一种模糊红外目标边缘和不变特征提取方法

针对红外图像中模糊目标难以分割和识别的情况,提出以小波多尺度滤波分解后的逼近图像作为自适应域值进行图像二值化的方法,由此分割出模糊图像中的目标,提取目标的轮廓边缘.然后,提出一种新的矩计算方法提取目标的不变性特征.实验结果表明,该方法具有很强的抗噪和抗扰性能,能有效提取复杂背景中模糊目标的平移、缩放和旋转不变量,极大提高了运动模糊目标识别的可靠性.     

利用Krawtchouk矩不变量实现基于形状的图像检索

图像在经过平移、旋转和尺度变化后是否仍具有很好的检索效果是基于形状的图像检索研究的一个难点.本文提出了一种利用Krawtchouk矩不变量实现基于形状的图像检索方法.该方法首先对图像进行灰度变换,然后提取图像的低阶矩,取16个低阶矩不变量作为图像的特征向量,并按照相似性度量输出相似图像从而实现基于形状的图像检索.文中给出了实验结果,并与基于几何矩不变量和基于Zernike矩不变量的图像检索方法进行了比较.结果表明本文的方法具有更好的检索性能,和上述两种方法相比,查全率分别提高了21.52%和7.6%,查准率则分别提高了16.25%和6.25%.     

一种基于印刷图像处理技术的模糊图像复原方法

根据印刷图像处理技术的基本原理,针对印前的电子出版图像处理中存在的原稿图像运动模糊现象,介绍了约束最小二乘方滤波复原技术消除图像模糊方法.阐述了运动模糊图像的退化模型和复原模型,利用二值图的信息来估计模糊方向,通过对二值图的矩阵变换来估计模糊尺度,再利用约束最小二乘方滤波的方法复原图像.实验表明,该方法行之有效.     

基于机器视觉实现电子警察系统车牌识别功能"计量"确认方法

为解决电子警察系统号牌识别率的计量问题,本文研究了机动车退化(模糊)图像的生成过程,将实验室(或野外)严格控制条件下的图像为过渡图片,建立了因机动车运动造成图像退化(模糊)的计算模型,获得退化图片用于号牌识别率的确定.模型能保证成像的曝光时间、响应特性、光照特征等复杂因素的可控性,实验程序证明了本方法的可行性.     

基于快速CCD位移探测的运动模糊图像的恢复

提出了一种可以对被任意形式的运动所造成的退化图像进行恢复的方法,给出了理论推导,并建立了一套实现系统.解决了以前的恢复方法存在的只能恢复特定运动形式(如匀速直线运动)的模糊图像的局限性问题.在主CCD曝光的同时,利用低分辨力的黑白快速CCD获得多帧图像,根据这些图像序列来计算位移,然后求得相对运动的瞬时速度,根据理论分析,点扩展函数和瞬时速度有着对应的关系,进而计算出模糊过程的点扩散函数(PSF),并用来RL迭代法来恢复模糊图像.实验结果表明,这种恢复方法对任意运动形式造成的模糊,能够得到较好的恢复效果.     

基于Z变换匀速旋转运动模糊图像的快速恢复

从离散直观角度分析了由匀速旋转运动引起图像模糊的机理,通过Z变换方法,建立了由匀速旋转运动引起图像模糊的退化模型和恢复模型,并给出了快速算法。将运动模型扩展到任意形式的匀速运动,并给出了数学模型。通过计算机仿真实验,验证了算法的正确性、有效性和快速性。本文推导的是理想模型,没有考虑噪声的影响。     

基于频域方法的运动模糊方向识别

本文通过深入研究匀速直线运动模糊图像的点扩展函数,提出一种识别运动模糊图像模糊方向的频域方法.首先对模糊图像的频谱图出现平行暗条纹的原因进行分析.从理论证明和实验说明指出暗条纹的方向与模糊方向垂直的特性,并采用RADON变换方法检测这些暗条纹.最后,给出了运动模糊方向精确的数值估算方法.实验结果表明,该算法可以准确地识别图像运动模糊方向,绝对误差不超过2°.     

匀速直线运动产生的图像模糊及复原研究

在拍照的曝光期间,由于景物和照相机之间的相对运动,往往造成图像的模糊,致使照片效果差无法使用。另外,图像在获取和传输过程中,往往产生大量随机噪声。运动模糊和噪声使图像质量退化,对进一步的边缘检测、图像分割、特征提取及模式识别带来不便。本文将对匀速直线运动的情况下产生的图像模糊以及复原进行研究。     

离焦模糊图像的自适应滤波及逆滤波器复原

在微操作中,显微视觉系统获取的图像通常是离焦模糊图像.根据最小二乘原理和回归模型设计自适应滤波器,用于消除图像噪声,提高图像的信噪比;离焦模糊图像的退化模型可用圆盘函数描述,利用模糊图像频域的零点位置来估计圆盘函数的模糊参数;采用基于简化Wiener滤波的逆滤波器方法对模糊图像进行复原.对算法进行了仿真和实验分析,结果表明,该方法能够以较少的运算时间代价获取较好的复原效果.     

流动颗粒显微图像测量技术研究

针对显微环境下流动颗粒测量的需要,构建了测量平台,研制了基于MEMS工艺的测量器件。在分析流动颗粒显微图像特征的基础上,提出了基于颗粒运动特性的图像测量流程,其中提出了基于基准桢差分的目标提取算法,解决了流动颗粒目标分割的问题,根据图像运动模糊的退化模型,研究了图像模糊恢复的问题。最后以润滑油中的磨损颗粒为例,验证了该文的分析方法对流动颗粒检测的有效性。     

Enhanced-resolution image restoration from a sequence of low-frequency vibrated images by use of convex projections

An algorithm to increase the spatial resolution of digital video sequences captured with a camera that is subject to mechanical vibration is developed. The blur caused by vibration of the camera is often the primary cause for image degradation. We address the degradation caused by low-frequency vibrations (vibrations for which the exposure time is less than the vibration period). The blur caused by low-frequency vibrations differs from other types by having a random shape and displacement. The different displacement of each frame makes the approach used in superresolution (SR) algorithms suitable for resolution enhancement. However, SR algorithms that were developed for general types of blur should be adapted to the specific characteristics of low-frequency vibration blur. We use the method of projection onto convex sets together with a motion estimation method specially adapted to low-frequency vibration blur characteristics. We also show that the random blur characterizing low-frequency vibration requires selection of the frames prior to processing. The restoration performance as well as the frame selection criteria is dependent mainly on the motion estimation precision.     

图像插值分析的交互式分层复原

为了复原模糊图像以得到可辨识的目标,分析相机与目标高速相对运动时产生的两种模糊性质,针对其退化函数难以确定的特点,提出一种基于图像插值分析的交互式分层复原方法,该方法首先对图像进行插值,以提高对低分辨率图像退化机理的分析能力,并在分析的基础上进行图像预处理.然后在图像复原的优化准则下,交互地选择出降质模型的最优参数组合,以得到两个降质函数,最后对原图像实施分层复原.对仿真图像进行实验,基本上恢复了目标图像的特征,证明该方法复原效果比较理想.     

Defocus deblurring for catadioptric omnidirectional imaging based on spatially invariant point spread function

The problem of catadioptric omnidirectional imaging defocus blur, which is caused by lens aperture and mirror curvature, becomes more severe when high resolution sensors and large apertures are applied. In order to overcome this problem, a novel method based on computational photography is proposed. Firstly, the defocus blur of catadioptric omnidirectional imaging is analyzed to calculate the point spread function for different scene points. Then, the defocus blur kernel of omnidirectional image is confirmed to be spatially invariant when rotating the focus ring of camera lens during an image’s integration time. Lastly, the deconvolution algorithm using prior sparse derivatives is applied to obtain all-focused/sharp omnidirectional images. Experimental results demonstrate that the proposed method is effective for omnidirectional image deblurring and can be applied to most existing catadioptric omnidirectional imaging systems.     

Recognition of motion-blurred images by use of the method of moments

Image motion causes a blur that changes features of objects and therefore complicates the task of automatic recognition. In this work we develop two recognition methods for motion-blurred images. For the first method we assume that the motion function and direction during the exposure are given. We develop the relation between the blurred-image moments and the original-image moments based on the motion function only. The recognition is carried out by comparing the moments of the restored image against the moments of the image database. In the second method the motion function is not known. In this case image moments that are invariant with respect to the motion blur are identified, and only these moments are used for recognition. The advantage of the suggested methods is that no time-consuming image restoration is required prior to recognition.     

复杂振动引起的图像退化分析与仿真

平台振动导致光学系统在曝光时间内与景物产生相对运动,严重影响了成像质量,而图像的退化模式可能并不单一,针对目前难于仿真高阶多模的复杂振动引起的图像退化问题,提出了基于像移矩阵的微分动态像移路径图像退化法,全面考虑了振动的空域和频域特性对图像退化的综合作用.从而在实际应用中只要已知振动函数,便可以通过一幅清晰的图像仿真得...     

Aspheric mirror with constant angular magnification II

Differential equations for a constant-angular-magnification aspheric-mirror surface shape are derived for a general dependence of the camera image height on the camera field angle. The explicit equations of the constant-angular-magnification mirror surface are given for some particular values of the angular magnification. For a series of odd integer values of the angular magnification, 10th-order polynomial approximations of the mirror surface are presented. The imaging performance of such a mirror with an angular magnification of 7 is analyzed and compared with a spherical mirror. The main cause of image blur in all-sky cameras at the edge of the field of view was found to be a strong image curvature. We show that increasing the camera-to-mirror distance and/or stopping down the camera lens reduces the image blur.     

Depth recovery and refinement from a single image using defocus cues

We present a technique to recover and refine the depth map from a single image captured by a conventional camera in this paper. Our method builds on the universal imaging principle: only scene at the focus distance will converge to a single sharp point on imaging sensor but other scene will yield different blur effects varying with its distance from the camera lens. We first estimate depth values at edge locations via spectrum contrast and then recover the full depth map using a depth matting optimization method. Due to the fact that some blur textures such as soft shadows or blur patterns will produce ambiguity results during the procedure of depth estimation, we use a total variation-based image smoothing method to smooth the original image, a smoothed image with detailed texture being suppressed can be generated. Taking this smoothed image as reference image, a guided filter is used to refine the final depth map.