最新刊期
卷 6 ， 期 4 ， 2001
- 摘要：Spatial query optimization should be the focus of attention in spatial area. Since relational optimizer is unsuitable for dealing with spatial data, spatial systems should have their own cost model and optimizer. In this paper, a spatial query optimization system—FQPro was presented. After the overview of general phrases of spatial query optimization, we put the emphasis on cost model, calculation of predicate costs and plan costs. In particular, we give a detailed introduction of the cost model based on R-tree. Similar to relational systems, FQPro defines a set of formula for predicate costs and predicate selectivity respectively. They are used in G/SQL. On top of these formulas, the idea and algorithm for forming the optimum execution plan is defined. Concluding this paper are some issues that should be the concerns of research on spatial optimization, primarily the cost model and the extensible system architecture. Also, this paper summarizes the challenges and opportunites facing spatial query processing in the end.3539|481|0更新时间：2024-05-07
- 摘要：The profit-and-loss revision technique may improve the accuracy of approximation to raw image data undergone a cubic B-spline smoothing. Comments are made on this technique from the viewpoint of image smoothing and restoration, giving highlights on the equivalence between spline smoothing and diffusion smoothing, and between profit-and-loss revision and inverse diffusion restoration; formulating the revision operators into a series of renewal recursions together with an estimation to the order of their deviations from the raw data; and exposing the numerical instability of both simple and renewal recursion of the profit and loss revision. Finally, a discussion is further made on the feasibility of applying the profit-and-loss revision to edge detection for images in the presence of noise.2655|403|0更新时间：2024-05-07
- 摘要：This paper introduces a method of edge detection. By comparison with topography, it is found that the character of edge of image shows the same valley' s character as relief map. Firstly, according to this character, primacy central point is detected by the exploring extremum method in the windows of 3×3 pixels. Then, basing on this central point, approximate normal line at±45°、0°and 90°angle are drew.if the minimums of normal line is at central point and the difference between the minimums and the maximum in the normal line is more than the threshold, this point is considered to the edge point of image. Because the brightness of this point varies with local image like valley—the valley geographic location is not always at the same level and it varies with physiognomy. So this method of edge detection is according to local minimum point in the normal line. the character of this method has self-adjusting situation of local image on detecting edge of image.2535|442|0更新时间：2024-05-07
- 摘要：Fractal coding of digital image offers many promising qualities. However the coding process suffers from the long search time of the matching between range blocks and domain blocks. So, classifying the blocks is usually used to reduce the long search time. The classifying is based on the special characters of the image blocks. And the special characters are presented as smooth area, edge area and texture area in an image. For an image block, smooth area can be considered as non-edge area, texture area also can be considered as quickly changed edge area. So important information of image character can be obtained through edge extraction. Edge extraction usually takes the use of several edge-detecting operators such as Sobel and Laplacian operators. Here, a Laplacian operator is applied in original image first because the operator can detect edge image with quickly changed. Then, from the edge image after above operation, a given-threshold gray level image is removed. So a redunance-removed and an edge character prominent image is obtained. This image is used for domain blocks classification. And several parameters are obtained by statistics or multiplied from the image. Finally 4 big classes and 12 small classes are derived from above parameters and all classes are used for fractal image coding.The proposed fractal method is tested by real gray level images under windows 98 platform with visual C language. For encoding an image effectively, in this paper, a quad-tree structure is used for image segmentation so that the encoding algorithm is an automatic iterative algorithm.Computer encoding and decoding simulation result shows that compared with other similar methods, the proposed fractal method can make more accurate and objective classifications, and has an improved encoding speed, compression ratio and can provide a better reconstructed image quality.2570|380|0更新时间：2024-05-07
- 摘要：Pyramidal lattice vector quantization(PLVQ) has drawn extensive attention by its promising property recently. The coding method based on zerotree (ZR) coding [1] has made a great coup during the last few years. Based on the traits of dyadic wavelet decomposition of signal and that of the distribution of wavelet image coefficients, PLVQ and ZR are conjoined by making use of D-4 lattice. Firstly, Pyramidal lattice vector quantization is adopted to quantize wavelet image coefficients. Nonzero lattice vectors and zero lattice vectors are formed. Secondly, nonzero lattice vectors are dealt with by adopting complex entropy coding. Finally, in order to fix on the position of nonzero lattice vector effectively, that is, to deal with zero lattice vectors effectively, the concept of significant map is introduced into. The significant map is scanned two times from down to up and from up to down. Based on this and the probability distribution of zerotree roots, zero lattice vectors are disposed by adopting improved zerotree coding. Experimental results demonstrate that the proposed algorithm performs better than traditional entropy coding based on runlength.2965|466|0更新时间：2024-05-07
- 摘要：To improve the accuracy of boundary locations and region homogeneity as well as to reduce the error rate in texture image segmentation, a novel approach based on wavelet-transform and using feature weighting is proposed in this paper. This new technique contains three consecutive stages: feature extraction, pre-segmentation and post-segmentation. In the feature extraction stage, texture features are extracted by using the pyramid-structured wavelet transform. The original image is then segmented initially using the means clustering algorithm in the pre-segmentation stage. According to the pre-segmentation results, the extracted features are weighted and the pre-segmented image is further processed with a minimum distance classifier in the post-segmentation stage to finally get the segmented image. All technical points are clearly described and presented in detail. Some segmentation experiments with different Brodatz's texture images are performed to test the performance of the new technique and are also included. Compared with a typical traditional method, the present approach shows visible improvements both in diminishing segmentation error, and in increasing boundary precision and region harmony.3148|505|0更新时间：2024-05-07
- 摘要：An image mosaicing new approach based on the integration of image matching and adjustment, which can effectively remove the residual geometric distortions between mosaiced images, was presented. At first, selecting one of mosaiced image as the reference, for example, the left side image, then the other image was matched with it in the overlapping area. A point feature-based matching algorithm was employed, and a quadratic polynomial fitting method was used to locate the corresponding points within one pixel. On the basis of these corresponding points, a adjustment algorithm was performed by adding a polynomial increment to every pixel position in the right side image so that geometric position distortions between the two images is minimal under Least Square principle, thus the two images could be mosaiced together seamlessly. At the same time, the usually used methods for radiometric difference reduction are presented .The proposed approach was applied to mosaic two rectified aerial photos, after image adjustment, the residual geometric distortion was greatly removed.关键词：Image matching;Corresponding points;Adjustment;Image mosaicing2455|510|0更新时间：2024-05-07
- 摘要：A new filter based on a Fuzzy Neural Network(FNN) of Sugeno type is presented for images corrupted by impulse noise.Impulse noise results in the quality decline of image and can be reduced by nonlinear image filters, such as FNN image filter. FNN image filter does better than other kind fo filters when judged of subjective vision quality because its way of working is even close to that of mankind's eyes. The network structure of filter is good at ditecting different patterns of noisy pixel while the fuzzy mechanism embedded in the network can remove impulse and keep details and textures. Sugeno type NN have simple structure and other merit, which makes it suit for constructing FNN filter. A learning method based on the genetic algorithm is adopted to adjust the network parameters from a set of training data. The preliminary experimental result shows that the Fuzzy Neural Network filter performs better than the Median Filter when used to cancel impulse noise from scene image.2845|466|0更新时间：2024-05-07
- 摘要：Contour filling is one of the most common problems in image and graphics processing and plays a very important role in many in many applications, such as image analysis, pattern recognition and computer graphics. The paper proposed a new concept of sub-chain and a new sub-chain based filling algorithm. The new algorithm is based on separating the whole contour into many simple sub contours and then does filling in each sub contour. Compared with the conventional algorithms, the new algorithm has five advantages. (1) Its speed is faster and its implementation is easier. (2) It needs less storage-just need size-fixed temporary memory or none in many cases. (3) It finds seeds for filling automatically and easily. (4) It needs neither sorting operation nor discrete Green's theorem to find the seeds for filling. (5) It can be implemented with flexible forms according to the different background of applications. Theory and experiments prove it can fill any complex regions with more convenient, faster speed, more simple, more applicable. It can be used widely in applications of graphics and image processing.3197|461|0更新时间：2024-05-07
- 摘要：Edge detection is one of the most important techniques in image processing, it is often used in the field of image analysis and image recognition for many applications. Pan and King firstly presented an algorithm of edge detection based on fuzzy sets, this algorithm has been found for many successful applications in the area of pattern recognition and medical image procesing. In this paper, an improved algorithm of edge detection proposed by Pal and King is presented, and the approach of edge detection is also developed to be an automatic one. The steps of this approach can be summarized as follows:firstly, a threshold is selected in an image by using an automatic algorithm of thresholding; secondly, in order to extract the fuzzy property plane from the spatial domain, a new membership function based on the threshold is defined; thirdly, image enhancement is performed in the fuzzy domain by using fuzzy enhancement operator; then, the modified spatial domain is obtained; finally, the edge detection is executed using min or max operators. This algorithm is also extended to the edge detection of the multi-thresholds image. The effectiveness of the algorithm is experimentally demonstrated.2666|516|0更新时间：2024-05-07
- 摘要：Stereo vision has long been one of the central research problems in computer vision, and stereo matching is the most important and difficulty issue of stereo vision. There are some limits for existing approaches to recover precise and dense disparity map. Feature-based stereo can produce more precise matching but only sparse disparity map. On the other hand, Area-based approaches can provide dense disparity map but less precise matching. In the situation of image synthesis for IBR, we need not only precise matching but also a dense disparity map. Thinking of the uncertain and fuzzy characteristic during matching, we introduce the widely used fuzzy set theory to the field of stereo matching, and propose an algorithm based on fuzzy identification. The algorithm uses the information of gradient magnitudes, angles of orientation and gray value information of nearby points as the identification facts. Experiments with real and synthetic images have been performed, they show that this algorithm is effective and it is of great value to use.3124|492|0更新时间：2024-05-07
- 摘要：In order to realize digital image deformation in an irregular polygon area rapidly, an image deformation algorithm is presented, which is based on triangle skeleton coordinate. First, any irregular polygon image area can be divided to a few of triangle areas. Then, according to skeleton coordinate system of triangle shell, skeleton coordinate can be calculated for any pixel in every triangle area. Because any change of a triangle shell will cause particular image deformation inside it, the change of a triangle shell can be designed intentionally to control image deformation inside it. Using skeleton coordinate system, a formula is proposed which can be used to compute any variation of a pixel's coordinate when a triangle shell is changed. Based on the formula, a corresponding relation of color is established between a new pixel after triangle shell change and original image pixels. Using the image deformation algorithm in an irregular polygon area, some image deformation problems such as motion simulation can be solved.3004|442|0更新时间：2024-05-07
- 摘要：In this paper, we presented the way to register or fuse CT and MR multi-modality image based on the Legendre moment. Because Legendre moment has the merits of orthogonal and minimal information redundancy, by using it, we can find the center of mass of CT and MR images, calculate the scale factor of these images, then the translation and rotation of these images can be performed, these images are registered precisely;Optimizing the Legendre moment's algorithm, we quickened up the registration or fusion of CT and MR images. This method proved to be effective,simple in the registration of multi-modality medical images in our experiment. Legendre moment is also important to the registration and fusion in multi-modality medical image, and in the radiotherapy treatment program system.2597|463|0更新时间：2024-05-07
- 摘要：It is well known that locating vehicle license plate is a very difficult problem in the fields of image segmentation and ITS(Intelligent Transprotation System).At the present time,the study of vehicle license plate locating mainly focuses on gray images so that the result is affected easily by the presence of shadows and illumination.In this paper,a new color edge detector ColorPrewitt and a new approach of vehicle license plate locating ColorLP are presented,which fully exploit color information and other features of vehicle license plate.ColorPrewitt not only is simple,but also has superiority over traditional color edge detectors in dealing with color vehicle license plate images because it doesn't just simply operate on the individual three channels of color space.It shows that the license plate edges detected using ColorPrewitt are clear,integrated and easy to be separated form the background.ColorLP combines ColorPrewitt and region growing image segmentation technology with high locating ratio and good generality,which is applicable to locate license plates in cases of various backgrounds,positions and illumination.3376|535|0更新时间：2024-05-07
- 摘要：Shiphandling simulator is a device that can partly imitate the true environment at sea,and is specially designed to satisfy marine education and trains and maritime research etc.One of its key techniques is to create the virtual environment at sea,and the terrain is its important component.According to the needs of the real time visual display of the shiphandling simulator, this paper analyses the requirements of the geometry precision of the important islands and background hills which are within the ships' visible scope,and brings forward the modeling methods of the hill's pileup and the hill's silhouette edges based on contour lines.It also presents the definition of error that the hill's silhouette edges graph has been given and the effective scope of application,and firstly established the error criterion of terrain model that is built in shiphandling simulator.With these two kinds of method,the size of data storage can be minimized greatly,and the requirements of high update rate and geometry precision for the real time visual display of the shiphandling simulator can be satisfied.2801|444|0更新时间：2024-05-07
- 摘要：This paper firstly analyzes problems existing in current rectification software,then presents a new rectification approach based on image and graphics overlaying and matching without the support of digital elevation model,and introduces fast overlaying technique of image and graphics based on indexed-color mode.To make rectification,this paper analyzes the feature of partial deformation,and presents a rectification formula for partial deformation based on experience.Finally,software of image rectification is developed combined general rectification and partial deformation rectification.In the experiment,a test image is rectified using the software with 13 selected control points,rectified image match the map very well by overlaying,and errors left are all within 2 pixels.The results show that rectification approach this paper presents is feasible and can be used to rectify image deformation induced by any factors.2962|432|0更新时间：2024-05-07
- 摘要：In areas such as virtual reality,it is often needed to establish virtual scene in computer from actual scene in real world.In this paper,a technical approach for realizing geometric modeling of 3D object is proposed,which combines computer vision and CAD geometric modeling.The range images of 3D objects are obtained by using the encoded light stripe patterns,then are segmented by our range image segmentation method based on the basic operations of methematical morphology. The meaningful regions obtained by range image segmentation correspond to the surface patches of 3D object.The 3D surface patches are then reconstructed by the algebraic surface fitting method;the surface parameters are estimated by solving generalized eigenvector problem. The geometric model of 3D object is constructed from reconstructed surface patches by using CAD geometric modeling tool GEOMOD.The primary experimental results of two mechanical parts are presented,which prove the proposed approach is feasible.3333|519|0更新时间：2024-05-07
- 摘要：Present line-generating algorithms, which include Bresenham algorithm, symmetrical algorithm and the algorithm based on the chain code theory of the line, are analyzed and compared in this paper. A property-based on the chain code theory of the line, are analyzed and compared in this paper. A property-based integrated line-generating algorithm, which is based on the Bresenham algorithm and makes full use of the symmetry, direction and continuity of the line, is presented to increase the speed of line generating. The results of our experiments have proved that the line-generating speed of the integrated algorithm is increased by more than 50 percent compared to that of Bresenham algorithm. The new algorithm is especially efficient for engineering drawings, in which the in- clinations of most lines are 0°, 180°,±90°,±45°and±135°. In can be thought that the integrated line-generating algorithm has make great progress in the way to reach the minimum value of the operation time in generating a line. Existing CAD&CG algorithms must take into account the particularity and entireness of the object while the integrity and universality of the processing object is pursued. To handle the related algorithms in some special way according to the characteristics of engineering drawings is an effective method to improve present CAD&CG algorithms.2567|452|0更新时间：2024-05-07
- 摘要：The measurement of color difference in machine vision is the basement of image segmentation based on the color features, but there is no colorimetrical system for machine vision. Traditional colorimetry has two major systems: (1) to build a color specification system experimentally and to use it as a reference (for example, the Munsell Book of Color). (2) to develop an analytical formulation based on discrimination experiments (such as, CIELAB, CIELUV). The color space based on the psychophysical experiments of human visual system is non-flat. That means the perceptual difference of colors can not be described by the Euclidian distances between the related two points in the color space and the map from perceptual difference to the Euclidian distances is not linear. In this paper, we built a virtual color space based on the physical models of light, reflectance of surfaces and the sampling function of visual system. In this virtual color space the chromatism of machine vision can be calculated linearly. We also suggest that the chromatism measurement of machine vision is different from the spectral reflectance of physical surfaces used in present computer models of color vision.4023|607|0更新时间：2024-05-07
- 摘要：This paper describes a method for video reorganization based on contents. The method uses the color information of images such as color histogram, color noment etc. to measure the similarity between frames, and to detect and cut the shots. Furthermore, three reorganization algorithms,“simplified reorganization”,“proportional reorganization”and“self-adapting reorganization”, are also described in detail. All these three algorithms get good results in the simulation. So it can be used for quick preview of the video-database or other video information data. It also can be used for video preview, video abstract, video retrieval and video substitution (in low net band) of Web-Video-Database based on Browser/Server technology.2477|461|0更新时间：2024-05-07
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