一种基于同态滤波原理的井下光照不均图像处理方法

传统的同态滤波函数基于高通滤波函数设计,采用该同态滤波函数处理的光照不均图像较暗。根据传统低通滤波器在截止频率半径为5时的图像滤波结果,得出导致图像光照不均现象的主要区域为半径5以内的低频区域的结论;介绍了一种新型同态滤波器的设计过程,进而提出一种基于同态滤波原理的井下光照不均图像的处理方法。该方法采用传统低通滤波函数抑制低频分量,采用传统高通滤波函数增强高频分量;对图像低频分量范围进行细化,对不同的低频分量采用不同的处理方法,即抑制低频分量抑制半径以内的低频分量,使低频分量抑制半径与高频分量增强半径之间较低频率范围内的低频分量基本保持不变,避免了过度抑制低频分量。测试结果表明,该方法在有效处理井下图像光照不均现象的同时避免了对图像整体亮度的过度削弱,效果较好。

A processing method for underground image of uneven illumination based on homomorphic filtering theory

Traditional homomorphic filtering function is based on high pass filler,and images processed by the function are dark.The paper analyzed image filtering result by traditional low pass filter at cut-off frequency radius of 5,and got a conclusion that illumination component mainly distributes in low-frequency range of 0~5 radius.It introduced a design scheme of novel homomorphic filter,and proposed a processing method for underground image of uneven illumination based on homomorphic filtering theory.The method uses traditional low pass filter to restrain low-frequency components and traditional high pass filter to strengthen high-frequency components,divides range of low-frequency components of underground images into two sections,and uses different processing methods in the two low-frequency sections,namely restraining low-frequency components in the range of restraining radius of low-frequency and making low-frequency components invariant which are between restraining radius of low-frequency and strengthening radius of high-frequency,so as to avoid restraining low-frequency component overly.The testing result showed that the method solves uneven illumination problem as well as avoids weakening overall illumination of underground images overly,which has good effect.