Application of wavelet transform based intelligent image processing system to the inspection of steel bridges rusty areas

• Main Authors: Jia-Xin Dai, 戴佳信
• Other Authors: Shih-Lin Hung
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/38wju4

碩士 === 國立交通大學 === 土木工程系所 === 92 === In the recent years, the advancement in computer technology allowed image processing to become more practical and cost-efficient. Following the continuous advancement in algorithm ability of computer processors, we are able to analyze the complicated images with image processing. Therefore, this study developed an intellectual bridge surface coating evaluation judgment model which combines wavelet transform, image processing and MATLAB programming language to identify and measure the corrosion situation of the surface coating on steel bridges. The system used the wavelet transform to gain shorter time duration, multi-resolution analysis feature, and time and frequency domain to process images. The system first uses standard deviation to determine the discrepancies in image plane of R, G, B, and selects 2D digital signal image with large discrepancy for wavelet transform. The 2D wavelet transform produces 4 matrixes, one represents the low resolution part, and the other three represent the details. The low resolution part contains the most part of energy in the image, also the most information and image outline. Processing the parameters of the low resolution part can obtain the corrosion area from the reconstructed image, and process the corrosion area in the same way to divide it into areas of different shades. Then, multiple it with discounted parameters to obtain the discounted corrosion area, and combines with the norm to evaluate and formulate remedy for the corrosion area. Fuzzy concept is adopted for ambiguous area. This study expects to provide objective, consistent, and quantified procedure for evaluation and judgment of corrosion images.