A Rate-distortion Based Quantization Level Adjustment Algorithm in Block-based Video Compression.
ABSTRACT In this paper, a rate-distortion based quantization level adjustment (RDQLA) algorithm is presented. Based on the rate-distortion
criterion, the quantization level adjustment algorithm effectively improves coding efficiency by adaptively optimizing quantization
levels of the signals near the boundaries of quantization cells and adjusting quantization levels per block. In addition,
it has no overhead and is fully compatible with the existing compression standards. The proposed algorithm can be applied
in any block based image and video coding method. In particular, the algorithm has been verified on the platform of H.264.
Experimental results show that the proposed algorithm improves objective and subjective performances substantially. It is
shown that the proposed algorithm has a gain of several dB comparing with the newest H.264 standard for high bit rates.
Conference Proceeding: Optimal quantizer step sizes for transform coders[show abstract] [hide abstract]
ABSTRACT: As evidenced by the theoretical modeling and simulation presented, the optimal quantizer solution for run-length and Huffman coding is quite addressable for the Laplacian case. The step sizes may be calculated in advance for images that share common statistics. Furthermore, the model can also be used for other uses such as bit-management for rate control and lower bound estimation for compressed file sizes; it is also the first step in the general solution to the transform coder quantization problemAcoustics, Speech, and Signal Processing, 1991. ICASSP-91., 1991 International Conference on; 05/1991 · 4.63 Impact Factor
Conference Proceeding: Wavelet image coding with adaptive dead-zone selection: application to JPEG2000[show abstract] [hide abstract]
ABSTRACT: Several quantization options are provided within JPEG2000. Part I of the standard includes only uniform scalar deadzone quantization. The dead-zone is equal to two times the other quantization bin sizes. Part II includes both uniform scalar dead-zone and wavelet trellis coded quantization (WTCQ) which combines the characteristics of a scalar and vector quantization. In this work we develop an adaptive quantization technique for JPEG2000 coding scheme. Using a simple statistical model for the subband or transform coefficients, we present a procedure to select the adaptive dead-zone width. After the zeroing process, the wavelet coefficients are then quantized using WTCQ strategy. Experimental results show that the rate-distortion performance of the proposed compression algorithm compares favorably with the one provided by JPEG2000 standard.Image Processing. 2002. Proceedings. 2002 International Conference on; 02/2002
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ABSTRACT: Optimal scalar quantization subject to an entropy constraint is studied for a wide class of difference distortion measures including rth-power distortions with r>0. It is proved that if the source is uniformly distributed over an interval, then for any entropy constraint R (in nats), an optimal quantizer has N=[e<sup>R</sup>] interval cells such that N-1 cells have equal length d and one cell has length c⩽d. The cell lengths are uniquely determined by the requirement that the entropy constraint is satisfied with equality. Based on this result, a parametric representation of the minimum achievable distortion D<sub>h </sub>(R) as a function of the entropy constraint R is obtained for a uniform source. The D<sub>h</sub>(R) curve turns out to be nonconvex in general. Moreover, for the squared-error distortion it is shown that D <sub>h</sub>(R) is a piecewise-concave function, and that a scalar quantizer achieving the lower convex hull of D<sub>h</sub>(R) exists only at rates R=log N, where N is a positive integerIEEE Transactions on Information Theory 12/2000; · 2.62 Impact Factor