最新刊期
卷 6 ， 期 2 ， 2001
- 摘要：The purpose of this paper is to present a survey of recent publications concerning visualization of medical images. These techniques are described in three profiles: segmentation and classification of 3D medical images, data integration of multimodality images, and rendering of volume data. The three catalogs of methods are classified and several specific examples of each class of algorithm are described. Many researchers are dealing with the problem of non invasive diagnosis. One way of doing this are the imaging techniques used in almost every clinical environment, e.g. Ultrasonography, X ray Computed Tomography(CT), Magnetic Resonance Imaging(MRI), fMRI, Positron Emission Tomography(PET), Single Photon Emission Tomography(SPET), ect. Segmentation aims at the location of segments of interest in the image and thus the partitioning of the image. The purpose of data integration is to combine image information from multiple modalities/protocols. Besides rendering, accurate and automatic segmentation and image registration/fusion techniques are both key problems in medical visualization. The visualization of multimodality images is the most challenging and promising direction in the field of three dimensional medical image visualization.3194|670|0更新时间：2024-05-07
- 摘要：The digital media, including text, image, graphics, audio and video etc., has become a main way for information communication along with the popularization of Internet and the development of multimedia techniques. People can get almost information through the Internet. But this gives rise to serious problems including wide spread copyright violation, illegal copying, easy forging etc. How to provide copyright protection and implement covert communication has drawn extensive attention in recent years. As a main method for covert communication and copyright protection(watermarking), information hiding has been widely studied and applied. In this paper, we make an introductory review on the information hiding techniques including the last achievement in this field. First, we give the general concepts and fundamental principles of information hiding such as the definition, characteristics, classification and general framework. Then, we analyze the processing model, the typical methods, the main application and the attack analysis of watermarking. Finally, we make a discussion on some open problems and point out possible directions for further research.6003|859|0更新时间：2024-05-07
- 摘要：Based-GIS studies of flood area and damage evaluation have been being a research focus in GIS application fields. In this paper, a new model of flood area based on seed spread algorithm and of the damage evaluation has been proposed. Two different cases so-called “non-source flood” and “source flood” exist when determining flood area based on DEM and under the given water level condition. Non-source flood corresponds to the case with well-distributed and large-area rainfall where all the low-lying land may have a flood disaster, and in this case all the points with elevations below the given water level should be included in the flood area. The “source flood” is the case of flood (e.g. from bank burst) flushing through the nearby regions and needs to consider “circulating” condition. It is because flood may be obstructed by ring structures or high lands and thus can only covers the place where it can flow and reach. The results of the flood area calculation and damage evaluation can also be visually and dynamically provided in the forms of graph, image, 3D or virtual reality. The model of flood area calculation and damage evaluation proposed in this paper, adopting Microsoft VC++ 6.0 programming language and Microsoft SQL Server 7.0 DBMS platform, has been successfully applied in the “Zhejiang Provincial Water Conservancy Management System” developed for a national project3514|589|0更新时间：2024-05-07
- 摘要：This paper presents a new method for color image compression coding by using correlation of color components combined with wavelet transform. In this method, one of the three color components of a color image is coded using wavelet transform zerotree coding, and the component is segmented into several non overlapping subregions in the same size. and the chromatism matrixs are figured out by the margin between the component and the other two components in each subregions, and then the correlation coefficients is ciphered out suing chromatism matrix analysis. Based on the calculated correlation coefficients, the coding for the other two components becomes the coding of correlation coefficients. During decoding, the component is first reconstructed using inverse quantization and wavelet inverse transform. Then according to this component and the reconstructed correlation coefficients, the other two components are calculated out. Finally the color image is reconstructed by the three color components. Experiment results show that this method is of high coding and decoding rates, and with quite good signal to noise ratio, compression rate and visual quality.3103|441|0更新时间：2024-05-07
- 摘要：In remote sensing applications, accurate registration is importment for data fusion and detection of object changes. When registering images with substantially different characteristics, the traditional method of tie points give inaccurate results. In this study, a registration method using a multi window cross correlation technique is developed. A moving window with different scales in the target image is cross correlation with a chosen fixed window in the reference image, and the best match is obtained to provide a satisfactory registration by comparing loop algorithm. Using cross correlation technique for separated windows from reference image, all the match location and the ratio between two images can be determined. Three registration tests employed this method were done between TM images at different time, SAR at different time, AVIRIS and aerial photo. Experimental results on sparately acquired TM images, SAR, AVIRIS images and aerial photos show that the described method can produce subpixel accuracy for registraction between complex images, and it is more convenience than the tie points methods.3531|580|0更新时间：2024-05-07
- 摘要：Independent Component Analysis(ICA) is a novel approach of blind source separation and has received attention because of its potential application in signal processing such as in speech recognition system, image processing, telecommunication and medical signal processing. In this paper, the fundamental theory and algorithm of ICA is introduced. The feasibility of ICA for sequential image processing is studied and a novel ICA based approach of moving target detection is proposed. One of the main tasks of moving target detection is how to remove the interference of background efficiently. In our research work, we find that ICA has the good performance for the background rejection. The steps of our method are that: firstly, we apply ICA to the sequential images of containing moving target to get the mixing matrix of ICA linear mixing model and the vector of the independent components. The result of ICA show that the background component is separated from other independent components. So, secondly we can set the independent components that contain obvious background image to be zero and then do the inverse computation of ICA using the mixing matrix. After the two processing steps above, we get the clear track of moving target. The experiment results illustrate that ICA has good performance for blind source separation, and the novel approach of moving target detection based on ICA is more effective than the traditional detection method.2738|533|0更新时间：2024-05-07
- 摘要：In the process of mapping using optical remote sensing images, due to the limit of the conditions obtaining the remote sensing data and the affect of weather, the obtained images often are covered by clouds, which causes the losing of the information in local area and affects the quality of image map in some degree. In this paper, a method is proposed by fusion of multi sensor images collected at different date to remove the affect due to cloud cover. It consists in two steps: firstly the auto registration is done around the region with clouds. In this step area based grey match is used to get tie point, and statistical relational matching is done iterative to adjust the initial match result more reliable. So the two image can be registrated local area with high accuracy according to the final matching points. Secondly the image with cloud is replaced automatically by the other sensor image which has been radiation corrected through histogram matching so as to prevent the false edge from emerging during image mosaicing. At last, the test that SPOT image with clouds is replaced by TM image is done. The result demonstrates that the proposed method is possible and valuable, and the information in cloud area is recovered properly.2728|425|0更新时间：2024-05-07
- 摘要：Nowadays X ray computerized tomography has been one of the most important diagnostic tools in medicine. However, sometimes the metallic implants absorb the X rays and therefore introduce streaks on the reconstructed images, which interfere diagnosis severely. In this paper, a simple interpolation method using quartic polynomials to fill in the missing projections is presented. The clipping on the pixel values of the reconstructed image is also proposed. The polynomial is determined by several criteria, namely smooth transition at the ends of the gap of missing projections, being as linear as possible inside the gap, and constant sum of interpolated projections in every direction. Value clipping eliminates irrational pixel values by evaluating the distribution of pixel values. Experiments show that by our method, the streaks caused by the metallic implants can be greatly suppressed and the contrast can be significantly improved.3012|443|0更新时间：2024-05-07
- 摘要：The generation of a digital X ray image is such a complex process which includes the production, the conversion and the transform of the X ray information. Generally, the interactions between X ray and other material include photoelectric absorption and comptom scattering, which have relations to the material's mass, density, equivalently atomic weight and the energy of X ray. In clinical use, X ray has a wide spectrum similar to the daylight, so its intensity will become harder and harder with different rate during it penetrates other material. Such nonlinearity and other stochastic noise will make a digital X ray image has no exact physical means. Due to the physical comparability, we use aluminium and lucite to simulate bone and software respectively, and image them under each kind of material thickness, then we can obtain an ideal image model use part of these data, which can be used to calibrate and linearize the X ray image. This method will be advantageous to the quantitative analysis of the human's physiological parameters such as the cardiac configuration, the blood flow, and the density of the contrast media in DSA.3047|417|0更新时间：2024-05-07
- 摘要：In 3-dimensional reconstruction from paralleled serial medical images, the two problems of contour correspondence and slice registration are often encountered. In the new method proposed in this paper, every contour in a slice is designated a value that represents its size and density, then the overall“Centroid”of the slice is found. For each contour, its corresponding contour on the adjcent slice is determined based on their designated value and their polar coordinate to the slice centroid. Some measures are taken to diminish computation complexity at a large scale. For the aim of slice registration, adjacent slices are first aligned roughly according to their centroid, furthermore, the optimal registration position nearby which minimizes the efficacy function which reflects the matching suitability at a given position. A witty method is designed to simulate the distribution of contours on adjacent slices. After testing the algorithms on the simulated case many times, we find that they are highly accurate and effective. Several optimal parameters are also given by experiment.2743|444|0更新时间：2024-05-07
- 摘要：Medical image recognition and analysis can provide quantitative evidence for medical diagnosis, while medical image segmentation is the first and significant step in this procedure. A novel feature distance based thresholding associated with color feature classification for ophthalmologic image segmentation is presented, and the segmented results can be used for the analysis of blood vessel region distribution on these images. Feature distance based thresholding can be widely used for segmenting the objects with any kinds of feature space structure, especially those with uncompact support, blurred boundary and uneven quantity, while Euclidean distance based method is only suitable for the sphere shaped feature space. Ophthalmologic image segmentation does not satisfy the conditions of Euclidean distance based method. In addition, a blocking algorithm based on 3D histogram to determine typical samples is proposed in this paper. Lots of experiments show that the algorithm in this paper can be effectively used in ophthalmologic image segmentation and good segmentation results have got. And the analysis results from segmented images meet the requirements of medical diagnosis.2766|481|0更新时间：2024-05-07
- 摘要：Motion estimation is essential for many interframe video coding techniques, block matching algorithms, such as FSA and TSS, have been widely used for motion estimation. The easiest implementation is the FSA, which evaluates all the blocks in the search window and has the highest computational cost. Therefore,many fast search algorithm including TSS, have been proposed to reduce the computational complexity, but most of them are based on the assumption that there should be only one optimal solution in the search window, however, in normal cases, there always exist multitudinous local optima, so they will miss the global optima, but get a suboptimal solution. In this paper, we propose a genetic search algorithm for motion estimation(GSAME) which applies genetic operation to motion estimation. We also introduce a scheme called competition evolution, which can bring the better solutions into the next evolution, and can accelerate the iteration process converging. In this method, the motion vector of block is defined as chromosome, after crossover, mutation and competition evolution, the global optimal solutions will be got. Last we compare the GASME to TSS, FSA, and the result shows that the method not only solve the problem of being trapped to local optima, but also have speed close to that of TSS.2772|421|0更新时间：2024-05-07
- 摘要：In recent years, image acquisition equipment has been widely adopted in the field of well logging. However, the data transfer rate of the logging system is limited by the transmission cables. Thus, data compression is necessary, but the common compression schemes were found to be not ideal for the well logging images, which have unique properties. In this paper, the properties of typical ultrasonic well logging images were studied and a suitable compression algorithm was proposed. Row and column correlation was found to be the major characteristic of the well logging images and 2 D correlation was not significant. Some subimages showed mainly row correlation and others showed mainly column correlation. According to this observation, an adaptive predictive lossless image compression coding based on image segmentation was proposed. An image is decomposed into blocks and pre row or pre column prediction is adaptively selected for every block to perform DPCM coding. An improved LZW algorithm is used to be encode the prediction error. Experiments showed that this coding scheme was able to achieve higher compression ratios than lossless JPEG and JPEG|LS for the ultrasonic well logging image, while the complexity was comparable. The algorithm is self|adaptive and thus no code table is needed. Since every block is independently processed, the error propagation problem associated with normal DPCM coding schemes is avoided.2709|424|0更新时间：2024-05-07
- 摘要：Virtual environmen(VE) is always involved in some visual deficit. In order to avoid causing visual problem by VE, two approaches for design of display system are presented, which are based separately on the inner mechanism of vision and on new technique of system hardware. In the first approach, for further study on VE, a new term named“the depth of field in vision”, which is the max scenes depth imaging clearly on retina when the eye status mainly for vergence and accommodation is fixed, is presented for the first time and is illustrated detailedly with its concept, principle and measurement method. This offers a new theory infrastructure for display system design to make immersion more comfortable against dizziness, eyestrain etc. In the second approach, the principle, application as well as their advantage or disadvantage of some new techniques in VE such as eye tracking system, liquid crystal glasses with microcomputer are analyzed. The adaptive capability of human vision is also concerned at the end of the paper.2614|402|0更新时间：2024-05-07
- 摘要：In process of OCR image scanning input, images may slant somehow. Severe image slant makes character segmentation next step difficult and lowers overall recognition accuracy of the system. Normally, in order to improve recognition accuracy and save image rescanning time, software correction is used to correct the slant before next step recognition processes of OCR are executing. This paper presents a novel slant correction method called Hough Transform OCR Image Slant Correction Method. The method uses Hough Transform to estimate the slant of scanning images. Because of heavy computing burdens of Hough Transform, the method employs Image Pyramid Processing to overcome the defeat of Hough Transform. Horizontal edge extracting processing is also used to speed the estimating process and to improve estimating accuracy. A great many artificial images and raw scanning images are used to test performances of the methodology. Experiment results show that the method can measure out slanting degree of scanning image efficiently and accurately just in a few seconds, and bears high noise endurance and application adaptability.关键词：OCR;Slant correction;Hough transform;Image pyramid processing7014|714|0更新时间：2024-05-07
- 摘要：To the video signal transmission on narrow band networks, this paper analyzes the quality degradation that cause the non optimized motion vectors during the traditional video transcoding when the frame rate conversion. We proposed a model of adaptive motion vectors based on the sum of the differential quantization errors, thus reduced search area. It is possible to achieve fast motion estimation for near optimal outgoing motion vectors. Based on the gray system theory, an efficient gray prediction search(GPS) algorithm for block motion estimation is proposed. The GPS can determine the motion vectors of image blocks quickly and correctly. We speed up the encoding in further using a method of adaptive fast video encoding based on the theoretical model for discrete cosine transform(DCT) coefficients. We also present a fast DCT algorithm to speed up the calculation of DCT further when the quantization step size is large. The experimental result show that the proposed scheme improves the video quality, with a minimal increase in computational complexity.关键词：Video;Transcoding;Adaptive;Motion estimation2488|446|0更新时间：2024-05-07
- 摘要：This paper is to realize the optical character recognition on grey scale level by adopting learning subspace method of principal component analysis(PCALSM). Compared with Arabic number images, the resolution of Chinese character images is small, which creates great difficulty in extracting the character features. And it will get worse especially when the quality of image is low. PCALSM can overcome the main shortages of classification on binary images, and keeps integrity features of character information dramatically. On the basis of PCA subspaces, training of each subspace is rotated in different ways of the supervised feedback learning algorithm; and better classification is therefore obtained. The time consuming subspace training can be accepted especially when the number of character classes is not large. Our experimental results have proved that recognition of car license plate characters (a limited Chinese character set) has been improved by PCALSM, which makes it highly worth applying this optical character recognition (OCR) method.2986|471|0更新时间：2024-05-07
- 摘要：Silhouettes play a very important role in graphics communication. Because silhouettes are view dependent, it is expensive to extract silhouettes for previous techniques when the object is moving in space. This paper presents two algorithms of extracting silhouettes from 3D models. By exploiting the property of local maximum value and connectivity of silhouettes, the methods first identify part of silhouettes, then extract external silhouettes of 3D models by simple comparisons. The first method divides the model into some zones evenly in X and Y direction. Then it calculates the maximum edges of the zones in X and Y direction. These edges are silhouette edges. By searching the neighbor maximum edges of the silhouette edges, it finds the silhouette of the model. The second approach begins from the top edge in Y direction. By comparing the angles between the silhouette edge and its neighbor edges, it obtains the silhouette easily. Experimental results illustrate the efficiency of the methods. The algorithms and previous methods are compared and analyzed at the end of the paper.关键词：3D models;Silhouettes;Extraction;Connectivity;Rendering3575|477|0更新时间：2024-05-07
- 摘要：This paper presents a method to combine so|called multiband DFT filter bank with bivariate Box splines to construct a perfect reconstruction model for image processing. Based on the theory of B|splines, which are useful tool in many fields, Box Spline is said to be an extension, with the aim at describing multi|variate functions. In this paper, firstly, it introduces the DFT filter bank, and presents the condition to form a perfect reconstruct model. Then it describes bivariate Box splines and its some properties in little more details. It especially presents a particular class of bivariate Box splines, and use it to construct a decomposition/reconstruction model, which may be candidates for some kinds of task in image processing. This model is proved to be satisfied by the perfect reconstruction condition, and thus can be quite useful theoretically. At last, some experimental results are given to demonstrate the use fulness of this model.2466|401|0更新时间：2024-05-07
- 摘要：This paper proposes a method of representation and comparability determination of thenar surface. The method is based on the geometric feature of three-dimensional surface. It calculates the normal vector of the points on the surface. The method segments the three-dimensional space into subspaces according to the direction angle of normal vectors and counts the number of normal vectors belonging to the three-dimensional subspace. Then the distribution of normal vectors of three-dimensional surface can be obtained. And it uses the distribution of normal vectors to represent three-dimensional surface. At last the method uses the difference between two normal vector cumulative distributing curves—NVCDCs to determine the comparability of two three-dimensional surfaces. The method proposed in this paper is not sensitive to small changes of the datum plane. Experimental results show that the method is valid in the representation and comparability determination of three-dimensional surfaces.2948|485|0更新时间：2024-05-07
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