基于小波的纹理合成方法

将KL变换与小波变换相结合提出了一种新的纹理合成方法,利用KL变换克服了合成彩色图时存在的颜色失真;对样图进行二维小波分解使得最佳匹配块的搜索仅在原样图的低频部分进行,从而提高了合成速度。在搜索最佳匹配块时,使用多尺度小波变换后的小波系数的差异作为误差度量,并在比较匹配误差时增加高频系数的权重,突出了纹理结构的匹配。实验结果表明,该方法不仅得到了较好的合成质量,而且在很大程度上减少了合成时间。

冲击响应谱测量仪电校准方法

基于对冲击响应谱测量仪的校准方法研究和分析,结合现场条件使用电信号比较测量的方式,采用合成小波作为冲击响应谱时域瞬态波形的合成波形,实现冲击响应谱测量仪电信号的输入,其输出通过与标准冲击响应谱输出比较进行校准。文章最后采用校准装置模拟输出标准电压信号作为输入,比较测量仪输出值和理论值之间的误差来验证方法的可行性。

2011年夏季广东季风槽暴雨与准双周振荡

采用小波分析、Lanczos时间滤波器、合成分析等方法分析了2011年夏季广东季风槽暴雨与大气低频振荡的关系。结果表明,2011年夏季降水主要存在准20 d的周期振荡,季风槽暴雨过程对应强的准双周振荡。选取与夏季降水显著相关的区域（102.5-117.5°E,20-27.5°N）平均的500 hPa高度场作为影响广东夏季降水的＂500 hPa关键区＂指数,同样选取区域（110-120°E,15-22.5°N）平均的850 hPa风场作为＂850 hPa关键区＂指数;2011年夏季500 hPa关键区与850 hPa关键区分别存在显著的准23 d、准22 d周期振荡,季风槽暴雨发生在500 hPa关键区准双周振荡的波谷、850 hPa关键区准双周振荡的波峰附近。从南海南部开始的3次低频纬向风、OLR、湿度的北传与从菲律宾以东的西太平洋向西传播的低频中心相遇,导致3次季风槽暴雨过程。利用典型个例的合成分析,对2011年6—8月广东3次季风槽暴雨的准双周振荡不同位相的大气环流场的共同演变特征进行分析,它们反映了季风槽暴雨从间歇-开始-旺盛-减弱-结束期的大气环流场演变特征,为广东季风槽暴雨的中期预报提供参考依据。

Fluorescence molecular imaging system and fusion algorithm based on 2CCD camera

Infrared and visible light images can be obtained simultaneously by building fluorescence imaging system,which includes fluorescence excitation,images acquisition,mechanical part,image transmission and processing section.This system studied the 2charge-coupled device(CCD)camera(AD-080CL)of the JAI company.Fusion algorithm of visible light and near infrared images was designed for the fluorescence imaging system with wavelet transform image fusion algorithm.In order to enhance the fluorescent moiety of the fusion image,the luminance value of the green component of the color image was changed.And using microsoft foundation classes(MFC)application architecture,the supporting software system was bulit in VS2010 environment.

天文巡天相机冲击响应谱分析及研究

为了验证天文巡天相机结构能否承受火箭的发射冲击环境,并为电动振动台提供一种有效的时域波形合成方法以模拟发射冲击环境,根据冲击响应谱时域合成一般原理,采用合成小波法,将冲击响应谱转换为时域波形,并使用改进的递归数值滤波法将生成的时域波形再转换为冲击响应谱,通过对各个小波分量的幅值参数优化迭代,使最终的冲击响应谱满足试验规范,再对各个小波分量的延迟时间参数优化迭代,使时域波形的加速度峰值在电动振动台的许可范围以内。建立天文巡天相机结构有限元模型,以冲击响应谱作为输入对巡天相机进行响应谱分析,以合成的时域波形作为输入对巡天相机进行瞬态分析。响应谱分析与瞬态分析结果最大应力值分别为726MPa和757MPa,均超过了结构屈服极限,表明相机无法承受发射冲击环境,两者重合度很好,证明了合成的时域波形的有效性。

AN EDGE DETECTOR BA SED ON WAVELET TRANSFORM FOR SAR IMAGE

Edge detecting is a f undamental issue in image analysis and image processing. In this paper, based on wavelet transform, an edge detector of SAR image is studied to serve the image aided navigation. Though wavelet transform is efficient as an edge detector, a l ot of false edges will be extracted from a SAR image, especially in areas of hig h reflectivity, with wavelet transform and a fixed threshold because SAR images are always contaminated by speckle. Therefore, this paper develops an algorithm by using a variable threshold with constant false alarm rates to help suppressin g the speckle in SAR images. Finally, two simulating tests are given and the res ults show that the effect of the multiplicative speckle is controlled and there are few false edges in the gotten edge images. Moreover, owing to the threshold from the wavelet transform coefficients, the algorithm can assure the real time of SAR image aided navigation.

ADAPTIVE RIVER SEGMENTATION IN SAR IMAGES

There is difficulty for distinguishing of river and shadow in Synthetic Aperture Radar (SAR) images. A method of river segmentation in SAR images based on wavelet energy and gradient is proposed in this paper. It mainly includes two algorithms: coarse segmentation and refined segmen- tation. Firstly, The river regions are coarsely segmented by the wavelet energy feature,and then refined segmented accurately by the gradient threshold which is got adaptively. The experimental results show the validity of the method, which provides a good foundation for targets detection above the river.

SAR imagery coding based on blocking high frequency energy matching

A new fractal image compression algorithm based on high frequency energy (HFE) partitioning andmatched domain block searching is presented to code synthetic aperture radar (SAR) imagery. In the hybridcoding algorithm, the original SAR image is decomposed to low frequency components and high frequencycomponents by wavelet transform (WT). Then the coder uses HFE of block to partition and searchthe matched domain block for each range block to code the low frequency components. For the high frequencycomponents, a modified embedded zero-tree wavelet coding algorithm is applied. Experiment resultsshow that the proposed coder obtains about 0. 3dB gain when compared to the traditional fractal coderbased on the quadtree partition. Moreover, the subjective visual quality of the reconstructed SAR imageof the proposed coder outperforms that of the traditional fractal coders in the same compression ratio(CR).

基于未匹配子带合成系数统计特性的立体图像质量评价算法

针对经典立体图像质量评价算法存在评价准确性低以及特征提取耗时较长的问题,提出一种基于未匹配子带合成系数统计特性的立体图像质量评价算法。首先,利用可控金字塔对左右视点图像进行多尺度、多方向的小波分解,并将左右视点图像在相同尺度、相同方向上未经视差图匹配的小波子带系数合成为子带合成系数。其次,提取小波子带合成系数中的统计分布特征,相同尺度相邻方向小波子带合成系数之间的相关性特征,以及相同方向相邻尺度子带合成系数之间的相关性特征。最后,利用所提取特征训练经典的支持向量回归模型,预测图像质量。在LIVE 3D和Waterloo IVC 3D数据库上的实验结果表明,与主流立体图像质量评价算法相比,本文算法在预测对称和非对称失真立体图像质量时都获得了更高的评价准确性。同时,由于子带合成系数的生成无需根据视差图进行匹配,算法执行效率高。