Image Processing Technology Applied Research In The Hardness Measurement System

The hardness is a characteristics of some material. Accurate calculation of hardness values is very important of the hardness of the material. Automatic micro-Vickers hardness measurement, is to sample an image under the microscope of the hardness map, send it to the computer, process the image with processing algorithms, and calculate the value of the Vickers hardness accurately.About a lot of hardness system, the edge of the indentation is considered to be a straight line. That will result in a deviation between hardness value and the actual hardness value. In this paper, offered an improved method. With bottom-up control strategy, pre-process and segmentate an image, then extract the edge with a threshold algorithm. The edge maybe approximate a straight line, and may be curved. So fit the edge with a wide-hough transform .That will received four coarse straight and four vertices from the indentation. To understand the image better, that is extending a certain area around every vertice. In every region, use a cluster analysis algorithm, to be two types of points. With the points for each category, use the least square method. That will get two straight lines. Solving the intersection of these two lines, it has been accurate positioning of the vertex of the indentation, and thus seek to the diagonal length of indentation. According to the hardness formula, the Vickers hardness value can be precise of some materials.The experimental results show that the measurement results are very close to the nominal value by this method. It is superior to that the edge is as a straight line only. This also proves that the results are real, effective and accurate.