Fast two-layer image watermarking without referring to the original image and watermark

A fast two-layer image watermarking without referring to the original image and watermark is proposed in this study. Two layers of algorithms are employed to simultaneously hide the same watermarks in the spatial domain. More specifically, the first layer watermarking resists high-frequency destruction, while that in layer two resists low-frequency destruction. Although the image is modified through two layers of watermarking, the watermarks are still invisible. In addition, the proposed watermarking has other advantages. First, the proposed embedding technique is based on an intra-relationship within the original image rather than an inter-relationship between the original and watermarked images so that the original image is not required during the detection process. Second, the proposed watermark is composed of fixed and variable parts. The fixed part allows the detection of the watermark existence and location without referring to the original watermark. The variable part permits greater flexibility and variety of watermarks. Third, the proposed watermark is a short serial number, which allows it to be duplicated. Because of the duplication, a majority voting strategy can be employed to facilitate watermark detection. Finally, the proposed method is fast and simple. It takes only one or two seconds for either the embedding stage or the detection stage. Various experiments have been conducted to verify the above advantages of the two layer watermarking.