Locating cross-shaped image feature with subpixel accuracy based on NCCO
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摘要: 利用标准互相关算子(NCCO)对机器视觉领域常用的十字图像特征进行匹配运算,发现相似函数在峰值区域的分布特征为4个互相对称的双曲面.据此提出一种基于NCCO图像匹配的双曲面拟合亚像素精密定位方法:首先进行粗定位,确定整像素级的相似函数峰值点;然后使用伪逆法对峰值区域的4个卦限分别进行最小二乘拟合;最后求解4个拟合双曲面的交点,得到图像特征的亚像素定位坐标.在微装配显微视觉系统上实现了该算法并进行了实验验证.实验表明:与常用的高斯拟合或二次曲面拟合方法相比,双曲面拟合方法在定位精度上为0.25个像素,而计算量大为减少.Abstract: Normalized cross correlation operator (NCCO) was used for image matching to localize popular cross-shaped features in machine vision. Distribution feature of similarity function around peak zone was found to be four symmetry hyperboloid planes(FSHP). An approach of subpixel localization based on hyperboloid fitting algorithm (HFA) was presented according to the character of FSHP. A coarse pattern position was localized by one-dimension searching in x and y direction respectively to reduce the computational complexity. The discrete NCCO points around the coarse position were fitted to four hyperboloid planes in four quadrants respectively through least square fitting method. The point of four hyperboloid intersection was adopted as subpixel localization position. The HFA was realized on a microscopy vision system of MEMS device micro-assembly work-cell. Experimental results show that the subpixel localization precision of HFA can reach 0.25 pixel. It has greatly decreased computative cost under the comparisons with conicoid fitting algorithm and Gaussian fitting algorithm.
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Key words:
- vision /
- image analysis /
- correlation theory /
- alignment
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[1] West G A W, Clarke T A. A survey and examination of subpixel measurement techniques . In:Proceedings of the Meeting, Close-range Photogrammetry Meets Machine Vision . Bellingham:Society of Photo-optical Instrumentation Engineers,1990.456~463 [2] Canny J. A computational approach to edge detection[J] IEEE Transactions on Pattern Analysis and Machine Intelligence, 1986, 8(6):679~698 [3] Lyvers E P, Owen R M, Mark L A, et al. Subpixel measurements using a moment-based edge operator[J] IEEE Transactions on Pattern Analysis and Machine Intelligence, 1989, 11(12):1293~1308 [4] Alzahrani FM, Chen T A. A real-time edge detector:algorithm and VLSI architecture[J] Real-Time Imaging, 1997, 3:363~378 [5] Brown L G. A survey of image registration techniques[J] ACM Computer Surveys, 1992, 24(4):325~376 [6] 于起峰,陆宏伟,刘肖琳. 基于图像的精密测量与运动测量[M] 京:科学出版社,2002.148~150 Yu Qifeng,Lu Hongwei,Liu Xiaolin. Precision measurement and motion measurement based on image[M] eijing:Science Press,2002.148~150(in Chinese) [7] 朱志刚,林学门 言 ,石定机. 数字图像处理[M] 京:电子工业出版社,2002.420~425 Zhu Zhigang, Lin Xueyin, Shi Dingji. Digital image processing[M] eijing:Publishing House of Electronic Industry,2002.420~425(in Chinese)
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