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US 6,144,800 AGranted
Noise reduction in correlated digital signals
AssigneeSony Corporation
InventorHiroshi Kobayashi
Life of this patent
Estimating the term…
Abstract
A noise component is extracted from an input correlated digital signal, such as a digital video signal in which image information is substantially the same from one frame to the next. The extracted noise is multiplied by a feedback coefficient that varies non-linearly with respect to the value of the extracted noise, this feedback coefficient being switched on a random or pseudo-random basis.
Claims22
A method of reducing a noise component in a correlated digital signal comprising the steps of:
- detecting a non-correlated component in said digital signal to produce a magnitude value representative thereof;
- adjusting the gain of said detected component by a non-linear coefficient K, where K exhibits a value .ltoreq.1 and said value of K is a function of the magnitude value of said detected component;
- switching between different stored tables of K, wherein the values of K in one of said stored tables differ from the values of K in another of said stored tables by generating a plural-bit M series signal, generating a plural-bit control signal of user selected valued, summing said M series signal and said control signal, and selecting a stored table of K as a function of the summed signals;
- and
- subtracting the gain-adjusted detected component from said digital signal to produce a noise-reduced digital signal.
2 more elements
Apparatus for reducing a noise component in a correlated digital signal comprising:
- detecting means for detecting a non-correlated component in said digital signal to produce a magnitude value representative thereof;
- non-linear means for adjusting the gain of said detected component by a nonlinear coefficient K, where K exhibits a value 0.ltoreq.K.ltoreq.1 and said value of K is a function of the magnitude value of said detected component, said non-linear means including plural stored tables of K, wherein the values of K in one of said stored tables differ from the values of K in another of said stored tables;
- means for switching between different ones of said stored tables of K to select a table from which said coefficient K is selected, including means for generating a plural-bit M series signal, means for generating a plural-bit control signal of user selected valued, means for summing said M series signal and said control signal, and means for selecting a stored table of K as a function of the summed signals;
- and
- subtractor means for subtracting the gain-adjusted component from said digital signal to produce a noise-reduced digital signal.
2 more elements
Dependencies are inferred from the claim text.