WATERMARKING OF COMPRESSED ENCRYPTED IMAGES

Abstract

In digital images Digital asset management systems (DAMS) access the media data for the transfer over the channel in the form of compressed and encrypted image. This system apply watermark signal this compressed encrypted data for tamper detection or ownership declaration or copyright When media data is transform. There is a big problem to insert a watermark into compressed encrypted domain because the compression process applies over the each block of data or information. Which contain a redundant or a raw media which are replace by encryption process apply on low number of bits which are randomized and compressed process apply over each bit data or information which unable to see original data to unauthorized person for transmission purpose. Embedding process of a watermark to randomized bit stream cause degradation into image quality. So choose an encryption scheme for media data such that it will secure and will allow us to embed a watermarking scheme in a predictable manner into compressed encrypted domain and degradation of image should be Minimum.

Watermarking algorithms are described to apply watermark to different types of image format to compressed andencrypted images. Data can be transfer from sender to Receiver in the form of block cipher or stream cipher .there is different encryption algorithm depending Key Selection but encryption process apply over the stream type. In this we propose insert of watermarking done in the compressed-encrypted domain, but watermark can be extracted into decrypted domain. By studding embedding capacity, perceptual quality, robustness, and security there are three watermarking schemes such as Spread Spectrum (SS), Scalar Costa Scheme Quantization Index Modulation (SCS-QIM), and Rational Dither Modulation (RDM).