Reversible 2-dimensional pre-/post-filtering for lapped biorthogonal transform
AssigneeMicrosoft Corporation
InventorsSridhar Srinivasan, Chengjie Tu
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Abstract
An efficient lapped transform useable in digital media codecs is realized using a reversible 2-dimensional overlap operator for pre/post filtering that is applied on a staggered grid relative to a core transform. The 2-dimensional lapped operator is based on a separably applied 1-dimensional reversible lapped operator, which is re-arranged as a sequence of elementary transforms in interleaved stages on subsets of points of the respective block and further implemented in lifting steps for computational efficiency. The interleaved stages include applying rotation and scaling stages between initial and final stages involving a normalized 2×2 Hadamard transform
Claims20
A method of processing 2-dimensional digital media data as a lapped transform, the method comprising:
- applying a reversible 2-dimensional overlap operator to a first set of 2-dimensional blocks of the digital media data on a staggered grid basis;
- and
- applying a reversible 2-dimensional block transform to a second set of 2-dimensional blocks of the digital media data on an aligned grid basis, the staggered grid basis being spatially staggered relative to the aligned grid basis, the applying the reversible 2-dimensional overlap operator and the reversible 2-dimensional block transform together effecting the lapped transform of the 2-dimensional digital media data.
A 2-dimensional digital media processor, comprising:
- a data storage buffer for storing 2-dimensional digital media data to be processed using a lapped transform;
- a processor programmed to:
- apply a reversible 2-dimensional overlap operator to a first set of 2-dimensional blocks of the digital media data on a staggered grid basis;
- and
- apply a reversible 2-dimensional block transform to a second set of 2-dimensional blocks of the digital media data on an aligned grid basis, the staggered grid basis being spatially staggered relative to the aligned grid basis, and application of the reversible 2-dimensional overlap operator and the reversible 2-dimensional block transform together effect the lapped transform of the 2-dimensional digital media data.
Dependencies are inferred from the claim text.