Abstract
This paper proposes a new subband coding approach to compression of document images, which is based on nonlinear binary subband decomposition followed by concatenated arithmetic coding. We choose to use the sampling-XOR(Exclusive OR)subband decomposition to exploit its beneficial characteristics to conserve the alphabet size of symbols and to provide a small region of support while providing the perfect reconstruction property. We propose a concatenated arithmetic coding scheme to alleviate the degradation of predictability caused by subband decomposition, where three highpass subband coefficients at the same location are concatenated and then encoded by an octave arithmetic coder. A appropriate context and a new symbol unicolor map, improve the performance of compression more. Simulation results show that each of the functional blocks proposed in the paper performs very well and consequently the proposed subband coder provides very good compression of document images.
