In this paper, an enhanced version of embedded zerotree wavelet (EZW) imagecoding algorithm is proposed, referred to as EZW-SC. By exploiting a new principle that relies on a subband classification concept, the enhan...
详细信息
In this paper, an enhanced version of embedded zerotree wavelet (EZW) imagecoding algorithm is proposed, referred to as EZW-SC. By exploiting a new principle that relies on a subband classification concept, the enhanced algorithm allows the prediction of insignificant subbands at early passes, along with the use of an improved significance map. This reduces the redundancy of zerotree symbols, speeds up the coding process and improves the coding of significant coefficients. In fact, the EZW-SC algorithm scans only significant subbands and significantly improves the lossy compression performance with the conventional EZW. Moreover, new EZW-based schemes are presented to perform colour imagecoding by taking advantage of the interdependency of the colour components. Experimental results show clear superiority of the proposed algorithms over the conventional EZW as well as other related EZW schemes at various bit rates in both greyscale and colour image compression.
A multi-objective genetic algorithm for the design of biorthogonal filter banks for embedded image coding application is presented. To be effective, the filter bank would satisfy multiple requirements related to such ...
详细信息
ISBN:
(纸本)9781424456499
A multi-objective genetic algorithm for the design of biorthogonal filter banks for embedded image coding application is presented. To be effective, the filter bank would satisfy multiple requirements related to such application. Flexibility in the design is introduced by imposing Near Perfect Reconstruction (N-PR) condition instead of entire PR condition as in conventional designs. Especially for embeddedcoding purposes, the filter banks are designed to be near-orthogonal. This can only be made possible by minimizing the deviation from the orthogonality in the optimization process. The optimization problem is formulated as a constrained multi-objective problem and solved using a constrained Non-dominated sorting genetic algorithm (C-NSGA) by searching solutions that achieve the best compromise between the different objective criteria, these solutions are known as Pareto Optimal Solutions. Experiment results show that our designed filter banks lead to improved performances of imagecoding compared to those achieved by the 9/7 filter bank of JPEG2000.
Contourlet transform (CT) is a new image representation method, which can efficiently represent contours and textures in images. However, CT is a kind of overcomplete transform with a redundancy factor of 4/3. If it i...
详细信息
Contourlet transform (CT) is a new image representation method, which can efficiently represent contours and textures in images. However, CT is a kind of overcomplete transform with a redundancy factor of 4/3. If it is applied to image compression straightforwardly, the encoding bit-rate may increase to meet a given distortion. This fact baffles the coding community to develop CT-based image compression techniques with satisfactory performance. In this paper, we analyze the distribution of significant contourlet coefficients in different subbands and propose a new contourlet-based embedded image coding (CEIC) scheme on low bit-rate. The well-known wavelet-based embedded image coding (WEIC) algorithms such as EZW, SPIHT and SPECK can be easily integrated into the proposed scheme by constructing a virtual low frequency subband, modifying the coding framework of WEIC algorithms according to the structure of contourlet coefficients, and adopting a high-efficiency significant coefficient scanning scheme for CEIC scheme. The proposed CEIC scheme can provide an embedded bit-stream, which is desirable in heterogeneous networks. Our experiments demonstrate that the proposed scheme can achieve the better compression performance on low bit-rate. Furthermore, thanks to the contourlet adopted in the proposed scheme, more contours and textures in the coded images are preserved to ensure the superior subjective quality.
Zerotree based imagecoding techniques use a standard multiresolution representation of images obtained by a repeated 2-band Discrete Wavelet Transform of images. A lot more modularity and flexibility can be achieved ...
详细信息
ISBN:
(纸本)9781424471379
Zerotree based imagecoding techniques use a standard multiresolution representation of images obtained by a repeated 2-band Discrete Wavelet Transform of images. A lot more modularity and flexibility can be achieved by use of hybrid transforms of images. In this paper we explore the advantages, issues and tree structures for hybrid transforms of images. A few new algorithms for embedded image coding using hybrid transforms have been drafted. The results, interpretations and scenarios where hybrid transforms might find better application than existing methods have been discussed.
This paper presents an embedded wavelet packet imagecoding algorithm which is based on context classification and quadtree ordering (CCAQO). To match up well with the quadtree-based embedded coder, a new cost functio...
详细信息
ISBN:
(纸本)0819459763
This paper presents an embedded wavelet packet imagecoding algorithm which is based on context classification and quadtree ordering (CCAQO). To match up well with the quadtree-based embedded coder, a new cost function for the best basis selection is adopted in discrete wavelet packet transform (DWPT). In addition, combined with the structure of the best wavelet packet basis, a complete quadtree representation of wavelet packet coefficients is established to explore the ordering procedure of embedded image coding. Since subband correlation is mainly captured by significance coding, our focus is on significance coding. The significance probability of wavelet coefficient is estimated by convoluting a 9 x 9 FIR filter matrix kernel with the significance states of neighboring coefficients, and then a context classifier based on Lloyd-Max algorithm is used to categorize the wavelet coefficients with the same or similar significance probability into several contexts. The significance state of wavelet coefficient with respect to a given threshold is encoded using adaptive arithmetic coder based on the classified context. Due to the optimal context classifier and the flexible quadtree representation ability of wavelet packet coefficients, the proposed CCAQO embeddedimage coder offers improvement in subjective and objective quality for texture-rich images and experimental results show that it offers coding performance superior to or comparable to the state-of-the-art image coders.
In this paper, an object-based embedded image coding algorithm based on context classification and quadtree ordering in wavelet packet domain (OB-CCAQO) is proposed. To match up well with the quadtree-based embedded c...
详细信息
In this paper, an object-based embedded image coding algorithm based on context classification and quadtree ordering in wavelet packet domain (OB-CCAQO) is proposed. To match up well with the quadtree-based embedded coder, a new cost function for the best basis selection is adopted in SA-DWPT (shape adaptive discrete wavelet packet transform). The significance probability of wavelet coefficient is estimated by convoluting a 9 x 9 FIR filter matrix kernel with the significance states of neighboring coefficients, and then a context classifier based on Lloyd-Max algorithm is used to categorize the wavelet coefficients with the same or similar significance probability into several contexts. The significance state of wavelet coefficient with respect to a given threshold is encoded using adaptive arithmetic coder based on the classified context. In addition, combined with the structure of the best wavelet packet basis, a complete quadtree representation of wavelet packet coefficients is established to explore the ordering procedure of embedded object-based imagecoding. Experimental results show that the proposed object-based embeddedimage coder offers coding performance superior to the popular object-based coders and is also comparable to or better than the state-of-art embeddedimage coder when applied in the framed-based imagecoding. (c) 2005 Elsevier B.V. All rights reserved.
The explosive growth of the network, end-host performances and their heterogeneities have resulted ever changing advancement and complexity of distributed computing environments. The users in such environment have not...
详细信息
ISBN:
(纸本)9781424403219
The explosive growth of the network, end-host performances and their heterogeneities have resulted ever changing advancement and complexity of distributed computing environments. The users in such environment have not been provided a satisfactory service when they access the required objects. In this paper we focus on adaptive WWW content delivery, which is the most ubiquitous and popular way of information dissemination, primarily in the form of web-server, web-browser interaction. In these applications, we address controlling the Quality of delivery and time of access tradeoff of the WWW contents. We implement this as a httpa protocol, which is an adaptive transcoding methodology for embeddedimages in web pages, according to available channel bandwidth and other accessibility parameters at the client side. Compared to the conventional form of server side adaptive content delivery proposed in the literature, we propose a hybrid form of adaptation: client side progressive parameter estimation and server side transcoding of images, which is more scalable and flexible. Through experimental results we verify the performance of httpa.
This paper describes a method that uses the well known S + P and TT transforms to encode a specially important part of an image, a region of interest (ROI) in a lossless mode. Other parts of the image (the background)...
详细信息
This paper describes a method that uses the well known S + P and TT transforms to encode a specially important part of an image, a region of interest (ROI) in a lossless mode. Other parts of the image (the background) are given lower quality levels allowing higher compression. The ROI coding is done in the framework of an embedded wavelet-based image compression algorithm. Entire coding, regional and full image, is done in a naturally progressive manner all the way up to lossless. (C) 1999 Elsevier Science B.V. All rights reserved.
We present a modified version of an embedded wavelet coding scheme, first suggested by Shapiro (see IEEE Transactions on Signal Processing, vol.41, no. 12, p.3445-3462, 1993), that improves the performance of the orig...
详细信息
ISBN:
(纸本)0780331222
We present a modified version of an embedded wavelet coding scheme, first suggested by Shapiro (see IEEE Transactions on Signal Processing, vol.41, no. 12, p.3445-3462, 1993), that improves the performance of the original algorithm in a visual subjective distortion sense. We preserve the features of the original Shapiro's embedded coder. It is possible to choose a fixed target bit rate, as the information needed to represent an image coded at some rate always contains the needed information for the same image coded at lower rates. Therefore, the decoder can cease decoding the bit stream at any point, simulating an image coded at a lower rate corresponding to the truncated bit stream. We also introduce some perceptive improvements by adopting different (more regular) filters with respect to the original QMF pyramid filters proposed by Simoncelli, Hingorani et al. (1987) and used by Shapiro. These filters are synthesized using a "wavelet approach" instead of a "subband approach", and this leads to a better control on their regularity properties, jointly with better perceptual performance.
We study the performance difference of the discrete cosine transform (DCT) and the wavelet transform for both image and video coding, while comparing the other aspects of the coding system on an equal footing. Based o...
详细信息
ISBN:
(纸本)0819425869
We study the performance difference of the discrete cosine transform (DCT) and the wavelet transform for both image and video coding, while comparing the other aspects of the coding system on an equal footing. Based on the state-of-the-art coding techniques, we point out that, for still images, the performance gap between DCT and wavelet based coding is within one dB in PSNR at the same bitrate. This is in contrast to the common perception that the wavelet transform is much superior to the DCT for image compression. For video coding, the advantage of using the wavelet transform over the DCT is even less pronounced.
暂无评论