R-D quantisation of complex coefficients in zerotree coding
T.H. Reeves, N. G. Kingsbury · 2002
This paper describes a rate-distortion (R-D) optimal scheme for bit-plane based quantisation of complex coefficients, which is suitable for zerotree image coding systems. Most zerotree-type image codecs operate on real-valued wavelet coefficients. The dual-tree complex wavelet transform, which has several advantages over the discrete wavelet transform, produces complex coefficients. Our scheme offers progressive bit-by-bit refinement of coefficient magnitude and phase values. It ensures that refinement decisions always maximise the expected distortion decrease.