Security on Fragile and Semi-fragile Watermarks Authentication

Digital image manipulation software is now readily available on personal computers. It is therefore very simple to tamper with any image and make it available to others. Ensuring digital image security has therefore become a major issue. Watermarking has become a popular technique for copyright enforcement and image authentication. The aim of this paper is to present an overview of some possible attacks which may cause harm the present watermarking techniques. Here we have identified the attacks which frequently attacks some very well known fragile and semifragile watermarking techniques..