A multiscale edge detection algorithm based on wavelet domain vector hidden Markov tree model |
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Authors: | Junxi Sun [Author Vitae] [Author Vitae] Yazhu Chen [Author Vitae] [Author Vitae] |
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Affiliation: | a Institute of Biomedical Engineering, Shanghai Jiaotong University, Shanghai 200030, China b Department of Computer Science, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK |
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Abstract: | The wavelet analysis is an efficient tool for the detection of image edges. Based on the wavelet analysis, we present an unsupervised learning algorithm to detect image edges in this paper. A wavelet domain vector hidden Markov tree (WD-VHMT) is employed in our algorithm to model the statistical properties of multiscale and multidirectional (subband) wavelet coefficients of an image. With this model, each wavelet coefficient is viewed as an observation of its hidden state and the hidden state indicates if the wavelet coefficient belongs to an edge. The WD-VHMT model can be learned by an expectation-maximization algorithm. After the model is learned, we employ an extended Viterbi algorithm to uncover the hidden state sequences according to the maximum a posterior estimation. The experiment results of the edge detection for several images are provided to evaluate our algorithm. |
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Keywords: | Edge detection Hidden Markov tree (HMT) models Expectation-maximization (EM) Wavelets |
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