A Novel Digital Image Watermarking Scheme for Data Security Using Bit Replacement and Majority Algorithm Technique
Koushik Pal, Goutam Ghosh, M. Bhattachary · InTech eBooks · 2012
Recent history has witnessed the rapid development in information technologies that has given an extended and easy access to digital information.Along with several developments it leads to the problem of illegal copying and redistribution of digital media.As a result the integrity and confidentiality of the digital information has come under immense threat.The concept of an emerging technology, digital watermarking came in order to solve the problems related to the intellectual property of media.(P.W.Wong, 1998).Digital Watermarking is a technique which allows an individual to add hidden copyright notices or other verification messages or even classified information to digital media.(Rafael C Gonzalez and Richard E. Woods, 2002), (Cox I. J., Miller M., Bloom J., 2002).Watermarks can either be visible or invisible.Here in this chapter we utilize the invisible technique.This is used in public information settings such as digital images libraries, museums, and art galleries and also in defense communication where data security is of prime importance.Watermark embedding utilizes two kinds of methods; one is in the spatial domain and the other in the transform domain.In the spatial domain the watermark is directly embedded into the image pixels whereas in the frequency domain the image is decomposed into blocks and then mapped into the transform domain (M.Kutter, F. A. P. Petitcolas, 1999).This is basically a process of hiding information in an image known as cover image.Copyright protection is achieved by robust watermarking while image authentication is usually achieved by fragile watermarking techniques.In the fragile watermarking scheme if any alteration of the message is found then it is broken and it can be easily detected as tampered by the provider of the watermark.In general, fragile schemes modify the leastsignificant-bits LSB planes of the original image in an irreversible way.Often a secret key is also used to encrypt the information (P.W. Wong, 1998).Invertible watermarking is a new process which enables the exact recovery of the original image upon extraction of the embedded information (M.L. Miller, I.J.Cox, J.M.G.Linnartz and T. Kalker, 1999).This work implements both authentication and confidentiality in a reversible manner without affecting the image in any way.Security of images imposes three mandatory characteristics: confidentiality, reliability and availability (J.Fridrich,2002).