最新刊期
卷 12 ， 期 2 ， 2007
- 摘要：H.264 introduces intra-prediction coding and uses Lagrangian rate-distortion optimization(RDO) technique to decide the best intra-coding mode.Although the intra-prediction greatly improves the intra-coding efficiency,it enormously increases the computational complexity.In order to decrease the computational complexity of the algorithm,a fast algorithm for intra-prediction mode decision based on pixel's directional relativity is presented in this paper.Experimental results show that compared with the original intra-prediction coding scheme,the proposed algorithm reduces the computational complexity of intra-prediction coding dramatically with only trivial loss of PSNR and increment of bite-rate.关键词：video coding;H.264/AVC;rate-distortion optimization(RDO);intra-prediction;mode decision4620|187|0更新时间：2024-05-07
- 摘要：This paper brings forward a text embedding digital watermarking method based on image's DWT domain,meanwhile,using the chaotic sequences to encrypt the text data and BCH code to correct them.The experimental results show that the method enlarges watermark capacity and improves the ability to resist the usual attack.关键词：text watermark;chaotic sequences;LWT;BCH4827|212|0更新时间：2024-05-07
- 摘要：In order to protect the copyright of the transmission and sharing of the geospatial information,this paper presents a robust watermarking algorithm for 2D vector graphics.In GIS system,vector graphics is a basic type of imformation and a large dataset of 2D vector graphics are often needed to perform watermark embedding for the security purpose.The processing method,Includes: Firstly,decompose the vector graphics into the polygons that layer has;Then analyze these polygons and embedded the watermark in the start and end points of the selected line.In the procedure of extracting watermark,the original graphics and the watermarked graphics were analyzed and extracted the sequence of the watermark information according to the position or the coordinate of the vector.The experimental results show that the method is rubust against the general operations of the spatial graphics such as transformation,translation,rotation,scaling,cropping and vertex insertion/removal etc.关键词：watermarking;vector graphics4416|190|0更新时间：2024-05-07
- 摘要：Embedding watermark in a digital vector map could generally degrade the quality of the map data.However,invertible watermarking(or lossless data hiding) is more appropriaue to vector maps for its ability to recover the original cover data.A lossless data hiding algorithm for digital vector maps based on difference expansion is proposed in this paper.According to the vector map's special requirement to data precision,an embedding condition is firstly presented.The watermark can be embedded by modifying the coordinate differences between the adjacent vertices and the original map can be recovered bit-by-bit after the watermark has been extracted.Two kinds of original maps are used in the experiments and the results indicate that higher payload and lower distortions could be achieved in the maps with higher correlated coordinates.The potential usages of the proposed scheme would include the map data authentication,meta data format compatibility,and secret communication based on vector maps.关键词：vector map;lossless data hiding;difference expansion;payload4386|196|0更新时间：2024-05-07
- 摘要：Previous proposed steganographic schemes based on tolerable error range(TER) can restrict the distortion caused by data-hiding within an accepted range,but both the stego-image and the original cover image are necessary for extracting the secret message.This paper presents a novel TER-based steganographic scheme,in which JPEG compression under a certain quality factor is regarded as TER,and the modification caused by data-hiding on each pixel is less than that caused by JPEG compression.Furthermore,the JPEG version of a stego-image is completely the same as that of the corresponding original one.At receiver side,the embedded secret data can be extracted by subtracting the stego-image from its JPEG version,so that the original cover is needless.Experimental results show that the presented scheme can gain a stego-image which is superior to its JPEG version in quality,and possesses a capability of withstanding the statistical analysis.关键词：steganography;JPEG compression;tolerable error range(TER)4364|250|0更新时间：2024-05-07
- 摘要：This paper presents several models of index algorithm and analysises,the property of lifting wavelets transform.To solve the problems of the space needed for the index-matrix,we change the 5/3 wavelet,and propose a novel image multiscale transform method.The dynamic ranges of both high-frequency coefficients and low-frequency coefficients generated by the proposed new transform are the same as those of the original input image.Thus,the multi-level reversible index transform is realized.The experimental results show that the implementation of the multiscale transforms based on index method is faster than that of the general method.关键词：index algorithm;multiscale transform;fast algorithm;lookup table3922|199|0更新时间：2024-05-07
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- 摘要：Region-based Image Retrieval(RBIR) is a sub-branch of Contentbased Image Retrieval(CBIR).It employs image segmentation to extract local visual feature and retrieves images by similarity matching.However,as precise image segmentation is still immature,the performance of RBIR systems is subject to redundant and inaccurate segmentation.In order to reduce adverse effect of image segmentation in RBIR,a new method based on partition of foreground and background is proposed.In the method,image segmentation regions are obtained by applying regular block,classification and valid region location.And the principal object is extracted using the Central Object Extraction Algorithm(COEA).Then images are retrieved by similarity matching based on extracted color and texture feature.In the paper,a RBIR system named ObFind is implemented according to the proposed method.The experimental results show that the proposed method not only has comparable performance to SIMPLIcity but also reduces computation complexity.关键词：region-based image retrieval;foreground partition;image segmentation4758|211|0更新时间：2024-05-07
- 摘要：A novel automatic image annotation approach is proposed to bridge the semantic gap of content-based image retrieval.Our approach first performs segmentation of images into regions,followed by the clustering of regions to blobs using a semi-supervised image clustering algorithm with soft constraints which utilizing the visual and semantic information of images.And a graph-based algorithm is used to compute the probabilistic relation between concepts and region blobs which can be used to annotate new images.Experiments conducted on standard dataset demonstrate the effectiveness and efficiency of the proposed approach for image annotation.关键词：semi-supervised clustering;soft constraints;image annotation;Manifold ranking4867|232|0更新时间：2024-05-07
- 摘要：A practical tracking system is required to update the appearance changes of moving objects in real-time.The system with fixed-size tracking window could not trace an object effectively when scale of the object has distinct changes,therefore it is important to select the scale of tracking window automatically.The information measure of multi-scale image in scale space has been used to differentiate the scale and is introduced into moving object tracking in this paper.Automatic updating method of tracking window is proposed,and is integrated into the classical Mean-Shift tracking algorithm based on color histogram.Experimental results demonstrat that the improved algorithm could select the proper size of the tracking window in the scenarios that not only of increasing scale but of decreasing scale.关键词：object tracking;information measure;Mean-shift4968|228|0更新时间：2024-05-07
- 摘要：In Mobile Graphics Computing,3D graphics is generally illustrated by meshes of 3D geometric model.In order to overcome the difficulty of storage,transmission and rendering for Mobile Graphics,a novel algorithm to construct progressive meshes based on reverse subdivision is proposed.A method for transmission progressive meshes over wireless network and its rendering on mobile devices is presented.The dense mesh is simplified into coarse base mesh and a series of errors by decimating the redundant information level by level.Loop subdivision scheme,which is an approximating scheme,is adopted as interpolatory one in the simplification process.The implementation of our algorithm consists of three key steps: splitting,predicting and updating.The mesh can be reconstructed lossless.The experimental results show that the algorithm is highly efficient and faster than previous related techniques.关键词：progressive mesh;progressive transmission;reverse subdivision;graphics rendering5392|215|0更新时间：2024-05-07
- 摘要：Due to the problems in Geometric Modeling for Historical Cultural Relics(HCR), a new geometric modeling mending method based on many knot spline interpolation is proposed in this paper. Using Many-Knot spline’s local explicit interpolation properties,“null holes”generated in image based geometric modeling in stereo vision system can be filled by many knot spline interpolation algorithm, while geometric modeling for partly damaged HCR can also be mended by Many-Knot spline interpolation algorithm.关键词：many-knot spline interpolation;geometric modeling mending;historical cultural relics(HCR);stereo vision;image based modeling&rending(IBMR)4437|191|0更新时间：2024-05-07
- 摘要：This paper presents a real time cartoon smoke simulation algorithm based on fluid dynamics and particle system.The smoke path is controlled by the Navier-Stokes equation to get an impressive effect.The density function and working radium are added to the particle properties,thus very little particles are needed to generate the smoke density field.To get the cartoon effect,primitives designed by animators are mapped to the scene according to the smoke density during the rendering process.Experimental results show that the algorithm is simple and effective to achieve real time cartoon smoke simulation.关键词：cartoon smoke;Navier-Stokes equation;particle system;computer animation4989|254|0更新时间：2024-05-07
- 摘要：H.264,the latest video coding standard,achieves significant improvement in coding efficiency compared with previous standards.The high coding efficiency is based on some new techniques which also lead to high computational-complexity.H.264 uses variable-block-size motion estimation,which is the most time-consuming module.In this paper,we propose a fast variable-block-size motion estimation algorithm for H.264.The algorithm is based on three schemes: stationary block prediction,predictive search for non-stationary blocks and adaptive refinement search in merging process.Experimental results show that our algorithm can reduce the computational-complexity to 3% of fast full search motion estimation algorithm,with negligible PSNR loss and bit rate increase.关键词：H.264;video coding;motion estimation3288|209|0更新时间：2024-05-07
- 摘要：Fractal image coding is a very promising compression technique,but it suffers from long encoding time.The time to encode fractally an image is mostly spent on searching for the best-matched block for each of range blocks in a usually-large domain pool.This paper thus proposed a fast fractal encoding algorithm based on fractional box-counting dimension of an image block,which can find out the best-matched block for an input range block with a reduced search.Experimental results show that the proposed algorithm can significantly shorten the encoding time,while achieving the same or better decoded image quality as baseline fractal algorithm with full search.关键词：fractal;fractal image coding;fractal image compression;fractional box-counting dimension3489|219|0更新时间：2024-05-07
- 摘要：Video transcoding for reduced spatial resolution needs a lot of computation.Restricted by real-time demand,the quality of transcoded stream will decrease in variant degree.In order to improve the quality of transcoded stream,a new scheme is proposed in this paper which estimates the distortion degree of downscaled texture and motion vector according to the condition of neighbor macroblocks' texture and the cluster degree of their motion vectors,and then adaptively chooses one arithmetic to transcode.Experimental results show that this scheme can bring some improvement to the quality of transcoded stream,and at the same time avoid extensive motion search and introducing much of intra-coded macroblocks.关键词：transcoding;motion vector;Euclidean distance;residual;intrarefresh3245|204|0更新时间：2024-05-07
- 摘要：Watermarking of 3D models is one of hot research topics in the field of watermarking.The difficulties for 3D model watermarking are robustness and blind detection.To achieve robustness,implement blind detection and make the detection result unambiguous,this paper proposes a new blind 3D model watermarking algorithm for triangular meshes.The scheme embeds the watermark,which is readable character string rather than meaningless pseudo-sequence,by modifying the location of vertices in their local coordinate system.The original model is not required for detecting watermarks.Experimental results show that the algorithm has good visual quality and is resilient against attacks such as translation,rotation,scaling,model cropping and vertex permutation.关键词：digital watermarking;3D model;triangular mesh;copyright protection2936|206|0更新时间：2024-05-07
- 摘要：In this paper,a method is proposed for projector calibration in 3D photography systems using grating projection.An image with intersection lines between grating planes and a known objective plane can be captured by a digital camera.According to the image a pair of points can be extracted from each of intersection lines.If we move the known objective plane to known positions,we can get more pairs of points belonging to the same plane.At the last,every grating plane equation can be approached with Least Square Fit Algorithm based all corresponding sample 3D points on it.关键词：3D photograph;grating projection;least-squares fit;projector calibration;reverse engineering2779|199|0更新时间：2024-05-07
- 摘要：In many computer vision tasks,in order to improve the accuracy and robustness to the noise,wavelet analysis is preferred for its natural multi-resolution property.However,the wavelet representation suffers from the dependency on the starting point in shape matching.For overcoming the problem,the Zernike moments are introduced,and a novel Starting-Point-Independent wavelet coefficient shape matching algorithm is presented.The proposed matching algorithm firstly gains the object contours,and gives the translation and scale invariant object shape representation.The object shape representation is converted to dyadic wavelet representation by wavelet transform,and then the Zernike moments of wavelet representation in different scales are calculated.With respect to property of rotation invariant of Zernike moments,consider the Zernike moments as the feature vector to calculate the similarity between the object and template image,which overcoming the problem of dependency on starting point.The experimental results indicates that the proposed algorithm is efficient,precise,and robust.关键词：shape matching;Zernike Moments;wavelet transform2658|201|0更新时间：2024-05-07
- 摘要：In order to overcome the deficiency of approximation to the wavelet coefficient joint probability with two-state Gaussian mixture model(GMM) and the shortcoming of the independence between wavelet labels in wavelet domain hidden Markov tree model(HMT),a new image segmentation algorithm based on wavelet domain hierarchical Markov model is proposed.The new image model is described as wavelet coefficient joint distribution with finite general mixture model(FGM),while the GMM in HMT model is only one of the FGMs.Vitilizing on the local interactions of labels described by Markov random field(MRF),the label field priori probability model with explicit expression,which overcomes the shortcoming of the independence between labels in the HMT model,is determined.Using Bayes principle,the recursive algorithm of image segmentation is derived.The proposed model inherits not only the characteristics of spatial domain hierarchical MRF model with effective recursive algorithm but also the characteristics of HMT model with the variable Markov parameters in different scales.The experiments with real images and synthetic texture images are carried out,the results show that the proposed method outperforms other standard segmentation methods,such as accurately locating image edges,correctly identifying different regions.关键词：wavelet domain Markov random field;maximum a posterior(MAP) probability;image segmentation;Expectation-maximization algorithm3475|208|0更新时间：2024-05-07
- 摘要：This paper presents a novel algorithm for license plate detection in complex environments.The algorithm generates connective components by hierarchical distances between edge points based on vehicle edge map and then gets the relevant minimum enclosing rectangular by searching the whole map.Afterwards,it picks up candidate regions of plates according totopological characteristics and color features.In this paper,least constraints are imposed on the working environment.In the experiment for locating license plates,526 images taken from various scenes and under different conditions were processed with an accuracy of 98.3%.At the same time,the average locating time is less than 40ms.关键词：intelligent transport system;license plate recognition;license plate location;edge detection;distance between edge points;color space;real-time3124|253|0更新时间：2024-05-07
- 摘要：This paper proposes a new local Gabor filter bank to overcome the disadvantage of the traditional Gabor filter bank,which needs a lot of time to extract Gabor feature vectors and the high-dimensional Gabor feature vectors are very redundant.In order to evaluate the performance of local Gabor filter bank,a Facial Expression Recognition(FER) system based on Gabor feature is presented.Firstly the FER system extracts Gabor feature of pure facial expression images after preprocess,then it uses a two-stage method PCA plus LDA to select and compress the sub-sampled Gabor feature,finally it adopts K nearest neighbor classifier to recognize facial expression.Experimental results show that the method is effective for both dimension reduction and recognition performance.The novelty of the method is to select partial Gabor filter bank with part of m scales and n orientations to extract Gabor feature.The best average recognition rate of 97.33% was achieved,which indicated this method was suit for facial expression analysis.关键词：local Gabor filter bank;feature extraction;PCA;LDA;facial expression recognition4096|243|0更新时间：2024-05-07
- 摘要：One new multifocus image fusion algorithm is proposed based on human vision system.According to the characteristics of multifocus images,one approach which can search the approximate(crude) position of focus region in images based on comparison of the contrast error of blocks every certain rows and columns is adopted,and the correct position of the focus region is confirmed based on the approximate position using the comparison of the contrast error of blocks again,then the image is divided into three parts:focus region,nonfocus region and the boundary between the focus region and nonfocus region.Take the focus regions in the two candidate images,and calculate the weighted sum of the boundares,then we can obtain the fused image.Experiments prove that the new algorithm is faster and more precise than traditional wavelet-based fusion algorithm and block-based algorithm.关键词：focus image;image fusion;pixel;feature of human vision system3465|225|0更新时间：2024-05-07
- 摘要：In this paper,an improved fully-automatic image mosaic algorithm is presented.Firstly,phase correlation is used to sort the unordered image sequence and roughly compute the translation offset between adjacent images,which speeds up corner match procedure and improves matching stability as well.Secondly,RANSAC algorithm is used to eliminate outliers to ensure effectiveness of the matched corner pairs.Then,Singular Value Decomposition-Least Square(SVDLS) method and Levenberg-Marquardt optimization are used to robustly determine the 8 parameters transform model,which aims to reduce the registration error and also improve the stability when handling very small number of matched corners.At the last of the algorithm,a multi-band blending technique is used to generate the final panorama.Invalid parameters are verified by the translation offset to make Levenberg-Marquardt optimization more successful and robust.The experimental results show that the proposed image mosaic algorithm exceeds existing ones at matching speed,stability,and it has less blur or ghost effect after blending, especially when there are noise,moving objects,repeated texture and small overlaps presented in the images.关键词：phase correlation;corner matching;SVDLS;panorama;multi-band blending7688|227|0更新时间：2024-05-07
- 摘要：The iterative simulation equation set of high accuracy surface modeling,HASM3,is upgraded into HASM4 on the basis of numerical tests repeatedly in order to give a solution to the computing time problem of HASM3.The experimental results show that HASM4 has greatly shortened the computing time comparing with HASM3.With increase of total number of grid-cells in the computational domain,the computing time of HASM4 becomes shorter and shorter,which can be formulated by a function of negative power exponent.In the meanwhile,iteration times of HASM4 for reaching its convergence rectilinearly decrease with increase of total number of grid-cells in the computational domain,comparing with the ones of HASM3.HASM4 has not only shortened computing time,but also enhanced simulation accuracy,comparing with HASM3.关键词：high accuracy surface modeling;numerical test;computing time;simulation error3825|216|0更新时间：2024-05-07
- 摘要：There often exist some problems,such as long training time and bad training effect etc.,when self-organizing map neural network(SOM) technology is employed in reverse engineering to reconstruct B-spline surface from scattered data points.In this paper,a new initialization method and a divide-and-conquer training scheme is presented.The approach functions as follows: firstly,the scattered data points are split into segments through principal component analysis(PCA);the neurons of output layer with quadrilateral topology are initialized on the least-square fitting planes of every segment.All the mesh surfaces obtained by training every segment respectively are integrated into a whole.Secondly,the boundary and interior neurons in the whole mesh surface are then trained and an approximate bi-linear B-spline surface is reconstructed.Finally,the B-spline surface reconstruction error is improved.Experiments show the proposed method can reduce SOM network training time and improve neural network training effect obviously.关键词：reverse engineering;surface reconstruction;self-organizing map neural network(SOM);data segmentation3225|217|0更新时间：2024-05-07
- 摘要：This paper proposes a novel algorithm for surface-based hierarchical clustering simplification that aims to accelerate view-dependent point set rendering.The remarkable advantage of this algorithm is that it uses a normal cone semi-angle metric to trace surface curvature variation and provides the clustering simplification process with a reliable global error control,rather than commonly used spatial partition scheme.In off-line simplification phase,combined with various predefined clustering constraint conditions the algorithm constructs a continuous multi-resolution hierarchical representation for point set model.In real-time rendering phase,hierarchical visibility culling and optimized tree traversal efficiently improve system integral performance.Moreover,an additional silhouette enhancement mechanism is introduced to ensure a well rendering vision quality in spite of a larger screen projection error and higher model reduction rates.关键词：simplification;level of detail;point based rendering;multi-resolution3299|199|0更新时间：2024-05-07
- 摘要：Land surface temperature(LST) retrieval has been a key issue in the thermal infrared remote sensing research area. Landsat5 TM data with a higher spatial resolution thermal infrared band of 120m was of ten used to retrieve land surface temperature. However, the fact that Landsat5 possesses only one thermal infrared band is also a critical limitation for LST retrieval. In most cases, only at-satellite brightness temperature was thus obtained from TM6 data, which is far different from the land surface temperature. Hence the precision of land surface temperature retrieval was actually not so satisfied. While the proposal of the generalized single-channel algorithm in 2003 makes it possible to figure out land surface temperature from TM6 data with high precision. Based on this algorithm, a test for land surface temperature retrieval of Beijing region was carried out with Landsat5 TM data acquired on 6 May 2005. MODIS data received on the same day was used to compute the total atmospheric water vapor content which is necessary for the algorithm. Furthermore, the retrieving result has been validated using simultaneously measured in situ data, and compared with that of using standard atmosphere data. A significantly high precision with a rootmean square deviation(rmsd) of 1.67℃ has been achieved by the approach introduced in this paper, which shows the advantages of synthetically utilizing multi-satellite data.关键词：generalized single-channel algorithm;land surface temperature;Beijing;total atmospheric water vapor content;MODIS3652|209|0更新时间：2024-05-07
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