基于温度梯度的电力设备红外图像盲元块补偿

Blind-element block compensation of infrared image in power equipment based on temperature gradient

红外设备的成像质量直接决定了电力设备红外诊断的准确度。盲元问题作为影响成像质量的重要因素,得到了广泛的关注。现有的盲元补偿算法对单一盲元点均有较好的补偿效果,但缺乏对盲元块和边缘位置盲元的适应性,存在算法复杂、补偿精度不高、易造成边缘模糊等问题。基于传热学温度梯度基本理论,提出了一种新的基于梯度变化的补偿算法。先确定盲元块大小,再计算盲元块周围同样大小正常像元块的灰度均值,通过像元块灰度均值的差确定盲元块所处位置及梯度变化方向,最后选取合适像元块,计算其沿梯度变化方向各像元间的灰度变化系数对盲元块进行补偿。实验结果表明,相比传统补偿算法,基于梯度变化的补偿算法的峰值信噪比(PSNR)和结构相似度(SSIM)分别提高了0~14 d B,0~0.002 8,对红外图像中的盲元块具有较好的补偿效果。可以在实际红外系统中实现对电力设备红外图像盲元块的有效补偿,提高故障定位精度。

The imaging quality of infrared equipment directly determines the accuracy of infrared diagnosis of electrical equipment. As an important factor affecting the imaging quality,the blind-element problem has received widespread attention. The existing blind-element compensation algorithm has a good compensation effect for single blind-element point but lacks the adaptability to the blind-element block and the blind-element in the edge location,and has some problems such as complex algorithm,low compensation accuracy and easy edge blurring. Based on the basic theory of temperature gradient in heat transfer,a new compensation algorithm based on gradient variation is proposed in this paper. First,the size of the blind-element block is determined,then the average gray value of the same size of the block of pixels around the blind-element block is calculated,and the position of the blind-element block and the direction of the gradient is determined by the difference of the gray mean of the pixel block. And finally,the appropriate pixel block is selected,the gradient along the gradient direction of each pixel of the gray coefficient of variation of blind-element block compensation is calculated. The experimental results show that the peak signal to noise ratio( PSNR) and SSIM of the compensation algorithm based on gradient change is increased by 0 ~ 14 dB and 0 ~ 0.0028,respectively,compared with the traditional compensation algorithm,has a good compensation effect. The actual infrared system can be achieved on the power equipment infrared image blind-element block effective compensation,improve fault location accuracy.