An improved sub-pixel location method for image measurement

Abstract

Sub-pixel edge location is an effective way to improve measurement accuracy. For the deficiency of traditional gaussian interpolation algorithm for sub-pixel location, this paper presents an improved algorithm: After obtaining pixel-accuracy edge of object to be measured by LoG operator, use Hough transform to get the curve slope of the boundary line and the normal of the corresponding point on the edge; Weighing Lagrange interpolation in the normal direction is performed to obtain the gray values in the direction of the gradient under new coordinate system; finally, perform sub-pixel relocation in the gradient direction based on the gaussian interpolation algorithm. Experimental results show that the improved method can get much better precision than the traditional algorithm. © 2011 Springer-Verlag Berlin Heidelberg.