In this work, we extend arithmetic coding.and present a dataencryption scheme that achieves datacompression and data security at the same time. This scheme is based on a chaotic dynamics, which makes use of the fact...
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ISBN:
(纸本)0819441899
In this work, we extend arithmetic coding.and present a dataencryption scheme that achieves datacompression and data security at the same time. This scheme is based on a chaotic dynamics, which makes use of the fact that the decoding.process of arithmetic coding.scheme can be considered as the repetition of Bernoulli shift map. dataencryption is achieved by controlling the piecewise linear maps by a secret key in three kinds of approach: (i) perturbation method, (ii) switching method, and (iii) source extension method. Experimental results show that the obtained arithmetic codes for a message are randomly distributed on the mapping domain [0,1) by using different keys without seriously deteriorating the compression ratio, and the transition of the orbits in the domain [0,1) is similar to the chaotic dynamics.
Fractal imagecoding.represented the static imagedata with parameters of dynamic iterating processes and was able to break through the theoretical limitation of entropy coding. It had attracted wide interests of many...
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ISBN:
(纸本)0819442798
Fractal imagecoding.represented the static imagedata with parameters of dynamic iterating processes and was able to break through the theoretical limitation of entropy coding. It had attracted wide interests of many researchers. In this paper, we applied fractal coding.to multispectral remote sensing imagecompression and made some improvements to the quad-tree-partition based fractal coding.method according to the properties of multispectral remote sensing images. For the improvements, the same partition scheme was assigned to images in different bands. In addition, the size of the searching space of affine transform was diminished to further improve the compression ratio and also the coding.speed by making use of the spectral correlation. Experimental results showed that the proposed method could improve the performances of the quad-tree-partition based fractal coding.algorithm obviously. Satisfactory results were obtained. Keywords: multispectral remote sensing image, imagecompression, fast fractal coding. quad-tree partition, sharing quad-tree partition, supervised matching, near-lossless compression, lossless compression, JPEG, DPCM.
The first part of the article gives a brief examination of the state of art in terms of methodologies, hardware available and algorithms used in space applications. Particular emphasis is given to the lossless algorit...
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ISBN:
(纸本)0819441899
The first part of the article gives a brief examination of the state of art in terms of methodologies, hardware available and algorithms used in space applications. Particular emphasis is given to the lossless algorithms used and their characterization. In the second part a more detailed analysis, in terms of data entropy, is presented. At the end the preliminary results in the determination of compressibility of the file will be presented.
Huge amounts of data are generated thanks to the continuous improvement of remote sensing systems. Archiving this tremendous volume of data is a real challenge which requires lossless compression techniques. Furthermo...
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ISBN:
(纸本)0819441899
Huge amounts of data are generated thanks to the continuous improvement of remote sensing systems. Archiving this tremendous volume of data is a real challenge which requires lossless compression techniques. Furthermore, progressive coding.constitutes a desirable feature for telebrowsing. To this purpose, a compact and pyramidal representation of the input image has to be generated. Separable multiresolution decompositions have already been proposed for multicomponent images allowing each band to be decomposed separately. It seems however more appropriate to exploit also the spectral correlations. For hyperspectral images, the solution is to apply a 3D decomposition along the spatial and the spectral dimensions. This approach is not appropriate for multispectral images because of the reduced number of spectral bands. In recent works, we have proposed a nonlinear subband decomposition scheme with perfect reconstruction which exploits efficiently both the spatial and the spectral redundancies contained in multispectral images. In this paper, the problem of coding.the coefficients of the resulting subband decomposition is addressed. More precisely, we propose an extension to the vector case of Shapiro's embedded zerotrees of wavelet coefficients (V-EZW) with achieves further saving in the bit stream. Simulations carried out on SPOT images indicate the outperformances of the global compression package we propose.
In this paper, we introduce new approaches to remove the boundary artifacts of tile reconstructed images caused by transforms using overlapping non-symmetrical cosine-IV bases in imagecompression. In tile field of im...
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ISBN:
(纸本)0819441899
In this paper, we introduce new approaches to remove the boundary artifacts of tile reconstructed images caused by transforms using overlapping non-symmetrical cosine-IV bases in imagecompression. In tile field of imagecompression, overlapping cosine-IV bases call reduce the block artifacts that occur in JPEG. These basis functions are longer than the block size and they decay to zero at their boundaries. These cosine-IV bases have, however. one important disadvantage. They are not symmetric. Therefore the symmetric periodic extension cannot be applied to sequences of finite length. Artifacts appear at low bit rates in imagecompression if only the periodic extension is used. With the aid of the folding operator, we derive the symmetric periodic extension for cosine-IV bases. Weighting functions are introduced. We point out that no artifacts appear at image boundaries if our weighting functions are used. In the second part of our paper, we present a new approach which avoids the extension of the image. There is no overlap at the image boundaries. The efficiency of our proposed methods in imagecompression is studied. We show, that there are no artifacts at image boundaries in the reconstructed image if our methods are used.
This work focuses on estimating the information conveyed to a user by either multispectral or hyperspectral imagedata. The goal is establishing the extent to which an increase in spectral resolution can increase the ...
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ISBN:
(纸本)0819441899
This work focuses on estimating the information conveyed to a user by either multispectral or hyperspectral imagedata. The goal is establishing the extent to which an increase in spectral resolution can increase the amount of usable information. As a matter of fact, a tradeoff exists between spatial and spectral resolution, due to physical constraints of sensors imaging with a prefixed SNR. Lossless datacompression is exploited to measure the useful information content. In fact, the bit rate achieved by the reversible compression process takes into account both the contribution of the "observation" noise i.e., information regarded as statistical uncertainty, the relevance of which is null to a user, and the intrinsic information of hypothetically noise-free data. An entropic model of the image source is defined and, once the standard deviation of the noise, assumed to be Gaussian and possibly nonwhite, has been preliminarily estimated, such a model is inverted to yield an estimate of the information content of the noise-free source from the code rate. Results both of noise and of information assessment are reported and discussed on synthetic noisy images, on Landsat TM data, and on AVIRIS data.
Near-lossless compression, i.e., yielding strictly bounded reconstruction error, is extended to preserve the radiometric resolution of data produced by coherent imaging systems, like Synthetic Aperture Radar (SAR). Fi...
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ISBN:
(纸本)0819441899
Near-lossless compression, i.e., yielding strictly bounded reconstruction error, is extended to preserve the radiometric resolution of data produced by coherent imaging systems, like Synthetic Aperture Radar (SAR). First a causal spatial DPCM based on a fuzzy matching-pursuit (FMP) prediction is adjusted to yield a relative-error bounded compression by applying a logarithmic quantization to the ratio of original to predicted pixel values. Then, a noncausal DPCM is achieved based on the Rational Laplacian Pyramid (RLP), recently introduced by the authors for despeckling. The baseband icon of the RLP is (causally) DPCM encoded, the intermediate layers are uniformly quantized, and the bottom layer is logarithmically quantized. As a consequence, the relative error, i.e., pixel ratio of original to decoded image, can be strictly bounded around unity by the quantization step size of the bottom layer of the RLP. Experimental results reported on true SAR data from NASA/JPL AIRSAR show that virtually lossless images can be achieved with compression ratios larger than three.
Time-domain and frequency-domain spreading algorithms are presented in this paper. However, detection algorithm does not rely on correlation method, but based on patchwork method. Time-domain algorithm can survive tra...
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ISBN:
(纸本)0819441899
Time-domain and frequency-domain spreading algorithms are presented in this paper. However, detection algorithm does not rely on correlation method, but based on patchwork method. Time-domain algorithm can survive translation and clipping attacks. Frequency-domain algorithm is robust against compression attack. Embedding and detection functions are presented. Simulation results show the effectiveness of the algorithms.
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