PCB Edge Detection with DWT
| Autor: | Heng-chia Hsu, 許恆嘉 |
|---|---|
| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 To develop an appropriate algorithm for PCB (Printed Circuit Board) image edge detection is the main subject of this thesis. The algorithm proposed in this thesis can be applied only on digital gray-level images of PCBs. Instead of the conventional idea of difference, DWT (Discrete Wavelet Transform), an alternative and novel method for basis change despite Fourier Transform, is employed. In this thesis, digital gray-level images of PCB are considered as vectors existing in the vector space constructed by selected basis that are the dilations and translations of Harr function and box function. By using DWT, image-edge-related information in digital gray-level images can be extracted easily. Not only DWT but also optimization algorithms are involved. Two well-known optimization algorithms, gradient method and one-dimensional Newton's method, are adopted for tuning the result into the best condition. The purpose of adopting two-stage optimization algorithm, gradient method and one-dimensional Newton's method, is to diminish the elapsing time in etermining the weighting vectors by searching the maximum step-size in the determined descent direction. Step-size and descent direction are determined by one-dimensional Newton's method and gradient method, respectively. When the weighting vectors are obtained, the two-stage optimization can be abandoned. Only are the weighting vectors and DWT used for PCB image edge detection in the rest of PCBs. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|