IMAGE WATERMARKING USING DISCRETE WAVELET TRANSFORM

With the beginning of internet, creation and delivery of digital data (images, video and audio files, digital storehouses and libraries, web publishing) has grown many fold. With this, issues like, protection of rights of the content and proving ownership, arises. Digital watermarking came as a technique and a tool to overcome shortcomings of current copyright laws for digital data. To prove ownership and protect right, a watermark is embedded in data but to save watermark from fakers we need to find locations which are invariant to all kind of attacks (rotation, expansion, compression, cropping, filtering, and distorting). Every image has regions, also known as patches, which are invariant to attacks.Watermarkingis the process of embedding data called a watermark into a multimedia object such that watermark can bedetected or extracted later to make an assertion about the object. The object may be anaudio, image or video. A simple example of digital watermark would be a visible “seal”placed over an image to identify the copyright. However the watermark might containadditional information including the identity of the purchaser of a particular copy of theobject. Based on the purpose of the watermark, it is embedded either visibly or invisibly. In this work we havestart with the type of watermarks and their characteristics .Four different types of watermarking algorithms are proposed. They are in spatial domain, DCT domain, DWT domain and spread spectrum technique. But the commonly used technique is wavelet transforms as it is a part of the currentcompression standards (JPEG2000), sowavelet-based techniques would allow a much easier and optimized way to include a copyright protection device in the compression code itself.