Document Image Compression by Nonlinear Binary Subband Decomposition and Concatenated Arithmetic Coding
Jeong-Kwon Kim, Kyeong Ho Yang, Choong Woong Lee · IEEE Transactions on Circuits and Systems for Video Technology · 2000
This paper proposes a new subband coding approach to compression of document images, which is based on nonlinear binary subband decomposition followed by the concatenated arith- metic coding. We choose to use the sampling-exclusive OR (XOR) subband decomposition to exploit its beneficial characteristics to conserve the alphabet size of symbols and 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 high-pass subband coefficients at the same location are concatenated and then encoded by an octave arithmetic coder. The proposed concatenated arithmetic coding is performed based on a conditioning context properly selected by exploiting a nature of the sampling-XOR subband filter bank as well as taking the ad- vantage of noncausal prediction capability of subband coding. We also introduce a unicolor map to efficiently represent large uniform regions frequently appearing in document images. Simulation re- sults show that each of the functional blocks proposed in the paper performs very well, and consequently, the proposed subband coder provides good compression of document images.