基于机器视觉的多孔材料缺陷检测

针对多孔材料在生产工艺中易出现阻塞和缺角等缺陷,本文设计了一种基于机器视觉的多孔材料表面缺陷检测方法,通过对目标区域的有效分割、模糊度检测、形态学处理和分析等技术手段,实现了该类材料的表面缺陷的快速定位和特征分析.经实验检测,本文算法的准确性和检测效率可以满足工业生产实时检测需求.     

Are Edges Incomplete?

We address the problem of computing a general-purpose early visual representation that satisfies two criteria. 1) Explicitness: To be more useful than the original pixel array, the representation must take a significant step toward making important image structure explicit. 2) Completeness: To support a diverse set of high-level tasks, the representation must not discard information of potential perceptual relevance. The most prevalent representation in image processing and computer vision that satisfies the completeness criterion is the wavelet code. In this paper, we propose a very different code which represents the location of each edge and the magnitude and blur scale of the underlying intensity change. By making edge structure explicit, we argue that this representation better satisfies the first criterion than do wavelet codes. To address the second criterion, we study the question of how much visual information is lost in the representation. We report a novel method for inverting the edge code to reconstruct a perceptually accurate estimate of the original image, and thus demonstrate that the proposed representation embodies virtually all of the perceptually relevant information contained in a natural image. This result bears on recent claims that edge representations do not contain all of the information needed for higher level tasks.     

变速运动图象的恢复

从胶片曝光原理分析了图象像素运动的亮度变化过程,由此建立了退化及 恢复的数学模型,并用计算机进行模拟面恢复图像,质量较高,实野性一较好。     

基于互相关模糊长度估计的图像复原

为提高含噪运动图像的复原质量,提出一种基于互相关原理的运动模糊长度估计算法。根据图像的Radon变换得到运动模糊角度,提取模糊中心各模糊路径上的像素灰度值,通过互相关计算确定模糊长度,采用Lucy-Richardson迭代算法对观测图像进行复原。实验结果表明,该算法的抗噪性较好,迭代收敛速度较快。     

复杂背景下快速车牌定位算法

提出了一种复杂背景下的快速实时车牌定位算法。车牌定位的实时性和精确性是车牌识别系统高效运行的保障。提出了一种整型特殊核并利用差分运算来实现车牌定位。在分析了混合高斯函数卷积的车牌定位方法上的基础上,针对二维高斯核计算复杂度较高的问题提出了改进,直接在获取的垂直边缘图上进行混合高斯卷积,重新提出了一种整型的特征核,并用差分的方法代替了卷积,即用少量的加法操作代替了卷积大量的浮点乘法操作。对比分析了两种不同方法的定位效果和时间复杂度。实验结果表明在保持定位精度不变的情况下运行效率有较大提高,达到了实时性的要求。     

Rational Filters for Passive Depth from Defocus

A fundamental problem in depth from defocus is the measurement of relative defocus between images. The performance of previously proposed focus operators are inevitably sensitive to the frequency spectra of local scene textures. As a result, focus operators such as the Laplacian of Gaussian result in poor depth estimates. An alternative is to use large filter banks that densely sample the frequency space. Though this approach can result in better depth accuracy, it sacrifices the computational efficiency that depth from defocus offers over stereo and structure from motion. We propose a class of broadband operators that, when used together, provide invariance to scene texture and produce accurate and dense depth maps. Since the operators are broadband, a small number of them are sufficient for depth estimation of scenes with complex textural properties. In addition, a depth confidence measure is derived that can be computed from the outputs of the operators. This confidence measure permits further refinement of computed depth maps. Experiments are conducted on both synthetic and real scenes to evaluate the performance of the proposed operators. The depth detection gain error is less than 1%, irrespective of texture frequency. Depth accuracy is found to be 0.51.2% of the distance of the object from the imaging optics.     

基于深度编码–解码器的图像模糊核估计

在图像去模糊问题中,显著边缘结构对图像的模糊核估计具有重要的作用.本文提出一种基于深度编码-解码器的图像模糊核估计算法.首先,通过构建训练数据集对深度编码-解码器进行训练,进而自适应地获得模糊图像的显著边缘结构;接着,结合显著边缘结构和模糊图像,利用L2范数正则化对模糊核进行估计;最后,利用超拉普拉斯先验和所估计的模糊核对清晰图像进行估计.与传统的方法相比,所提出的方法不需要多尺度迭代框架.实验结果表明,所提出的算法在获得较好的显著边缘结构以及清晰图像的同时,能够减少算法计算的时间.     

基于Benford定律的高斯模糊篡改取证

针对自然图像篡改手段中常用的高斯模糊,提出一种基于Benford定律的模糊篡改图像真实性取证方法.通过借助DCT域AC系数的Benford模型分别对自然图像的3个通道进行统计,构造特征,根据篡改前后差异的显著性水平设定阈值进行判定,最后给出实验结果.     

数字图像复原技术综述

数字图像复原的目的是将所观测到的退化图像恢复到退化前的原始图像,该恢复过程在很多图像处理应用中至关重要。近年来,图像复原技术虽已得到广泛研究,但仍有值得改进之处。为了使该领域的研究人员对当前各种图像复原方法有较全面的了解,在众多技术文献中选取了具有典型性的95篇来对各种图像复原方法进行分类综述。首先通过对复原技术问题的描述,揭示了复原技术的数学背景;其次以数字图像复原技术发展为主线,将复原方法归结为两大类进行详细讨论。一类是经典图像复原方法,另一类是现代图像复原方法。前者反应复原技术背景与发展过程,后者体现复原技术的发展趋势与面临的困难。最后,在总结全文的基础上,指出在今后进一步研究中值得关注的7项问题。     

后期模拟制作相机镜头背景模糊效果

在摄影实践中,虚化背景是突出主体的常用手段。但是由于消费级DC镜头的实际焦距都很短,因此实现浅景深而虚化背景的难度较大。如果我们希望用消费级DC也能达到虚化背景突出主体的效果,那么,Photoshop后期处理可以派上用场。