A hardness measuring method based on Hough fuzzy vertex detection algorithm

This paper proposes the use of a new automatic Vickers hardness measuring method called Hough fuzzy vertex detection algorithm (HFVDA). To overcome the unavoidable effects of vertex detection due to surface contaminations or specimen texture, HFVDA transforms all the indentation edge pixels into the Hough space. Within the Hough space, a weighted fuzzy c-means algorithm along with local maximum detection is proposed to find the indentation edge lines. Inasmuch as indentation deformation usually occurs in the hardness test process, an approach that overcomes the measurement inaccuracy due to indentation deformation is also proposed in this paper. It shows that HFVDA is able to find the indentation vertices and calculate the hardness number with high accuracy for either specular-polished or rough-polished specimens.