Title :
A novel entropy-constrained adaptive quantization scheme for wavelet pyramid image coding
Author :
Ni, J.Q. ; Ho, K.L. ; Tse, K.W.
Author_Institution :
Dept. of Electr. & Electron. Eng., Univ. of Hong Kong, Hong Kong
Abstract :
The orthogonal wavelet transform with filters of nonlinear phase gives poor visual results in low bit rate image coding. The biorthogonal wavelet is a good substitute, which is, however essentially nonorthogonal. A greedy steepest descent algorithm is proposed to design an adaptive quantization scheme based on the actual statistics of the input image. Since the L2 norm of the quantization error is not preserved through the nonorthogonal transform, a quantization error estimation formula considering the characteristic value of the reconstruction filters is derived to incorporate the adaptive quantization scheme. Computer simulation results demonstrate significant SNR gains over standard coding techniques, and comparable visual improvements
Keywords :
adaptive codes; digital filters; entropy codes; estimation theory; image coding; image reconstruction; transform coding; wavelet transforms; L2 norm; SNR; biorthogonal wavelet; entropy-constrained adaptive quantization scheme; greedy steepest descent algorithm; low bit rate image coding; nonorthogonal transform; quantization error estimation formula; reconstruction filters; statistics; wavelet pyramid image coding; Adaptive filters; Algorithm design and analysis; Bit rate; Computer simulation; Estimation error; Image coding; Image reconstruction; Quantization; Statistics; Wavelet transforms;
Conference_Titel :
Communication Technology Proceedings, 1996. ICCT'96., 1996 International Conference on
Conference_Location :
Beijing
Print_ISBN :
0-7803-2916-3
DOI :
10.1109/ICCT.1996.544971