Robust transparent image watermarking system with spatial mechanisms

A very robust against JPEG compression, difficult for collusion attack, and transparent secret key digital watermarking system, which takes a spatial- domain approach, is presented in this paper. The unique watermark that cons ists of both the owner's logo and the user's licence number provides the ow nership protection and traceability of illicit dissemination. The technique of block-oriented and modular-arithmetic-based watermark embedding and ext raction achieves the robustness against image processing such as lossy comp ression, filtering, and cropping. The random perturbation of the pixels wit hin the marked block as well as the unique and fused watermark information result in difference images with irregular-shape and uneven-luminance blobs , hence greatly increase the difficulty of collusion attack. Transparency i s further fulfilled by means of embedding the information bits around but n ot on the exact edges of the features to avoid edge sharpening or smoothing , which effectively magnifies the contrast among the distributed images. Th e experimental results demonstrate that the proposed watermarking system is superior to Voyatazis and Pitas's scheme with respect to image processing, and is much more secure than the method of Cox et al.'s method. (C) 2000 E lsevier Science Inc. All rights reserved.