1,721,128 research outputs found
Two algorithms to estimate fractal dimension of gray-level images
No full text[[abstract]]The fractal dimension is a fascinating feature highly correlated with the human perception of surface roughness, and has been successfully applied to texture analysis, segmentation, and classification. Several approaches have been developed to estimate the fractal dimension. Among them, the box-counting (BC) method is nonstochastic and popular in estimating the fractal dimension of a two-tone image. The differential box-counting (DBC) method, a generalization of the classical BC method, was proposed to compute the fractal dimension for a 2-D gray-level image. However, the classical BC and the DBC methods have several major drawbacks, such as overcounting and undercounting the number of boxes. Hence, the real value of the fractal dimension cannot be reached. In this work, two algorithms that can obtain more accurate estimates of the fractal dimension are proposed. The first one, a modified algorithm of the DBC method, is called the shifting DBC (SDBC) algorithm, and the second one is called the scanning BC (SBC) algorithm. We theoretically prove that the SDBC algorithm approaches the estimated value closer to the exact fractal dimension than the DBC method. Simulation results show that the two proposed algorithms can resolve the drawbacks that the BC and the DBC methods possess. Compared to the DBC method, the two proposed algorithms consistently give more satisfactory results on synthetic and natural textured images. (C) 2003 Society of Photo-Optical Instrumentation Engineers.[[note]]SC
On the fast search algorithms for vector quantization encoding
No full text[[abstract]]One of the major difficulties arising in vector quantization (VQ) is high encoding time complexity. Based on the well-known partial distance search (PDS) method and a special order of codewords in VQ codebook, two simple and efficient methods are introduced in fast full search vector quantization to reduce encoding time complexity. The exploitation of the "move-to-front" method, which may get a smaller distortion as early as possible, combined with the PDS algorithm, is shown to improve the encoding efficiency of the PDS method. Because of the feature of energy compaction in DCT domain, search in DCT domain codebook may be further speeded up. The experimental results show that our fast algorithms may significantly reduce search time of VQ encoding. (C) 2003 Wiley Periodicals, Inc.[[note]]SC
Data compression for arterial pulse waveform
No full text[[abstract]]The arterial pulse possesses important clinical information in traditional Chinese medicine. It is usually recorded for a long period of time in the applications of telemedicine and PACS systems. Due to the huge amount of data, by recognizing the strong correlation between successive beat patterns in arterial pulse waveform sequences, a novel and efficient data compression scheme based mainly on pattern matching is introduced. The simulation results show that our coding scheme can achieve a very high compression ratio and low distortion for arterial pulse waveform.[[note]]SC
High performance data compression method with pattern matching for biomedical ECG and arterial pulse waveforms
No full text[[abstract]]Biomedical waveforms, such as electrocardiogram (ECG) and arterial pulse, always possess a lot of important clinical information in medicine and are usually recorded in a long period of time in the application of telemedicine. Due to the huge to compress the biomedical waveform data is vital. By recognizing the strong similarity and correlation between successive beat patterns in biomedical , waveform sequences, an efficient data compression scheme mainly based on pattern matching is introduced in this paper. The waveform codec consists mainly of four units: beat segmentation, beat normalization, two-stage pattern matching and template updating and residual beat coding. Three different residual beat coding Huffman/ run-length coding in discrete such as Huffman/ run-length coding methods, cosine transform domain, and vector quantization, are employed. The simulation results show that our compression algorithms achieve a very significant improvement in the performances of compression ratio and error measurement for both ECG and pulse, as compared with some other compression methods. (C) 2003 Elsevier Ireland Ltd. All rights reserved.[[note]]SC
Wavelet-based adaptive vector quantization for still-image coding
No full text[[abstract]]Wavelet transform coding (WTC) with vector quantization (VQ) has been shown to be efficient in the application of image compression. An adaptive vector quantization coding scheme with the Gold-Washing dynamic codebook-refining mechanism in the wavelet domain, called symmetric wavelet transform-based adaptive vector quantization (SWT-GW-AVQ), is proposed for still-image coding in this article. The experimental results show that the GW codebook-refining mechanism working in the wavelet domain rather than the spatial domain is very efficient, and the SVVT-GW-AVQ coding scheme may improve the peak signal-to-noise ratio (PSNR) of the reconstructed images with a lower encoding time. (C) 2002 Wiley Periodicals, Inc.[[note]]SC
Paleoseismology of the Rueisuei segment of the Longitudinal Valley fault, eastern Taiwan
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