With the recent spate of cases involving faux currency, no one has to be reminded of the importance of watermarking. A watermark is a kind of image or text that’s imprinted onto paper, which provides proof of its credibility. Digital watermarking is an extension of this concept within the digital world. In recent years the exceptional growth of the net has highlighted the necessity for mechanisms to shield ownership of digital media, specifically identical copies of digital information such as pictures, text or audio, are often created and distributed with ease. In such a state of affairs, who is the creator and who is the plagiarist? it absolutely was impossible to tell, until now. Digital watermarking could be a technique that has an answer to the longstanding issues visage with copyrighting digital data. Digital watermarks are pieces of data additional to digital information (audio, video, or still images) which will be detected or extracted later to form an assertion concerning the data. This information is often textual data concerning the author, its copyright, etc; or it may be a picture itself. The data to be concealed is embedded by manipulating the contents of the information allowing someone to spot the original owner, or in the case of illicit duplication of purchased material, the buyer concerned. These digital watermarks stay intact under transmission and transformation, permitting us to safeguard our ownership rights in digital space.
Watermarks could also be visible, within which case their use is two-fold — to discourage unauthorised usage, and conjointly act as a poster. However, the main target is on invisible watermarks, as they do not cause any degradation within the aesthetic quality or within the utility of the info. They can be detected and extracted later to facilitate a claim of possession, yielding relevant information yet. Watermarks may additionally be classified as strong or fragile. Robust watermarks are those that are tough to get rid of from the article within which they’re embedded, despite numerous attacks they may be subjected to, mentioned later. Fragile watermarks are those who are simply destroyed by any conceive to tamper with them. Absence of a watermark in an exceedingly antecedent watermarked document would cause the conclusion that the data has been tampered with. For a digital watermark to be effective for possession assertion, it should be strong, redeemable from a document, give the initial data embedded dependably, be non-intrusive, and also removable by authorised users.