A modified image enhancement algorithm based on color constancy

According to the color constancy theory, a modified variation Retinex is proposed for improving the visibility of the dark regions in images under insufficient and/or non-uniform lighting conditions. A new penalty functional based on nonlinear diffusion and correlation between the reflectance and the given image is designed for the intensity image enhancement, followed by adaptive color compensation. With high computational efficiency achieved by an improved multi-resolution algorithm, simulation results prove that the proposed method shows more colorful and vivid visual performance, and achieves wider dynamic range with higher objective standard values.     

LED大屏幕空间显色恒定性

通过两组三基色LED(发光二极管 )样品色度和光强空间分布的测量 ,计算了由这两组LED制作的大屏幕再现的D6 5白平衡点、我国青年女性面部肤色、红旗丝织绸、蓝布和绿滤色片等五种色样在CIELUV均匀颜色空间的色度随观察角 ( 0°～ 70°)的变化及其与正向 ( 0°)再现色之间的色差。结果表明 ,LED单管光强随观察角的变化幅度和三基色管光强空间分布特性的一致性是影响大屏幕空间显色恒定性的主要因素。在确定大屏幕空间显色恒定性允差后 ,可用文中提供的方法对制作大屏幕的LED进行筛选。     

Fast and robust color constancy algorithm based on grey block-differencing hypothesis

Color constancy is a fundamental research topic in color and vision. Numerous methods have been proposed in recent years. New methods are highly accurate but tend to be more complex. This paper proposes a simple low-level statistical algorithm based on a new hypothesis, the grey block-differencing hypothesis, which states that the average of reflectance differences of adjacent blocks in a scene is achromatic. The new method has almost the same complexity as the simplest methods (i.e., grey world and max-RGB). Experimental results demonstrate that the accuracy of the proposed method is exceptional.     

A recursive color image edge detection method using Green's function approach

In this paper, an extended version of image edge detector using Green's function approach is proposed for detection of edges in the color vector space field. In the proposed method, the relationship between the Red, Green and Blue components is considered to design a differential operator for detection of edges in color images. By using the proposed operator, partial derivatives of all components of color image can simultaneously affect on the edge detection process. Therefore the proposed method can preserve the vector nature of color images during the edge processing stages. Also, the proposed method is compared both quantitatively and qualitatively with other color edge detectors. Experimental results show that the proposed method can efficiently preserve the edges even when the color images corrupted with different levels of noise.     

Color representation method using RGB color binary-weighted computer-generated holograms

We propose a method for color electroholography using a simple red–green–blue(RGB) gradation representation method without controlling the respective brightness of the reference RGB-colored lights. The proposed method uses RGB multiple bit planes comprising RGB binary-weighted computer-generated holograms with various light transmittances. The object points of a given three-dimensional(3D) object are assigned to RGB multiple bit planes according to their RGB gradation levels. The RGB multiple bit planes are sequentially displayed in a time-division-multiplexed manner. Consequently, the proposed method yields a color gradation representation of a reconstructed 3D object.     

Color image edge detection method using VTV denoising and color difference

The traditional Canny edge uses Gaussian filter to suppress the noise, it also smoothes out the image edges. An improved Canny edge detection method for color image is proposed in this paper, the improved method uses fast vectorial total variation (VTV) minimization model to remove noise in color image, and then calculates the color difference and direction in CIELAB color space, which is used for non-maximal suppression. Finally, the improved method extracts the edges by the double-threshold method. The experimental results show that the proposed method achieves better performance than the traditional Canny edge detector. It can remove noise while preserving the image edges, and effectively detect the image edges.     

Efficient evaluation of edge diffraction integrals using the numerical method of steepest descent

For the problem of edge diffraction from an edge of finite length a frequency-domain solution, obtained from an analytical time-domain solution, has been presented by Svensson et al. [Acta. Acust. Acust. 95, 568-572]. This formulation takes the form of a Fourier-type integral whose evaluation is expensive in the high frequency range. This paper demonstrates that by using tailored highly oscillatory quadrature methods based on asymptotic properties of the integral, accurate approximations in the high frequency case can be obtained with little computational effort.     

研究椭圆积分物理问题的一种方法

在一些力学问题的研究中,严格的求解必须进行椭圆积分,这使问题变得复杂．但如果运用被积函数的某些性质,通过简单的数学运算,就可以化难为易,得到问题定性的、大致的结果．     

A complete method for efficient fuzzy modal analysis

The objective of this paper is to determine both the fuzzy eigenvalues and eigenvectors of a finite element model defined with fuzzy parameters. The proposed method introduces the concepts of mode shape pairing and the functional dependence of eigensolutions with respect to design parameters. High-order approximations are then introduced to limit the computational cost associated with variability management. Numerical test cases are used to highlight the abilities of this method to predict behaviour modifications due to variations in the physical parameters.     

A new method of ultrasound color flow mapping

Conventional ultrasound color flow mapping systems estimate and visualize only the axial velocity component. To obtain the transverse velocity component a modification of a multiple-beam method is proposed. The new two-dimensional color flow mapping system has a small size and consists of three transducers. The central transducer is an appodized and focused phased array. The other transducers are unfocused probes. Three transducers act as receivers and the central transducer operates as a transmitter. All receivers acquire rf scan lines that are then processed to estimate three axial velocity components using an autocorrelation method. These estimates are then combined to estimate the transverse velocity component, taking into account the geometric relationships among three transducers. Two algorithms for transverse velocity estimation are proposed. The first uses the Doppler angle estimate for calculation of the transverse velocity component. The other algorithm calculates the transverse velocity component directly from the axial components. The accuracy of the flow velocity estimators is estimated by simulations. Analysis of accuracy allows choosing the more effective algorithm for two-dimensional velocity estimation, which is insensitive to variations of the Doppler angle.     

New color correction method for multi-view video using disparity vector information

Color inconsistency is an urgent problem to be solved in free viewpoint television. In this letter, a new color correction method is proposed by using disparity vector information. At first, we separate foreground and background from the scene with a method of mean-removed disparity estimation. Then the correction parameters are estimated by adopting linear fitting for foreground and background regions, respectively. Next, with expectation-maximization algorithm, we integrate correction parameters of foreground and background to get the final corrected image. Finally, video tracking technique is performed to correct multi-view video. Experimental results show that the proposed method is quite effective.     

Statistical measures derived from the correlation integrals of physiological time series

In this work correlation integrals are used for the analysis of various EEG signals from rabbits in resting states and under the influence of an anesthetic. The comparison with surrogate data reveals nonlinear dynamics in all of the time series. Our attempt to determine the correlation dimension D(2) by the modified algorithm of Theiler [Phys. Rev. A 34, 2427 (1986)] failed since no saturation is reached with increasing embedding dimension. The hypothesis of low-dimensional chaos turns out to be inconsistent with our results, but we can still distinguish, at least qualitatively, between different states of brain dynamics. A quantitative characterization of the time series is possible by defining correlation parameters P(a) derived from correlation integrals reflecting also autocorrelation of the signal. (c) 1996 American Institute of Physics.     

Evaluation of the integrals of target/seabed scattering using the method of complex images

In this paper the integrals which arise in target/seabed scattering problems are examined. These are the integrals which express the propagation of a spherical harmonic term in a fluid above or below a half-space and the integrals which compute the conversion coefficients of outgoing spherical harmonics into incident spherical harmonics after a seabed reflection. A very efficient and accurate method of computing these integrals, using the method of complex images, is derived. Numerical comparisons with the exact integral expressions show the accuracy of this approach.     

A method of making a true color stereoscopic hologram

A true color stereoscopic hologram is made with one-wavelength laser. Under illuminating incandescent lamp, a true color stereoscopic image can be seen from the hologram. A diffused reference light and a project object light are used in the recording of the hologram. The three primary color images of natural scenery are encoded on a white-and-black film. With the help of the encoded film, a true color hologram is recorded on a plate by single exposure and a true color stereoscopic by two exposures. The simplification of this method is apparent. Further more, it largely decreases the scattering noise of the hologram and averts the problem of color lack fidelity of the holographic image.     

A collocation reliability analysis method for probabilistic and fuzzy mixed variables

The main bottleneck of the reliability analysis of structures with aleatory and epistemic uncertainties is the contradiction between the accuracy requirement and computational efforts.Existing methods are either computationally unaffordable or with limited application scope.Accordingly,a new technique for capturing the minimal and maximal point vectors instead of the extremum of the function is developed and thus a novel reliability analysis method for probabilistic and fuzzy mixed variables is proposed.The fuzziness propagation in the random reliability,which is the focus of the present study,is performed by the proposed method,in which the minimal and maximal point vectors of the structural random reliability with respect to fuzzy variables are calculated dimension by dimension based on the Chebyshev orthogonal polynomial approximation.First-Order,Second-Moment(FOSM)method which can be replaced by its counterparts is utilized to calculate the structural random reliability.Both the accuracy and efficiency of the proposed method are validated by numerical examples and engineering applications introduced in the paper.