A New Method for Automatically Measurement of Vickers Hardness Using Thick Line Hough Transform and Least Square Method

A new method for automatically analysing the digital image of Vickers hardness test using Thick Line Hough Transform and Least Square method fitting is presented. First, edge detection is implemented to obtain the edge points using Sobel operator. Second, Thick Line Hough Transform is utilized to fit the edge points. We could obtain four regions where the four vertexes are inside by computing the intersections of these thick lines. In every region, edge points are clustered into two classes using Hough Transform, and then Least Square method is used to fit two lines. The intersection point of the two lines in every region is the vertex of indentation. Then the length of the diagonal and the Vickers hardness could be computed. Experiments prove that the proposed method is better than the traditional method.