Embedded and scalable image coding based on virtual SPIHT

In this paper, a wavelet-based embedded and scalable algorithm of image coding is presented. The proposed image codec is based on discrete wavelet transform (DWT) using lifting scheme. The advantages of lifting scheme are lower computational complexity, transforming signal without extension and reducing memory requirement. It decomposes DWT into two sets named predictor and updater. Based on the lifting scheme, we propose a modification of 2-D set partitioning in hierarchical trees algorithm for embedded and scalable image coding. It was first introduced in video coding. This paper uses it in gray-scale image and experimental result are provided at the same time. This modified algorithm called 2-D virtual SPIHT (2-D VSPIHT), virtually decomposes the coarsest level of the wavelet coefficients to reduce the number of two-dimensional sets in the 2-D SPIHT algorithm. The low complexity of the codec and the embedded property of the output bit-stream make the applications more convenient for instance in bit-stream transmitting in low bit-rate channel.