Browsing by Author "Liao, HYM"

Now showing 1 - 12 of 12

3-D shape retrieval using cognitive psychology-based principles
(2005)
Lin, HYS
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Lin, JC
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Liao, HYM
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資訊工程學系
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Department of Computer Science
In this paper, we incorporate a set of principles that originated in cognitive psychology into tire design of 3-D drape analysis and retrieval systems. Based on the "visual salience-guided mesh decomposition "scheme we proposed previously, a 3-D shape represented in mesh form is first broken into parts such that human visual perception of the parts can be appropriately mimicked. Next, tire decomposed parts are individually analyzed and quantified according to the properties of visual salience. To establish the indices of 3-D meshes, for the subsequent retrieval process, spherical parameterization is adopted to map the decomposed parts onto the surface of a unit sphere. In this way, the degree of similarity between a query provided by a user and models in the database call be calculated. The experiment results show that the retrieval performance of the proposed scheme is indeed efficient and powerful.
A cognitive psychology-based approach for 3-D shape retrieval
(2005)
Lin, HYS
;
Liao, HYM
;
Lin, JC
;
資訊工程學系
;
Department of Computer Science
In this paper, we incorporate a set of principles originated from cognitive psychology into the design of 3-D shape analysis and retrieval algorithms. Based on the "visual salience-guided mesh decomposition" we previously proposed, a 3-D mesh-based shape is first broken up into parts such that human visual perception on parts can be appropriately mimicked. Next, the decomposed parts are individually analyzed and quantified according to the properties of visual salience. To establish the indices of 3-D meshes for shape matching, spherical parameterization is adopted to map the decomposed parts onto the surface of a unit sphere. In this way, the dissimilarity degree between the query acquired from users and a model in database can be calculated. The experimental results have shown that the matching performance of the proposed scheme is indeed efficient and powerful.
A new LDA-based face recognition system which can solve the small sample size problem
(2000-10-01)
Chen, LF
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Liao, HYM
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Ko, MT
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Lin, JC
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Yu, GJ
A new LDA-based face recognition system is presented in this papal. Linear discriminant analysis (LDA) is one of the most popular linear projection techniques for feature extraction. The major drawback of applying LDA is that it may encounter the small sample size problem. In this paper, we propose a new LDA-based technique which can solve the small sample size problem. We also prove that the most expressive vectors derived ill the null space of the within-class scatter matrix using principal component analysis (PCA) are equal to the optimal discriminant vectors derived in the: original space using LDA. The experimental results show that the new LDA process improves the performance of a face recognition system significantly. (C) 2000 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
Authentication of 3-D polygonal meshes
(2004)
Lin, HY
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Liao, HYM
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Lu, CS
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Lin, JC
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資訊工程學系
Designing a powerful fragile watermarking technique for authenticating 3-D polygonal meshes is a very difficult task. Yeo and Yeung [17] were first to propose a fragile watermarking method to perform authentication of 3-D polygonal meshes. Although their method can authenticate the integrity of 3-D polygonal meshes, it is unable to distinguish malicious attacks from incidental data processings. In this paper, we propose a new fragile watermarking method which not only is able to detect malicious attacks, but also is immune to incidental data processings. During the process of watermark embedding, mesh parameterization techniques are employed to perturb the coordinates of invalid vertices while cautiously maintaining the appearance of the original model. Since the proposed embedding method is independent of the order of vertices, the hidden watermark is immune to some attacks, such as vertex reordering. In addition, the proposed method can be used to perform region-based tampering detection. The experimental results have shown that the proposed fragile watermarking scheme is indeed powerful.
Fragile watermarking for authenticating 3-D polygonal meshes
(2005-12-01)
Lin, HYS
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Liao, HYM
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Lu, CS
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Lin, JC
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資訊工程學系
Designing a powerful fragile watermarking technique for authenticating three-dimensional (3-D) polygonal meshes is a very difficult task. Yeo and Yeung [34] were first to propose a fragile watermarking method to perform authentication of 3-D polygonal meshes. Although their method can authenticate the integrity of 3-D polygonal meshes, it cannot be used for localization of changes. In addition, it is unable to distinguish malicious attacks from incidental data processings. In this paper, we trade off the causality problem in Yen and Yeung's method for a new fragile watermarking scheme. The proposed scheme can not only achieve localization of malicious modifications in visual inspection, but also is immune to certain incidental data processings (such as quantization of vertex coordinates and vertex reordering). During the process of watermark embedding, a local mesh parameterization approach is employed to perturb the coordinates of invalid vertices while cautiously maintaining the visual appearance of the original model. Since the proposed embedding method is independent of the order of vertices, the hidden watermark is immune to some attacks, such as vertex reordering. In addition, the proposed method can be used to perform region-based tampering detection. The experimental results have shown that the proposed fragile watermarking scheme is indeed powerful.
Robust video retrieval using temporal MVMB moments
(2005)
Chen, DY
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Liao, HYM
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Lee, SY
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資訊工程學系
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Department of Computer Science
In this paper, we propose motion pattern-based descriptor which exploits both spatial and temporal features to characterize video sequences in a semantics-based manner. The Discrete Cosine Transform (DCT) is applied to convert the high-level features from the time domain to the frequency domain. The energy concentration property of DCT allows us to use only a few DCT coefficients to precisely capture the variations of moving blobs. In comparison with the frequently used motion activity descriptors, the RLD and SAH of MPEG-7, the proposed descriptor yields 38% and 19% average gains over RLD and SAH, respectively.
Robust video sequence retrieval using a novel object-based T2D-histogram descriptor
(2005-04-01)
Chen, DY
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Lee, SY
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Liao, HYM
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資訊工程學系
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Department of Computer Science
Due to the tremendous growth in the number of digital videos, the development of video retrieval algorithms that can perform efficient and effective retrieval task is indispensable. In this paper, we propose a high-level motion activity descriptor, object-based transformed 2D-histogram (T2D-histogram), which exploits both spatial and temporal features to characterize video sequences in a semantics-based manner. The discrete cosine transform (DCT) is applied to convert the object-based 2D-histogram sequences from the time domain to the frequency domain. Using this transform, the original high-dimensional time domain features used to represent successive frames are significantly reduced to a set of low-dimensional features in frequency domain. The energy concentration property of DCT allows us to use only a few DCT coefficients to effectively capture the variations of moving objects. Having the efficient scheme for video representation, one can perform video retrieval in an accurate and efficient way. (c) 2004 Elsevier Inc. All rights reserved.
Untitled
(2006-05-01)
Chiang, CC
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Liao, HYM
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Fan, KC
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資訊工程學系
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Department of Computer Science
Visual salience-guided mesh decomposition
(2004)
Lin, HYS
;
Liao, HYM
;
Lin, JC
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a novel mesh decomposition scheme called "visual salience-guided mesh decomposition". The concept of part salience is originated from cognitive psychology and it asserts the salience of a part can be determined by (at least) three factors: the protrusion, the boundary strength, and the relative size of a part. We try to convert these "conceptual" rules into "real'' computational processes and then use them to "guide" a 3D mesh decomposition process. The experimental results have shown that the proposed scheme is indeed effective and powerful in decomposing a 3D mesh into significant components.
Wavelet-based optical flow estimation
(2000)
Chen, LF
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Lin, JC
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Liao, HYM
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資訊工程學系
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Department of Computer Science
In this paper, a new algorithm for accurate optical flow estimation using discrete wavelet approximation is proposed. In traditional gradient-based approaches, the computation of optical flow depends on minimizing the image and smoothness constraints. The proposed method takes advantages of the nature of wavelet theory, which can efficiently and accurately represent "things," to model optical flow vectors and image related functions. Each flow vector and image function will be represented by linear combinations of wavelet basis functions. From such wavelet-based approximation, the leading coefficients of these basis functions carry the global information of the approximated "things." The proposed method cab successfully convert the problem of minimizing a constraint function into that of solving a linear system of a quadratic and convex function of wavelet coefficients. Once all the corresponding coefficients are decided, the flow vectors can be determined accordingly. Experiments have been conducted on both synthetic and real image sequences and the results have reflected that our approach outperformed the existing methods in terms of accuracy.
Wavelet-based optical flow estimation
(2002-01-01)
Chen, LF
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Liao, HYM
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Lin, JC
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資訊工程學系
;
Department of Computer Science
In this paper, a new algorithm for accurate optical flow (OF) estimation using discrete wavelet approximation is proposed. The computation of OF depends on minimizing the image and smoothness constraints. The proposed method takes advantages of the nature of wavelet theory, which can efficiently and accurately approximate any function. OF vectors and image functions are represented by means of linear combinations of scaling basis functions. Based on such wavelet-based approximation, the leading coefficients of these basis functions carry global information about the approximated functions. The proposed method can successfully convert the problem of minimizing a constraint function into that of solving a linear system of a quadratic and convex function of scaling coefficients. Once all the corresponding coefficients are determined, the flow vectors can be obtained accordingly. Experiments have been conducted on both synthetic and real image sequences. In terms of accuracy, the results show that our approach outperforms the existing methods which adopted the same objective function as ours.
Why recognition in a statistics-based face recognition system should be based on the pure face portion: a probabilistic decision-based proof
(2001-07-01)
Chen, LF
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Liao, HYM
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Lin, JC
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Han, CC
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資訊工程學系
It is evident that the process of face recognition, by definition, should be based on the content of a face. The problem is: what is a "face"? Recently, a state-of-the-art statistics-based face recognition system, the PCA plus LDA approach, has been proposed (Swets and Weng, IEEE Trans. pattern. Anal. Mach. Intell. 18 (8) (1996) 831-836). However, thr authors used "face" images that included hail, shoulders, face and background. Our intuition tells us that only a recognition process based on a "pure" Face portion can be called face recognition. The mixture of irrelevant data may result in an incorrect set of decision boundaries. In this paper, we propose a statistics-based technique to quantitatively prove our assertion. For the purpose of evaluating how the different portions of a Face image will influence the recognition results, a hypothesis testing model is proposed. We then implement the above mentioned face recognition system and use the proposed hypothesis testing model to evaluate the system. Experimental results show that the influence of the "real"-face portion is much less than that of the nonface portion. This outcome confirms quantitatively that recognition in a statistics-based face recognition system should be based solely on the "pure" face portion. (C) 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.