US5289283A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inter-frame video filter having selective linear and non-linear transfer characteristics as function of inter-frame differences
Assignee: British Telecommunications PLC
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Filing: 1990-08-09
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Granted: 1994-02-22
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Expires: 2010-08-09
Abstract
Abstract Temporarily filtered video samples are formed as the sum of a previous frame output sample and a non-linear function of the difference between current and previous samples. The function is non-linear only for absolute values of differences less than 50% (preferably 10%) of the maximum range of the difference, and a smaller lookup table is used for implementing the non-linear function than would otherwise be the case.
Inventors
- 👤 Robert W. Hopper
- 👤 Michael W. Whybray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:17
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/21
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
179 words
A filter for filtering digitally coded video signals comprising: means for forming the difference (D) between each sample of an input signal (S) and the filter output corresponding to an earlier frame of the video signal (P); and means for forming an output sample (S') by adding said filter output corresponding to an earlier frame of the video signal (P) to a non-linear function (f(D)) of the difference (D); the non-linear function (f(D)) including a non-linear portion for absolute values of the difference (D) less than a threshold and a linear portion for absolute values of the difference (D) greater than the threshold, said threshold being equal to 50% or less of the maximum possible absolute value of the difference (D); the filter including non-linear processing means having: a memory for storing values of the non-linear function (f(D)) corresponding to absolute values of difference (D) less than the threshold; and switching means responsive to each absolute value of difference (D) to select for output either the unmodified difference (D) or the corresponding stored value of said non-linear function (f(D)).
Claim 2
Dependent Claim
179 words
A filter for filtering digitally coded video signals comprising: means for forming the difference (D) between each sample of an input signal (S) and the filter output corresponding to an earlier frame of the video signal (P); and means for forming an output sample (S') by adding said filter output corresponding to an earlier frame of the video signal (P) to a non-linear function (f(D)) of the difference (D); the non-linear function (f(D)) including a non-linear portion for absolute values of the difference (D) less than a threshold and a linear portion for absolute values of the difference (D) greater than the threshold, said threshold being equal to 50% or less of the maximum possible absolute value of the difference (D); the filter including non-linear processing means having: a memory for storing values of the non-linear function (f(D)) corresponding to absolute values of difference (D) less than the threshold; and switching means responsive to each absolute value of difference (D) to select for output either the unmodified difference (D) or the corresponding stored value of said non-linear function (f(D)).
Claim 3
Dependent Claim
24 words
A filter according to claim 1 in which the threshold is 10% or less of the maximum possible absolute value of the difference (D).
Claim 4
Dependent Claim
114 words
An inter-frame digital video signal filter having means for forming the inter-frame difference between each sample of an input video signal and a filter output corresponding to an earlier frame of the video signal, said filter comprising: a first circuit for passing unaltered input video signals having an inter-frame difference above a threshold value; a second circuit connected to said first circuit for processing predetermined least significant bits of input video signals having an inter-frame difference below said threshold value; and a switch connected to said first and second circuits for effecting the filter output in dependence upon the value of the inter-frame difference between said video signals being above or below said threshold.
Claim 5
Dependent Claim
114 words
An inter-frame digital video signal filter having means for forming the inter-frame difference between each sample of an input video signal and a filter output corresponding to an earlier frame of the video signal, said filter comprising: a first circuit for passing unaltered input video signals having an inter-frame difference above a threshold value; a second circuit connected to said first circuit for processing predetermined least significant bits of input video signals having an inter-frame difference below said threshold value; and a switch connected to said first and second circuits for effecting the filter output in dependence upon the value of the inter-frame difference between said video signals being above or below said threshold.
Claim 6
Dependent Claim
27 words
An inter-frame digital video signal filter as in claim 3 wherein said threshold is 50% or less of the maximum possible absolute value of said inter-frame difference.
Claim 7
Dependent Claim
27 words
An inter-frame digital video signal filter as in claim 3 wherein said threshold is 10% or less of the maximum possible absolute value of said inter-frame difference.
Claim 8
Dependent Claim
103 words
An inter-frame digital video signal filter having means for forming the inter-frame difference between each sample of an input video signal and a filter output corresponding to an earlier frame of the video signal, said filter comprising: a first circuit for conveying digital video signals; a non-linear digital signal processing circuit connected to process predetermined least significant bits of said digital video signals; and a switch connected to select as the filter output either said digital video signals of non-linearly processed versions of those signals including outputs from the non-linear processing circuit in dependence on the value of the inter-frame video signal difference.
Claim 9
Dependent Claim
103 words
An inter-frame digital video signal filter having means for forming the inter-frame difference between each sample of an input video signal and a filter output corresponding to an earlier frame of the video signal, said filter comprising: a first circuit for conveying digital video signals; a non-linear digital signal processing circuit connected to process predetermined least significant bits of said digital video signals; and a switch connected to select as the filter output either said digital video signals of non-linearly processed versions of those signals including outputs from the non-linear processing circuit in dependence on the value of the inter-frame video signal difference.
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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) | 1997-02-21 | 1997-08-23 | 1998-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-21 | 2001-08-23 | 2002-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-21 | 2005-08-23 | 2006-02-22 | $7700.00 | Window Closed / Lapsed |