图像灰度与腐蚀特征的相关性研究

RELATIVITY BETWEEN IMAGE GRAYSCALE AND CORROSION CHARACTERISTICS

根据实验数据研究腐蚀图像灰度和实际腐蚀深度的相关性,发现对孤立、规则圆孔的图像,经双向扫描校准后,其局部平均灰度和孔深存在很好线性关系,相关系数达0.95;对实际腐蚀图像,其局部平均灰度和对应位置坑深仍在0.95置信度下线性相关,但复杂深坑可能导致灰度值偏高(亮),而且,坑深和灰度统计分布相关曲线表现为斜率不同(以坑深0.045 cm为转折点)的两段直线.综上所述,基于图像灰度的腐蚀形貌诊断更适合腐蚀发展初期.此外,图像灰度和实际腐蚀参数的相关性研究表明,图像灰度极差是平均腐蚀速度及最大坑深的良好表征,它们在0.95置信度下线性相关.

The relationship between corrosion image grayscale and pit depth was studied based on experimental data. A good linear relationship was observed and their relationship coefficient was high up to 0.95 for corrected image of isolated and regulation holes by double - direction scanning. For actual corrosion images, the relationship was still linear under confidence level 0.95. However, the complex deep pits might cause error and corresponding image grayscale became higher in values（brighter）. Moreover, the correlation curve of statistical distribution between gray and pit depth showed two lines with different slopes, which turning point was 0. 045 cm. Therefore it could be decided that corrosion morphology diagnoses based on image grayscale were more suitable for early corrosion stages. In addition, the relationship between image grayscale and corrosion parameters was also investigated and the results showed that image grayscale range was good characterization for average corrosion rate and max. pit depth, that they had good linear relationship under confidence level 0.95.