Stadardization of Image Processing Techniques for Fractography

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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.