Multispectral images are composed of a series of images at differing optical wavelengths, Since these images can be quite large, they invite efficient source coding schemes for reducing storage and transmission requir...
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Multispectral images are composed of a series of images at differing optical wavelengths, Since these images can be quite large, they invite efficient source coding schemes for reducing storage and transmission requirements, Because multispectral images include a third (spectral) dimension with nonstationary behavior, these multilayer data sets require specialized coding techniques. In this paper, me develop both a theory and specific methods far performing optimal transform coding of multispectral images, The theory is based on the assumption that a multispectral image may be modeled as a set of jointly stationary Gaussian random processes, Therefore, the methods may be applied to any multilayer data set which meets this assumption, Although we do not assume the autocorrelation has a separable form, we show that the optimal transform for coding has a partially separable structure, In particular, we prove that a coding scheme consisting of a frequency transform within each layer followed by a separate KL transform across the layers at each spatial frequency is asymptotically optimal as the block size becomes large, Two simplifications of this method are also shown to be asymptotically optimal if the data can be assumed to satisfy additional constraints, The proposed coding techniques are then implemented using subband filtering methods, and the various algorithms are tested on multispectral images to determine their relative performance characteristics.
This paper describes a highly scalable hybrid image coding scheme (HS-HIC). The proposed hybrid coding scheme combines simply modification of the data in the wavelet domain and the high performance of the set partitio...
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This paper describes a highly scalable hybrid image coding scheme (HS-HIC). The proposed hybrid coding scheme combines simply modification of the data in the wavelet domain and the high performance of the set partitioning in hierarchical trees (SPIHT) coding. The modification of the subband image data is done based on the transformation of the high-frequency subband (details) in the wavelet domain. It is based on linear modification of 9-subband image data within three-layer in the wavelet domain. Except the image data in LL3, all other image data will be linearly modified based on the discrete Fourier transform (DFT) components. The modification process provides a new subband image data containing almost the same information as the original one but having a smaller frequency spectrum. The modified data is then located in the corresponding position and the simple SPIHT coder followed by adaptive arithmetic coder is applied on the resulting hierarchical representation to generate the symbol stream. Simulation results demonstrate that, with small addition in the computational complexity of the coding process, the PSNR performance of the proposed algorithm is much higher than that of the SPIHT test coder and some of famous image coding techniques. (c) 2007 Elsevier Inc. All rights reserved.
The objective of multiple description coding (MDC) is to represent a source into multiple descriptions such that various reconstruction qualities are obtained from different subsets of the descriptions. In this paper,...
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The objective of multiple description coding (MDC) is to represent a source into multiple descriptions such that various reconstruction qualities are obtained from different subsets of the descriptions. In this paper, we propose a simple scheme that combines the multiple descriptions transform coding (MDTC) method with the discrete wavelet transform (DWT). We compare the performance of the proposed scheme with a discrete cosine transform (DCT)-based scheme prevalent in other papers. Simulation results show that our proposed DWT technique outperforms both objectively and subjectively the method based on DCT in the case of packet loss. (C) 2006 Elsevier GmbH. All rights reserved.
This paper present a fast disparity estimation algorithm based on limited range, directional search and selective sample decimation is presented. The proposed algorithm has focused on reduction of complexity while ret...
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This paper present a fast disparity estimation algorithm based on limited range, directional search and selective sample decimation is presented. The proposed algorithm has focused on reduction of complexity while retaining good objective performance. The simulation results show that complexity can be significantly reduced while the PSNR for Y, Cb and Cr is close to the one of full search. In addition, the entropy for disparity vectors is reduced compared to the one of full search.
Multiple description coding (MDC) provides a favorable solution for human-centered image communication, which takes into account people's varying watching situations as well as people's demand for real-time im...
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Multiple description coding (MDC) provides a favorable solution for human-centered image communication, which takes into account people's varying watching situations as well as people's demand for real-time image display. As an effective technique for MDC, three-description lattice vector quantization (3D-LVQ) is considered for image coding in this paper. Based on intra- and inter-correlation in the 3D-LVQ index assignment as well as wavelet intra-subband correlation, a novel predictive decoding method for 3D-LVQ-based image coding is proposed to enhance side decoding performance, which attempts to predict lost descriptions (sublattice points) in a good way for better reconstructions of wavelet vectors (fine lattice points) in the side decoding. Experimental results validate effectiveness of the proposed decoding scheme in terms of rate-distortion performance.
image coding plays a very important role in a digital TV system. In this paper we focus on the discussion of the image compression in DTV systems. We propose a regular, efficient algorithm, which has effectively much ...
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image coding plays a very important role in a digital TV system. In this paper we focus on the discussion of the image compression in DTV systems. We propose a regular, efficient algorithm, which has effectively much lower complexity. Our algorithm would require only 12 bits of coefficient wordlengths to achieve the CCITT/ISO specification. But the traditional method would need 12 similar to 48 bits to achieve the same specification. The hardware cost is about 35% higher than the traditional method. But the input block length to our design is 64, which is much higher than traditional algorithm, whose block length is generally between 8 and 16. This dictates that the throughput of our algorithm is about 2 to 4 time higher than the traditional algorithms.
Classification of blocks of subband samples according to their energy and variable bit allocation within the subsequent classes has demonstrated considerable gains in coding efficiency. The gains due to classification...
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Classification of blocks of subband samples according to their energy and variable bit allocation within the subsequent classes has demonstrated considerable gains in coding efficiency. The gains due to classification increase as smaller blocks are used;however, this increases the overheads for transmitting the classification information. In this paper, a quadtree based method is proposed. This method allows for more efficient classification by using variable-sized blocks in order to maximize the classification gain, while maintaining a limit on the classification overheads. This method is applied for subband coding of images and the results indicate that it performs better than the other methods currently available in the literature. (C) 2003 Elsevier Inc. All rights reserved.
In this paper, a new class of fractal image coders is described. As in previously published fractal coding algorithms, the encoder models each image to be coded as an attractor of a simple affine mapping, and finds th...
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In this paper, a new class of fractal image coders is described. As in previously published fractal coding algorithms, the encoder models each image to be coded as an attractor of a simple affine mapping, and finds the parameters in such a mapping by a blockwise image analysis. The image code consists of the parametric description of the mapping, which is selected to provide the best affine fit to the image in the l2 sense. The decoder uses the parametric description it receives to synthesize the attractor of the mapping through a simple iterative procedure. Although the resulting coders are strongly related to previously published fractal coders, they are modified in a way that gives exact decoder convergence towards the attractor in the lowest possible number of iterations - typically three or less. In contrast to what has been the case with previous fractal coding algorithms, this number of iterations is image independent. The resulting decoder can be implemented in a computationally very efficient pyramid structure. Also, a coder offering non-iterative decoding is included as a special case. The paper describes the modifications of previously known fractal coders that are necessary to obtain the fast convergence. It is shown that the image quality remains unimpaired by these modifications. The computational complexity of the decoding algorithm in the new coder class is analyzed, and an efficient pyramid structure for the decoder is outlined. Finally, a coding example is given.
Multiple description (MD) coding is a promising alternative for robust transmission of information over non-prioritized and unpredictable networks. In this paper, an effective MD image coding scheme is introduced base...
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Multiple description (MD) coding is a promising alternative for robust transmission of information over non-prioritized and unpredictable networks. In this paper, an effective MD image coding scheme is introduced based on the MD lattice vector quantization (MDLVQ) for the wavelet transformed images. In view of the characteristics of wavelet coefficients in different frequency subbands, MDLVQ is applied in an optimized way, including an appropriate construction of wavelet coefficient vectors, the optimization of MDLVQ encoding parameters such as the choice of sublattice index values and the quantization accuracy for different subbands. More importantly, optimized side decoding is employed to predict lost information based on inter-vector correlation and an alternative transmission way for further reducing side distortion. Experimental results validate the effectiveness of the proposed scheme with better performance than some other tested MD image codecs including that based on optimized MD scalar quantization.
Compressive sensing (CS)-based image coding scheme has been enthusiastically studied, but it still has a poor rate-distortion performance compared with the traditional image coding techniques. In this paper, we propos...
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Compressive sensing (CS)-based image coding scheme has been enthusiastically studied, but it still has a poor rate-distortion performance compared with the traditional image coding techniques. In this paper, we propose a CS multi-layer residual coding scheme to rectify this problem to a certain extent. By dividing CS measurements into multi-layers and predicting a particular layer's measurements with all its preceding layers' measurements, we can transform CS measurements into multi-layer residual coefficients, which are easier to compress. By calculating the residual between the quantized ground-truth CS measurements and their corresponding quantized inference measurements and using Huffman coding to associate each residual quantization index with a binary code, we can reduce the redundancies among CS measurements efficiently. Besides, the prediction and quantization process is designed to be layer-independent, which can save much of the encoding time. The proposed approach introduces a novel framework for using CS in the compression domain. The experimental results show that the proposed scheme can significantly outperform JPEG2000 and approach or reach the performance of HEVC-Intra on some test images.
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