Using the Dual-Tree Complex Wavelet Transform for Improved Fabric Defect Detection

Figure 1

Three-level DWT decomposition. and are low-pass and high-pass filters, respectively. denotes the original signal; cA1, cA2, and cA3 denote the approximation coefficients at level 1, level 2, and level 3, respectively, while cD1, cD2, and cD3 denote the detail coefficients at level 1, level 2, and level 3, respectively.