In December 1992 Digital Watermarking was introduced by Andrew Tirkel and Charles Osborne. The first successful embedding and watermarks experimented in 1993. The first watermark used in the 13th century in Italy. They mostly use this technique for identifying papermakers or trade guild that manufactured the paper. In late 13th century, this technique spread across all over Europe. Leonardo da Vinci intelligently uses watermark technique in the 15th century to hide the message inside their painting. Mona Lisa is his state of the art painting in which he used this technique.
What Is Digital Watermarking ?
A Digital watermark is a sort of marker secretly embedded in a noise-tolerant signal, for example, a sound, video or picture information. It is regularly used to identify responsibility of copyright for such signal. "Watermarking" is the way toward covering up computerized data into a carrier signal. It is kind of digital pattern or signal which inserted into computerized picture. This pattern is available for each unaltered copy of the original picture. Computerized watermark is unique for each piece of data or common for multiple piece information. It will verify authority and integrity of carrier signal or show identity owner.
Advanced watermarking can likewise be differentiated with public-key encryption which also converts original file into another form. It is typical practice this day to encrypt digital records with the goal that they become unviewable without the decryption key. Unlike encryption, however, digital watermarking leaves the original image or file basically intact and recognizable.
Why Digital Watermarking?
There is two type of computerized watermarking which depend on their visibility to its viewer. A visible watermark is used in a much same way like the bond paper predecessor, whereby the in-transparent of paper is changed by manual stamping it with an identifying pattern. This is done to mark the paper manufacturer or paper type. One might view digitally watermarked documents and images as digitally "stamped". Visible watermarks are mainly useful for convincing an immediate claim of ownership. A familiar example of a visible watermark is in the video domain where CNN and other television networks place their translucent logo at the bottom right of the screen image.
Invisible watermark, on the other hand, is useful for identifying the source, author, creator, owner, distributor or authorized consumer of a data or image. For this purpose, the objective is to permanently and unalterable mark the image so that the credit or work is beyond dispute. In the event of illegal usage, the watermark would facilitate the claim of ownership, the receipt of copyright revenues, or the success of prosecution.
Digital Watermarking is most efficient and useful technique to protect audio, video files. But most of the people use a watermark on the image which is not only protected image but also it is useful for transporting advertising message.
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