학술논문
Rate-constrained adaptive quantization scheme for wavelet pyramid image coding
Document Type
Conference
Source
1996 IEEE International Symposium on Circuits and Systems (ISCAS) Circuits and systems Circuits and Systems (ISCAS), 1996 IEEE International Symposium on. 2:636-639 vol.2 1996
Subject
Language
Abstract
It is well known that orthogonal wavelet transform with filters of nonlinear phase gives poor visual results in low bit rate image coding. Biorthogonal wavelet is a good substitute, which is, however essentially nonorthogonal. A greedy steepest descend algorithm is proposed to design an adaptive quantization scheme based on the actual statistics of the input image. Since the L/sup 2/ 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 technique, and comparable visual improvements.