A novel stereo image coder based on quad-tree analysis and morphological representation of wavelet coefficients

In this paper, we propose a novel stereoscopic image coder, which consists of a coding unit based on the morphological representation of the wavelet transform coefficients and a disparity compensation unit based on the quad-tree analysis and the disparity compensation between the images of a stereo pair. The coding unit employs a Discrete Wavelet Transform followed by a morphological coder, which exploits the intra-band and inter-band statistical properties of the wavelet coefficients in order to create partitions between significant and insignificant coefficients that reduce the entropy. The disparity compensation procedure employs the block-matching algorithm, which is implemented on blocks of variable size that appear after a quad-tree decomposition of the target image using a simplified rate-distortion criterion. Initially, the target image is segmented into blocks of homogeneous intensity by its quad-tree decomposition with an intensity difference threshold. Then, quad-tree decomposition with a simplified rate-distortion criterion follows, which permits the splitting of an already existing block to four children blocks only if there is a rate-distortion benefit. The extensive experimental evaluation, shows that the proposed coder demonstrates very good performance as far as PSNR measures and visual quality are concerned and low complexity with respect to others state of the art coders.