最新刊期
卷 9 ， 期 4 ， 2004
- 摘要：Speckle noise is an intrinsic property of Synthetic Aperture Radar (SAR) imagery. The demand for speckle reduction of SAR images is to smooth the speckle noise while preserving the structure information of the original images. Existing speckle suppression methods possess respective merits and drawbacks, without universal adaptability. Integrating the statistical characteristic of speckle noise in SAR images with wavelet domain hidden Markov models (HMMs) structure of images, we propose a new wavelet domain speckle reduction method. Simulation and experimental results using real data show that the proposed method is able to effectively suppress speckle noise and to better retain edge structure. Compared with wavelet domain soft thresholding denoising algorithm and Lee multiplicative speckle filter, the wavelet domain HMMs method offers significant improvements on smoothing speckle and preserving edge. In addition, the proposed method also gets a better visual effect.2897|215|0更新时间：2024-05-08
- 摘要：A new kind of infrared image adaptive contrast enhancement approach based on simulated annealing algorithm and incomplete Beta function is given. Firstly, an efficient criterion is given based on gray level histogram of input image. Input image contrast type is determined by the criterion mentioned above, and then the criterion is used to determine the searching space of gray transformation parameters and guide the search orientation and the selection of initial values of simulated annealing algorithm. The optimal gray transformation parameters are obtained in the parameter space with the simulated annealing algorithm. Thus an optimal gray transformation curve is obtained and global contrast enhancement is done to the input image based on the optimal gray transformation curve. The performance of the new approach is analyzed. Lots of experiments have been done in order to validate the efficiency of the new approach. Based on the experimental result, the new approach can enhance the global contrast of the infrared image effectively while it also keeps the details of the target in the infrared image well. In visual quality, the new approach is better than traditional histogram equalization method and un sharp mask method.3141|189|0更新时间：2024-05-08
- 摘要：Choosing auto focusing evaluation function for images is a key factor for passive auto focusing system of automatic microscope. The basic requirements for a practical auto focusing system are speed, sharpness and robustness to noise. With the relationship between focused and defocused images of a scene, some well known focusing measures (such as gradation variance operator, gradation gradient operator and energy spectrum measure) have been investigated. Based on them, a sum modified Laplacian (SML) operator has been proposed as focusing measures for the first time. The operator is applied to measure the relative sharpness of image sequence at different object distances. Step and threshold are introduced to effectively alleviate the effect of the noise. All of the above mathematical models have been analyzed and compared. Experimental results are presented that demonstrate the accuracy and robustness of the proposed method. The results show that the SML operator is more accurate, stable and reliable than other auto focusing evaluation functions for microscopy images. The algorithm has been applied successfully to automatic focusing system of microscope and testified to be feasible and effective.3288|221|0更新时间：2024-05-08
- 摘要：By using image difference and gray stretch technique, image histogram analysis method was used to investigate the movement of particles in image sequence. The result shows that the movement of particles has close relation with the dispersivity of pixels' greyvalue. The number of pixels with high brightness indicates the fierceness of particles. The brightness of pixels with similar grayscale will decrease with the slowdown of particles. After eliminating the influence of noise and taking consider of the gray level of pixels within certain range, a weight factor based on logarithm function was introduced to evaluate the intensity of particles' movement. Application of this algorithm in image sequence of fluidized bubble verifies the validity of this method.2673|232|0更新时间：2024-05-08
- 摘要：Usually,there is guass noise and isolated noise in many nature images simultaneously.And it is difficult to getting rid of guass noise and isolated noise only by Median filter or Mean filter at the same time. In allusion to this question, Lee and Kassam proposed an improved algorithm of mean filter. Although they have maked an great improvement, the effect of MTM is still not ideal. It is a threshold that consumedly affect the effect of MTM.In this article ,we preposed an improved method of median.filer on the basis of analysing the character of MTM and traditional filter method. This new method applies auto-adapted operators on theN×Narea of every point in the processed image.For the different area of the image,the operators are different too.The election of operator weight mostly depends on the median ofN×Narea. The more the gray value be close to the median ,the more the weight of operator is strong. In real application, the new method not only shows better performance than the MTM filter, but also is not affected by any threshold.5485|266|0更新时间：2024-05-08
- 摘要：This paper presents an ordering threshold switching median filter to solve the contradiction between noise attenuation and image detail preserving. From the ordering information of the pixels in the window, and based on extremum median filtering the image corrupted by impulse noise is divided into three pixel classes, that is, noise pixels, edges and details, and smooth regions. With the statistic of a lot of standard images tested, the parameters of the classifier are properly chosen in order to deal with most images adaptively. Then switching median filtering is applied with the classifier. Therefore the smooth regions and noise pixels are filtered by median filters that have a good noise removing capability, especially with the 'salt and pepper' noise. However, most of the edges and details of the image are untouched, so that the restored image can keep details even in variable magnitude impulse noise conditions. A comparison of median filter, extremum median filter and the method in this paper is provided both in subjective images and objective MAE and MSE data. Obviously, the results indicated that the new method has better properties.3678|236|0更新时间：2024-05-08
- 摘要：In this paper, an automatic and robust image mosaic algorithm is presented. In this algorithm, Harris corner detector is used to extract feature points, which gains sub pixel precision for features extraction. Then, a pseudo matching set is obtained by comparing local neighborhoods of features through intensity cross correlation method and these pseudo matches are divided into inliers and outliers using robust RANSAC algorithm. In the inliers sub set, LM algorithm is used to estimate the point transformation matrix between two images accurately. In the end, the image color of the overlapping band is smoothed with bilinear interpolation technique. The whole algorithm is completed automatically. It filters the noisy or wrong input data iteratively, then estimates the model parameters through pure data, so it has strong error tolerant capacity for the image noise and inaccuracy of feature extraction. When estimating the model parameters, the energy function is constructed based on the position errors of features instead of the features' intensity errors, which conquers the original methods' shortcoming of sensitivity to illuminating conditions and makes this algorithm more practical. Experimental results show the image mosaic effect is wonderful and the algorithm is stable very much. It is high valuable in practice.4330|343|0更新时间：2024-05-08
- 摘要：In this paper a novel method for image superresolution is proposed. The primary theory is proved that the 2-dimension image data can be approximated by the products of 1-dimension functions whose variables are separated from the image' s variables. Therefore, the image superresolution can proceed conveniently through the 1-dimension superresolution. Concretely, the digital image (M×N) can be expressed by the summation of the products ofM-dimension vectors andN-dimension vectors. So the image superresolution process can be converted to the M-dimension vector processing and theN-dimension vector processing easily. Thus the method is based on the eigenvectors. In the mean-square-error sense, this expression or decomposition is optimum. It is also proved to be identical with the literature[3] when the hits go to infinite. At last the applications verify the theoretical result. Namely, this method has the better results and can reduce the calculations because the image can be adjusted adaptively and be expressed by the less parameters. In addition, this method can also be applied to other fields of image processing and the information processing of the great-capacity data.3156|214|0更新时间：2024-05-08
- 摘要：To implement accurate metric measurement within a large field of view with common off the shelf cameras, the image distortion caused by wide angle lenses should be corrected. A simple and precise method for calibrating the radial distortion is proposed. Any planar pattern in which the feature points form a grid can be used to obtain the calibration image. The proposed method first constructs an ideal image based on the positions of feature points extracted from the distorted image. Then the radial coordinates of the distorted and ideal feature points are calculated under the hypothesis of given center of distortion, and the relation function between the ideal and distorted radial coordinates is obtained by solving linear equations or by polynomial fitting. The set of parameters with the minimum mean square error is regarded as the calibration result. One merit of the proposed method is that both the undistorted to distorted and distorted to undistorted expression can be obtained at the same time by the same way. Moreover, the inverse power proportion relation between calibration result and resolution of rectified image is derived, and the influence of the order of distortion function on rectified image is discussed. Experiment results show that 4th or 5th order function would result better outcome.4344|252|0更新时间：2024-05-08
- 摘要：This paper considers the problem of estimating image features in an image from image features in two other images. The problem in computer vision has a wide practical appliance, such as Visual Recognition, model based vision Animation, View Synthesis, and object detection and tracking. O.Faugeras and L.Robert have shown that features can be estimated in the third image as a bilinear function of its image in the first two cameras. Since relied on the use of the given fundamental matrix, the method has a serious deficiency that rules it out as a practical approach. In this paper, a new method was provided to estimate image features in the third image based on the trifocal tensor, and, obviously, it is continuous and development of the former. Furthermore, a theorem given in this paper shows that the condition is as weak as the one provided by O.Faugeras, but the method is simpler and more systemic. Finally, the applicability of the method was demonstrated with experiments on synthetic and real data.2938|202|0更新时间：2024-05-08
- 摘要：Choosing a good interpolating template is the key to better recover the subsampled image with low distortion. In this paper, by analysis of a novel 1-dimension overlapping digital filter in frequency domain, the corresponding model of FIR filter and the condition for linear phrase are presented. According to the above result, the ways to design 2-dimension interpolating template without window、with single and double windows are respectively introduced. Transmission properties of 7×7 templates of three systems are compared in detail, which indicates that the ripples in the pass period of windowed template are obviously much fewer than that of template without window. Among the three types of systems, template with double windows is better than that of single window and none window in smoothness but has the widest transition period. Finally, the simulations to recover the subsampled images with different frequency components by applying 7×7、11×11 and 17×17 templates are made, as well as analyzing and comparing the results. It proves that the images recovered by three types of windowed templates from subsampled image have higher SNR and better subjective and objective quality than that recovered in no overlapping way.2456|193|0更新时间：2024-05-08
- 摘要：To solve the problem of improving the quality of triangulation and its optimum speed, some exports have proposed many methods, whereas there is too much calculation and determining in these prevail methods, which has been a key question. The paper presents the algorithm for triangulation and its optimum based on angle of chord mapping parameters, and it introduces the conception of angle of chord and proves its property. And triangulation optimum is actually diagonal selection of convex quadrangle. In a convex quadrangle including two triangles, it shows the facts that angle of chords are mapped to become mapping parameters on the perpendicular bisector of two adjacent triangles' common edge, then the paper proves that mapping parameters has the same triangulation determining quality as angles of chord own one. Consequently triangulation and locale optimum is turned to a problem of mapping parameters' determining. Theoretic analysis and practicing show that the implementation of the method is very easy, the computation of mapping parameters is simple and convenient, and its result is credible; the angle of chord mapping parameter determining method has avoided calculating the angles or radiuses distances, which are necessary in conventional methods. The angle of chord mapping parameter determining method improves evidently calculation efficiency.2885|207|0更新时间：2024-05-08
- 摘要：Models merging is widely used in many domains such as geography modeling, 3D design of highway and railway route and so on, so it is essential to design an efficient models merging algorithm. The objective of this paper is to research on models merging algorithm based on Delaunay triangulation. A method of obtaining model merged intersection lines quickly and an algorithm of searching triangles on the inside of the intersection lines fast are proposed. For the purpose of implementing Delaunay triangulation models mergence, two main steps, such as insert the merged intersection lines into the Initial Delaunay Triangulation (IDT), and cut the triangles inside of the intersection lines in IDT out, are adopted. The processes of models merging are expatiated detailedly. The proposed algorithms are implemented by using VC programming language and tested by some experimental data. The experimental result validated the correctness and feasibility about the proposed algorithms.关键词：computer graphics;Delaunay triangulation;cut out;model merging;algorithm2788|176|0更新时间：2024-05-08
- 摘要：In this paper, a method for performing single view 3D reconstruction is present, in which the user provides image points and geometric information about the corresponding 3D points. The main application is to structured scene, mostly planar structures where there are plentiful constraints to be had from parallelism and orthogonality. There are two components to the reconstruction process. First, the camera calibration and metric structure of each plane is computed, that is to calibrate a square pixel camera from three vanishing points of orthogonal directions and metric rectify each plane by computing the imaged circular points and the vanishing line. The second stage involves stitching the individually rectified planes together, accounting for the arbitrary scale factors in the rectification of each plane and the relative orientation of planes not known to be orthogonal. Real image have been used to test the proposed method, and good results have been obtained and have demonstrated the proposed method is easy to use.2825|217|0更新时间：2024-05-08
- 摘要：In this paper,an improved listless zerotree coding(LZC)Algorithm is presented. LZC is an image coding algorithm that uses no list during encoding and decoding, permitting the omission of the lists requirement in Said and Pearlman's set partitioning in hierarchical trees(SPIHT) algorithm. Consequently, the memory requirement in a VLSI implementation is reduced significantly. The improved LZC algorithm not only includes the advantage of original LZC in which lists do not be used and that is implemented easily in hardware, but also improves the work efficiency of LZC and reduces the complexity of LZC by changing the coding order of spatial subbands, using the concept of block in the coding process and adopting entirely the ordinal structure in the improved LZC image compression algorithm aiming at the disadvantages of original LZC algorithm such as the unreasonable scanning order and the complicating recursive structure. Finally, the experimental results show that our proposed coding method not only has the properties of good vision effect, non square effect and no edge oscillation, but also performs better than that of original LZC algorithm in the aspects of the quality of image reconstruction and PSNR under the basis of the same ratio of compression.2761|165|0更新时间：2024-05-08
- 摘要：The image is a vital tool used for communication in the multimedia application. The real time and secure transmission of the image is important to the prevalence of the multimedia application over the Internet. However, when the image transmits over the packets loss channel such as the Internet, the receiver may wait for a long time to get the total Bit stream and then to reconstruct it to the image. This paper presents a new Fine Granular Scalable coding based on the image object, which incorporate the image object coding with the Bit plane coding. On the one hand, this algorithm has the ability granularly enhancing the quality of the image. On the other hand, it has more flexibility in controlling the ROI(region of interest)than the other coding algorithm by setting the priority of the image object and upshifting the bit plane. Firstly, this paper describes the coding framework of this algorithm and then separately discuss the key techniques such as the bit plane coding,selective enhancement,bit stream structure and the controlling strategy. At last, the experiments are given to validate the two features of this algorithm: the fine granular and the flexible control.2711|301|0更新时间：2024-05-08
- 摘要：Block matching motion estimation (BMME) plays a very important role in video coding. The performance of BMME greatly affects the quality of the encoded bit stream. Full Search (FS) is the optimal algorithm for BMME. But the tremendous computation payload of it is unaffordable for practical applications, especially for real time applications. To overcome this problem, a lot of fast algorithms were developed. In this paper, a novel fast motion estimation algorithm designed for the new video coding standard H.264/MPEG 4 AVC is proposed. Based on an adaptive search range, the proposed algorithm makes use of the statistical characteristics between successive frames and the spatial and temporal correlations among the motion vectors of adjacent blocks to speed the process of motion estimation while maintaining the PSNR with no loss. The simulation results show that the algorithm is able to fit for all types of video sequences adaptively in spite of the degree of the motions. Compared with other algorithms, it is more than 280 times faster than FS (Full Search) and more than 1.8 times faster than 3SS (3 Steps Search) in average with no PSNR loss. And it is a better one than the traditional fast motion estimation algorithms, such as N3SS (New 3 Steps Search) and 4SS (4 Steps Search).2869|220|0更新时间：2024-05-08
- 摘要：The new standard MPEG 4 not only has the excellent compression impact on the motion video , but also defines Visual Texture Coding, which is used for the compression of still image. MPEG 4 VTC can encode arbitrarily shaped still object as well as producting progressive scalable bitstream which is robust to error. A encoding frame consilient with syntax of MPEG 4 VTC is presented . This paper offers different scanning and quantization algorithm according to the syntax of MPEG 4 VTC. Comparison with other compression standard for still image shows that the VTC has better rate distortion performance and many attractive useful characteristic.2613|195|0更新时间：2024-05-08
- 摘要：Video encryption is a suitable method to protect video data. In this paper, the existed MPEG video encryption algorithms are classified into four types according to the relationship between encryption process and compression process. They are complete encryption algorithm, partial encryption algorithm, DCT coefficient encryption algorithm and entropy encoding encryption algorithm. Each of them is evaluated from the four aspects: security, compression ratio, computing complexity and operationality. Theoretical analyses and experimental results are presented to compare these algorithms. And their application fields are given, which are consistent with their properties. According to the development direction of video application, the encryption algorithms combining with encoding process will be studied deeply in the future, such as DCT coefficient encryption algorithm, entropy encoding encryption algorithm or novel algorithm combining with error correcting code and so on.关键词：video encryption;MPEG encoding;cryptography;information security;cryptanalysis3477|236|0更新时间：2024-05-08
- 摘要：In order to analyze the correlation laws between fractal feature and equipments worn states, the software used to identification particles contours and to compute the fratcal dimension of the particles contours is programmed based on the computer. This paper presents the fractal parameter and its calculation method of the worn particles based on particles contours' chain code. Some worn experimental tests were carried out at the pin on disc experiments and the worn debris were sampled at varies running in stages. It is found that, when the subroutine be used to compute the particles' parameters, the change of the fratcal dimension of the worn debris is corresponded to the machine worn states at different running in stages. The results show that it is convenient to compute the fratcal dimension of the particles contours with this subroutine. The software offers effective and simple methods in researching the correlation law between fractal feature and equipments worn states.2700|186|0更新时间：2024-05-08
- 摘要：During the course of present investigation,a method for simulating the rain in 3D terrain scene in the real time is proposed,using particle systems. The applicable attributes have been analyzed with reference to the rain particle system and the rain particles, in accordance with the basic principles of particle systems. Methodological approach includes the employment of feasible techniques or algorithms such as defining a cube outside the top of the view frustum as the generation shape of rain particles, using a point in pixels and a subsequent line as the shape of a rain particle,simulating the gravity influence in the course of rain particles' put down,replenishing continuously rain particles using particle groups and, testing the fall heights of rain particles in the real time etc. The results of experimentation have proved that this method is more effective in the representation of rain in 3D terrain scene which also found to be realistic at the time of satisfying basic need of real time interactive navigation.3112|223|0更新时间：2024-05-08
- 摘要：Oil bearing layers and their sedimentary microfacies are generally analyzed by collecting oil well logs in the oilfield development. The well log time series is the correct reflection of geological characteristics of the oil bearing layers with quite a high probability. Unfortunately, feature extraction is of certain difficulty to the computer sedimentary microfacies recognition with well log time series. Oil bearing layers are the resultants of sedimentary layer sequence. The formation of oil bearing layers is very complicated and variable. Extracting the chaotic features is promising. But proving that well log time series are chaotic is prerequisite to extract their chaotic features. There are several methods developed for the chaos identification at present. In this paper, the well log time series is proved to be chaotic indeed by phase space reconstruction technology and G P algorithm, which is a practical algorithm for computing the correlation dimension of a time series. The experiment results indicate that the correlation dimension of an oil layer group is related to its structure. Another interesting phenomenon is that the correlation dimension of an oil layer group is generally larger than that of the whole well.2571|185|0更新时间：2024-05-08
- 摘要：Many digital watermarks now available for images are sensitive to geometric distortions, which particularly prevent blind detection of a public watermark. In this paper, a watermarking algorithm based on singular value decomposition (SVD) is proposed, which is robust to common geometric distortions. The watermark is embedded into image's singular values. By the algebraic properties of SVD, it is proved rigorously that singular values of the watermarked image are invariant when it goes through the geometric distortions of transpose, mirror reflection, rotation, scale, and translation. Experimental results show that the watermarking algorithm performs well in robustness. The embedded watermark can be detected reliably, following these geometric distortions, usual signal processing, or JPEG compression.3530|217|0更新时间：2024-05-08
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