DIGITAL IMAGE WATERMARKING BASED ON GRADIENT DIRECTION QUANTIZATION

The advancement of the Internet has resulted in many new opportunities for the creation and delivery of content in digital form. Applications include electronic advertising, real-time video and audio delivery, digital repositories and libraries, and Web publishing. But the important question that arises in these applications is the data security. It has been observed that current copyright laws are not sufficient for dealing with digital data. Hence the protection and enforcement of intellectual property rights for digital media has become a crucial issue. This has led to an interest towards developing new copy deterrence and protection mechanisms. One such effort that has been attracting increasing interest is based on digital watermarking techniques. In general, there are two approaches in watermarking namely Spread Spectrum (SS)-based watermarking and quantization-based watermarking. In SS type watermarking, a pseudorandom noise-like watermark is added to the host signal which has been shown to be robust to many types of attacks.