Fabric Defect Detection in Stockwell Transform Domain

To improve the accuracy and speed of the fabric defect detection, a novel and automated algorithm is proposed in this paper. The method is based on the Stcokwell transform (or S-transform, ST), a mathematical operation that provides the frequency content at each time point within a time-varying signal. Firstly, gray level integral projection is performed on the fabric image data to obtain a one-dimensional space series. Secondly, the space series for every point at horizontal or vertical direction is subjected to the S transform to obtain a timefrequency spectrum. A function multiplying the S-transform coefficients in low frequencies is defined, which can effectively restrain the texture background, depress the noise and enhance the defect signal. Finally, the adaptive thresholds in the frequency space and the spatial space based on the S-transform coefficients are presented for defect detection. Experimental results show that the proposed algorithm can accurately detect and locate the defects for the real fabric images. The proposed method is simple, robust and easy to implement in real time systems. Copyright © 2014 IFSA Publishing, S. L.