Digital Watermarking Embedded in the Discrete Wavelet Domain for Authentication

Watermarking techniques have recently become important in a number of applications．Fragile watermarks are destroyed as soon as the object is modified too much．This can be used to prove that an object has not been tampered with and it is credible．We can call it ownership identification．Robust marks have the property that it is infeasible to remove them or make them useless without destroying the object．This can be used to protect the copyright．In this paper，we proposed a fragile watermark used in authentication．It is embedded in the discrete wavelet domain of the image to acquire both local space and frequency support．We do not need the original image while extracting the watermark．Through defining combined correlation of the original watermark with the extracted one，we can detect whether the image has been tampered with and the type of tampering．