最新刊期
卷 10 ， 期 12 ， 2005
- 摘要：Starting off the research of respective advantages and disadvantages of fractal image coding and zerotree image coding and their bonding points, a hybrid image coding based on image texture analysis of fractal and SPIHT(Set Partition in Hierarchical Trees) is presented to make full use of scenery characteristics and eye's vision features and then improve the cooperation ability of fractal and zerotree in the area of image coding.The prominent feature of this method is that it makes full use of the progressiveness of bit plane coding used in SPIHT coder and combine the fractal and SPIHT with statistical characteristic taxonomy based on grey-model and then get the coding scheme that is more suitable for eye's vision features.The result shows this method can classify the image block clearly and get high compression rate.And this method gains a better effect when generally considers the recovery image quality and compression rate,under the condition of the permission of eyes and high compression rate.关键词：hybrid image coding;fractal image coding;SPIHT zerotree coding;wavelet transform;image texture analysis2503|188|0更新时间：2024-05-07
- 摘要：Based on the investigation of EZW,the relationship between space redundancy(scaled by edge active measure) of the compressed image and the result of EZW coding is analyzed,and the concept that there exists an optimal wavelet decomposition level in EZW is proposed.The relationship in EZN coding between different compression ratio,different decomposition level and different images is reported.The executing time is also used as a factor for selecting decomposition level.The experimental results indicate that the three-level decomposition in EZW should be adopted for high compresssion ratio and the four-level decomposition is optimal for low ratio.The results provide a basis for further research on adaptive EZW algorithms.关键词：image edge active measure;EZW(embedded zerotree wavelets);wavelet decomposition level2658|184|0更新时间：2024-05-07
- 摘要：When roaming in a 3D virtual scene,texture mapping is a main tactic to display the reality of the scene.But for some special cases i.e.the position of the object or other difficulties which can't be overcome,the texture with perspective distortion is got.Here how to rectify the plain texture to remove perspective distortion and corresponding texture mapping are discussed.This process is as follows: applying projective transformation on the plane,using interpolation method to acquired texture,and then mapping it on the model.This is based on reconstruction from two views.Some existing algorithms are used and some changes are made to achieve a good result during projective transformation.Then the result of test is analyzed and discussed.This method can be used to construct a virtual scene,or clarify the blur of the photos for the reason of perspective distortion.关键词：reconstruction from two views;perspective distortion;projective transformation;collinearity;camera calibration matrix;key point;texture mapping2910|196|0更新时间：2024-05-07
- 摘要：The information identification is the most difficult in the application of high-resolution remote sensing images.This paper focused on the method of QuickBird image's information extraction.Six kinds of land cover types: road,water,forest,agriculture,nuke and residence in the study area,Zhuzhou,Hunan,were identified by visual interpretation,supervised classification and non-supervised classification respectively,and the accuracy is 98.2%,72.64% and 60.71% correspondingly.At the same time,pre-processed images of QuickBird,ETM+ and TM were identified by supervised classification and non-supervised classification respectively and the accuracy of QuickBird image classification is lower than that of ETM+ and TM.This showed that resolution's improvement couldn't raise the accuracy of classification by the method of traditional classification.This paper avoided the traditional classification based on pixel-to-pixel and applied new method of classification based on object's gray character and shape characters.QuickBird image based on pixels was changed into new image based on objects first by segmentation,then models of measuring objects' area,perimeter,length,width,length/width,rectangle and roundness were built.Six kinds of land types were classified again by computer stimulating visual interpretation in the study area,the composite accuracy of classification is up to 91.6%,this showed that the method based on objects is a very effective way to improve the accuracy of classification of QuickBird image.关键词：high-resolution remote sensing;QuickBird image;classification;shape factors;accuracy3346|208|0更新时间：2024-05-07
- 摘要：In this paper,two problems are researched.First,we propose five topology characteristics and geometry characteristics that are invariant under perspective transformation to describe polygon.Then the definition of homograph is given in terms of these characteristics.On the basis of this definition,we give a procedure for recognizing homographs.Second,a new algorithm for recognizing polyhedrons from a perspective line drawing based on principle of homograph is presented.Homograph as defined by us can be employed to distinguish between surfaces with different characteristics and to classify the surfaces of polyhedron.As homographs' categories are few in number and as it is only necessary to put the polygon to be recognized in one of these few categories,efficiency of recognition is greatly raised.We introduced the topological structure to analyze homograph qualitatively,therefore the algorithm is insensitive to noises;and employ geometrical structure to analyze homograph quantitatively,thus the algorithms can show fine discrimination between polyhedrons.Thus,it can not only recognize polyhedrons of different shape but also distinguish between polyhedrons that are of the same shape but their sizes and proportions are different.Comparing with other recognition algorithms,our algorithm has obtained obvious improvement.The effectiveness of the algorithm is demonstrated preliminarily by computer simulation.关键词：homograph;perspective drawing;line drawing;recognition2627|177|0更新时间：2024-05-07
- 摘要：The Mobile target's detection and analysis from SAR(synthetic aperture radar) image is a key step of SAR ATR(automatic target recognition).An approach of the mobile target's detection and analysis from SAR image is proposed in this paper.After pre-processing of SAR image,Constant false alarm ratio(CFAR) algorithm based on the hypothesis that the intensity distribution of the clutter is exponential and morphological operation are applied to original SAR scene to get region-of-interest(ROIs),the CFAR detector is a rapid algorithm for detecting targets in clutter and the morphological operation can eliminate false alarms.Then the feature vector consist of 8 features for each target area is extracted to describe target in detail.Features are length,width,area,the position of centroid,azimuth,fractal dimension,rotational inertia and Mean bright.The experimental results show that this algorithm is fast in computing speed,and can get lots of useful information from target areas.Moreover,this algorithm has definite currency.关键词：synthetic aperture radar(SAR);image;feature extraction;CFAR detection;morphological operation2702|200|0更新时间：2024-05-07
- 摘要：The analysis of McCann99 algorithm with regard to high dynamic image display is demonstrated here.The improved plot was proposed based on the weakness of McCann99 in dealing with very dark and light region of HDR images.Combining the new research result,the initial value and reflectance value were adjusted.In addition to the suitable visualization of HDR image,the improved algorithm also has the facility of contrast adjustment.关键词：illumination image;reflectance image;multi-resolution image;HDR image;halo3140|174|0更新时间：2024-05-07
- 摘要：The key of application and practicalization of image fusion technology is whether the used fusion algorithm has fast speed and high reliability or not,so the research of computationally efficient algorithms which can produce good results is very important.Conventional multiresolution image fusion methods with weighted average fusion rule exhibit high level of fused image quality,but their fusion rules represent computationally expensive solutions.To reduce their computational complexity,using the defined correlated signal intensity ratio,a computationally efficient algorithm of multiresolution image fusion with weighted average fusion rule is presented.Compared with those conventional methods,the proposed algorithm achieves a considerable improvement in real time capabilities.The experimental results show that images achieved by this efficient algorithm are of equivalent or better quality than those obtained from more complex,conventional image fusion methods.关键词：efficient method;image fusion;multiresolution analysis;correlated signal intensity ratio3403|206|0更新时间：2024-05-07
- 摘要：Due to the large span,small elasticity and feebleness damp in aerospace,the solar panel easily generates non-linear vibration with low frequency.It is difficult to measure the vibration with traditional sensors.This paper gives a design to measure the vibration with photogrammetric survey,and at the same time,the method of bundle adjustment is applied to modify the position of targets.Sometimes the parameters of the camera may be changed,bundle adjustment is secondly applied to modify the changed parameters,which advances the robust of this design.At last,this paper testifies the feasibility of bundle adjustment applied in the design to modify the camera's parameters with numerical emulator.关键词：bundle adjustment;solar panel;photogrammetric survey3052|194|0更新时间：2024-05-07
- 摘要：In this paper,a new automated approach is proposed to extract the centerlines from 2D angiogram images.The centerline extraction is the basis of 3D reconstruction of the blood vessels,so the accurate localization of centerlines counts is extremely important.The characteristics of multiscale Gabor even filters,flexible frequency bands and enhancement effects,are fully utilized to enhance centerlines of the blood vessels in various size,which greatly reduce the background noise.Then the non-maximum suppression algorithm is adopted, guided by the directions provided by calculating the Hessian matrix of the image,to get the local maximum points on the response map.Finally,vessel centerlines are extracted by a hysteresis-thresholding segmentation.The experimental results demonstrate the robustness of the algorithm and good quality of the extracted vessel centerlines.关键词：centerline extraction;Gabor filtering;multiscale;digital angiogram vessel3150|192|0更新时间：2024-05-07
- 摘要：A new semi-fragile image watermarking algorithm based on visual masking is proposed in this paper.On the basis of the visual masking of human visual system,the watermark can be adaptively embedded into host image in the wavelet domain by using group quantization in our algorithm.The proposed semi-fragile watermarking is effective for copyright protection and content authentication simultaneously without resorting to the original host image.Experimental results show that our semi-fragile watermarking scheme is invisible and is robust to common image processing(such as JPEG compression,noise adding,filtering). The proposed watermarking algorithm is fragile to content modification(such as cropping),can detect effectively the tampered regions,and has a lower probability of missing and lower probabilities of a false alarm compared with other popular semi-fragile watermarking schemes.关键词：semi-fragile watermarking;visual masking;group quantization2684|172|0更新时间：2024-05-07
- 摘要：Sharing between various spatial data has always been a main problem to the development of VR-GIS,which is a new field integrating GIS and VR(Virtual Reality).This paper analyzed the structure and feature of CNSDTF(Chinese National Geo-spatial data transfer format) and OpenFlight,a spatial data standard format for VR.Then by regarding CNSDTF as a spatial data media-format,the format transformation from OpenFlight to CNSDTF was implemented.Thus this study advanced an effective solution for Spatial Data Interoperability based on CNSDTF.关键词：GIS;spatial data;interoperability;CNSDTF;OpenFlight;VR3047|193|0更新时间：2024-05-07
- 摘要：CAUPS(computer aided urban planning system) is an object and Agent based computer aided urban planning system.It changes the traditional urban planning pattern that needs multiple software to design cooperatively,and realizes a kind of novel urban planning pattern,i.e.,it firstly defines the urban objects that will be used by typical designers in planning,and then adds them to the evaluation sub-system,which will evaluate the design case automatically.One of the most important advantages is that it can increase the planning efficiency greatly.The method of design and implementation of CAUPS is presented in this paper.One of the main characters of CAUPS is that the relational data form in traditional GIS is transformed into the object-oriented form in CAUPS where object is regarded as the basic unit.Another main character of CAUPS is it uses the entity agents as its basic units during the process of urban planning.This system has been implemented successfully in the Planning Project of Hangzhou Westlake.关键词：urban planning;GIS;object;entity agent2836|212|0更新时间：2024-05-07
- 摘要：Video transcoding is a key technology to support video communications over heterogeneous networks.In this paper,we propose a new bit-rate transcoding method for MPEG video streams,which can utilize human visual system characteristics adequately.Compared with the conventional method,this method uses skillfully foveation visual model to improve transcoding efficiency,and it can produce new lower bit-streams with better visual quality while achieving computation reduction.关键词：video transcoding;Foveation visual model;rate control2873|162|0更新时间：2024-05-07
- 摘要：A new fast searching algorithm of adaptive directional diamond is developed for H.264/AVC based on the traditional diamond searching algorithm and the prediction of the motion vector through combining some elements including hypo-optimal compensation point and adaptive compensation threshold with the optimal compensation point.As a result,the searching direction is fixed and the global optimal compensation point can be reached quickly.Experimenal results show that the searching time cost of the new algorithm decreases 40% as compared with the traditional diamond searching algorithm under the condition that the searching precision does not deteriorate,and it suits for the new video compression standard(H.264/AVC) better.关键词：motion matching;diamond searching;adaptive threshold;directional2519|195|0更新时间：2024-05-07
- 关键词：video coding;H.264/AVC;block-size selection;residual2679|164|0更新时间：2024-05-07
- 摘要：As a new video coding standard,H.264 has an enhanced motion estimation method based on block matching that each partition in an inter-coded macroblock is predicted from an area of the same size in a reference picture,the offset between the two areas(the motion vector) has 1/4-pel resolution(for the luma component).Sub-pixel motion compensation can provide significantly better compression performance than integer-pixel compensation,at the expense of increased complexity.Quarter-pixel accuracy outperforms half-pixel accuracy.Motion estimation,whose efficiency has great effect to the whole coding efficiency,is an important part during the video coding process.In this paper,we compare the basic algorithm and some fast algorithms of 1/4-pel accuracy motion estimation,then put forward a fast algorithm which use composite vector.Experiments show that this algorithm is effective.3508|190|0更新时间：2024-05-07
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