Stadardization of Image Processing Techniques for Fractography

断口学图像处理技术的标准化得到了促进，各种处理和估计断口表面的算法和软件已经开发出来。得到的结果如下：1。除了对腐蚀坑的形状和尺寸进行三维估计，作为循环试验的凹窝和条纹间距的评估，面尺寸的计算，晶间和穿晶断裂面积分数以及拉伸区尺寸的计算已经成功地进行了足够的精度。对于图像分析之前的预处理，需要对灰度进行归一化和美化，以使拍摄条件标准化，增强对比度和/或进行中值滤波以降低噪声。此外，还必须考虑边缘和线条的检测以及一些预处理来缩短cpu时间。为了从立体照片中重建三维地形，寻找相同的位置是最重要的，并明确了相互相关算法、SSDA算法和逻辑算子算法的优缺点。对于凹窝的评价，提出了用三角形单元面积法计算断裂面和相邻3个像素的净面积。新提出了计算小面尺寸的截面阈值法和断裂面矢量法，计算条纹间距的边线检测法和FFT法，计算晶间和晶间破裂面积的共生矩阵二化法和矩阵映射法，计算拉伸区尺寸的单调递增截面法和切线法。系统地阐述了各种算法的优缺点及应用指南。

Standardization of image processing techniques for fractorgraphy has been promoted and various algorithms and softwares to process and to estimate the fracture surfaces have been developed. The results obtained are as follows.1. In addition to 3 dimensional estimation of shapes and dimensions of corrosion pits, emaluation of dimples and striation spacings as a round robin trial, calculations of facet sizes, inter- and transgranular fracture area fractions, and stretch zone sizes have been successfully conducted with an enough accuracy.2. As for a pre-processing prior to the image analysis, normalizing and flattering of gray levels so as to standardize the photographing condition and to intensify the contrast and/or a median filtering to reduce noises are necessary. In addition, detection of edges and lines as well as some pre-processings to shorten cpu time must be considered.3. To re-construct the 3 dimensional topographies from a stereo photographs the search of identical positions is the most important, and the merits and demerits of the mutual correlation algorithm, the SSDA, and the logic operator one have been made clear.4. As for the evaluation of dimples, area of triangular element method to calculate the net area of fracture surfaces and 3 neighboring pixels one have been devised.5. The threshold method of cross section and the fracture surface vector one to calculate facet sizes, the detection of edges and lines method and the FFT one to calculate striation spacings, the binatization method of co-occurrence matrix and the mapping one of the matrix to calculate inter- and transgranular fracture area fractions, the monotonously increasing section method and the tangent line one to calculate stretch zone sizes have been newly devised. The merits and demerits of those algorithms and the application guide have been systematically made clear.