Yunjie Pang

An Application of Fourier-Mellin Transform in Image Registration

Fourier-Mellin transform (FMT) is frequently used in content-based image retrieval and digital image watermarking. This paper extends the application of FMT into image registration and proposes an improved registration algorithm based on FMT for the alignment of images differing in translation, rotation angle, and uniform scale factor. The proposed algorithm can eliminate the conversion from Cartesian to log-polar coordinates, avoid the process of interpolation required in the conversion, and obtain a more significant improvement than the conventional method using cross-correlation. Experiments show that the algorithm is accurate and robust regardless of white noise

The Transmitted Strategy of Proxy Cache Based on Segmented Video

Using proxy cache is a key technique that may help to reduce the loads of the server, network bandwidth and startup delays. Basing on the popularity of clients’ request to segment video,we extend the length for batch and patch by using dynamic cache of proxy cache for streaming media. Present transmission schemes using dynamic cache such that unicast suffix batch, unicast patch, multicast patch, multicast merge and optimal batch patch by proxy cache based on segmented video. And then quantitatively explore the impact of the choice of transmission scheme, cache allocation policy, proxy cache size, and availability of unicast versus multicast capability, on the resultant transmission cost.

A new approach to estimating fundamental matrix

A new linear approach to estimating the fundamental matrix is proposed in this paper. The approach is based on the orthogonal least-squares technique for estimating the fundamental matrix. Using eigenvectors corresponding to the two smallest eigenvalues achieved by the technique mentioned above, we construct a 3x3 generalized eigenvalue problem. The solutions to the problem give not only the fundamental matrix but also the corresponding epipoles. The performance of the new approach is compared with several existing linear methods. It is shown that the approach achieves the higher accuracy.

The batch patching algorithm using dynamic cache of proxy for streaming media

The proxy cache for streaming media is the important method to economize the resources of the Internet. The cache policies influence the effect for proxy cache. In this paper, based on the clients request rate, cached the video based on segment, we proposed that the policies for batch, patch and batch patching using dynamic cache. The policies of batch and batch patching using dynamic cache based on segment enlarge the width of the batch and patching. It combines dynamic cache based on segment with the excellence of patch. Presented that allocation relation of the cache between the batch and patch using dynamic cache, and assured that batch patching using dynamic cache of proxy based on segment is optimal.

Robust estimation of the fundamental matrix based on an error model

A new method is presented for robustly estimating fundamental matrix from matched points. The method comprises two parts. The first uses a robust technique - the random sample consensus (RANSAC) to discard outliers in an initial set of matched points. It adopts the sampling strategy to generate inliers from the initial set. The second part of the method is an algorithm for computing fundamental matrix, using the output of the RANSAC. This algorithm is based on the consistent fundamental matrix estimation in a quadratic measurement error model. An extended system for determining the estimator is proposed, and an efficient implementation for solving the system - a continuation method is developed. The proposed algorithm avoids solving total eigenvalue problems. Results for both synthetic and real images show the effectiveness of the proposed method.

The Strategy of Batch Using Dynamic Cache for Streaming Media

The batch is an important technique for delivering video over Internet or VoD. It is a key method to improve effect for video multicast. In this paper, we research the batch strategy of proxy cache for streaming media using dynamic cache, proposed the three kind of cache algorithm for proxy cache: window batch, size batch, efficient batch. These methods increased the length of batch, solved the problem for latency time of batch in video muticast, improved the byte-hit ratio of proxy cache for streaming media, and economized the resources of network backbone. Event-driven simulations are conducted to evaluate these kinds of strategy are better than prefix cache and segment cache.

ADAPTIVE DIRECTIONAL WEIGHTED MEDIAN FILTERING

A novel filtering algorithm called adaptive directional weighted median (ADWM) filtering is proposed. The ideas of the directional filtering and the weighted median filtering are combined with each other to construct the ADWM filter model, which is a highly nonlinear image smoothing and enhancement technique. The use of the variance of the moving window and the base variance supports the adaptivity of the ADWM filter. The ADWM filter has the features of directional filter, which is especially effective at preserving edges, and the features of center weighted median (CWM) filter, which can reduce random noise, and moderate (amounts) of impulsive noise also, to some extent, as well as preserve the details via adaptively determining the weight of the center pixel according to the lowest variance of pixels within all the sub-windows.

Method for acoustic leak detection of fast reactor steam generator using maximum modulus based on wavelet transform

It is one of the important measures for safe operation of the fast reactor to use technology of acoustic leak detection to detect water/steam leak of the fast reactor steam generator. Based on experimental data about sodium loop experiment completed by the Liquid Metal Laboratory of Tsinghua University, this paper makes an analytical study on how to introduce maximum modulus theory of wavelet transform into leak detection. Result shows that at high temperature (350 /spl deg/C), maximum modulus characteristics of signal can be used to make correct judgment on occurrence of leak occurred. In case of small leak at low temperature (250 /spl deg/C), maximum modulus characteristics of wavelet transform of the signal are not obvious, but it will become visible gradually with increase of leak rate.

A fast algorithm for image analogy using particle swarm optimization

This work employs particle swarm optimization (PSO) based texture synthesis approaches, it differs from the pixel-based texture synthesis method, in this way, and the synthesis speed is increased. We apply particle swarm optimization (PSO) to improve the process of searching and matching in patch-based texture synthesis, change the throughout search method of the original algorithm; speed up the process of synthesis without influencing the quality of the image. This algorithm also accomplishes orientation control of matching patches in structure and details through appropriate parameter setting. In our proposed approach, only a single input sample is required to achieve desirable analogy results.

The patched algorithm of dynamic cache for streaming media

The patch is an important technique for delivering video over the Internet or VoD. It is a key method to improve the effect for the video server. We research the patch technique of proxy cache for streaming media using dynamic cache, and propose three kinds of patch strategy using dynamic cache: window patch; size patch; efficient patch. These methods increase the patch length, solve the problem of using the patch channel of the video server, improve the byte-hit ratio of the proxy cache for streaming media, and economize the resources of the network backbone and the video server. Event-driven simulations are conducted to evaluate whether these kinds of strategy are better than prefix cache and segment cache.