Reversible 2-dimensional pre-/post-filtering for lapped biorthogonal transform

摘要

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 2x2 Hadamard transform