Method and apparatus for spatially adaptive filtering for video encoding
First Claim
1. A method of spatially adaptive filtering a displaced frame difference, a DFD, the DFD is a difference between a video frame and an estimated video frame, the method comprising:
- determining, using a noise variance determiner, a noise variance of the DFD based on a predetermined signal-to-noise ratio;
determining, using a local variance determiner, a local variance of the DFD based on the noise variance and the predetermined signal-to-noise ratio;
determining, using a noise visibility determiner, a noise visibility function based on the noise variance, the local variance, and a predetermined image type;
determining, using a Gaussian kernel determiner, a Gaussian kernel for every pixel in the DFD based on the noise visibility function, a predetermined normalizing coefficient, and a predetermined base variance; and
convolving, using a convolver, the DFD with the Gaussian kernel to provide an adaptively filtered DFD.
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Abstract
The present invention provides a method (200) and an apparatus (100) for spatially adaptive filtering for video encoding. The apparatus filters a video sequence prior the encoding process. The apparatus comprises a noise variance determiner (102), a local variance determiner (104), a noise visibility function determiner (106), a Gaussian kernel determiner (108), and a convolver (110). The apparatus removes noise directly from a Displaced Frame Difference, DFD, signal. This novel approach removes noise and miscellaneous high frequency components from the DFD signal without the introduction of the filtering artifacts characteristic of current techniques. By reducing the miscellaneous high frequency components, the present invention is capable of reducing the amount of information that must be encoded by the video encoder without substantially degrading the decoded video sequence.
61 Citations
24 Claims
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1. A method of spatially adaptive filtering a displaced frame difference, a DFD, the DFD is a difference between a video frame and an estimated video frame, the method comprising:
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determining, using a noise variance determiner, a noise variance of the DFD based on a predetermined signal-to-noise ratio; determining, using a local variance determiner, a local variance of the DFD based on the noise variance and the predetermined signal-to-noise ratio; determining, using a noise visibility determiner, a noise visibility function based on the noise variance, the local variance, and a predetermined image type; determining, using a Gaussian kernel determiner, a Gaussian kernel for every pixel in the DFD based on the noise visibility function, a predetermined normalizing coefficient, and a predetermined base variance; and convolving, using a convolver, the DFD with the Gaussian kernel to provide an adaptively filtered DFD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for spatially adaptive filtering a displaced frame difference, a DFD, the DFD is a difference between a video frame and an estimated video frame, the apparatus comprising:
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a noise variance determiner, operably coupled to receive the DFD and a predetermined signal-to-noise ratio, for determining a noise variance of the DFD based on the predetermined signal-to-noise ratio; a local variance determiner, operably coupled to the noise variance determiner and operably coupled to receive the DFD, for determining a local variance of the DFD based on the noise variance and the predetermined signal-to-noise ratio; a noise visibility determiner, operably coupled to the noise variance determiner and the local variance determiner and operably coupled to receive a predetermined image type, for determining a noise visibility function based on the noise variance, the local variance, and the predetermined image type; a Gaussian kernel determiner, operably coupled to the noise visibility determiner and operably coupled to receive a predetermined base variance, for determining a Gaussian kernel for every pixel in the DFD based on the noise visibility function, a predetermined normalizing coefficient, and the predetermined base variance; and a convolver, operably coupled to the Gaussian kernel determiner and operably coupled to receive the DFD, for convolving the DFD with the Gaussian kernel to provide an adaptively filtered DFD. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification