An Edge Detection Method Designed for Pavement Distress Images

Abstract:

An edge detection method designed for pavement images was presented in this study to overcome the difficulties in traditional methods of edge detection for pavement images such as nonuniform background illumination,low proportion of distress pixels and irregular directions of distress.The method offered in this study brought image preprocessing and edge enhancement to traditional edge detection methods.The image preprocessing was composed of background correction,Gaussian smoothing and histogram transformation based on the conception of effective range of gray levels which was proposed by this study for the first time,while the edge enhancement included the morphological dilation and median filtering operation.A pavement distress image was tested by Sobel detector of eight directions and Otsu method following the procedure above.The result shows that the proposed procedure can dramatically dampen the impact of noise on edge detection,and the background corrections as well as the histogram transformation based on effective range of gray levels are the key components of the method.Besides,Otsu method can provide good segmented edge maps if the images have been preprocessed.