最新刊期
卷 13 ， 期 11 ， 2008
- 摘要：Texture synthesis has been well studied in recent years. It has become an active research topic of computer graphics, vision, and image processing. Aiming at the current progress of texture synthesis, this work we set forth the algorithms based on synthesis sampling, character matching, constrained synthesis and multi objects synthesis. Further more, we analyze typical algorithms’ advantage and the disadvantage on the point of synthesis quality and efficiency. At last, we discuss the orientation of texture synthesis and emphasize that the constrained synthesis techniques would speed up the study development and become the key point of synthesis application.4651|349|0更新时间：2024-05-08
- 摘要：Sub pixel image registration is required in many applications. In this paper, firstly recent sub pixel registration algorithms as well as classical algorithms are classified into three categories: interpolation based method, extension of phase correlation and method that formulates the problem as an optimization problem. Basic theories, performance characteristics, and recent improvements of the three methods are presented in detail. Secondly, the reviewed methods are evaluated in some criterions, factors affecting performance are analyzed. And lastly future development is discussed.关键词：image registration;sub pixel;phase correlation;interpolation;optimization problem6811|394|0更新时间：2024-05-08
- 摘要：The chaotic characteristics of Cellular Automata are analyzed simply and the definition of fractal dimension is constructed. Cellular Automata are applied to image encryption and image watermarking technique. The attacking examinations show that the characteristics of Cellular Automata are rather well in the application field of images.关键词：cellular automata;chaos;image encryption;watermarking technique3711|309|0更新时间：2024-05-08
- 摘要：In the application fields of computer vision, camera non linear distortion should be rectified in order to enhance the accuracy of the image measurement and 3D reconstruction. In this paper, a new approach to automated rectification of the camera radial distortion is proposed. The method makes use of a set of image point correspondences from two images to accomplish the estimation of the radial distortion from the estimation of fundamental matrix. Based on the intrinsic geometric relations between the two images, the distortion parameters and the fundamental matrix between the corrected images can be acquired automatically. Neither the camera intrinsic parameters nor knowledge about the scene structures is required in the process. Experimental results indicate that the algorithm proposed is effective and reliable.关键词：len’s Distortion;epipolar geometry;fundamental matrix;distortion rectification3370|296|0更新时间：2024-05-08
- 摘要：Super resolution (SR) technique is the task of estimating High resolution (HR) images from a sequence of Low resolution (LR) observations, which has been a great focus for compressed images. Based on the theory of regularization, a novel spatio temporally adaptive SR algorithm is developed and analyzed using the information from the compressed bitstream. A new form of regularized cost function to control the balance between temporal data and spatial prior information is proposed. An iterative gradient descent algorithm is utilized to reconstruct the HR image. The regularization parameter is simultaneously estimated at each iteration step in the reconstruction process of the HR image. Experimental results demonstrate that the proposed algorithm has an improvement in terms of both objective and subjective quality，and it is applicable for compressed images.关键词：regularization;adaptive;super resolution reconstruction;compressed image3288|252|0更新时间：2024-05-08
- 摘要：With the rapid development of information technology, compress coding has become a heated topic in the field of multimedia storage and transmission. Aiming at the coding efficiency of video compression, ITU T and ISO/IEC jointly developed a new video coding standard named H.264/AVC in 2003. In order to transmit video efficiently on certain bandwidth, the rate fluctuation should be controlled to make it as close to the target bandwidth as possible. Although rate control is not a part of the standard, it has been playing an important role in the standard all the time. For this purpose, on the basis of JVT G012 algorithm, a new rate control algorithm based on Spatial Temporal Gradient Scale (STGS) image is presented for H.264/AVC coding to select the size of basic unit adaptively. The rate fluctuation resulted from the proposed algorithm is always close to the best case of JVT G012 algorithm. Moreover, for the low computational complexity, the proposed algorithm is easy to implement in real time applications.关键词：H.264/AVC;rate control;G012;STGS image3548|262|0更新时间：2024-05-08
- 摘要：In this paper, we proposed an efficient joint source channel rate control algorithm for real time wireless video transmission which use automatic repeat request scheme to retransmission the error packet. The two state Markov model was used to simulate the wireless channel, and the Cauchy distribution based rate and distortion model were used as the source model. In the new scheme, at frame level, a PID controller based buffer control algorithm was developed to improve the buffer control ability which allocated frame target bit based on the channel bandwidth and buffer status; at macroblock level, the frame bit budget was distributed among macroblocks using the new rate distortion model and Lagrange optimization method. Experimental results show that, the proposed algorithm can improve the average PSNR and decrease the number of skipped frames significantly.关键词：wireless video transmission;rate control;Markov model;rate distortion model;Cauchy distribution3313|218|0更新时间：2024-05-08
- 摘要：Syntax/semantics, correlation detection of errors and concealment were studied in this paper, and AVS(audio video coding standard working group of china) technology characteristics was analyzed. An error detection method with two step based AVS and an adaptive error concealment(EC) based on the coded frame type(I,P,B) are presented. The experimental results indicate that errors in AVS stream can be located accurately by two step detection method,and good results are gained by the adaptive EC. Meanwhile, these methods neither interrupt the decoder nor decrease the speed of decoder.关键词：syntax/semantics detection;correlation detection;audio video coding standard working group of china (AVS);adaptive error concealment2922|242|0更新时间：2024-05-08
- 摘要：The denoising of a natural image corrupted by Gaussian noise is a classical problem in image processing. Chen et al. have proposed an effective wavelet thresholding scheme using incorporating neighboring coefficients, namely NeighShrink. NeighShrink’s disadvantages are to use a suboptimal universal threshold and fixed neighboring window size for every subband. In this paper, we improve NeighShrink using Stein’s unbiased risk estimation(SURE). Our method can determine an optimal threshold and neighboring window size for every subband. Experimental results show that our proposed method is significantly better than NeighShrink in all test examples. It also outperforms Balster et al’s FeatShrink which is a recent sophisticated image denoising algorithm.关键词：adaptive method;image denoising;neighborhood;wavelet thresholding3309|236|0更新时间：2024-05-08
- 摘要：To improve the precision of vessel segmentation and analysis affected by the quality of portal vein angiography images, a new function of comparability is presented in this paper to enhance the contrast between hepatic portal vein and other tissues such as liver parenchyma, which is based on a thorough analysis of the Hessian matrix based multiscale filter. An automated definition of interested grey range was achieved by analyzing the characteristics of portal vein angiography images. Then in which range a function of comparability, combined the multiscale Hessian matrix’s eigenvalue characteristics and original angiography’s intensity information, is used to enhance the portal vein angiography images. And the results show that the improved Hessian matrix based multiscale filter can significantly enhance the portal vein with multislice spiral CT angiography.关键词：multislice spiral CT angiography;hepatic portal vein;Hessian matrix;multiscale3306|252|0更新时间：2024-05-08
- 摘要：We describe the development of the objective quality estimation. For some typical methods, we classified them into several groups. Spearman correlation coefficient and Pearson correlation coefficient of given image quality methods of different kind of distortion such as compression, noise and so on are analyzed. It turns out that different methods have different simulations to different distorted images. After that multilinear regression analysis is used to integrate the advantages of different methods and then we get a new image quality estimation which can simulate smartly all kind of distortions. In our experiment, by analyzing the correlation coefficient we prove that our new quality estimation is robust.关键词：image quality estimation;correlation coefficient;linear regression analysis;human visual system3059|248|0更新时间：2024-05-08
- 摘要：The synthetic aperture radar (SAR) auto target recognition (ATR) algorithm developed at Lincoln Laboratory is a standard algorithm for target detection/recognition. It has three main stages: a prescreener, a discriminator and a classifier. The clustering algorithm between the prescreener stage and the discriminator stage is significant for the performance of the detection algorithm. This letter introduces the steps of the common clustering algorithm and analyzes its disadvantages. We improve the common clustering algorithm from two aspects of the read sequence of image data and the calculation means of clustering quasicenter coordinates. The clustering results based on two actual images testify the efficiency of improved clustering algorithm.2961|237|0更新时间：2024-05-08
- 摘要：Background model is a common method for detecting moving object in traffic surveillance video. The effect of Gaussian Mixture Model used in training background model is good, but its convergence velocity is low. At present, many improved models only accelerate the initial convergent velocity. For accelerating the convergent velocity when background changes in the process of surveillance, the models need to detect whether background has changed or not real time and then to be initialized again if background changes. In this paper we put forward a new improved Gaussian Mixture Model, which needn’t be initialized again if background information changes and avoids redundant steps of detecting whether background has changed or not real time. Experiment result of the new model shows the convergent velocity in the process of surveillance is improved evidently.关键词：Fast convergence;Gaussian mixture model;background model;object detection3478|262|0更新时间：2024-05-08
- 摘要：A new method was provided based on the empirical mode decomposition(EMD) to solve the difficulties of infrared image dim small target detection in complex background of sky and sea. The decomposition in this paper is based on Delaunay triangulation and piecewise cubic polynomial interpolation. Application to infrared images has shown that the performance of the algorithm can detect infrared small target in background of sky and sea exactly and quickly. The method presented in this paper appears instructive from both theoretical and practical points of view.关键词：empirical mode decomposition(EMD);infrared small target;Delaunay triangulation;cubic polynomial interpolation3491|261|0更新时间：2024-05-08
- 摘要：Transducer and curved component may interfere during automatic ultrasonic inspection.Using the characteristics of collision interference between cylindrical transducers and curved components, a hierarchy method of collision interference detection was proposed. Firstly, algorithms of bounding box and geometric intersection were used to remove most cases where components were separated. Then triaxial components which may collide were projected onto diaxial plane. Finally, collision interferes were accurately identified according to orthographic projections overlap or not. The engineer application results showed that the method can meet the efficiency and accuracy requirements of the ultrasonic inspection. It can also be applied to the cases of assembly and NC machining, where needs rapid collision detection between cylinder and complex curved components.关键词：ultrasonic inspection;collision interference;hierarchy algorithm;orthographic projection3006|253|0更新时间：2024-05-08
- 摘要：Orthogonal moments have been widely used for image recognition and classification duo to their useful properties such as being less sensitive to noise and being very accurate in image reconstruction. However, their do not natively possess scaling invariance, essential image normalization and binarization process will lead to error of resampling and requantifying. A new scaling and rotation invariant analysis method for image recognition is proposed. In the proposed method, the Radon transform is utilized to project the image onto projection space, and then the analytic Fourier Mellin transform is applied to the projection space to convert the rotation of the original image to a phase shift and the scaling of the original image to a scaling of amplitude. In order to achieve a set of completely invariant descriptors, a rotation and scaling invariant function is constructed. Based on four features of the invariant function, a k-nearest neighbor classifier is employed to implement classification. Theoretical and experimental results show the high classification accuracy of this approach in comparison to the orthogonal moments based methods as a result of using the rotation and scaling invariant function instead of images binarization and normalization, it also shows that this method is more robust to white noise than the orthogonal moments based methods.关键词：RADON transform;pattern recognition;Fourier Mellin transform;invariant analysis3246|270|0更新时间：2024-05-08
- 摘要：No single subspace feature extraction algorithm outperforms others under all circumstances, but applying dual space feature extraction algorithm can overcome the limits of single subspace. To increase the recognition rate of classified results, a new dual space feature extraction algorithm is put forward based on PCA (principal component analysis) and ICA (independent component analysis). The algorithm uses ICA as PCA’s complementary space to realize feature extraction. The aim of the algorithm is to reproject the samples into ICA subspace to classify, which are difficult to be classified in PCA subspace. The proposed dual space extraction algorithm includes two steps. Step 1 is called preclassify, which uses two classifiers in a single subspace to classify the testing samples. If a testing sample is classified into different classes by two classifiers, it would be added into the new testing samples set. In step 2, the algorithm projects the samples of the new testing samples set into another subspace and classifies them. Then, the recognition results of two subspaces are tested together. The experimental results in ORL and FERET database prove the dual space feature extraction algorithm outperforms the traditional feature extraction algorithm in recognition rate.关键词：dual space algorithm;principal component analysis;independent component analysis;feature extraction;face recognition3345|270|0更新时间：2024-05-08
- 摘要：To reduce the influence of geometrical deformation on image matching, we put forward a method which can detect multipixels edge of image. The method is based on difference of gray level between the border upon pixels. Adopting matching method of multipixels edge, matching between datum image and real time image is improved observably because of deformation, such as edge excursion, rotate and scale transformation. The result show that, the multipixels edge detecting and matching method is of simple model, perfect real time quality and power ability to counteract the effect of geometrical deformation. The whole system can be realized easily.关键词：edge detecting;matching and locating;single pixel edge;multi pixels edge3383|387|0更新时间：2024-05-08
- 摘要：A watershed segmentation method combining multiscale morphological gradient reconstruction with marker extraction is proposed. Considering the idea of multiscale, this method employs different sizes of structure elements to reconstruct morphological gradient image and extracts markers of regional minima from each gradient image by using thresholds. The union set of a series of marker images is regarded as the final marker image. Then the markers are used to modify morphological gradient image. Finally, the watershed transformation of the marker modified gradient image is performed to achieve the regional segmentation of the image. Experimental results show that this method can effectively avoid over segmentation of watershed algorithm and maintain important objects at different scales. Furthermore, better segmentation results can be achieved by adjusting the chosen parameters during segmentation process according to the features of the image and specific requirements.关键词：image segmentation;watershed algorithm;morphological gradient;morphological reconstruction;marker extraction4791|374|0更新时间：2024-05-08
- 摘要：Real time object tracking method is proposed in this paper. It provides the ability to track the moving object in color image sequences. Firstly, an improved motion detection method is used to acquire potential regions with moving object regions in the image. Then it tracks the object by combining the Mean Shift algorithm and moving detection algorithm. The experiment results show that the algorithm which can track the moving objects quickly and precisely, and the algorithm is robust to size changes of the moving objects and can track sudden appearance of objects.3589|333|0更新时间：2024-05-08
- 摘要：In this paper a novel approach for object tracking using multiple cues is presented, based on the investigation of human eye tracking. In this approach, multiple cues with serial structure are used in tracking. First, some candidate objects are found through near neighbor principle. Then multiple cues with different priorities select the candidates in order. At last, the only survive candidate is fined by the modified module to get more accurate tracking result. The most salient characteristic of this approach is the principles of self organization and self adaptation of the changing environment during tracking. Multiple cues compete and cooperate in the system, which make the tracking has strong adaptation and vitality. Experiments show the robustness and accuracy of the tracking algorithm.3063|341|0更新时间：2024-05-08
- 摘要：The theory and technology of 3D reconstruction is one of the important problems in the computer visual field, and 3D restruction based on the single image has been the difficult problem in the century since without enough geometry information it was hard to reach the anticipative effects. This thesis aimed at the fact that most of the objects have the characteristics of symmetry or decompose into the limited symmetry objects, and put forward the principle of perspective reversible transformation. At first, the angle, inclination angle and pivot angle should be established in the ternary perspective transformed matrix, then the calibration which indicated the outline of the object can pick up the characteristic straight line. It extractes the host extinguishes information in accordance with the similar features of the parallel group of lines projection angle, then ensured the viewpoint situation and the symmetry surface of object. Based on this three pairs of the known symmetry image coordinates and the space coordinates of the corresponding points confirm with the perspective transformative matrix T. The result is reversed to calculate the other space coordinates of the surface of objects. Finally the objects of 3D reconstruction model can be realized by utlizing OpenGL software.关键词：symmetry object;viewpoint situation;perspective reversible transformation;reversely prove 3D coordinates;reconstruct the hardware model3287|255|0更新时间：2024-05-08
- 摘要：The Log polar mapping is a rigid invariant image matching algorithm, Levenberg Marquardt Algorithm （LMA）can calculate image registration parameters with high precision， but the LMA algorithm fails when facing an image pair with intense scene variance. In this paper we propose an image registration algorithm with sensitive region introduced in LMA phase, only pixels in the manually selected sensitive region are calculated in the iteration. The algorithm is used to register five representative photos of the Shanxi South China Tiger. The experiment shows that the method is a valuable improvement to the LMA algorithm.关键词：Log polar mapping;Levenberg Marquardt algorithm iteration;sensitive region2809|236|0更新时间：2024-05-08
- 摘要：The fusion of multispectral (MS) and panchromatic (PAN) images is the nodus of Remotely Sensed Images Fusion. In order to improve the quality of the fused image, in this paper, a novel fusion strategy based on non subsampled contourlet transform (NSCT) is presented. Due to the non subsampled contourlet transform (NSCT) is obtained by coupling a non subsampled pyramid structure with the non subsampled directional filter bank (DFB), and the non subsampled contourlet transform (NSCT) is shift invariant and high directionality, it can remedy the limitation of the subsampled contourlet (CT) transform and solve the low directional problem of discrete wavelet transform (DWT). In the experiment we used the images of Landsat TM5 and SPOT to validate this strategy, and compared with the DWT and CT use the method of direct replace, chose the maximal absolute value and chose the maximal local Variance. The experimental results show that our method is more effective than other methods in improving the quality of image. This also proves that NSCT is an effective strategy in the field of remotely sensed images fusion, and it can be successfully used in the application of remotely sensed images fusion.关键词：non subsampled contourlet transform;wavelet transform;remotely sensed image fusion3186|308|0更新时间：2024-05-08
- 摘要：A novel texture image retrieval approach based on generalized Gaussian distribution statistic model in the complex wavelet domain is presented for common representation of texture that lacks precision and real DWT that have shift sensitivity and poor directionality. Generalized Gaussian distribution statistic model is constructed by taking advantage of the statistical attribution of complex wavelet transformation coefficients. Image feature is obtained by using this new model. A texture image retrieval project is designed based on new statistic model combining with Kullback Leibler distance (KLD). Extensive experiments from Brodatz texture images clearly show the superiority of the novel approach which obtained accuracy 6.96 percent higher than method that is based on complex wavelet transform,and 18.6 percent more than method that is based on Gabor texture features. So the new method is valuable for texture image retrieval in the future.关键词：texture image retrieval;complex wavelet transform;generalized Gaussian distribution statistic model;Kullback Leibler distance(KLD)2904|289|0更新时间：2024-05-08
- 摘要：Mesh simplification is an important research topic in scientific visualization and virtual reality. The detail characters are important parts of an object model and the vertex normal is one kind of characteristic representations. In order to preserve the detail characteristics in mesh simplification, the discrete curvature of curves is introduced to the method based on quadric error metric (QEM) in this paper. In addition, the average triangle normal is used as the vertex normal in order to get a better visual effect. The experimental result shows that the proposed method can maintain more object features at the same decimation rate as QEM method, while keeping a good visual effect.关键词：mesh simplification;edge collapse;average normal;curvature of curves3209|296|0更新时间：2024-05-08
- 摘要：To improve the realistic effect of smoke simulation, a real time smoke shadow simulation algorithm based on direct projection and diffusion is proposed. Firstly, the 3D smoke density field is directly projected to a 2D plane and accumulated into a light buffer to generate a texture which describes the shadow energy. Then, diffusion is used as a novel energy spread scheme to deal with the shadow excessive accumulation induced by direct projection. Finally, the shadow texture is mapped to a corresponding surface in 3D scene by projective texture based on programmable graphics hardware. Experiment results show that the algorithm is efficient, simple and effective to achieve real time smoke shadow for 3D computer games and animation.关键词：shadow texture;direct projection and diffusion;excessive accumulation;projective texture;smoke shadow2634|217|0更新时间：2024-05-08
- 摘要：Based on the Waters muscle model（WMM）, a novel lip muscle model（LMM）is proposed in this paper. LMM perfects the inaccurate description of the complicated lip muscle movements in WMM. On the basis of facial anatomy, the global lip movement is divided into a few submovements. The reconstruction of the lip movement is based on the linear combination of the submovements. In the application of modeling talking face, several feature points are marked to obtain a group of lip parameters. All kinds of lip shapes are synthesized using the proposed LMM and the adjacent linear muscle model. The experimental results show that the proposed model is practical in view of its low computational cost and ability of producing all kinds of realistic synthesized lip shapes.关键词：Waters’muscle model;lip muscle model;sub movement;talking face;linear muscle2967|226|0更新时间：2024-05-08
- 摘要：Due to the inherent complexity of terrain models, the development speed of computer hardware is far from satisfaction for real time rendering of large scale terrain model. To resolve this problem, we enhance the traditional ROAM algorithm and therefore realize view dependent real time rendering of large scale terrain model with GPU programming. Here, the enhanced ROAM (real time optimally adaptive meshes) algorithm is employed to create view dependent continuous LOD models, and the GPU programming is employed to calculate the vertices’ transform, normal vector, texture coordinate, texture sampling and fragment lighting and accomplish the rendering for the terrain in the end. Experimental results show that, GPU programming is an effective way to improve the algorithm performance and to achieve real time roaming on relatively large scale terrain.关键词：GPU programming;terrain visualization;real time optimally adaptive meshes (ROAM)3367|277|0更新时间：2024-05-08
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