Digital Image Watermarking Based on Discrete Wavelet Transform

This paper aims at digital watermarkwhich is a new popular research topic recently, presents some methods toembed digital watermark based on modifying frequency coefficients indiscrete wavelet transform (DWT) domain. First, the present progress ofdigital watermark is briefly introduced; after that, starting from Pitas'smethod and discarding his pseudo random number method, the authors use adigital image scrambling technology as preprocessing for digitalwatermarking. Then the authors discuss how to embed a 1-bit digitalimage as watermark in frequency domain. Finally another digitalwatermarking method is given in which 3-D DWT is used to transform agiven digital image. Based on the experimental results, it is shown thatthe proposed methods are robust to a large extent.