Image segmentation with scalable spatial information

A general approach is proposed for the design of image segmentation algorithms utilizing spatial information which is the combined properties of a collection of neighborhood pixels. With different types of properties and different number of neighborhood pixels being utilized, segmentation algorithms with different speed and accuracy performance can be designed. Six algorithms have been implemented with their performance investigated and compared.published_or_final_versio

An Analytic Theory for the Orbits of Circumbinary Planets

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Maximum a posteriori spatial probability segmen

An image segmentation algorithm that performs pixel-by-pixel segmentation on an image with consideration of the spatial information is described. The spatial information is the joint grey level values of the pixel to be segmented and its neighbouring pixels. The conditional probability that a pixel belongs to a particular class under the condition that the spatial information has been observed is defined to be the a posteriori spatial probability. A maximum a posteriori spatial probability (MASP) segmentation algorithm is proposed to segment an image such that each pixel is segmented into a particular class when the a posteriori spatial probability is a maximum. The proposed segmentation algorithm is implemented in an iterative form. During the iteration, a series of intermediate segmented images are produced among which the one that possesses the maximum amount of information in its spatial structure is chosen as the optimum segmented image. Results from segmenting synthetic and practical images demonstrate that the MASP algorithm is capable of achieving better results when compared with other global thresholding methods.published_or_final_versio

Ultrasonic Detection using Wideband Discrete Wavelet Transform

This paper describes the design of a wideband spatial processor for the detection of a straight-line object by an ultrasonic pulse-echo detection system. An ultrasonic pulse is transmitted from the transducer and the two wavelets diffracted from the two end points of the straight-line object are received by three spatially separated receivers. Three stages of signal processing are carried out. At the first stage, the mother wavelet operator generates three sets of two-dimensional wavelet coefficients. At the second stage, cross wavelet transforms are performed on wavelet coefficients obtained in the first stage. At the third stage, cross wavelet transforms are performed on cross wavelet coefficients obtained in the second stage. As a result of this three-stage operation, a high-resolution image of the environment is generated and the range and bearing of the two end points of the straight-line object are obtained. A simulation program is developed to investigate the processing algorithm in an ultrasonic detection environment.published_or_final_versio

An iterative image segmentation algorithm utilizing spatial information

An iterative image segmentation algorithm that segments an image on a pixel-by-pixel basis is described. The observation information to be utilized is the joint gray level values of the pixel to be segmented and those of its neighborhood pixels. The iterative process is initialized by thresholding the image with Otsu's (1979) method. Each pixel is segmented into a class when the a posteriori probability, conditioned on the observation information, that it belongs to this class is a maximum. The newly segmented image is employed to re-estimate the a posteriori probabilities and the segmentation process is repeated until there is no further pixel classification change in a particular run. Among those segmented images generated in the iterative process, the best segmented image is chosen, according to a maximum entropy criterion. Simulation studies demonstrate that the proposed algorithm can achieve very significant improvement in segmentation performance as compared to the more popular thresholds approach. Furthermore, the performance is neither sensitive to the initial threshold value nor the form of the probability density function of the image. Segmentation of practical images also demonstrates that the proposed algorithm is capable of good segmentation results for real-life images.published_or_final_versio

The control of switching dc-dc converters : a general LQR problem

Author name used in this publication: C. K. LiVersion of RecordPublishe

An improved LQR-based controller for switching dc-dc converters

Author name used in this publication: C. K. LiVersion of RecordPublishe

Parameter control by the entire search history: Case study of history-driven evolutionary algorithm

Special Session on Evolutionary Computer VisionHistory-driven Evolutionary Algorithm (HdEA) is an EA that uses the entire search history to improve searching performance. By building the approximated fitness landscape and estimating the gradient using the entire history, HdEA performs a parameter-less adaptive mutation. In order to decrease the number of parameters that makes the HdEA more robust, this paper proposes a novel adaptive parameter control system. This system is as an add-on component to HdEA, which uses the whole search history in HdEA to control the parameters in an automatic manner. The performance of the proposed system is examined on 34 benchmark functions. The results shows that the parameter control system gives similar or better performance in 24 functions and has the benefit that two parameters of the HdEA are eliminated; they are set and varied automatically by the system. © 2010 IEEE.published_or_final_versio

A longitudinal study of infection attack rates among hospital outpatients in Hong Kong during the epidemic of the human swine influenza A/H1N1 virus in 2009 by tracking temporal changes in age-specific seroprevalence rates

Poster Presentations: Emerging / Infectious Diseases: abstract no. P110-Ab0092Conference Theme: Translating Health Research into Policy and Practice for Health of the Populationpublished_or_final_versio

Emission mechanism of GeV-quiet soft gamma-ray pulsars: a case for peculiar geometry?

postprin