Multiresolution representation of images provides a flexible tool for information rate control in video coding for transmission and storage purposes. In this work, the different spatial resolution capability of the hu...
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ISBN:
(纸本)0819422134
Multiresolution representation of images provides a flexible tool for information rate control in video coding for transmission and storage purposes. In this work, the different spatial resolution capability of the human visual system withthe angular displacement from the foveal line of sight is exploited. When the region of interest of the observer can be determined with sufficient reliability, the resolution is regulated according to the expected receptive resolution. this leads to significant bitrate savings in some typical applications.
the performance of wavelet compression algorithms is generally judged solely as a function of the compression ratio and the vidual artifacts which are perceivable in the reconstructed image. the problem then becomes o...
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ISBN:
(纸本)0819422134
the performance of wavelet compression algorithms is generally judged solely as a function of the compression ratio and the vidual artifacts which are perceivable in the reconstructed image. the problem then becomes one of obtaining the best compression with fewest visible artifacts--a very subjective measure. Our wavelet compression algorithm uses an information theoretic analysis for the design of the compression maps. We have previously shown that maximizing the information for a given visual communication channel also maximizes the visual quality of the restored image. We utilize this to design quantization maps which maximize information for a given compression ratio. Hence we are able to design quantization maps which maximize the restorability of an image--i.e. the information content, the image quality, and the mean-square difference fidelity--for a given compression ratio.
Fractal interpolation functions have become popular after the works of *** and his co-authors on iterated function systems and their applications to data compression3'4. Here, we consider the following problem: gi...
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ISBN:
(纸本)0819422134
Fractal interpolation functions have become popular after the works of *** and his co-authors on iterated function systems and their applications to data compression3'4. Here, we consider the following problem: given a set of values of a fractal interpolation function, recover the contractive affine mappings generating this function. the suggested solution is based on the connection, which is established in the work, between the maxima skeleton of wavelet transform of the function and positions of the fixed points of the affine mappings in question.
Keywords: Fractal interpolation,wavelets, data compression.
An image compression method based on wavelet transforms and the human visual system (HVS) is presented in this paper. In the proposed method, we emphasize on the issue of designing a quantizer for wavelet transform co...
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the method in which the wavelet transform and fractal theories are applied to detect chaotic signals withthe additive observed noises is presented in this paper. Smoothing operator is derived from wavelet transform a...
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ISBN:
(纸本)0819422134
the method in which the wavelet transform and fractal theories are applied to detect chaotic signals withthe additive observed noises is presented in this paper. Smoothing operator is derived from wavelet transform and used to process the chaotic time series. According to its character of no-scale interval in certain scales, a detected example of the noisy chaotic behavior produced by a Lorenz attractor is provided by using the improved G-P algorithm to calculate its fractal dimension. the results shows that the method introduced here expresses a good ability to detect chaos.
In this contribution we present a steerable pyramid based on a particular set of complex wavelets named circular harmonic wavelets (CHW). the proposed CHWs set constitutes a generalization of the smoothed edge wavelet...
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ISBN:
(纸本)0819422134
In this contribution we present a steerable pyramid based on a particular set of complex wavelets named circular harmonic wavelets (CHW). the proposed CHWs set constitutes a generalization of the smoothed edge wavelets introduced by Mallat, consisting of extending the local differential representation of a signalimage from the first order to a generic n-th order. the key feature of the proposed representation is the use of complex operators leading to an expansion in series of polar separable complex functions, which are shown to possess the space-scale representability of the wavelets. the resulting tool is highly redundant, and for this reason is called hypercomplete circular harmonic pyramid (HCHP), but presents some interesting aspects in terms of flexibility, being suited for many imageprocessingapplications. In the present contribution the main theoretical aspects of the HCHPs are discussed along with some introductory applications.
We present a unified image compressor with spline biorthogonal wavelets and dyadic rational filter coefficients which gives high computational speed and excellent compression performance. Convolutions withthese filte...
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In this paper, a high-quality, space-frequency adaptive, trellis coded waveletimage codec is presented. the algorithm seeks jointly optimal space and frequency segmentation of an image. For this, first, wavelet packe...
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ISBN:
(纸本)0819422134
In this paper, a high-quality, space-frequency adaptive, trellis coded waveletimage codec is presented. the algorithm seeks jointly optimal space and frequency segmentation of an image. For this, first, wavelet packets are formed to localize the high-energy frequency bands. then, the wavelet coefficients are further classified to maximize the coding gain. Design target is set to minimize Lagrangian cost functions which are formed with distortion in l2 norm being the cost and coding rate as constraint. Resultant mapping is used to quantize the wavelet coefficients with trellis code quantization. this is followed by adaptive arithmetic coding producing the final compressed bitstream. Described approach is tested on several ISO standard images and results are compared to other compression techniques. Representative examples are included.
image authentication watermarking scheme can substantially solve the security of digital images transmitted through insecure channel. In this paper we propose a semi fragile watermarking scheme for image authenticatio...
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ISBN:
(纸本)9781538652398
image authentication watermarking scheme can substantially solve the security of digital images transmitted through insecure channel. In this paper we propose a semi fragile watermarking scheme for image authentication, localizing and recovering. the approximation sub-band of the second Discrete wavelet Transformation (DWT), LL2 is used as recovery watermark while the fifth approximation sub-band LL5 is used as authentication and localizing watermark. the two watermarks are embedded into the first approximation sub-band LL1 using the Quantization Index Modulation (QIM). To reduce the size of the recovery watermark, Data Representation through Combination (DRC) is practically used. the experimental results show that our proposed algorithm can resist JPEG compression and give an acceptable estimation of the watermarked image even after the watermarked image has been tampered.
Using wavelet networks, it is possible to capture the characteristics of non-linear dynamic systems in a multi- scale modeling strategy. Starting from the coarsest approximation we go step-wise to the finer scales. At...
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ISBN:
(纸本)0819422134
Using wavelet networks, it is possible to capture the characteristics of non-linear dynamic systems in a multi- scale modeling strategy. Starting from the coarsest approximation we go step-wise to the finer scales. At each step the error signal or the residue of the system is modeled. this procedure is repeated until the residual drops below some modeling error bound. the modeling is carried out using compactly supported biorthogonal wavelets. By choosing appropriate wavelet basis, it is possible to obtain a near optimal model.
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