A color vision inspection system for integrated circuitmanufacturing

An inspection system is introduced that can measure critical film thicknesses, segment IC images, and detect an entire class of color defects that would be difficult or impossible to detect with typical gray-scale imaging. This inspection is carried out on a unique multiwindow parallel hardware architecture which allows the inspection process to be performed at high speeds. The inspection is based on image understanding techniques and is carried out in a two-stage fashion where defects are first rapidly hypothesized and then verified in detail only within the salient regions of an image, thus eliminating a large amount of irrelevant data. The system has been tested on numerous IC images and shows promising results     

结合光谱和尺度特征的高分辨率图像边缘检测算法

高分辨率遥感图像具有高度细节化的多尺度表达能力,在有效表达地物边缘信息的同时,目标内部几何细节常以噪声的形式出现.提出将光谱相异性和小波变换相结合的边缘特征检测算法,克服了小波变换导致的边缘变形,并能够有效抑制噪声.根据光谱角原理定义归一化光谱相异性模型,并与二进小波变换结合,同时利用梯度方向余弦值对各个波段的梯度幅值加权,最后根据向量场模型计算多光谱图像的梯度幅值和梯度方向,细化后获取由细到粗的多层次边缘特征.实验结果与小波变换和传统检测算子的检测结果相比,表明该算法利用光谱相异性信息增强边缘响应强度,保证了所有尺度下获取的边缘轮廓不失真,边缘点定位准确;加权处理突出了多波段梯度主方向信息,也有效抑制了高分辨率图像上目标内部精细几何细节形成的噪声.     

基于小波影响锥的天波雷达瞬态干扰抑制方法

针对瞬态干扰严重影响天波超视距雷达(OTHR)目标检测性能的问题,提出了一种基于小波影响锥的瞬态干扰抑制方法。该方法利用一维离散平稳小波变换确定信号的奇异点(瞬态干扰),然后将每一奇异点对应的影响锥内的小波细节系数置零,最后通过一维逆离散平稳小波变换重构数据。该方法避免了杂波抑制和插值重构,运算量小,实用性强。对天波雷达实测数据的处理实验表明:提出的方法是有效的。     

基于多关节激光测量系统和GEOMAGIC QUALIFY的铸造件快速检测

在对复杂曲面的铸造件零件检测时,传统的检测方法无法对铸件曲面有效的检测,而且检测周期长,检测难度大,检测精度不高。本文采用多关节激光测量系统对一个复杂曲面铸造件进行数据采集,应用Geomagic Qualify软件与产品3D数据进行对齐,3D比对,快速得出误差分析表及误差色温图,实现了复杂曲面铸造件检测的数字化,可视化,有效的提高了复杂曲面铸造件的曲面检测质量和效率,对铸造件的制造工艺提供了可靠±据。     

Clinical evaluation of respiratory motion compensation for anatomical roadmap guided cardiac electrophysiology procedures

X-ray fluoroscopically guided cardiac electrophysiological procedures are routinely carried out for diagnosis and treatment of cardiac arrhythmias. X-ray images have poor soft tissue contrast and, for this reason, overlay of static 3-D roadmaps derived from preprocedural volumetric data can be used to add anatomical information. However, the registration between the 3-D roadmap and the 2-D X-ray image can be compromised by patient respiratory motion. Three methods were designed and evaluated to correct for respiratory motion using features in the 2-D X-ray images. The first method is based on tracking either the diaphragm or the heart border using the image intensity in a region of interest. The second method detects the tracheal bifurcation using the generalized Hough transform and a 3-D model derived from 3-D preoperative volumetric data. The third method is based on tracking the coronary sinus (CS) catheter. This method uses blob detection to find all possible catheter electrodes in the X-ray image. A cost function is applied to select one CS catheter from all catheter-like objects. All three methods were applied to X-ray images from 18 patients undergoing radiofrequency ablation for the treatment of atrial fibrillation. The 2-D target registration errors (TRE) at the pulmonary veins were calculated to validate the methods. A TRE of 1.6 mm ± 0.8 mm was achieved for the diaphragm tracking; 1.7 mm ± 0.9 mm for heart border tracking, 1.9 mm ± 1.0 mm for trachea tracking, and 1.8 mm ± 0.9 mm for CS catheter tracking. We present a comprehensive comparison between the techniques in terms of robustness, as computed by tracking errors, and accuracy, as computed by TRE using two independent approaches.     

Edge-preserving image compression using adaptive lifting wavelet transform

In this paper, a novel 2-D adaptive lifting wavelet transform is presented. The proposed algorithm is designed to further reduce the high-frequency energy of wavelet transform, improve the image compression efficiency and preserve the edge or texture of original images more effectively. In this paper, a new optional direction set, covering the surrounding integer pixels and sub-pixels, is designed. Hence, our algorithm adapts far better to the image orientation features in local image blocks. To obtain the computationally efficient and coding performance, the complete processes of 2-D adaptive lifting wavelet transform is introduced and implemented. Compared with the traditional lifting-based wavelet transform, the adaptive directional lifting and the direction-adaptive discrete wavelet transform, the new structure reduces the high-frequency wavelet coefficients more effectively, and the texture structures of the reconstructed images are more refined and clear than that of the other methods. The peak signal-to-noise ratio and the subjective quality of the reconstructed images are significantly improved.     

基于小波分析的倒装芯片主动红外缺陷检测

随着微电子技术的需求和发展,倒装芯片技术在高密度微型化封装领域得到了快速发展和广泛应用,而现有的一些倒装芯片检测方法存在一定的不足之处。为此,研究了主动红外的倒装芯片缺陷检测方法。实验中使用激光加热对倒装样片施加非接触热激励,通过红外热像仪获取样片温度分布。采用小波分析方法提取包括小波熵在内的信号特征,采用自组织神经网络对不同类型焊球进行聚类识别。研究表明,通过自组织神经网络可以有效地将不同缺陷焊球与参考焊球通过距离映射法映射到不同区域从而区分开,并且可以将未知焊球信号映射到相应的区域实现聚类识别。因此该方法可以有效实现倒装芯片的缺陷检测。     

基于机器视觉的印刷品缺陷检测与识别

阐述了印刷品缺陷检测在印刷成品的质量控制和印刷工艺管理中的重要地位和作用;提出了一种新的缺陷检测算法,并给出了系统的设计和缺陷检测流程;研究了一种基于小波变换的图像边缘检测方法,通过与传统缺陷检测算法进行对比,表明基于小波变换的图像边缘检测方法不仅能有效地滤除噪声、检测弱小目标在内的图像的边缘,而且还具有较强的抗噪性能,能检测出印刷品上的微小印刷缺陷;最后通过实验验证了该算法的可行性、可靠性和有效性。     

MULTI-SPECTRAL AND HYPERSPECTRAL IMAGE FUSION USING 3-D WAVELET TRANSFORM

Image fusion is performed between one band of multi-spectral image and two bands of hyperspectral image to produce fused image with the same spatial resolution as source multi-spectral image and the same spectral resolution as source hyperspeetral image. According to the characteristics and 3-Dimensional （3-D） feature analysis of multi-spectral and hyperspectral image data volume, the new fusion approach using 3-D wavelet based method is proposed. This approach is composed of four major procedures： Spatial and spectral resampling, 3-D wavelet transform, wavelet coefficient integration and 3-D inverse wavelet transform. Especially, a novel method, Ratio Image Based Spectral Resampling （RIBSR）method, is proposed to accomplish data resampling in spectral domain by utilizing the property of ratio image. And a new fusion rule, Average and Substitution （A＆S） rule, is employed as the fusion rule to accomplish wavelet coefficient integration. Experimental results illustrate that the fusion approach using 3-D wavelet transform can utilize both spatial and spectral characteristics of source images more adequately and produce fused image with higher quality and fewer artifacts than fusion approach using 2-D wavelet transform. It is also revealed that RIBSR method is capable of interpolating the missing data more effectively and correctly, and A＆S rule can integrate coefficients of source images in 3-D wavelet domain to preserve both spatial and spectral features of source images more properly.     

基于二维提升结构的SAR相干斑噪声抑制

针对SAR图像提出了一种新的二维提升变换斑点噪声抑制方法.这种方法利用提升结构构造的双正交小波所具有的良好的逼近和重构性能,以及平滑面区域的特性而实现.仿真时将阈值去噪环节加入变换中.仿真结果表明,本文提出的二维提升变换方法在充分抑制图像斑点噪声的同时,能很好地保持均匀区域内的辐射特性,图像中的边缘、细小特征和点目标,以及图像的纹理特征,克服了传统降噪方法的不足,具有较好的视觉效果.     

采用小波变换和数学形态学的小目标检测

鉴于常用检测方法不能准确稳定地检测出复杂背景中小目标,结合小波变换和数学形态学,提出了一种小目标检测新方法.首先对图像进行单尺度小波变换,提取高频分量系数;其次,利用阈值算法将各个高频分量系数图像转化为二值图像后对其进行多结构元素形态学滤波,滤波结果与原二值图像相减后在差值图像上得到可能的小目标.将3个方向的高频系数的检测结果相关联获得单帧检测结果;最后将多个单帧检测结果进行流水线检测,得到最终的检测结果.仿真结果表明该方法能够准确稳定地检测出信噪比(SNR)大于2的弱小目标.     

Wavelet functions to estimate velocity in spatiotemporal signals

This paper establishes a framework to estimate velocity from spatiotemporal signals using the wavelet transform and multiresolution techniques. Initial theory is derived with the assumption that the spatiotemporal signal can be represented by a polynomial of order M. Wavelet functions are derived for polynomials of different degree from which the velocity can be estimated as the ratio of two of the four components of a two dimensional (2-D) wavelet transform of the signal. We have characterized two classes of wavelet and scaling functions: one with nonuniform support and another with symmetry and uniform support. For a wavelet function of order M, the velocity estimates are exact if the signal can be represented by a polynomial of the same order or less. In many cases, the velocity error is very low, even when there is no match. We also present the error estimates for three different signals: a polynomial of degree four, a sinusoid (polynomial of degree infinity), and a function with analytical value for the velocity. The paper also demonstrates how error in the velocity estimates can be reduced by using multiresolution techniques. Even though results are presented using one-dimensional (1-D) signals, the extension to higher dimensions (images) is straightforward and uses the same wavelet functions derived in this paper     

Non-destructive imaging of defects in Ag-sinter die attach layers – A comparative study including X-ray,Scanning Acoustic Microscopy and Thermography

In typical power electronic modules several semiconductor dies such as MOSFET or IGBT are soldered to a DBC substrate. During module production the quality of the solder layers can be monitored by the use of X-ray inspection and the void rate can be determined. Recently, the more robust Ag-sinter technology is deployed for attaching the power dies to the substrate, especially for high reliability or high temperature requirements. Besides voiding also adhesion problems can occur during sintering due to multiple reasons (e.g. contamination). In contrast to volume defects, pure adhesion problems cannot be detected by means of X-rays. Accordingly, other methods have to be applied for process monitoring. The present investigation compares the advantages and disadvantages of different non-destructive imaging techniques towards the detection of defects in sinter layers. Besides X-ray, Scanning Acoustic Microscopy (SAM) and Lock-in Thermography methods (DLIT + ILIT) were studied and evaluated in terms of suitability for detecting different defect types, resolution (minimum defect sizes), inspection time and possible integration into the assembly process.     

Embedded wavelet-based coding of three-dimensional oceanographicimages with land masses

We describe the wavelets around land masses (WAVAL) system for the embedded coding of three-dimensional (3-D) oceanographic images. These images differ from those arising in other applications in that valid data exists only at grid points corresponding to sea. Grid points that cover land or lie beyond the bathymetry have no associated data. For these images, the WAVAL system employs a 3-D lifting wavelet transform tailored specifically to the potentially sparse nature of the data by processing only the valid sea data points between land masses. We introduce successive-approximation runlength (SARL) coding, an embedded-coding procedure that adds successive-approximation properties to the well known stack-run (SR) algorithm. SARL is employed to code wavelet coefficients resulting from the 3-D transform in the WAVAL system. However, it is a general technique applicable to other coding tasks in which embedded coding is desired but for which zerotree techniques are impractical. Experimental results show that the WAVAL system achieves substantial improvement in rate-distortion performance over the technique currently used by the US Navy for compression of oceanographic imagery     

基于循环平移Contourlet变换的红外小目标检测方法

分析了在有噪声和背景干扰情况下检测红外小目标的方法,提出了一种将循环平移Contourlet变换去噪 方法和自适应阈值分割方法相结合的红外小目标检测算法。该方法首先对原始图像进行循环平移阈值去噪,再用原始图像减去 去噪图像,对得到的残差图像进行自适应阈值分割,分离出少量的候选目标点,最后利用目标运动的连续性和一致性检测出 目标。分别用Contourlet变换法、小波变换法和本文提出的检测法对小目标进行了检测。仿真结果表明,本文提出的检测方法 能较精确地检测出序列图像中的红外小目标,检测效果优于Contourlet变换法和小波变换法。     

基于计算机视沉的轮胎缺陷检测

利用计算机视觉实现轮胎X光图像的质量缺陷检测,是当前轮胎生产质量监控自动化的关键环节。通过对大量正常轮胎图像纹理特征的研究,发现其X-光图像纹理呈现明显的准周期性和规则性,鉴于此设计了能反映该规律性的小波函数,实现对轮胎内存在异物和钢丝帘线分布不匀等异常检测,实验结果与传统的灰度共生矩阵法相比,本文方法具有对缺陷位置定位精确、运算快速等优点。     

Robust fabric defect detection and classification using multiple adaptive wavelets

The wavelet transform has been widely used for defect detection and classification in fabric images. The detection and classification performance of the wavelet transform approach is closely related to the selection of the wavelet. Instead of predetermining a wavelet, a method of designing a wavelet to adapt to the detection or classification of fabric defects has been developed. For further improvement of the performance, the paper extends the adaptive wavelet-based methodology from the use of a single adaptive wavelet to multiple adaptive wavelets. For each class of fabric defect, a defect-specific adaptive wavelet was designed to enhance the defect region at one channel of the wavelet transform, where the defect region can be detected by using a simple threshold classifier. Corresponding to the multiple defect-specific adaptive wavelets, the multiscale edge responses to defect regions have been shown to be more efficient in characterising defects, which leads to a new approach to the classification of defects. In comparison with the single adaptive wavelet approach, the use of multiple adaptive wavelets yields better performance on defect detection and classification, especially for defects that are poorly detected by the single adaptive wavelet approach. The proposed method has been evaluated on the inspection of 56 images containing eight classes of fabric defects, and 64 images without defects. In defect detection, 98.2% detection rate and 1.5% false alarm rate were achieved, and in defect classification, 97.5% accuracy was achieved.     

Defect detection of IC wafer based on two-dimension wavelet transform

Defect detection of integrated circuit (IC) wafer based on two-dimension wavelet transform (2-D DWT) is presented in this paper. By utilizing the characteristics many of the same chips in a wafer, three images with defects located in the same position and different chips are obtained. The defect images contain the standard image without any defects. 2-D DWT presented in the paper can extract the standard image from the three defect images. The algorithm complexity of the method is close to that of 2-D DWT. After obtaining the standard image, the speed and accuracy of defects detection can be greatly enhanced using the detection method presented in the paper. Using the image gray-scale matching technology, impact of illumination on IC defect detection is solved. Experiments demonstrate that 2-D DWT is fast and accurate to defects detection in an IC image, and the method has high robustness for illumination.     

带限MPSK信号码元宽度的盲估计

理想MPSK信号在码元跳变处表现为相位的不连续性。小波变换能有效检测出这些信号细节,从而为估计码元宽度提供了依据。实际系统常采用脉冲成形技术减小发射带宽,改变了信号包络,从而影响了小波变换的检测性能。本文对截获接收机输出的信号进行预处理后再利用基于Haar小波变换的算法提取码元宽度信息,理论分析和实际信号处理表明,这种算法能有效检测码元跳变,从而估计出码元宽度。     

Frequency domain volume rendering by the wavelet X-ray transform

We describe a wavelet based X-ray rendering method in the frequency domain with a smaller time complexity than wavelet splatting. Standard Fourier volume rendering is summarized and interpolation and accuracy issues are briefly discussed. We review the implementation of the fast wavelet transform in the frequency domain. The wavelet X-ray transform is derived, and the corresponding Fourier-wavelet volume rendering algorithm (FWVR) is introduced, FWVR uses Haar or B-spline wavelets and linear or cubic spline interpolation. Various combinations are tested and compared with wavelet splatting (WS). We use medical MR and CT scan data, as well as a 3-D analytical phantom to assess the accuracy, time complexity, and memory cost of both FWVR and WS. The differences between both methods are enumerated.