Automatic surface inspection using wavelet transforms
| Autor: | Bo Hsiao, 蕭金本 |
|---|---|
| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 In this research we aim at automatic surface inspection using wavelet transforms for both structural and statistical textures. Small surface defects generally appear as local anomalies embedded in a homogeneous texture. The nature of the defects leads us toward the multi-scale and multi-resolution analysis method of wavelet transforms, which permits an efficient local spectral analysis. Wavelet transforms have been traditionally implemented for texture analysis and defect detection by selecting proper textural features in wavelet coefficient matrix. The proposed method does not reply on local texture features. It is based on an image restoration scheme using the wavelet transform. For each wavelet-transformed image, we obtain one smoothed residual sub-image and three detail sub-images, which contain fine structures with horizontal, vertical and diagonal orientation. By properly selecting the smoothed sub-image or detail images for backward wavelet transform, the restored image will remove homogeneous, periodic textures and signify only local anomalies. Experiment on structural textures such as machined surface and textile fabrics, and statistical textures such as sandpaper and leather have shown promising results using the proposed method. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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