<title>Wavelet-based image compression and content authentication</title>

Abstract

In the digital information age, digital content (audio, image, and video) can be easily copied, manipulated, and distributed. Copyright protection and content authentication of digital content has become an urgent problem to content owners and distributors. Digital watermarking has provided a valid solution to this problem. Based on its application scenario, most digital watermarking methods can be divided into two categories: robust watermarking and fragile watermarking. Here, we will concentrate on fragile watermarking of digital images, which is for image content authentication. Our fragile watermarking method is heavily based on the new image compression standard JPEG 2000. We choose a compressed bit stream from JPEG 2000 as the hash of an image, and embed the hash back to the image. The exceptional compression performance of JPEG 2000 solves the tradeoff between small hash size and high hash confidence level. In the authentication stage, the embedded compressed bit stream will be extracted. Then it will be compared with the compressed bit stream of the image to be authenticated. The authentication decision comes from the comparison result. Besides content authentication, we will also show how to employ this watermarking method for hiding one image into another.