Wednesday, February 27, 2008

INTRODUCTION

Overview of The Project

PRESENT SYSTEM: -

Digital Watermark is an invisible mark inserted into the digital multimedia data so that it can be detected in the later stage of evidence of rightful ownership. A great deal of research efforts has been focused on digital watermark in recent years. The techniques proposed so far can be divided into two main groups of according to the embedding domain of the container image.

1) Spatial Domain Approach:

One group is SPATIAL domain approach .The earliest watermarking techniques are mainly this kind and the simplest example is to embed the watermark into least significant bits(LSB) of the image pixels. However, this technique has relatively low information hiding capacity and can be easily erased by lossy image compression.

2) Frequency Domain Approach:

The other group is FREQUENCY domain approach. This can embed more information bits and is relatively robust to attacks. They embedded a Guassian distributed sequence into the perceptually most significant frequency components of the container image. Another technique embedded an image watermark into selectively modified middle frequency of discrete cosine transform coefficients. One more algorithm embedded watermark using Fourier transformations that is invariant to image manipulations or attacks due to rotation scaling and translation. Still several methods used to hide the data to the frequency domain such as HVS, JND.