Intelligence-Based Adaptive Digital Watermarking for Images in Wavelet Transform Domain

Basics Of Digital Watermarking

Digital Watermarking is defined as a process of inserting a piece of digital data called watermark into digital images that are to be protected. The watermark to be inserted can be of logo, text data, numbers or any other type of images. The cover data could be of digital images, digital video sequences and digital audio signal. The inserted watermark should be extractable in future for verification of it to the intended purposes. One of the important properties of digital watermarking is its robustness against various attacks. Robustness is defined as the existence of the watermark even after various attacks as discussed in Hartung & Kutter (1999).

Steganography is a technique using which secret information could be hidden within another unrelated cover image for secret communication. Some of the techniques of steganography include spacing patterns in printed documents, coding messages in music compositions etc as outlined in Anderson & Petitcolas (1998)’s work. The other applications include ownership protection, proof of ownership, fingerprinting, authentication and tampering detection if the robustness property is also considered.

Digital Watermarking can be considered as a special technique of steganography where the secret information could be inserted into any other media data which may be related to each other. The most common examples of watermarking are the presence of specific patterns in currency notes, which are visible only when the note is exposed to light and company logos in the background of printed text documents. In some applications invisible watermarking could also be carried out. The watermarking techniques prevent forgery and unauthorized replication of any digital content.