Abstract: Aiming at the requirements of efficiency and accuracy in the process of flexible printed circuit board (FPC) production detection, a registration method based on template and discrete cosine transform (DCT) descriptor is proposed. First, in order to solve the problem of registration accuracy, the corresponding image is obtained by analyzing the engineering drawing of circuit board file, which provides a better template for subsequent processing. Then, the corresponding relationship between the template and the detected image is established by using the frequency-domain energy aggregation characteristics of discrete cosine descriptor, so as to calculate the alignment parameters. Secondly, mipmap technology is used to process the template, which provides different precision template images for the registration stage, which is helpful to improve the accuracy and efficiency. The experimental results show that: the maximum error and average error of the improved algorithm are smaller than the original method; for the circuit board such a large resolution image, under the condition of mipmap sampling template, it can obtain higher accuracy, and the processing speed is greatly improved.

Key words: template, image registration, DCT transform, mipmap, flexible printed circuit board (FPC)