Embedding Multiple Watermarks in a Transform Domain

Definition:Multiple watermarks can be embedded in an image by using different subbands.

In a recent non-blind watermarking paper [1], two visual watermarks are embedded in the DWT domain through modification of both low and high values of DWT coefficients. Since the advantages and disadvantages of lower and higher subband watermarks are complementary, embedding multiple watermarks in an image would result in a scheme that is highly robust with respect to a large spectrum of image processing operations. After performing a two level decomposition of the cover image, the authors embed the first watermark in the LL2 band, and the second watermark in the HH2 band. According to their experimental results, embedding in the LL2 band is more resistant to JPEG compression, wiener filtering, Gaussian noise, scaling, and cropping while embedding in the HH2 band is more resistant to histogram equalization, intensity adjustment, and gamma correction. Nevertheless, the implementation of the idea is...