In thermal wave NDT,the contrast is low and noise is high. In order to resolve the problem,the wavelet transformation is introduced in image enhancing step. At first,the theory of image enhancement of wavelet transformation is explained,and image enhancing process is designed. To get the best enhancing effect,threshold value,enhancing factors of enhance function are studied. The conclusions are as follows: noise reduction is influenced mainly by threshold value T; enhancing parameter K1 is relevant with enhancing effect of transition region; improvement of picture contrast depends on enhancing parameter K2. On the basis of the conclusion,threshold value T is set to be 670,K1 to be 10,K2 to be 0.1. Test image of certain composite material is processed. Compared with the original picture,the enhancing effect is quite good,which proves the availability of this enhancing method.%为解决红外热波检测图像高噪声,低对比度的问题,将小波变换引入到图像增强环节中.先对小波变换的图像增强原理进行介绍,并对增强过程进行设计.为得到最佳增强效果,对增强函数中的阈值、增强系数的选取进行了研究,并指出,阈值T主要影响降噪效果,增强系数墨主要影响过渡区域的增强效果,增强系数K2主要影响图像的对比度,并对参数的选取方法进行说明.在此基础上,最终选取阈值T为670,K1为10,K2为0.1,对某复合材料的红外热图进行增强处理,通过与原图对比,证明了该方法的有效性.
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