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US5387946A
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Method and apparatus for measuring noise in video signals
Assignee: Vantiva SA
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Filing: 1993-03-22
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Granted: 1995-02-07
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Expires: 2013-03-22
Abstract
Abstract A method of measuring noise in a television signal includes the steps of storing an estimated noise value N. The activity values A of blocks of pixels are measured and periodically compared with the estimated noise value N. A first correction value C v1 is added to the estimated value when A>N and a second correction value C v2 is subtracted from the noise value N when A≦N. The second correction value C v2 is substantially greater than the first correction value C v1 .
Inventors
- 👤 Michael Knee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:30
CPC Classifications
H; H04; H04N; H04N17/00; G; G01; G01R; G01R29/00; G01R29/26
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
120 words
A method of applying a low noise signal to a television display by measuring noise in a television signal comprising the steps of: storing an estimated noise value N; measuring the activity values A of blocks of pixels; periodically comparing said activity value A with said estimated noise value N; adding a first correction value C v1 to said estimated value when A>N and subtracting a second correction value C v2 when A≦N, said second correction value C v2 being in the order of 10 to 100 times greater than said first correction value C v1 ; and determining said activity values A by subtracting the value of each pixel from the mean value of all pixels within the block.
Claim 2
Independent Claim
120 words
A method of applying a low noise signal to a television display by measuring noise in a television signal comprising the steps of: storing an estimated noise value N; measuring the activity values A of blocks of pixels; periodically comparing said activity value A with said estimated noise value N; adding a first correction value C v1 to said estimated value when A>N and subtracting a second correction value C v2 when A≦N, said second correction value C v2 being in the order of 10 to 100 times greater than said first correction value C v1 ; and determining said activity values A by subtracting the value of each pixel from the mean value of all pixels within the block.
Claim 3
Dependent Claim
28 words
The method of claim 1 wherein said activity values are determined by filtering said television signal and taking the difference between the filtered signal and a predicted value.
Claim 4
Dependent Claim
23 words
The method of claim 1 wherein said activity values are determined by filtering said television signal with a one-dimensional analog high pass filter.
Claim 5
Dependent Claim
23 words
The method of claim 1 wherein said activity values are determined by summing the absolute values of the differences obtained by said subtraction.
Claim 6
Dependent Claim
34 words
The method of claim 1 wherein said activity values A are determined at a first period and said noise values N are accumulated and change at a second period less than said first period.
Claim 7
Dependent Claim
39 words
The method of claim 5 further including the step of taking the logarithm of said activity value A before comparing said activity value to said noise value N, and adding a fixed correction value to said noise value N.
Claim 8
Dependent Claim
164 words
Apparatus for measuring noise in a video signal comprising: a pseudorandom noise generator; means responsive to said noise generator for receiving blocks of data representative of activity in said video signal at intervals determined by said noise generator; means for calculating the mean values of for each block of data; means for subtracting said mean values from values of the current block to establish difference values; means for calculating absolute values of said difference values; means for summing said absolute values for each block and providing activity values for each block; means for storing estimated noise values; means for comparing said activity values with said noise values; and means responsive to said means for comparing for adding a first correction value to said estimated noise value when said activity value exceeds said noise value and for subtracting a second correction value from said value when said noise value exceeds said activity value, said second correction value being substantially greater than said first correction value.
Claim 9
Dependent Claim
164 words
Apparatus for measuring noise in a video signal comprising: a pseudorandom noise generator; means responsive to said noise generator for receiving blocks of data representative of activity in said video signal at intervals determined by said noise generator; means for calculating the mean values of for each block of data; means for subtracting said mean values from values of the current block to establish difference values; means for calculating absolute values of said difference values; means for summing said absolute values for each block and providing activity values for each block; means for storing estimated noise values; means for comparing said activity values with said noise values; and means responsive to said means for comparing for adding a first correction value to said estimated noise value when said activity value exceeds said noise value and for subtracting a second correction value from said value when said noise value exceeds said activity value, said second correction value being substantially greater than said first correction value.
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