Digital watermarking: A state-of-the-art review

Digital watermarking is the art of embedding data, called a watermark, into a multimedia object such that the watermark can be detected or extracted later without impairing the object. Concealment of secret messages inside a natural language, known as steganography, has been in existence as early as the 16^th century. However, the increase in electronic/digital information transmission and distribution has resulted in the spread of watermarking from ordinary text to multimedia transmission. In this paper, we review various approaches and methods that have been used to conceal and preserve messages. Examples of real-world applications are also discussed.