Abstract: Based on practical application of computer vision for mechanical parts geometry parameter inspection‚a new approach is presented to determine the ramp edge at the level of pixel using Laplacian of Gaussian （LOG） function．The pixel level edge to subpixel accuracy is then located by using the MLS linear regression on the condition that the model of the edge is known．Contrastive experiments have been conducted to test the algorithm of the spatial moment subpixel localization for the straight line edge and the algorithm proposed in this paper．The experiment results show that the precision of two algorithms is satisfactory and the velocity of the MLS linear regression subpixel localization is faster． 

Key words: edge inspection, LOG operator, linear regression, spatial moment, subpixel