This paper presents a new method for automatically analyzing the digital image of Vickers hardness indentation called Region-Point detection algorithm. This method effectively overcomes the error of vertex detection due to curving indentation edges. In the Region-Detection, to obtain four small regions where the four vertexes locate, Sobel Operator is implemented to extract the edge points and Thick-line Hough Transform is utilized to fit the edge lines, then the four regions are selected according to the four intersection points of the thick lines. In the Point-Detection, to get the vertex's accurate position in every small region, Thick-line Hough Transform is used again to select useful edge points and Last Square Method is utilized to accurately fit lines. The interception 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 calculated. Experiments show that the measured values agreed well with the standard values

Date Published: 31 December 2008
PDF: 6 pages
Proc. SPIE 7130, Fourth International Symposium on Precision Mechanical Measurements, 71304C (31 December 2008); doi: 10.1117/12.819716

Published in SPIE Proceedings Vol. 7130:
Fourth International Symposium on Precision Mechanical Measurements
Yetai Fei; Kuang-Chao Fan; Rongsheng Lu, Editor(s)