EURASIP Journal on Applied Signal Processing
Embedded zerotree wavelets coding based on adaptive fuzzy clustering for image compression
Image and Vision Computing
Low-complexity and energy efficient image compression scheme for wireless sensor networks
Computer Networks: The International Journal of Computer and Telecommunications Networking
Direction-adaptive context modeling for sign coding in embedded wavelet image coder
ICIP'09 Proceedings of the 16th IEEE international conference on Image processing
BISK scheme applied to sign encoding and to magnitude refinement
ACIVS'05 Proceedings of the 7th international conference on Advanced Concepts for Intelligent Vision Systems
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Wavelet transform coefficients are defined by both a magnitude and a sign. While efficient algorithms exist for coding the transform coefficient magnitudes, current wavelet image coding algorithms are not as efficient at coding the sign of the transform coefficients. It is generally assumed that there is no compression gain to be obtained from entropy coding of the sign. Only recently have some authors begun to investigate this component of wavelet image coding. In this paper, sign coding is examined in detail in the context of an embedded wavelet image coder. In addition to using intraband wavelet coefficients in a sign coding context model, a projection technique is described that allows nonintraband wavelet coefficients to be incorporated into the context model. At the decoder, accumulated sign prediction statistics are also used to derive improved reconstruction estimates for zero-quantized coefficients. These techniques are shown to yield PSNR improvements averaging 0.3 dB, and are applicable to any genre of embedded wavelet image codec.