A Digital Watermarking Algorithm for Certificate Identifying

In this paper we introduce a watermarking arithmetic for certificate identifying. The arithmetic is based on the FMT transformation. We insert special information in the digital photograph of the certificate and study on it after printing and scanning. The relationship of printing resolution, scanning resolution and the image is discussed, which effects the scheme´s efficiency. The experiments show that the watermarking algorithm is robust to printing and scanning. Some preprocess is needed before extracting watermark, such as cropping and resizing the print-scan photographic image.