A High Precision Laser Spot Center Location Method Based on Multi-scale Image Analysis

This paper presents a multi-scale high-precision method for locating the centers of laser spots with various sizes in an image. The method works as follows: First, for each scale in the image scale space, it computes the specially designed operators from the eigenvalues of Hessian matrix at every pixel. The spot center pixel location and the associated scale are determined by searching the local extrema of the operator functions through different scales. Finally, the image intensity function around the spot center pixel location is approximated by second order Taylor expansion and the sub-pixel center location is computed by finding the maxima of the approximated intensity function. Both the synthetic and real experiments verified the accuracy and robustness of the proposed method.