Image Watermarking using Dither Modulation in Dual-Transform Domain

A new method for inserting invisible watermark into a digital image is described, which uses two layers of orthogonal transforms, pseudorandom data shuffling and a dither modulation technique. Neither the original host image nor the inserted data string is needed in extraction of the watermark. Experiments show that watermark embedded in this way is sufficiently transparent and robust. A desired tradeoff between in- visibility, robustness, and embedding capacity can be achieved by appropriately choosing the system pa- rameters and the candidate coefficients for embedding.