Methods and devices for data compression with adaptive filtering in the transform domain
AssigneeBlackBerry Limited
InventorsXiang Yu, Dake He, En-hui Yang
Life of this patent
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Abstract
Methods and devices for encoding and decoding data using adaptive transform domain filtering are described. The encoder determines a set of transform domain filter coefficients to be applied to a transform domain prediction. The filtering may, in some cases, also apply to quantized transform domain coefficients. Rate-distortion optimization may be used to determine the optimal filter coefficients on a frame-based, coding-unit-basis, or other basis.
Claims36
A method of encoding an image in an encoding device using a processor, the image including blocks of samples, the method comprising:
- spectrally transforming the blocks of samples to obtain blocks of transform coefficients;
- for each of the blocks of samples, spectrally transforming a block of prediction samples to obtain a block of prediction transform coefficients;
- generating a block of transform domain filter coefficients based upon the blocks of transform coefficients and the blocks of prediction transform coefficients;
- and
- for each of the blocks of transform coefficients, calculating filtered transform domain residuals by applying the block of transform domain filter coefficients to at least a portion of the block of prediction transform coefficients associated with that block of transform coefficients.
A method of filtering for use in a decoder for reconstructing a block of samples for an image, wherein the decoder has a predictive block of samples associated with the block of samples, the method comprising:
- spectrally transforming the predictive block of samples to obtain a transformed prediction block;
- calculating a filtered transform domain reconstruction by applying a block of filter coefficients to at least a portion of the transformed prediction block.
An encoder for calculating filter coefficients for use in encoding an image, the image including blocks of samples, the encoder comprising:
- a processor;
- a memory storing the blocks of samples;
- and
- an encoding application stored in memory and containing instructions for configuring the processor to
- spectrally transform the blocks of samples to obtain blocks of transform coefficients,
- for each of the blocks of samples, spectrally transform a block of prediction samples to obtain a block of prediction transform coefficients,
- generate a block of transform domain filter coefficients based upon the blocks of transform coefficients and the blocks of prediction transform coefficients, and
- for each of the blocks of transform coefficients, calculate filtered transform domain residuals by applying the block of transform domain filter coefficients to at least a portion of the block of prediction transform coefficients associated with that block of transform coefficients.
A decoder for filtering during reconstruction of a block of samples for an image, wherein the decoder has a predictive block of samples associated with the block of samples, the decoder comprising:
- a processor;
- a memory;
- and
- a decoding application stored in memory and containing instructions for configuring the processor to
- spectrally transform the predictive block of samples to obtain a transformed prediction block, and
- calculate a filtered transform domain reconstruction by applying a block of filter coefficients to at least a portion of the transformed prediction block.
Dependencies are inferred from the claim text.