基于MVOtsu和对数型模糊隶属度函数的电力设备NSST域红外图像增强

Electrical Equipment Infrared Image Enhancement of NSST Domain Based on MVOtsu and Log-type Fuzzy Membership Function

针对电力设备红外图像细节模糊、边缘不清等问题,提出了一种基于非下采样剪切波变换(nonsubsampled shearlet transform,NSST)域的电力设备红外图像处理方法。该方法采用NSST将原始图像分为高频部分和低频部分。为了精确分割低频电力设备与背景环境并提高二者对比度,低频部分设计了一种结合均值与方差的MVOtsu(mean and variation otsu)算法,并分别对设备和背景进行线性增强和直方图均衡增强。为了增强高频边缘细节,抑制非边缘噪声,高频部分提出一种对数型模糊隶属度函数,将隶属度值域下界拓展到0,解决经典Pal-King隶属度增强后逆映射时低灰度值区域扁平化问题。最后按照NSST变换合成增强结果。该算法与相关算法相比,边缘强度、信息熵、对比度、标准差等评价指标至少增长15.06%、2.03%、33.78%、1.28%。实验结果表明:文中算法能有效的提高电力设备红外图像整体对比度,对细节和边缘增强效果明显,便于人眼识别和智能故障定位,适用于变电站、巡线等多种环境红外图像增强处理。

In order to solve the problems of fuzzy detail and fuzzy edge of infrared image of electrical equipment,an infrared image processing method based on NSST(non-subsampled shearlet transform,NSST) is proposed.This method divides the original image into high frequency part and low frequency part.For accurately dividing the lowfrequency part into target device and the background and improving the contrast,a MVOtsu(mean and variation otsu)algorithm combining mean and variance is designed,and use the linear enhancement and the histogram enhancement to enhance the equipment and background.For enhancing the high frequency edge details and suppress nonedge noise,a logarithmic fuzzy membership function is proposed,it can expand the lower bound of high frequency membership to 0,and this algorithm can solve the problem of flattening of low gray value area in the inverse mapping of classic Pal-King membership.Finally,in accordance with the NSST inverse transformation reconstruct enhanced results.Comparing the proposed method with related algorithm,the intensity of edge,information entropy,contrast,and standard deviation can be improves at least 15.06%,2.03%,33.78%,1.28% respectively.Experimental results show that the algorithm can effectively improve the overall electrical equipment infrared image contrast,detail and edge enhancement effect is obvious,convenience of human eye identification and fault location,suitable for transformer substation,patrol and other infrared image enhancement processing.