Decoder and a method therof for improving decoding of image and video signals

摘要

A solution according to one or more embodiments of the present invention is to reconstruct image blocks where only the frequency coefficient that is most sensitive to changes of an average value of the residual image block, typically the lowest frequency coefficient, is present with a flat residual image. The other image blocks are reconstructed by applying an inverse spatial 2D transform. Hence, the other image blocks comprise image blocks with multiple coefficients and image blocks with a single coefficient and wherein the single coefficient is not the coefficient determining that is most sensitive to changes of an average value of the residual image block.