“…In general, the implementation of these methods involves the following three steps: (1) contrast enhancement, (2) mathematical morphological processing, and (3) information extraction using linear filters. Other machine learning methods, such as artificial neural networks (ANN) (Adeli and Yeh, ; Eldin and Senouci, ; Jin and Zhou, ), support vector machine (SVM) (Qu et al., ), Adaboost (Cord and Chambon, ), K‐nearest neighbors algorithm (Lei and Zuo, ), grouping techniques (Yeum and Dyke, ) and Restricted Boltzmann Machine (Rafiei and Adeli, , ; Rafiei et al., ) have also been used in the field of civil engineering for crack or damage detection and achieved some good results. However, a common problem with these methods is the inability to handle complex background images.…”