2D lossless discrete cosine transform

Abstract

Since the lossless DCT is compatible with JPEG or MPEG, it is expected to play an important role in unified lossless/lossy image coding. However, there is a problem that the difference between the transform coefficients of the lossless DCT and those of the (lossy) DCT is not very small. We present the design of a two dimensional lossless DCT based on a 4-point two dimensional lossless WHT and indicate that its number of rounding off becomes smaller than that of the one dimensional lossless DCT and, as a result, the difference between its transform coefficients and those of the DCT becomes small.