Image/video coding based on evolutive unidirectional transforms

This paper proposes new type of coding scheme, which uses unidirectional transform, unlike conventional image/video coding schemes such as JPEG, MPEG-2, H.265/HEVC, whose encoder uses forward and inverse transforms and decoder uses inverse transform. In our proposal, even encoder (and decoder as well) uses unidirectional (in conventional manner, inverse) transform. Because of this preferable property, the encoder can arbitrarily design nonlinear, content-specific transforms, regardless of obtaining its inverse transform, to optimize coding performance. In our preliminary experiment, BD-Rate gain of 1.18 % was observed against HEVC reference software HM12.