Zhiwen Xu

The blood vessel recognition of ocular fundus

Today, iris recognition, fingerprint recognition, face recognition, voice recognition and other biometric technology are experiencing rapid development. This paper addresses a new biometric technology - skeleton recognition for blood vessel of optic fundus. The green grayscale ocular fundus image is utilized. The skeleton feature of blood vessel of optic fundus is extracted at first. After filtering treatment and extracting feature, vector curve of blood vessels is obtained. Shape curve matching is later carried out by means of reference point matching. The recognition for blood vessel optic fundus has been demonstrated in this paper to possess high recognition rate, low recognition rejection rate as well as good universality, exclusiveness and stability. With more and more progress made in extracting technology, the optic fundus blood vessel recognition is to become an effective biometric technology.

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.

An adaptive soft-morphological-gradient-filter-for-edge-detection

In this paper, a novel adaptive soft morphological gradient (ASMG) filter is proposed, based on a combination of the idea of the soft morphological filtering and the adaptive technique. ASMG filtering is an efficient nonlinear sharpening method, which can be applied for edge detection. By employing four directional structuring elements, ASMG filtering has the capability of selecting the directional structuring element with the maximum response, whose direction varies depending on the change of directional edges. In addition, by comparing the variance of the moving structuring window with the base variance, the ASMG filter provides an adaptive algorithm for morphological operations. The experimental results show that the ASMG filter is better than the traditional operators in edge detection and noise suppression.

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.

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.

Noise suppression of fluorescein angiogram sequences using bilateral filter

In this paper, a relatively flexible filter called extended bilateral filter is proposed, by which some particular filters can be designed via selecting an appropriate pixel of interest (POI) and defining a kernel for the filter according to some specified requirements. Based on the filter, a fluorescein-angiogram-oriented filter, high-intensity preserving (HIP) filter is introduced to solve the problems of high-intensity preservation when denoising. The results of the experiments show that the HIP filter has the ability of noise suppression, and the ability of high-intensity preservation, which can keep the intensities of bright pixels from degrading via distributing the weights adaptively according to the location and the intensity of each pixel.

An EAWA Filter for Denoising of Filtering of Fluorescein Angiogram Sequences

In this paper, a novel filter model called extended adaptive weighted averaging (EAWA) filter model is proposed, by which some particular filters can be designed via selecting an appropriate pixel of interest (POI) and defining a weight distribution function for the filter according to some specified requirements. Based on the novel model, a fluorescein-angiogram-oriented filter, high-intensity preserving (HIP) filter is introduced to solve the problems of high-intensity preservation when filtering noise. The results of the experiments show that the HIP filter has the features of frame-averaging, which can achieve noise suppression efficiently, and the features of high-intensity preservation, which can keep the intensities of bright pixels from degrading via distributing the weights adoptively according to the intensity of each pixel

The Dynamic Cache-Multicast Algorithm for Streaming Media

The transmission of large capacity and high bit rate for streaming media becomes a challenging study problem for the Web application. The proxy cache for streaming media is an efficient method to solve this problem. In this paper, we proposed the algorithm of dynamic cache-multicast based on partial cache method such as the prefix cache, segmentation-based cache et al. The idea of the algorithm is using a dynamic cache to keep partial media object requested by users in an interval time. The advance is that reference frequency of partial media in interval time is higher than that of full media requested by users. The dynamic cache-multicast algorithm enhances the efficiency of proxy cache for streaming media, mitigates network burden from content server, and saves the traffic resource for network backbone. Event-driven simulations are introduced to evaluate this algorithm is very efficient.

The powered method of proxy cache for streaming media

High capacity and high bit rate transmission for streaming media becomes a challenging study problem for Web applications. The proxy cache for streaming media is an efficient method to solve this problem. We propose a dynamic cache-multicast algorithm based on a partial cache method, such as prefix cache, segmented cache, etc. The idea of the algorithm is to use a dynamic cache to keep a partial media object requested by clients in a time interval. The advance is that the reference frequency of the partial media in a time duration is higher than that of the full media requested by clients. The cache-multicast method enhances the efficiency of proxy cache for streaming media, mitigates the network burden from the content server, and saves the traffic resources for the network backbone. Event-driven simulations introduced to evaluate this algorithm show that it is very efficient.