METHOD AND APPARATUS FOR ADAPTIVE LOOP FILTER WITH CONSTRAINED FILTER COEFFICIENTS

摘要

Methods and apparatuses for processing of coded video using ALF are disclosed. Embodiments according to the present invention apply ALF with constrained data range to reconstructed video data. The ALF parameters comprise a center coefficient, one or more non-center coefficients, and an offset term. As an example, the constrained data range for the center coefficient is selected from [0.0, 2.0) and [0.5, 1.5). In another example, the constrained data range for said one or more non-center coefficient is selected from [−1.0, 1.0) and [−0.5, 0.5). The constrained data range can also be applied to the offset term. For example the range of [−2^D/N, (2^D−1)/N) can be applied to the offset term, wherein D denotes pixel bit depth and N is a power-of-two integer. Alternatively, the constrained data range for the offset term can be [−2^M,2^M), wherein M is an integer.