Showing papers by "William A. Pearlman published in 1992"
TL;DR: Comparative coding simulations with a 256*256 and 512*512 image show that DCT tree coding with postcoding is clearly superior to DCT quantization and that a variable block rate assignment gains about 3 dB over a fixed block rate Assignment.
Abstract: A tree code, asymptotically optimal for stationary Gaussian sources and squared error distortion, is applied suboptimally to encode the discrete cosine transform (DCT) of image subblocks. The variance spectrum of each block DCT is estimated and specified uniquely by a set of one-dimensional autoregressive parameters. The average pel rate for each block is allowed to vary to meet the specification of the same average distortion per block. Since the variance spectrum and rate are different for every block. so is the code tree. Comparative coding simulations with a 256*256 and 512*512 image show that DCT tree coding with postcoding is clearly superior to DCT quantization and that a variable block rate assignment gains about 3 dB over a fixed block rate assignment. >
12 citations
04 Oct 1992
TL;DR: In this article, the equivalence of linear prediction and autoregressive (AR) modeling equations is used to estimate source spectra from subbands, and a method to optimally allocate a prediction order p/sub m/ to the m/sup th/ subband such that the sum of the p/ sub m/'s from m=1 to M equals p, where p is the full-band order of prediction and M is the number of subbands.
Abstract: The results of previous work by the authors (see Conf. on Inform. Sci. and Syst., 1992) are used to prove that subband differential pulse-code modulation (DPCM) provides a coding gain over full-band DPCM for finite orders of prediction. The equivalence of linear prediction and autoregressive (AR) modeling equations are used to estimate source spectra from subbands. Subband decomposition of a source results in a whitening of the composite subband spectrum. This implies that for any stationary source, a p/sup th/-order prediction error filter (PEF) can be found that is better than the p/sup th/ PEF obtained by solving the Yule-Walker equations resulting from full-band data. The existence of such a superoptimal PEF is demonstrated, and a method to optimally allocate a prediction order p/sub m/ to the m/sup th/ subband such that the sum of the p/sub m/'s from m=1 to M equals p, where p is the full-band order of prediction and M is the number of subbands, is proposed. >
12 citations
23 Mar 1992
TL;DR: A new algorithm for multirate vector quantization is used for coding image pyramids, called alphabet and entropy-constrained pairwise-nearest-neighbor (AECPNN).
Abstract: A new algorithm for multirate vector quantization is used for coding image pyramids. The algorithm, called alphabet and entropy-constrained pairwise-nearest-neighbor (AECPNN), designs codebooks choosing subcodebooks from a large generic codebook. The algorithm is the natural extension of the ECPNN design technique with constrained alphabet. Results of coded image pyramids obtained using the present algorithm are comparable to results for the ECPNN design technique. >
3 citations
01 Nov 1992
TL;DR: A new image sequence coding scheme which employs backward motion compensation, quadtree segmentation, and pruned tree-structured vector quantization, which indicates that the proposed scheme is suitable for low rate video applications.
Abstract: In this paper, we present a new image sequence coding scheme which employs backward motion compensation, quadtree segmentation, and pruned tree-structured vector quantization. Based only on the previous reconstructed frames, the backward motion compensation technique eliminates the necessity to transmit the motion displacement vectors as side information, and thus achieves a bit rate saving. Quadtree segmentation is used to exploit the regional characteristics of the signal. To take the advantage of the fact that many large areas of the motion compensated frame difference contain only low activity, the motion compensated frame difference is decomposed into large, low activity blocks and small, high activity blocks. The large blocks are encoded by their means while the small blocks are encoded by pruned tree-structured vector quantization (PTSVQ) at different rates. PTSVQ is both a multi-rate and variable rate coding technique and has the fast codebook search property due to its tree structure. It has been shown recently that PTSVQ may outperform full search unstructured VQ in the low bit rate range. Excellent results have been obtained in the computer simulation of this new scheme. When tested on the Salesman sequence, this interframe coding technique has achieved an average peak signal-to-noise ratio of 40.55 dB at an average bit rate of 0.43 bits per pixel, which indicates that the proposed scheme is suitable for low rate video applications.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
2 citations
04 Oct 1992
Abstract: The theory of stationary processes is applied to homogeneous functional sequences Examples of time and frequency shifts and dilations are considered It is proved that the functional sequences are homogeneous (stationary) and therefore correspond to a one-dimensional stationary vector field The spectral properties of these sequences are explored It is also shown that the Gabor expansion corresponds to a two-dimensional homogeneous vector field The spectral properties of the Gabor (1946) expansion are considered, and the formula for the coefficients of the Gabor decomposition is derived >
1 citations
TL;DR: A new algorithm for multirate vector quantization is used for coding image pyramids using alphabet- and entropy-constrained pairwise-nearest-neighbor (AECPNN), which is the natural extension of the ECPNN design technique with constrained alphabet.
Abstract: A new algorithm for multirate vector quantization is used for coding image pyramids. The algorithm, called alphabet- and entropy-constrained pairwise-nearest-neighbor (AECPNN), design codebooks choosing sub-codebooks from a large generic codebook. The algorithm is the natural extension of the ECPNN design technique with constrained alphabet. Results of coded image pyramids of the present algorithm are comparable to the ECPNN design technique.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
1 citations
23 Mar 1992
TL;DR: A new algorithm for nonorthogonal decomposition is proposed and applied to Gabor decomposition of image and gives much lower reconstruction error that the method using biorthogonal functions, at a cost of a greater amount of computer time.
Abstract: A new algorithm for nonorthogonal decomposition is proposed and applied to Gabor decomposition of image. The algorithm is iterative and its advantages are discussed. Also a modified version of the algorithm is considered which increases the rate of convergence. Image simulations show that this method gives much lower reconstruction error that the method using biorthogonal functions, at a cost of a greater amount of computer time. >
04 Oct 1992
TL;DR: In this article, the wavelet scaling function that has the best combined time-frequency localization of all members of this family is found, and it is suggested that power complementary QMFs are sufficiently regular in practice.
Abstract: Most existing quadrature mirror filters (QMFs) closely match the derived analytical expression for an efficient class of QMFs. Closed-form expressions are derived for the corresponding family of orthonormal wavelet bases, giving a simple and general analytic framework for wavelet analysis of QMFs. The wavelet scaling function that has the best combined time-frequency localization of all members of this family is found. It is suggested that power complementary QMFs are sufficiently regular in practice. When the number of pyramid stages is small, perfect reconstruction schemes that satisfy regularity considerations are not likely to significantly surpass power complementary QMFs in practice. >