Image coding using the directional ADPCM
Chen-Chang Lien, Chang-Lin Huang, I-Chang Chang · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1994
This paper proposes a new ADPCM method for image coding called directional ADPCM which can remove more redundancy from the image signals than the conventional ADPCM. The conventional ADPCM calculates the two-dimensional prediction coefficients by using the correlation functions and solving the Yule-Walker equation. Actually, the quantities of correlation functions are replaced by the sample averages. Therefore, this solution will not be optimum. Our directional ADPCM utilizes the directional filters to obtain the energy distribution in four directions and then determines the four directional prediction coefficients. All the directional filters are designed by using the singular value decomposition (SVD) method and the two-dimensional Hilbert transform technique. In the experiments, we illustrate that the M.S.E. for the directional ADPCM is less than that of the conventional ADPCM.