Optimal filter design for low entropy pyramid coding

In a previous published work, the lowest entropy for lossless encoding of the standard image "Lena" was found to be 5.311 bpp (D. Houlding and J. Vaisey, IEEE Trans. Image Proc., vol. 4, no. 8, pp. 1150-1153, 1995). In this paper, we design an optimal filter using the hybrid method approach that will give lower entropy of 4.198 bpp for the same image and with saving in computation complexity and encoded sample of 32% and 20%, respectively compared to that of the earlier work.