Noise reduction filter circuitry and method
First Claim
1. Filter circuitry for reducing noise in an input stream of image signals having luminance and chrominance components, comprising:
- spatial filter circuitry configured, for a current image signal of the input stream, to generate a spatially filtered internal signal from at least the luminance component of the current image signal;
comparison circuitry configured to compare the current image signal with temporal data derived from multiple image signals of said input stream, and to generate a control signal dependent on said comparison; and
combining circuitry configured to combine, in a ratio determined by said control signal, the spatially filtered internal signal with at least a luminance component derived from said temporal data, in order to generate at least the luminance component of a current output image signal forming a noise reduced version of the current image signal.
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Abstract
The present invention provides filter circuitry for reducing noise in an input stream of image signals having luminance and chrominance components. Spatial filter circuitry is provided which, for a current image signal of the input stream, generates a spatially filtered internal signal from at least the luminance component of the current image signal. Comparison circuitry is configured to compare the current image signal with temporal data derived from multiple image signals of the input stream, and to generate a control signal dependent on the comparison. Combining circuitry is then used to combine, in a ratio determined by the control signal, the spatially filtered internal signal with at least a luminance component derived from the temporal data, in order to generate at least the luminance component of a current output image signal that forms a noise reduced version of the current image signal. Such a form of filter circuitry has been found to provide a filtered stream of image signals with significant noise suppression, and is particularly well suited to providing a filtered stream of image signals for input to video encoding circuitry, enabling significant improvements in the efficiency of the encoding circuitry by virtue of the manner in which the noise is suppressed.
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Citations
20 Claims
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1. Filter circuitry for reducing noise in an input stream of image signals having luminance and chrominance components, comprising:
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spatial filter circuitry configured, for a current image signal of the input stream, to generate a spatially filtered internal signal from at least the luminance component of the current image signal; comparison circuitry configured to compare the current image signal with temporal data derived from multiple image signals of said input stream, and to generate a control signal dependent on said comparison; and combining circuitry configured to combine, in a ratio determined by said control signal, the spatially filtered internal signal with at least a luminance component derived from said temporal data, in order to generate at least the luminance component of a current output image signal forming a noise reduced version of the current image signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of reducing noise in an input stream of image signals having luminance and chrominance components, comprising the steps of:
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employing spatial filter circuitry, for a current image signal of the input stream, to generate a spatially filtered internal signal from at least the luminance component of the current image signal; comparing the current image signal with temporal data derived from multiple image signals of said input stream, and generating a control signal dependent on said comparison; and combining, in a ratio determined by said control signal, the spatially filtered internal signal with at least a luminance component derived from said temporal data, in order to generate at least the luminance component of a current output image signal forming a noise reduced version of the current image signal.
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20. Filter circuitry for reducing noise in an input stream of image signals having luminance and chrominance components, comprising:
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spatial filter means for generating, for a current image signal of the input stream, a spatially filtered internal signal from at least the luminance component of the current image signal; comparison means for comparing the current image signal with temporal data derived from multiple image signals of said input stream, and for generating a control signal dependent on said comparison; and combining means for combining, in a ratio determined by said control signal, the spatially filtered internal signal with at least a luminance component derived from said temporal data, in order to generate at least the luminance component of a current output image signal forming a noise reduced version of the current image signal.
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Specification