; G06V30/40; G06V30/41; G06V30/412; A; A61; A61B; A61B6/00; A61B6/52; A61B6/5258; G06T2207/00; G06T2207/10; G06T2207/10116
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
114 words
A method for detecting grids in a digital image having a plurality of pixels for capturing an image, comprising the steps of: (a) performing a high pass filter operation on a sample of pixels for filtering out the image from the sampled pixels; and (b) performing a F test operation on the results of the high pass filter operation for determining when the digital image contains grids; wherein the F test is F=horizontal variance/vertical variance and vertical grid lines are present when the F-test results in the F-test having the horizontal variance less than the vertical variance, and the horizontal grid lines are present when the horizontal variance is greater than the vertical variance.
Claim 2
Independent Claim
114 words
A method for detecting grids in a digital image having a plurality of pixels for capturing an image, comprising the steps of: (a) performing a high pass filter operation on a sample of pixels for filtering out the image from the sampled pixels; and (b) performing a F test operation on the results of the high pass filter operation for determining when the digital image contains grids; wherein the F test is F=horizontal variance/vertical variance and vertical grid lines are present when the F-test results in the F-test having the horizontal variance less than the vertical variance, and the horizontal grid lines are present when the horizontal variance is greater than the vertical variance.
Claim 3
Dependent Claim
65 words
The method as in claim 1 wherein the high pass filter operation includes the steps of: (a1) forming a plot of pixel location versus the pixel value at the corresponding pixel location; (a2) smoothing the results of the plotting operation; and (a3) subtracting each plotted pixel value and each smoothed pixel value which are from the same pixel location for obtaining the high pass filter.
Claim 4
Dependent Claim
61 words
The method as in claim 2 wherein step (a1) includes: (ai) further sampling from the sampled pixels at least two spaced apart lines of pixels; (aii) averaging pixel values from each of the spaced apart lines which have a matching abscissa for removing noise from the digital image; and (aiii) forming the plot in step (a1) from the averaged pixel values.
Claim 5
Dependent Claim
32 words
The method as in claim 3 wherein step (aii) includes averaging pixel values from each of the spaced apart lines which have a matching ordinate for removing noise from the digital image.
Claim 6
Dependent Claim
15 words
The method as in claim 4 wherein the plot is autocorrelated for enhancing the plot.
Claim 7
Dependent Claim
26 words
The method as in claim 1 wherein no grids are present in the digital image when either of the conditions in step (b) are not met.
Claim 8
Dependent Claim
56 words
The method as in claim 6 wherein each of the sampled pixels designate a first signal if vertical grids are detected and designate a second signal if horizontal grids are detected for determining which of the first or second signals have a majority which, in turn, determines whether the digital image has vertical or horizontal signals.
Claim 9
Independent Claim
149 words
A method for detecting grids in a digital image having a plurality of pixels for capturing an image, comprising the steps of: (a) determining a pixel value for selecting which pixels in the digital image meet a predetermined test which is defined by the predetermined pixel value; (b) performing a high pass filter operation on a sample of pixels containing at least one of the pixels which meets the predetermined test for filtering out the image from the sampled pixels; and (c) performing a F-test operation on the results of the high pass filter operation for determining when the image contains grids; wherein the F test is F=horizontal variance/vertical variance and vertical grid lines are present when the F-test results in the F-test having the horizontal variance less than the vertical variance, and the horizontal grid lines are present when the horizontal variance is greater than the vertical variance.
Claim 10
Independent Claim
149 words
A method for detecting grids in a digital image having a plurality of pixels for capturing an image, comprising the steps of: (a) determining a pixel value for selecting which pixels in the digital image meet a predetermined test which is defined by the predetermined pixel value; (b) performing a high pass filter operation on a sample of pixels containing at least one of the pixels which meets the predetermined test for filtering out the image from the sampled pixels; and (c) performing a F-test operation on the results of the high pass filter operation for determining when the image contains grids; wherein the F test is F=horizontal variance/vertical variance and vertical grid lines are present when the F-test results in the F-test having the horizontal variance less than the vertical variance, and the horizontal grid lines are present when the horizontal variance is greater than the vertical variance.
Claim 11
Dependent Claim
65 words
The method as in claim 8 wherein the high pass filter operation includes the steps of: (a1) forming a plot of pixel location versus the pixel value at the corresponding pixel location; (a2) smoothing the results of the plotting operation; and (a3) subtracting each plotted pixel value and each smoothed pixel value which are from the same pixel location for obtaining the high pass filter.
Claim 12
Dependent Claim
61 words
The method as in claim 9 wherein step (a1) includes: (ai) further sampling from the sampled pixels at least two spaced apart lines of pixels; (aii) averaging pixel values from each of the spaced apart lines which have a matching abscissa for removing noise from the digital image; and (aiii) forming the plot in step (a1) from the averaged pixel values.
Claim 13
Dependent Claim
32 words
The method as in claim 10 wherein step (aii) includes averaging pixel values from each of the spaced apart lines which have a matching ordinate for removing noise from the digital image.
Claim 14
Dependent Claim
18 words
The method as in claim 8 wherein the predetermined test is determining the mean of the pixel values.
Claim 15
Dependent Claim
33 words
The method as in claim 12 wherein the high pass filter operation is performed on the sample containing at least one of the pixel values at or higher than the mean pixel value.
Claim 16
Independent Claim
110 words
A system for detecting grids in a digital image having a polarity of pixels for capturing an image, comprising: (a) means for high pass filtering a sample of pixels for filtering out the image from the sampled pixels; and (b) means for performing a F-test operation on the results of said high pass filter means for determining when the digital image contains grids; wherein the F test is F=horizontal variance/vertical variance and vertical grid lines are present when the F-test results in the F-test having the horizontal variance less than the vertical variance, and the horizontal grid lines are present when the horizontal variance is greater than the vertical variance.
Claim 17
Independent Claim
110 words
A system for detecting grids in a digital image having a polarity of pixels for capturing an image, comprising: (a) means for high pass filtering a sample of pixels for filtering out the image from the sampled pixels; and (b) means for performing a F-test operation on the results of said high pass filter means for determining when the digital image contains grids; wherein the F test is F=horizontal variance/vertical variance and vertical grid lines are present when the F-test results in the F-test having the horizontal variance less than the vertical variance, and the horizontal grid lines are present when the horizontal variance is greater than the vertical variance.
Claim 18
Dependent Claim
14 words
The system as in claim 14 wherein the predetermined mathematical operation includes a F-test.
Claim 19
Dependent Claim
64 words
The system as in claim 14 wherein said high pass filter includes: (a1) means for plotting pixel location versus the pixel value at the corresponding pixel location; (a2) means for smoothing the results of the plotting operation; and (a3) means for subtracting each plotted pixel value and each smoothed pixel value which are from the same pixel location for obtaining the high pass filter.
Claim 20
Dependent Claim
64 words
The system as in claim 16 wherein said plotting means includes: (ai) means for sampling from the sampled pixels at least two spaced apart lines of pixels; (aii) means for averaging pixel values from each of the spaced apart lines which have a matching abscissa for removing noise from the digital image; and (aiii) means for forming the plot from the averaged pixel values.
Claim 21
Dependent Claim
33 words
The system as in claim 17 wherein said averaging means includes averaging pixel values from each of the spaced apart lines which have a matching ordinate for removing noise from the digital image.
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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) | 2000-08-25 | 2001-02-24 | 2001-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-25 | 2005-02-24 | 2005-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-25 | 2009-02-24 | 2009-08-26 | $7700.00 | Window Closed / Lapsed |