Study Of Multiple Digital Image Watermarking Algorithm Based On Wavelet Transform

With the rapid development of the Internet and information technology, replication and transmission of digital information has more and more convenient. On the one hand, it facilitates our daily life; on the other hand, piracy and data tampering are rampant. It has become a hot issue to protect the copyright of digital works in recent years.The first generation of copyright protection is cryptography and digital signatures. Cryptography will be spread for the cipher text to achieve copyright protection. With digital signature to the message digest appended to the protection of information, the purpose is to prove that the protected information is true and complete. However, in the protection of digital multimedia information, cryptography and digital signature technology has shortcomings. It makes up with new copyright protection technology-digital watermarking technology.Recently, digital watermarking has become a new information hiding technology. The core of it is to embed copyright information into the redundancy of multimedia information, such as images, sounds, videos and other multimedia data. Password information as the watermark, the embedded watermark should not affect the use of multimedia and the commercial value. At the same time, it is convenient to extract the watermark to prove the copyright or determine the integrity.This paper studies copyright protection of digital images. Firstly, a review of digital watermark technology is made. Secondly, detail characters of digital watermark are illustrated, e.g., the concept of digital watermarking, general models, the characters, attacks and performance evaluation, the typical image watermarking algorithm etc. In this research, a large amount of meaningful information is embedded in an image to achieve copyright protection. Main contents and results are as follows:(1) Carrier image is decomposed by discrete wavelet transform (DWT).With significant gray and color images as watermark information, Pretreatment with the watermark information is embedded into the image spatial or wavelet transform domain to achieve the dual watermark. This study achieves watermark embedding, extraction and detection by experiment.(2) Basing on the wavelet analysis, we introduce wavelet packet transform (WPT). First,the carrier image is transformed by wavelet packet transform (WPT), then the multiple watermark is encrypted and embedded in WPT high frequency, low-frequency domain to achieve the dual watermark copyright protection. This paper focus on the image to achieve copyright protection and propose wavelet transform (DWT) domain, wavelet packet transform (WPT) domain digital images of double watermarking. The experiments prove the robustness and anti-attack ability of the proposed algorithm. Digital image copyright protection has a good practical and theoretical significance.