Title :
Efficient sign coding and estimation of zero-quantized coefficients in embedded wavelet image codecs
Author :
Deever, Aaron T. ; Hemami, Sheila S.
Author_Institution :
Eastman Kodak Co., Rochester, NY, USA
fDate :
4/1/2003 12:00:00 AM
Abstract :
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.
Keywords :
codecs; data compression; decoding; image coding; image reconstruction; transform coding; wavelet transforms; PSNR; compression gain; context model; decoder; efficient coding algorithms; efficient estimation; efficient sign coding; embedded wavelet image codecs; embedded wavelet image coder; entropy coding; intraband wavelet coefficients; nonintraband wavelet coefficients; projection technique; reconstruction estimates; sign prediction statistics; transform coefficient magnitudes; wavelet image coding algorithms; wavelet transform coefficients; zero-quantized coefficients; Codecs; Context modeling; Decoding; Entropy coding; Image coding; Image reconstruction; PSNR; Statistics; Wavelet coefficients; Wavelet transforms;
Journal_Title :
Image Processing, IEEE Transactions on
DOI :
10.1109/TIP.2003.811499