Browsing by Author "Jou, IC"

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On-line signature verification based on logarithmic spectrum
(1998-12-01)
Wu, QZ
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Lee, SY
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Jou, IC
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資訊工程學系
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Department of Computer Science
In this paper, an on-line signature verification scheme based on similarity measurement of logarithmic spectrum is proposed. The principal components of the logarithmic spectrum of each signature are extracted. We then compute the similarity of logarithmic spectrum between input signature and the reference template. By comparing the similarity of logarithmic spectrum with the verification threshold, we can determine the authenticity of the input signature. Based on the experimentation, the rates of false rejection errors and false acceptance errors are as low as 1.4 and 2.8%, respectively. This demonstrates the effectiveness of the proposed scheme. (C) 1998 Published by Elsevier Science Ltd on behalf of the Pattern Recognition Society. All rights reserved.
On-line signature verification based on split-and-merge matching mechanism
(1997-07-01)
Wu, QZ
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Lee, SY
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Jou, IC
;
資訊工程學系
;
Department of Computer Science
In this paper, an on-line signature verification scheme based on split-and-merge matching mechanism is proposed. Each word in the signature is specified with static and dynamic features: a sequence of (x, y) coordinates and a sequence of (x, y) velocities. We employ the split-and-merge matching mechanism for each input sequence of coordinates or velocities with the corresponding sequence of the reference template. Alignment and refinement are exploited in the matching to justify the data skew problem. The accumulated coordinate and velocity distances are compared with corresponding verification thresholds to determine the genuineness of the input signature, Algorithms to compute reference templates and verification thresholds are also proposed. The performed simulation results support the effectiveness of this signature verification scheme.
On-line signature verification using LPC cepstrum and neural networks
(1997-02-01)
Wu, QZ
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Jou, IC
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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, an on-line signature verification scheme based on Linear Prediction Coding (LPC) cepstrum and neural networks is proposed. Cepstral coefficients derived from linear predictor coefficients of the writing trajectories are calculated as the features of the signatures. These coefficients are used as inputs to the neural networks. A number of single-output multilayer perceptrons (MLP's), as many as the number of words in the signature, are equipped for each registered person to verify the input signature. If the summation of output values of all MLP's is larger than verification threshold, the input signature is regarded as a genuine signature; otherwise, the input signature is a forgery. Simulations show that this scheme can detect the genuineness of the input signatures from our test database with an error rate as low as 4%.
Rotation, scaling, and translation resilient image watermarking with side information at encoder
(2002)
Day, ML
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Jou, IC
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Lee, SY
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資訊工程學系
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Department of Computer Science
We propose a rotation, scaling and translation (RST) resilient blind image watermarking technique by using Fourier-Mellin transform and informed coding, where watermark detection does not require the existence of the original image. Although the Fourier-Mellin invariant domain is recognized to be nearly RST invariant, which supposedly would make it an ideal space for watermark embedding, however the inverse Log-Polar map (ILPM) could severely destroy the embedded watermark. Therefore a very strong watermark has to be employed to survive the self-destruction process from ILPM, but in turn this leads to a poorly watermarked image. To overcome this problem we introduce the concept of informed coding by embedding a slightly weaker watermark into the image so that both transparency and robustness can be achieved. Experimental results demonstrate that the resulting watermark is robust to a variety of image processing attacks.
The CMOS design of robust neural chip with the on-chip learning capability
(1996)
Wu, CY
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Liu, RY
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Jou, IC
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ShyhJYE, FJ
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電子工程學系及電子研究所
Watermark re-synchronization using sinusoidal signals in DT-CWT domain
(2004)
Day, ML
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Lee, SY
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Jou, IC
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資訊工程學系
;
Department of Computer Science
Embedding sinusoidal signals or tiles patterns into image in the spatial domain to form some peaks is an effective technique for geometric invariant image watermark detection. However, there are two drawbacks in these spatial domain based schemes: one is poor picture quality of resulting watermarked image and the other is weak peaks visibility which is hard to detect. The previous works suffer from requiring a very strong watermark embedding to ease re-synchronization peaks finding, which in turn leads to a poorly watermarked image. To overcome this problem, we explore embedding sinusoidal signals individually in each of the selected sub-bands of dual-tree complex wavelet transform domain (DT-CWT), and then detecting the re-synchronization peaks by using the accumulated embedding sub-bands. Experimental results demonstrate that by adopting our approach, the resulting re-synchronization peaks are robust to rotation, scaling and translation attacks while preserving the visual quality of the watermarked image, thereby resolve the unavoidable dilemma faced by the other schemes.