Research Article Determination of Geometric Parameters of Cracks in Concrete by Image Processing Yuriy Vashpanov , 1 Jung-Young Son, 2 Gwanghee Heo , 1 Tatyana Podousova, 3 and Yong Suk Kim 4 1 Civil Engineering Department, Public Safety Research Institute, Konyang University, Nonsan, Chungnam 32992, Republic of Korea 2 Biomedical Engineering Department, Public Safety Research Institute, Konyang University, Nonsan, Chungnam 32992, Republic of Korea 3 Applied Mathematics Department, Odessa State Academy of Civil Engineering and Architecture, Odessa 65029, Ukraine 4 Bio-IT Engineering Department, Public Safety Research Institute, Konyang University, Nonsan, Chungnam 32992, Republic of Korea Correspondence should be addressed to Yuriy Vashpanov; yuriy.vashpanov@gmail.com Received 31 May 2019; Revised 7 August 2019; Accepted 24 September 2019; Published 30 October 2019 Academic Editor: Mohamed ElGawady Copyright © 2019 Yuriy Vashpanov et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. e 8-bit RGB image of a cracked concrete surface, obtained with a high-resolution camera based on a close-distance pho- tographing and using an optical microscope, is used to estimate the geometrical parameters of the crack. e parameters such as the crack’s width, depth, and morphology can be determined by the pixel intensity distribution of the image. For the estimation, the image is transformed into 16-bit gray scale to enhance the geometrical parameters of the crack and then a mathematical relationship relating the intensity distribution with the depth and width is derived based on the enhanced image. is relationship enables to estimate the width and depth with ±10% and ±15% accuracy, respectively, for the crack samples used for the ex- periments. It is expected that the accuracy can be further improved if the 8-bit RGB image is synthesized by the images of the cracks obtained with different illumination directions. 1. Introduction Cracks in concretes are one of the important parameters in diagnosing the current status of structures [1–3]. e changing sizes and depths of the cracks in time are a ba- rometer of predicting the safety of a structure. Hence, the demands of measuring the geometrical parameters of the cracks accurately are ever increasing [4–8], and the number of articles for crack measurements has also been increased [9–17]. In this process, many methods such as using ul- trasounds [18–21], X-rays [22], and eddy current (EC) [23] sources are developed, and the images are reconstructed in 3D (three-dimensional) [24] form. Hence, it is considered that these methods have good prospects for practical use in civil engineering [25]. But, these methods require that the sources should be contacted to the concrete surface tightly to deliver the source energy to the concrete without much loss. ey require specialists and are inconvenient to use and time consuming. e more convenient and less time-consuming method is using a camera to take the image of the cracked concrete surface. Since it is a noncontact method of detecting the cracks and requires no specialist, the camera can be even mounted on a drone to cover a bridge. In the photos, the cracks are easily identified because of their darkness in comparison with the concrete surface. Software and hardware tools can easily determine the width and length of the cracks with sufficient accuracy from the image in each photo [17, 26–28]. Added on this, the photographing distances can be varied significantly with use of a telephoto lens [29]. Hence, the camera method is very convenient to Hindawi Advances in Civil Engineering Volume 2019, Article ID 2398124, 14 pages https://doi.org/10.1155/2019/2398124