最新刊期
卷 11 ， 期 7 ， 2006
- 摘要：This paper is the eight annual survey on multimedia researches and applications in China, 2005. Since multimedia is a cross-field research area, papers about multimedia technology are scattered over various journals. We checked about 3097 papers published on 9 Chinese journals in 2005, from which we picked up 410 related to multimedia technology and application. Then we made analysis and statistics on them comparing with data from 2001 to 2004. Looking through the data we can find that researchers in China have been continuously paying more and more attention to digital watermarking, virtual reality, muhimodal interface, infrastructure of pervasive computing, multimedia information retrieval technology, quality of service, computer supported cooperative work, GIS and digital earth, which are also the worldwide trends for a quite long period. We present here an overview on the progress in multimedia technology in China, 2005. This article tries to help the researchers not only in looking for references, but also in exploring the new direction of research.关键词：multimedia;virtual reality;hypermedia;multimedia communication;computer supported cooperative work(CSCW);multimodal interface;pervasive computing;wireless multimedia2707|174|0更新时间：2024-05-08
- 摘要：Identifying moving objects from a video sequence is a fundamental and critical task in many computer-vision applications. For surveillance video captured by static camera, the common approach is to perform background subtraction, which identifies moving objects from the portion of a video frame that differs significantly from a background model. However, there are many challenges in developing a good background subtraction algorithm for many factors such as changes in illumination should be considered in constructing a background model. This paper firstly expounds the universal process of detecting objects with background subtraction, all typical background modeling algorithms and their merits. Then their whole characteristics are summarized and the performances of some algorithms are compared based on experiments and other literatures. Finally, key issues and directions of future study in this area are pointed out.3994|268|0更新时间：2024-05-08
- 摘要：Camera calibration,which is to calculate the intrinsic and extrinsic parameters of a camera in viewing,is one of the basic tasks for analyzing the geometry of a scene and determining the shapes and locations of objects in vision. Since the optical system of a real camera has many types of distortions,and these distortions must be taken into account in three dimensional geometry reconstruction when high precision is needed,this will cause the relation of perspective transformation to be nonlinear. Many efforts have been made to solve the nonlinear calibration problem. A new linear three-step approach for camera calibration was proposed to deal with camera model of one order radial distortion. In the first stage all extrinsic parameters except those for translation vector in Z-axis are computed by using the Radial Parallelism Constraint(RAC). In the second stage the one order radial distortion parameter is computed by using cross ratio invariability. In the third stage all the missing parameters are computed by the least square method. Experiments with simulated data as well as real image show that the new approach is efficient,robust and accurate. And the approach eliminates the nonlinear iterative calculation processes.关键词：camera calibration;radial deformation;cross ration invariability;computer vision2754|228|0更新时间：2024-05-08
- 摘要：Block artifactwhich deteriorates the video subjective visual quality especially in low bit rate is a remarkable problem which usually appears in block based c1oding system. Unlike MPEG series coding system, H.264 does not use post processing filter but adds loop filter in motion vector compensation loop. Loopfilter is based on macroblock or piece. The most essential points in loop filter are strength—a value which indicates the strength of block artifact—and filtering operators. In order to obtain better subjective visual quality, a new loopfilter arithmetic where the filtering operators are added withmore details and some other factors are added in the arithmetic of computing strengths. In the experiment, it is showed that the subjective and objective quality of video can be improved remarkably.关键词：block artifact;loop-filter;macroblock2535|179|0更新时间：2024-05-08
- 摘要：A new fast and efficient search algorithm for block motion estimation is presented in this paper, The new algorithm can reduce the computational complexity of the fast motion estimation and improve the efficiency of video compression code. The algorithm accepts a multi-step search strategy, using motion vectors of the adjacent block to predict starting search point, using gradient descent method to optimize the search to reduce computation resource. For the area where optimal points located, a Diamond-Square Mask was used to carry out the refined search. Experimental results show that the proposed algorithm can reduce computational complexity efficiently, and at the same time while, ensuring the search accuracy.关键词：video coding;motion estimation;block-matching3031|186|0更新时间：2024-05-08
- 摘要：This paper explores the dynamic feature of human gait extracted by hidden Markov model(HMM),which is used for identifying people. At first,an improved angular vector representation is proposed for binarized human images in a gait sequence so that every image is turned into a one-dimension vector. Then these vectors act as feature vectors to build and train HMMs which are the final identifying tools for each person based on input gait sequences. The improved angular vector is equipped with better robustness against segment errors,so it is suitable for imperfectly segmented silhouettes. It is also easy to scale up or down,thus scarcely vulnerable to the change of walking direction and distance from data-collecting camera. HMM models not only the dynamic characteristic of gait but also the relation between images in the same sequence. Besides,it can guarantee a high-speed operation which carries out the whole process within 2min. The experiments on Soton and NLPR database yield encouraging correct identifying rate of 100% and 85%,which demonstrates the effectiveness of this method.关键词：biometrics;gait sequence;improved angular vector;HMM2296|214|0更新时间：2024-05-08
- 摘要：Robust real-time human ear tracking is a challenging task. In order to realize the fast tracking and locating of the human ear,a new method is proposed that combines both skin-color information and intensity contour information to detect and track the human ear in the sequence frames. CAMSHIFT as a fast computationally efficient algorithm on color-based tracking is applied to roughly track the side view of human face as the region of interest(ROI) and then contour fitting is operated in ROI,which can improve the calculation speed obviously,for further accurate locating due to the ample contour information the ear contains. Experimental results show that this method is fast,robust and effective,which can meet the real-time requirement and has certain tolerance of distractors and angle change of the ear caused by the head rolling. Furthermore,the method can be implemented under relative complex background situation and works well in practice.关键词：human ear tracking;skin-color probability distributions;CAMSHIFT algorithm;contour fitting;real time2397|196|0更新时间：2024-05-08
- 摘要：The fabric defect automatic inspection is one of the technical problems that the textile industry is facing. This paper brings forward a approach for textile flaw automatic detection based on optimal Gabor filters. At first the niche genetic algorithm is employed to attain the parameters of the optimal Gabor filters and segmentation threshold based on.the feature of the unflawed textile, and then apply the optimal Gabor filter and threshold on the fabric image to achieve the resnlts. Meanwhile, the shape characteristics of defects are also achieved from the distribution of minimums of response matrix. The approach is used to detect the flaw of cord fabrics. The test results demonstrate this method is efficient and practicable, and also characterized by wide applied range, strong capability of recognition and high testing speed.关键词：textile defect;Gabor filters;texture;niche genetic algorithm2884|186|0更新时间：2024-05-08
- 摘要：The recent researches have improved that local adaptive segmentation is particularly more attractive than the fully automatic segmentation when the property of the object’s localboundary is not similar. For improve the segmentation speed, This article describes a novel approach to the self2adaptable segmentation of irregular objects in an image. The algorithm is based on Moore Penrose operator. With adaptable energy function parameters, the Greedy Snake is attracted to boundaries by use of a direct feedback mechanism (Greedy Snake). To avoid undesirable localminima, every energy function’s weight is adaptable according to the test point’s property nearby, and a suitable local convergent algorithm is proposed which enables snakes to converge to target boundary points. Through computation simulation, the paper proves that the proposed approach is capable of inheriting the characters of the Greedy Snake algorithm, through adjusting the weight vector of the energy function, the newmodel changes the local character of the Snake, andmake it approach to the aim object’s boundary automatically. When applying the newmodel and traditionalmethod to extract contours from various images, the new greedy snakemodel performs better than related snakes.关键词：Greedy Snake(GS);edge detection;self-adaptable segmentation2819|209|0更新时间：2024-05-08
- 摘要：To solve the problem of automatic classification for ultrasound placenta images, we put forward an algorithm based on adaptive multiple neural networks. Two layers of BP net models were designed to carry Two-Stage separation of the placenta in this algorithm other than general one stage separation algorithm. When training networks, we do not adopt the common method which rounds the output of the networks, but propose a more reasonable grading rule, then present an adaptive threshold-gotten method to determine the reasonable placenta level. Experiments and clinic applications indicate that the similar classification result can be gotten by our algorithm as by experts, and the classification result by the algorithm before threshold division can give the doctor a good reference on the precise measurement of the placenta maturity, thereby, it has a good future in clinic applications.关键词：ultrasound placenta images;automatic classification;adaptive multiple neural networks;threshold division;two-stage separation2183|216|0更新时间：2024-05-08
- 摘要：In this paper a novel framework of panoramic mosaicing is presented based on phase correlation,particle filter and intensity difference minimizing. Combining the characteristics of frequency domain and spatial domain we construct a panorama from un-calibrated images for global optimization. The alignment consists of two phases: local alignment and global alignment. In the process of local alignment the lower accuracy,the proposed method employs phase correlation and feature based particle filter sequentially,by which we can obtain the swiftness and robustness of phase correlation as well as the corrective function of feature based particle filter. In the process of global alignment,because the initial value generated by the local alignment is close to the optimum one,the iterated algorithm could converge quickly. Meanwhile,a huge parameter space might be introduced by global optimization. We develop a strategy to reduce the dimensions of parameter space. In the experiment,this system shows the efficiency and robustness in the case of varying illumination,without camera calibration,less overlapping and less knowledge of the scene.关键词：full view panorama;image mosaics;phase correlation;feature matching;particle filter;global alignment2554|187|0更新时间：2024-05-08
- 摘要：Wavelet transform has its unique advantage in image processing, which analyze image subtly. Different from wavelet transform, computation using partial differential equations need to be iterated again and again. It deals with the image us a whole in the whole course. It can not only remove noise but also keep details of image. Combining with two methods, drawbacks will be overcome and better effect can be achiered. A nonlinear method for combining wavelet transform with nonlinear scale diffusion is proposed. By using the properties of time-frequency of wavelet transform and enhancing edges of nonlinear scale diffusion, the test results show the method is valid.关键词：nonlinear scale diffusion;partial differential equation;stabilized inverse diffusion equations(SIDEs);wavelet transform2263|186|0更新时间：2024-05-08
- 关键词：spatial databases;spatial data mining;spatial outliers;spatial neighborhood2491|188|0更新时间：2024-05-08
- 摘要：A 3D spatial data model is the foundation of 3D spatial database and 3D GIS,so it has great significance of research. A 3D spatial data model based on the 3D discrete domain,3D-realms,is introduced in this paper. It is the extension of the 2D realms in the 3D space. The basic definition,semantic description and the spatial operations of this spatial model are presented in this paper. This 3D spatial data model can be divided into four layers: 3D geometric primitives layer,3D-realms layer,basic spatial constructional elements layer and basic spatial objects layer which includes points object,lines object,regions object and bodies object. Each lower layer is the foundation of construction elements of the higher layer and provides supports for it. The 3D spatial data model based on 3D-realms can guarantee the correctness of topological relations,describe 3D spatial objects well and effectively support the 3D spatial topological operations.关键词：3D spatial database;3D spatial data model;realms;3D-realms;3D spatial topological operations2668|188|0更新时间：2024-05-08
- 摘要：Drainage information plays an important role in the presentation of spatial information and is widely used in terrain analysis, resource and environment management and Hydrology. Watershed, which indicates the characteristic of geology, geomorphology and hydrology, is a basic object in the research of earth surface hydrology. And it is very important in soil and water conservation and environmental monitoring. The automatic extraction of valley lines based on grid DEM is the base of the researches mentioned above. And the flow direction determination is one of the most important parts in the automatic ditch extraction. In this paper, we summarized and implemented the existing algorithms of flow direction determination in automatic ditch extraction, and proposed a new algorithm of flow direction determination, in which multiple flow directions and randomness were accounted for, based on the FD8 and Rho8 algorithm. We used two DEM data to validate the advantage of this algorithm in multiple flow direction and randomness.关键词：flow direction determination;ditch extraction;digital elevation model(DEM)2927|169|0更新时间：2024-05-08
- 摘要：The classic Dijkstra algorithm is based on the planar topographical network,the expanding time for searching Optimal Path will increase sharply when the number of network nodes enlarges. In this paper,a path algorithm,namely bidirectional hierarchical wayfinding algorithm(BHWA )which is based on hierarchically structured topographical network(HiTopo) has been developed to speed up searching path. BHWA has two novel features which distinguish itself from existing method. Firstly,structure HiTopo is based on local connectivity of the classified network other than spatial distance. Secondly,it searches arc from two directions which improves upon search node along one direction. An experimental work has been done with BHWA using the map of Beijing,which shown BHWA speeds up computation efficiently while keeps up low error. By farther research,another fact is noted. If the algorithm is optimized by heuristic search,its search speed can be accelerated three times at least.关键词：optimal path algorithm;hierarchically structured topographical network;bidirectional search path3659|249|0更新时间：2024-05-08
- 摘要：Polygon simplification and aggregation play an important role in automatic cartographic generalization, which is used for resolving spatial conflicts caused by reduction in the scale at which cartographic data are plotted. After analyzing the capabilities to detect conflict existed between polygons and in polygons of CDT-based SDR. Authors present a method for polygon simplification and aggregation to avoid the difference caused by separate operator. In this method, an improvement of conflict detection algorithm is applied to avoid the overmuch increase of area and the loss of characteristic vertex during polygon simplification and aggregation, which is caused by involving peaked triangles located at the edge of triangulate mesh. At last authors demonstrate the advantage of this method through experiments.关键词：CDT-based SDS model;polygon simplification;polygon aggregation2777|170|0更新时间：2024-05-08
- 关键词：boreal ecosystem productivity simulator;accidented terrain;net primary productivity;Changbaishan natural rteserve3169|224|0更新时间：2024-05-08
- 摘要：In order to design an image watermarking algorithm with high robustness, through the analysis of watermark embedding process, extracting process and performance, this paper presents a new scheme of Image adaptive Gray-scale Watermark Embedding and Extracting. After analyzing the characteristics of multiresolution of the two-dimension discrete wavelet transform, by using luminance sense and contrast sensitivity threshold of the Human Visual System and integrating the luminance and texture characteristic of each sub block of the image, the scheme embeds a gray-scale watermark into a host image according to the adaptive embedding intensity factor calculated. The optimal watermark extracting result can be calculated adaptively according to the watermark information extracted from different regions, which greatly improves the performance of the watermark system. The experimental results prove that the scheme is robust enough to many attacks, especially to smoothing, filtering, JPEG or JPEG2000 compression and bit plane cutting.关键词：human visual system;gray-scale watermark;adaptive;robustness2444|174|0更新时间：2024-05-08
- 摘要：This paper presents a new image content authentication algorithm based on image feature for effectively authenticate the tampered image. First the smooth-component and edge-character are drawn from the image with the dyadic wavelet transform multi-scale edge detection, which form an image feature set for generating the digital signatures. This can ensure the one-to-one mapping relationship between the feature set and the image, and avoid the counterfeit attack. After 32 bits coding, the smooth-component is embedded in the original image with the edge-character as watermark. When the image is verified, the smooth character and edge character are compared to confirm whether the content has been tampered. The experiments prove that this authentication algorithm can effectively detect the event and the location of vicious tamper, and it can also tolerate the damage produced by compression, filter and some other image procession. Even if the image is degraded by some noise, it can still pass through the authentication correctly.关键词：image content authentication;multiscale edges;wavelet transform;digital watermark2348|197|0更新时间：2024-05-08
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