Soo‐Chang Pei

National Taiwan University

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Jian–Jiun Ding

National Taiwan University

Jong-Jy Shyu

National University of Kaohsiung

Chun-Shien Lu

Institute of Information Science, Academia Sinica

Chien–Cheng Tseng

National Kaohsiung University of Science and Technology

Kuo-Wei Chang

Chunghwa Telecom (Taiwan)

Min-Hung Yeh

National Ilan University

Sung-Hsien Hsieh

Academia Sinica

Yun-Da Huang

National Taiwan University

Hsin‐Hua Liu

University of California, Berkeley

Peng‐Hua Wang

National Taipei University

Cooperative Institutions

National Taiwan University

115

National Yang Ming Chiao Tung University

Institute of Information Science, Academia Sinica

National Taiwan University of Science and Technology

National Cheng Kung University

Academia Sinica

National Chung Hsing University

National Tsing Hua University

National Taipei University

National Taipei University of Technology

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Underwater Images Enhancement by Revised Underwater Images Formation Model

IEEE Access (2022)

Soo‐Chang Pei Chia-Yi Chen

In this paper, we proposed the efficient and appealing technique for underwater images enhancement. Underwater images often suffer from haze, color distortion, low contrast and loss of the human acuity due to light scattering and absorption. To tackle these issues, proposed precise model is presented expressively showed that: (1) the estimation of the transmission map in atmospheric scatter model is divided into two cases, which are more applicable to underwater images in different situations, and make the enhanced results more robust; (2) model not only removes haze but also restores lost colors of underwater images in the image de-hazing step instead of color correction. First, we proposed a revised underwater dehazing model aiming to eliminate the color of water directly while solving the problem of haze in the underwater images. Then proposed color correction method can adaptively address the problem of color shifting without any additional information. Furthermore, we design a multi-scale illumination fusion to reveal more details and low illumination parts of the image. Experimental results demonstrate that our proposed method outperforms other methods significantly with 5%~77% quantitative improvement on all four evaluation performance indices and shows more obvious detailed underwater images. Our method can be applied to underwater detection and exploration as the pre-processing step.

Color correction

Haze

Distortion (music)

10.1109/access.2022.3213340

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Citations (18)

A moment-based approach for deskewing rotationally symmetric shapes

IEEE Transactions on Image Processing (1999)

Soo‐Chang Pei Ji-Hwei Horng

The covariance matrix of a pattern is composed by its second order central moments. For a rotationally symmetric shape, its covariance matrix is a scalar identity matrix. In this work, we apply this property to restore the skewed shape of rotational symmetry. The relations between the skew transformation matrix and the covariance matrices of original and skewed shapes are derived. By computing the covariance matrix of the skewed shape and letting the covariance matrix of the original shape be a scalar identity matrix, the skew transformation matrix can be solved. Then, the rotationally symmetric shape can be recovered by multiplying the inverse transformation matrix with the skewed shape. The method does not rely on continuous contours and is robust to noise, because only the second-order moments of the input shape are required. Experimental results are also presented.

Identity matrix

Skew-symmetric matrix

Matrix (chemical analysis)

Hollow matrix

10.1109/83.806629

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Citations (7)

Fractional Fourier Transforms and Wigner Distribution Functions for Stationary and Non-Stationary Random Process

Jian–Jiun Ding Soo‐Chang Pei

In this paper, we discuss the relations among the random process, the Wigner distribution function, the ambiguity function, and the fractional Fourier transform (FRFT). We find many interesting properties. For example, if we do the FRFT for a stationary process, although the result in no longer stationary, the amplitude of its covariance function is still independent of time. Moreover, for the FRFT of a stationary random process, the ambiguity function will be a radiant line passing through (0, 0) and the Wigner distribution function will be invariant along a certain direction. We also define the fractional stationary random process and find that a non-stationary random process can be expressed a summation of fractional stationary random processes. The proposed theorems will be useful for filter design, noise synthesis and analysis, system modeling, and communication.

Wigner distribution function

Stationary process

Stationary distribution

Ambiguity function

Stationary sequence

10.1109/icassp.2006.1660682

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Citations (3)

Design of variable comb filter using FIR variable fractional delay element

Signal Processing (2012)

Soo‐Chang Pei Yun-Da Huang Shih-Hsin Lin Jong-Jy Shyu

Comb filter

Finite impulse response

Butterworth filter

All-pass filter

10.1016/j.sigpro.2012.03.001

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Citations (17)

Image indexing using 3D model for image retrieval

Soo‐Chang Pei Hsin‐Hua Liu Jun-Horng Chen

Content-based image retrieval (CBIR) is an interesting but difficult topic of research. It uses the visual features to achieve the image searching on database. In this paper, we propose an image indexing for CBIR based on color feature, which consider both the computational complexity and the spatial relationship. We use a 3D mathematical model to design the color codebook and exploit the feature of the query image to adopt it. In the experiments, we discuss the three parameters affecting the performance and find out the corresponding optimal value to raise the retrieval speed and accuracy. Besides, we also demonstrate that the proposed scheme is robust for some image distortions and best matches human perception overall.

Content-Based Image Retrieval

Feature (linguistics)

10.1109/vcip.2011.6115916

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Citations (1)

Hiding multiple data in color images by histogram modification

Proceedings of the 17th International Conference on Pattern Recognition, 2004. ICPR 2004. (2004)

Soo‐Chang Pei Yi‐Chong Zeng

We present a new histogram-based data-hiding algorithm that secret data is embedded in the least significant bit of the histogram value. To change the pixel value, it alters the histogram to accomplish data-hiding work. In the proposed algorithm, it is able to perform data hiding on the one-dimension histogram, two-dimension histogram map and three-dimension histogram cube. Besides, the multiple secret data hiding in various combinations of histogram spaces are successfully demonstrated in our experimental results. In addition, the natural and limited color images are tested in our experiments.

Balanced histogram thresholding

Image histogram

Color histogram

Adaptive histogram equalization

Color normalization

10.1109/icpr.2004.1333893

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Citations (2)

Split-radix generalized fast Fourier transform

Signal Processing (1996)

Soo‐Chang Pei Tzyy-Liang Luo

Split-radix FFT algorithm

Rader's FFT algorithm

Convolution (computer science)

Prime-factor FFT algorithm

Radix (gastropod)

10.1016/s0165-1684(96)00103-x

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Citations (15)

Design of two-dimensional FIR digital filters with specified magnitude and group delay responses by analytical least-squares method

Signal Processing (1996)

Soo‐Chang Pei Jong-Jy Shyu

10.1016/s0165-1684(96)00113-2

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Citations (2)

What can be seen in a noisy optical flow field projected by a moving planar patch in 3D space?

Pattern Recognition (1997)

Soo‐Chang Pei Lin-Gwo Liou

Optical Flow

Motion field

Parallax

10.1016/s0031-3203(96)00174-4

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Citations (3)

Equiripple phase design of complex all-pass networks

Jong-Jy Shyu Soo‐Chang Pei

A new method is proposed for designing complex all-pass IIR filters, the all-pass IIR filters with complex coefficients, in this paper. By minimizing the integration of certain square phase error over interested frequencies, an eigenvector of an appropriate real, symmetric and positive-definite matrix is computed to get the filter coefficients. The stability is achieved by specifying properly the desired phase specifications. If an appropriate iterative process is used, equiripple complex all-pass filter design can be obtained. The method is simple and the performance is comparable to the existing methods. Several examples are presented to demonstrate the effectiveness of the approach.

2D Filters

Linear phase

Matrix (chemical analysis)

10.1109/apccas.1994.514555

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Citations (0)