Considering a video signal which has been degraded by a PAL codec and a noisy transmission on a satellite channel, two digital filtering schemes are presented for reducing the different resulting signal distortions (c...
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ISBN:
(纸本)0819424358
Considering a video signal which has been degraded by a PAL codec and a noisy transmission on a satellite channel, two digital filtering schemes are presented for reducing the different resulting signal distortions (cross-effect on the PAL-decoded signal components, impulses of the high-frequency demodulator, transmission noise) before its MPEG2 encoding. The first one deals with crossing-effect and transmission noise using a single non-linear filtering box, while the second scheme consists of several linear processing, each one devoted to one kind of distortion. Both filtering approaches are discussed, and their performances before and after the MPEG2 codec are compared, using objective, peak signal-to-noise ratio, as well as subjective, visual quality, criteria.
The Asynchronous Transfer Mode (ATM) appears as the standard protocol for image and video transmision. There is virtually no bandwidth limitations neither a restricted size of operating area. However, the main problem...
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ISBN:
(纸本)0819424358
The Asynchronous Transfer Mode (ATM) appears as the standard protocol for image and video transmision. There is virtually no bandwidth limitations neither a restricted size of operating area. However, the main problem stands in the non secured transmission when ATM native applications are implemented. This induced a new way of encoding images where the redundancy (classically managed by the network protocol) is generated into the CoDec. In this paper, we present the Mojette transform that generates the redundancy at the higher level of the coder in order to safely transmit image data. Block and wavelet implementations associated with the Mojette transform are presented and compared not only from the coder point of view but for the source and the channel characteristics. For this specific case we also present the asynchronous Mojette reconstruction. An adapted object oriented model has been developped accordingly.
In this paper, we propose a novel method of arbitrarily focused image acquisition using multiple differently focused images. First, we describe our previous select-and-merge method for all-focused image acquisition. W...
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ISBN:
(纸本)0819424358
In this paper, we propose a novel method of arbitrarily focused image acquisition using multiple differently focused images. First, we describe our previous select-and-merge method for all-focused image acquisition. We can get good results by using this method but it's not easy to extend this method for generating arbitrarily focused images. Then, based on the assumption that depth of the scene changes stepwise, we derive a formula for reconstruction between the desired arbitrarily focused image and multiple acquired images;we can reconstruct the arbitrarily focused image by iterative use of the formula. We also introduce coarse-to-fine estimation of PSFs of the acquired images. We show we can reconstruct arbitrarily focused images for a natural scene. In other words, we can simulate virtual cameras and synthesize images focused on arbitrarily depths.
Region segmentation of images is a well-known 'ill-posed problem', and a specific algorithm like regularization seems to be available. In this paper, an active region segmentation algorithm based on a regulari...
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ISBN:
(纸本)0819424358
Region segmentation of images is a well-known 'ill-posed problem', and a specific algorithm like regularization seems to be available. In this paper, an active region segmentation algorithm based on a regularization approach using the Hopfield neural network is proposed. The objective function to be minimized by the network is defined based on the criteria that integrate region growing and edge detection for the image segmentation. The energy of the network tends to converge on a local minimum, so that pyramid images are used to avoid such local minima and to achieve fast convergence. Moreover, the active region segmentation algorithm is applied to a sequence of color images to track an object region that change in appearance through complex and nonstationary background/foreground situations. Experimental results show that it's possible to segment images and track the object region using the minimization principle of the energy function of the Hopfield neural network.
A method for still image coding is proposed which allows for progressive transmission, because low detailed versions of the image can be reconstructed from a truncated bit stream. The proposed method is in its main as...
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ISBN:
(纸本)0819424358
A method for still image coding is proposed which allows for progressive transmission, because low detailed versions of the image can be reconstructed from a truncated bit stream. The proposed method is in its main aspects close to the classical pyramid approach of Burt and Adelson.(1) While retaining the main idea, of using a Laplacian pyramid type decomposition, the new proposal differs in the filters employed for pyramid decomposition and in the bit allocation and quantization. The image is decomposed into a centered spline Laplacian pyramid. The pyramid is quantized and coded following a layered quantization approach together with a layered coding method based on conditional arithmetic coding.(2) The encoder outputs an embedded bit stream. Thus the decoder may truncate the bitstream at any point, which results in a more or less detailed image. Besides this rate-distortion scalability the coder has a multiresolution property, due to the pyramid decomposition. An extension to hybrid video coding is also discussed.
We propose a design framework for perfectly reconstructed time-varying linear-phase paraunitary filter banks (LPPUFB) using a novel Adaptive Lapped Transform (ALT). The ALT is based on the Generalized Lapped Orthogona...
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ISBN:
(纸本)0819424358
We propose a design framework for perfectly reconstructed time-varying linear-phase paraunitary filter banks (LPPUFB) using a novel Adaptive Lapped Transform (ALT). The ALT is based on the Generalized Lapped Orthogonal Transform (GenLOT) proposed by Queiroz.(1) A time-varying filter bank is constructed through the factorization of the GenLOT into cascaded matrix stages. Variable length lapped transforms are subsequently generated by cascading a number of these matrix stages to build specific length filters. Several constraints on the design ensure perfect reconstruction and a fast implementation. An embedded ALT image codec is presented and the application of the ALT to the H.263 video coding standard is discussed. Preliminary results show that the ALT-based embeded image codec has a 1.61-2.35 and a 2.37-4.04 dB increase in peak signal-to-noise ratios (PSNR) compared to the JPEG(2) image coding standard for the Lenna and Barbara test images, respectively.
In this paper, we address the issue of designing a two-channel linear phase biorthogonal filter bank that maximizes the two most desired properties for Che wavelet transform in image coding applications, namely, ortho...
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ISBN:
(纸本)0819427497
In this paper, we address the issue of designing a two-channel linear phase biorthogonal filter bank that maximizes the two most desired properties for Che wavelet transform in image coding applications, namely, orthogonality and energy compaction. Proper cost functions are formulated for these two criteria and an efficient signal-adaptive optimization algorithm is proposed. Our algorithm is motivated by a number of interesting properties of the correlation matrix of typical image signals, and uses Lifting operations to efficiently represent the degrees of freedom subject to perfect reconstruction conditions. In addition, it offers a successive tradeoff between our two optimization goals. Experimental results on re popular Daubechies 9-7 and 10-18 filter banks reveal that considerable improvements in terms of both orthogonality and energy compaction can be achieved through the proposed optimization technique.
Wavelet transform which provides a multiresolution representation of images has been widely used in image and video compression. An investigation of wavelet decomposition reveals the cross-correlation among subimages ...
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ISBN:
(纸本)0819424358
Wavelet transform which provides a multiresolution representation of images has been widely used in image and video compression. An investigation of wavelet decomposition reveals the cross-correlation among subimages at different resolutions. To exploit this cross-correlation, a new scheme using classified vector quantization to encode wavelet coefficients is proposed in this paper. The original image is first decomposed into a hierarchy of three layers containing ten subimages by discrete wavelet transform. The lowest resolution (level 3) low frequency subimage is scalar quantized (with 8 bits/pixel) since it contains most of the energy of the wavelet coefficients. All high frequency subimages are vector quantized to utilize the cross-correlation among different resolutions. Vectors are constructed by combining the corresponding coefficients of the high frequency subimages of the same orientation at different resolutions. Classified vector quantization is used to reduce edge distortion and computational complexity. Computer simulations are carried out to evaluate the performance of the proposed method.
The celebration of the Centenary of Cinema in 1995 was the occasion to initiate new developments for the preservation of the international cinematic heritage and the restoration of old damaged films. 'Classical...
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ISBN:
(纸本)0819427497
The celebration of the Centenary of Cinema in 1995 was the occasion to initiate new developments for the preservation of the international cinematic heritage and the restoration of old damaged films. 'Classical' film restoration is based on special printing machines to improve the duality of (safekeeping-) copies. Only a small class of artifacts can be removed with such a process because the unit of manipulation is always a whole image sequence. With the help of digital imageprocessing techniques the restoration process can be adapted for each frame or even pixel. This creates new potentialities for the restoration of films beyond repair, especially nitrate based films produced before 1954 and early color films. This paper presents a short overview about a system for the digital restoration of image sequences, currently under development in the EUREKA project LIMELIGHT. After an introduction to the technical objectives and key figures, the restoration process (acquisition, sequence management. imageprocessing, restitution) is described for the case of 35mm film. Algorithms for the detection of artifacts, such as dust? image vibrations, scratches, (partially) distorted frames and brightness variations, based on a morphological detector, which uses spatial properties-and a dynamic detector, based on motion analysis, are presented. Furthermore an algorithm for 3D image interpolation used for the removal of scratches and subtitles is described. The main problem is the reconstruction of the missing image content for more than one frame in the same spatial location. Application examples for each defect class are given.
The problem of quantizing sub-images of a multiresolution image decomposition while preserving edges is considered. For this purpose, we propose a coding algorithm which exploits both spatial and frequency location of...
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ISBN:
(纸本)0819424358
The problem of quantizing sub-images of a multiresolution image decomposition while preserving edges is considered. For this purpose, we propose a coding algorithm which exploits both spatial and frequency location of wavelet coefficients within and across scales. This algorithm is dedicated to lour bit rate image coding. In this paper, we develop a new constrained quantizer based on a lagrangian formulation called Edge Adaptive Quantizer (EAQ). Given a significance map, this algorithm preserves significant coefficients while smoothing elsewhere. This is done by introducing a spatial adaptation term based on Markov Random Fields (MRF). A new criterion based on spatial models and entropy constraint is then derived. With this new formulation, a practical solution to the multiresolution optimization problem is presented in the form of a bit allocation procedure. An optimal quantizer is constructed minimizing this new criterion for a target bit rate. Experiments using constraint quantization demonstrate PSNR gains over standard uniform scalar quantization and appreciable visual improvements. A simple extension of the algorithm allows for the use of other scalar quantizers.
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