激光大屏幕显示中图像点数的研究

本文研究了大屏幕显示中的光学振镜扫描机理,探讨了增加像点数的途径.

Domain-based noise removal method using fourth-order partial differential equation

Due to the fact that the fourth-order partial differential equation （PDE） for noise removal can provide a good trade-off between noise removal and edge preservation and avoid blocky effects often caused by the second-order PDE, a domain-based fourth-order PDE method for noise removal is proposed. First, the proposed method segments the image domain into two domains, a speckle domain and a non-speckle domain, based on the statistical properties of isolated speckles in the Laplacian domain. Then, depending on the domain type, different conductance coefficients in the proposed fourth-order PDE are adopted. Moreover, the frequency approach is used to determine the optimum iteration stopping time. Compared with the existing fourth-order PDEs, the proposed fourth-order PDE can remove isolated speckles and keeps the edges from being blurred. Experimental results show the effectiveness of the proposed method.

A Non-symmetric Digital Image Secure Communication Scheme Based on Generalized Chaos Synchronization System

Based on a generalized chaos synchronization system and a discrete Sinai map, a non-symmetric true color （RGB） digital image secure communication scheme is proposed. The scheme first changes an ordinary RGB digital image with 8 bits into unrecognizable disorder codes and then transforms the disorder codes into an RGB digital image with 16 bits for transmitting. A receiver uses a non-symmetric key to verify the authentication of the received data origin, and decrypts the ciphertext. The scheme can encrypt and decz：Fpt most formatted digital RGB images recognized by computers, and recover the plaintext almost without any errors. The scheme is suitable to be applied in network image communications. The analysis of the key space, sensitivity of key parameters, and correlation of encrypted images imply that this scheme has sound security.

Non-Gaussian Phase Screen Based on log-Poisson Distribution and Effect on Imaging

Gaussian models without intermittency are extensively used in estimating the effect of turbulence,but italso brings some puzzles,for example the observed pulse shape that disagrees with the result of the standard theoryof interstellar scintillations.Indeed the property of intermittency is inherent in turbulence,i.e.,all the quantities thatcharacterize it suffer from strong fluctuations.So it is necessary to consider turbulent intermittency in many applications.In this paper we propose a non-Gaussian phase screen,which obeys log-Poisson statistics,and also offers the correspondingpoint spread function(PSF).These results describe that intermittency leads to the more extent and different directionaldistribution of PSF.Theoretical analysis is made under the hypothesis of the phase difference satisfying log-Poissonstatistics,and the average point spread function,which accord qualitatively with the result of the above generated phasescreen,is derived.

Mutual Information for Image Registration

Image registration is the overlaying of two images of the same scene taken at different times or by different sensors. It is one of the essential steps in information processing in remote sensing. To attain a highly accurate, reliable and low computation cost in image registration a suitable and similarity metric and reduction in search data and search space is required. In this paper, the author shows that if the right bin size is chosen, mutual information can be more robust than correlation in the registration of multi-temporal images. The author also compares the sensitivity of mutual information and correlation to Gaussian and multiplicative speckle noise. The author investigates automatic subimage selection as a reduction in search data strategy. The author proposes a measure, called alienability, which shows the ability ofa subimage to provide reliable registration. Alternate subimage selection methods such as using gradient, entropy and variance are also investigated. The author furthermore looks into a search space strategy using a gradient approach to maximize mutual information and show our first results.

Research on the Influence of X-ray Phase Contrast Imaging Parameters with Micro-focus Source

X-ray in-line phase contrast imaging enables weakly to absorb specimens to be imaged successfully with high resolution and definition. In this paper we use computer simulation method to analyze how each parameter influences the quality of the image. It can avoid wasting unnecessary time and materials in the course of experiment to get ideal images.

An Improved Fixed-point Algorithm for Independent Component Analysis of Functional MRI Data

The fixed-point algorithm and infomax algorithm are two of the most popular algorithms in independent component analysis(ICA).However,it is hard to take both stability and speed into consideration in processing functional magnetic resonance imaging(fMRI)data.In this paper,an optimization model for ICA is presented and an improved fixed-point algorithm based on the model is proposed.In the new algorithms a small step size is added to increase the stability.In order to accelerate the convergence,an improvement on Newton method is made,which makes cubic convergence for the new algorithm.Applying the algorithm and two other algorithms to invivo fMRI data,the results show that the new algorithm separates independent components stably,which has faster convergence speed and less computation than the other two algorithms.The algorithm has obvious advantage in processing fMRI signal with huge data.

A Brief Introduction of the Achievements of Key Project Image-based Modeling and Rendering for Virtual Reality Applications

1. Background The virtual reality （VR） technology is now at the frontier of modern information science. VR is based on computer graphics, computer vision, and other fresh air topics in today＇s computer technology. Nowadays the VR technology has been applied successfully in variety of fields such as military simulation, industry, medical training and visualization, environment protection and entertainment.