Analysis of Visual Angle Influence on Infrared Thermal Image Detecting of Insulator Contamination Grades
Yunpeng Liu, Hdhl Electrical · Gao dianya jishu · 2008
In order to improve the accuracy of detecting insulator contamination grade by infrared imaging,a method to determine the best visual angle using comparative analysis of pollution grade classification features Abstracted from insulator infrared images is proposed. The image region of the ceramic piece surface of insulator is intercepted manually after the contrast of the original thermal image was enhanced by histogram equalization. The intercepted image is binarizated according to the segmentation threshold extracted from the histogram envelope line. The ceramic piece surface image of insulator is extracted through morphological filtering on the binarizated image. From which ten pollution grade classification features are extracted statistically,such as the highest temperature,the lowest temperature,the mean temperature,the temperature variance of the insulator surface. The Fisher criterion is applied to comparative analysis. The analytical result of porcelain insulator infrared thermal image from artificial pollution test indicates that the thermal field of insulator surface significantly changes with the angle of view,and the features of lower surface have better classification performance than the uppers. It is recommended that the visual angle should aim at the lower surface for detecting insulator contamination grades by infrared imaging.