基于同态滤波的电子散斑干涉图像处理

由于散斑具有可测的强度和确定的相位,正逐渐被人们重视和进一步研究,现广泛应用于无损检测领域。电子散斑干涉条纹图上总是附带大量的随机散斑颗粒噪声。一般来说,散斑图像记录的变形信息主要集中在低频部分,而噪声主要在高频部分。为了得到变形物体的连续相位分布,需要用适当的方法对散斑干涉条纹图像进行滤波降噪处理。同态滤波是一种将亮度范围压缩和对比度增强的频域处理方法。采用基于同态滤波原理设计出的新的低通滤波器,将其运用于3步相移电子散斑干涉条纹图像处理,并从理论上进行了详细的论述。结果表明,运用该滤波器处理散斑条纹图像,过滤了大量的散斑颗粒噪声,增强了散斑干涉条纹的对比度。

Electronic speckle interferometry image processing based on homomorphic filtering

More attention was paid to research of speckles because of their measurable intensity and certain phase.Now speckles are used extensively in the field of non-destructive test.The electronic speckle pattern interferometry (ESPI) is always full of a lot of noise.Generally,the information about deformation recorded by the fringe is mainly distributed in the low frequency domain,whereas the noise is in the high frequency part.In order to obtain the continuous phase distribution of the deformed object,it is necessary to take some proper methods to remove the noise in the fringe.Homomorphic filtering is a frequency domain operation to compress image intensity area and enhance contrast.A new filter based on the principle of homomorphic filtering was designed,which was used for three-step phase-shifting electronic speckle image processing.A theoretical analysis was also proposed in detail.The experimental results show that the speckle noise was removed to the large extent and the contrast of ESPI fringes can be increased by the proposed method.