The Research And Implementation Of Gray-Level Digital Watermarking Algorithm Based On Frequency Field

With the rapid development of computer network and communication technology, digital media, including digital images and digital video frequency and digital audio frequency, have been abroad applied. Information security of digital media and the protection of information property right and authentication are becoming more and more pressing and have become a very hot and important topic of discussion. As a effective supplement measure of conventional encryption methods, digital watermark is a new technology which can protect copyright and authentication source and integrality in the open network. In recent years, digital watermarking has brought high recognition and has become a hotspot for study.In former methods, the watermark is usually the pseudo-random sequence and the bi-level image, which process short protection information for information property right and secrecy. Aiming at the problem, a watermarking algorithm which uses gray-level image processing abundant information is designed in this paper, namely gray-level digital watermarking algorithm.At first, the concept and essential characteristic and application of digital watermark is introduced, and the basic theory and frame class of embedding gray-level digital watermark is concluded, and the actual gray-level digital watermarking algorithm is recommended and analyzed from the preprocessing and the embedding and the detecting of gray-level digital watermark. Improve on the existing algorithms is based on the study of the existing algorithms and a gray-level digital watermarking algorithm based wavelet transformation is designed. In the algorithm of this paper, gray-level watermark is embedded as a bi-level form. And in the course of embedding, the watermark is embedded into the important coefficients of intermediate frequency using the idea of the Embedded Zero-tree Wavelet Code for reference and the theory of quantization index modulation with the distortion compensation. Quantization step is adaptively changed making use of the average of the wavelet coefficients and the surroundingwavelet coefficients in the original image. In the detecting, the watermark can be distilled using the key only.Experiments proves that this algorithm not only give attention to the intensity of embedding watermarking but also guarantee the quality of image combining with human visual system better, and it has good robust under the image processing attacks such as cutting, filter, smoothing, sharping, and JPEG compression etc.