红外无损检测加热不均时的图像处理方法

在红外热像无损检测中,为了减小加热不均的不良影响,提高缺陷对比度和检测深度,以碳纤维增强塑料试件的脉冲热像检测为例,研究了加热不均时的热像序列处理方法.分析和总结了加热不均产生的原因;提出了基于最小二乘法的去除拟合背景法、多项式拟合法及综合法等三种数据处理方法;通过实验对这三种处理方法进行了验证和比较;采用基于统计学的图像评估标准对处理效果作了定量评价.结果表明去除拟合背景法可有效地去除非均匀加热对缺陷识别的干扰,多项式拟合法兼有减小加热不均效应和增强缺陷对比度的作用,而综合法集成了前面二种方法的优点,可更显著地增强图像的缺陷对比度.

Image processing algorithms for uneven heating in infrared thermographic NDT

In infrared thermographic non-destructive testing, to reduce the effects of non-uniform heating and increase defect contrast and inspection depths, the thermal image sequence processing algorithms were studied based on the pulsed thermography of carbon fibre reinforced plastic samples. The factors that produce uneven heating were analyzed and summarized. Three types of data processing algorithms, including deleting fitted background, polynomial fitting and integrated technique, were proposed based on the least square method. The algorithms were verified and compared by experiments and their processing effects were quantitatively evaluated by three statistical standards of image evaluation. The result shows that the deleting fitted background technique can effectively remove the bad influence of uneven heating on the defect inspection, the polynomial fitting method can decrease uneven heating effect and increase defect contrast at the same time, and the integrated approach has the advantages of the two forenamed methods and can more greatly enhance defect contrast.