One of the backbones in electronic manufacturing industry is the printed circuit board (PCB) manufacturing. Due to the fatigue and speed requirement, manual inspection is ineffective to inspect every printed circuit board. Hence, this paper presents an efficient algorithm for an automated visual PCB inspection system that is able to automatically detect and locate any defect on PCBs. The defect is detected by utilizing wavelet-based image difference algorithm. The coarse resolution defect localization algorithm, is also presented. The coarse resolution defect localization algorithm is applied to the coarse resolution differenced image in order to locate the defective area on the fine resolution tested PCB image. In addition, the performance of the algorithm is evaluated to verier the efficiency of the proposed algorithm in term of computation time. This new method tumed out 10 be computationally less intensive than traditional image difference operation. One conclusion from this paper is that the second level Haar wavelet transform should be chosen for the application of automated visual PCB inspection.

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This paper describes the (field programmable gate array) FPGA implementation of two dimensional forward and inverse Discrete Cosine Transform (2D-DCT and 2D-IDCT) using the lOOK gate ALTERA FLEXlOKlOO FPGA/CPLD. The architecture used in both 2D-DCT and 2D-IDCT is based on the conventional row-column decomposition method. The use of Fast algorithm and distributed arithmetic (DA) technique to implement the DCT and IDCT greatly reduces the hardware complexity.

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Satu daripada asas utama dalam industri pembuatan elektronik ialah pembuatan papan litar bercetak (PCB). Pembuatan PCB pada masa kini perlu melalui proses kikisan. Ini adalah proses satu hala. Proses cetakan yang dilakukan sebelum proses kikisan adalah penyebab utama kepada kecacatan pada PCB. Setelah PCB dikikis, kecacatan itu, jika ada menyebabkan PCB menjadi tidak berguna lagi. Disebabkan oleh keletihan dan keperluan kecepatan, pemeriksaan secara manual tidak efektif dilakukan untuk memeriksa setiap PCB. Oleh itu, pengilang memerlukan sebuah sistem automatik untuk mengesan kecacatan secara masa nyata yang mungkin berlaku semasa proses percetakan. Kecacatan itu akan dikesan dengan menggunakan algoritma pembezaan imej berasaskan wavelet. Seterusnya, kertas kerja ini mencadangkan satu algoritma untuk pemeriksaan visual PCB secara automatik yang berupaya mengesan dan menyari kecacatan pada PCB. Algoritma ini dijalankan pada resolusi kasar pembezaan imej bertujuan untuk mengesan kawasan kecacatan pada resolusi halus imej PCB yang di periksa. Kata kunci: pengesanan kecacatan; resolusi kasar; wavelets; pemeriksaan PCB One of the backbones in electronic manufacturing industry is the printed circuit board (PCB) manufacturing. Current practice in PCB manufacturing requires an etching process. This process is an irreversible process. Printing process, which is done before the etching process, caused most of the destructive defects found on the PCB. Once the laminate is etched, the defects, if exist would cause the PCB laminate to become useless. Due to the fatigue and speed requirement, manual inspection is ineffective to inspect every printed laminate. Therefore, manufacturers require an automated system to detect the defects online which may occur during the printing process. The defect is detected by utilizing wavelet-based image difference algorithm. Hence, this paper proposes an algorithm for an automated visual PCB inspection that is able to automatically locate and extract any defect on a PCB laminate. The algorithm works on the coarse resolution differenced image in order to locate the defective area on the fine resolution tested PCB image. Key words: defect localization; coarse resolution; wavelets; PCB inspection