Multi-scale wavelet transform filtering of non-uniform pavement surface image background for automated pavement distress identification

• Proposed a multi-scale wavelet transform based algorithm.
• Removed non-uniform background of pavement images.
• New algorithm outperformed median filter and morphological closing algorithms.
• Capable of extracting tiny cracks effectively.
• Suitable to automated pavement distress identification.

Non-uniform background of pavement images results in difficulties when segmenting pavement images for pavement distress identification. A novel and fast non-uniform background removal algorithm based on multi-scale wavelet transform is presented. The algorithm uses multi-scale wavelet transform to decompose pavement image and then reconstructs image background using low-wavenumber components through inverse wavelet transform. Brightness of image background is then corrected to achieve uniform background pavement image. The multi-scale wavelet transform algorithm is compared with median filter algorithm and morphological closing algorithm. Experimental results show that the proposed algorithm possesses the advantage of extracting tiny cracks more effectively than the other two algorithms, demonstrating its suitability to be used in automated pavement distress segmentation and identification.