By: U.Aruna M.Shanthi Priya

Allows users to embed special pattern or some data into digital contents without changing its perceptual quality. When data is embedded, it is not written at header part but embedded directly into digital media itself by changing media contents data Watermarking is a key process for the PROTECTION of copyright ownership of electronic data.

Invisible/Inaudible Information is embedded without digital content degradation, because of the level of embedding operation is too small for human to notice the change. Inseparable The embedded information can survive after some processing, compression and format transformation. Unchanging data file size Data size of the media is not changed before and after embedding operation because information is embedded directly into the media.

According to Human Perception Invisible Visible According to Robustness Fragile Semi fragile Robust According to types of Document Text Image Audio Video

 Logo or seal of the organization which holds the rights to the primary image, it allows the primary image to be viewed, but still visible it clearly as the property of the owning organization.  Overlay the watermark in such a way that makes it difficult to remove, if the goal of indicating property rights is to be achieved.

Watermark Image with watermark

 Embedding level is too small to notice  Can be retrieved by extraction software  Applications: ◦ Authentication ◦ Copyrighting ◦ Etc…

 A watermark is called fragile if it fails to be detected after the slightest modification.  A watermark is called semi-fragile if it resists beginning transformations but fails detection after malignant transformations.  A watermark is called robust if it resists a designated class of transformations.

 Text/Image/Audio watermarking refers to embedding watermarks in an text/image/audio in order to protect the image from illegal copying and identify manipulation.

Water marking Spatial domain water marking frequency domain watermarking Least significant bit DCT DWT Patch work

Algorithm for video watermarking DCT DWT Video watermarking refers to embedding watermarks in a video sequence in order to protect the video from illegal copying and identify manipulation

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. This technique has relatively low information hiding capacity and can be easily erased by lossy image compression.

 Lets consider images.  Each pixel of the color image has 3 components-red, green and blue(RGB).  3 bytes for each pixel.  Each color has 1 byte, or 8 bits.  each bits has its own value 2pow(n).

15 Digital Image Types : RGB Image Color image or RGB image: each pixel contains a vector representing red, green and blue components. RGB components

Purpose of Watermarking Copyright Protection Fingerprinting Broadcasting Monitoring Data Authentication