DIGITAL IMAGE WATERMARKING AND STEGNOGRAPHY

This paper attempts to give a brief overview of Steganography & digital water marking in general. Emphasis is made to expose the different techniques that can be carried out on Steganography. It also gives a brief description of Digital watermarking and its characteristics and finally concludes with the differences between Digital watermarking of images pictures and Steganography .Steganography means hidden or invisible messages.Its been one of the powerful techniques over the past few decades which provides security from the illegal access. For network distribution services of copyrighted digital data (such as pay web distribution of musics, or digital libraries), the possibility of illegal redistribution due to some licensed user, who obtained the data in a legal way from the server, should be considered. Such actions cannot be prevented by use of encrypted communication only. To prevent the illegal copying itself is not realistic, because digital data can be in general copied easily, without decreasing its quality. An alternative solution investigated recently is ``digital watermarking'', which is a technology to embed some auxiliary information into digital data.