Integer fast lapped orthogonal transform based on direct-lifting of dcts for lossless-to-lossy image coding
Integer lapped orthogonal transforms (LOTs) are vital technologies for the unification of lossless and lossy image coding, called lossless-to-lossy image coding. In this paper, we present an efficient realization of integer fast LOT (FLOT) based on direct-lifting of discrete cosine transforms (DCTs) which are type-II, III and IV. Although the conventional integer FLOTs suffer from degradation of coding performance due to much rounding error generated by cascading lifting structures, this paper presents a realization of a simpler, faster and more efficient transform with only some adders, 1-bit shifters and direct use of DCTs for lifting coefficients. As result, the proposed method is validated in lossless-to-lossy image coding.