A Digital Watermarking Algorithm for DEM Image Based on Stationary Wavelet Transform

A digital watermarking algorithm is proposed basing on the stationary wavelet transform algorithm to embed the digital watermark in the primitive DEM images and withdraw the watermark from the watermarked DEM images. Considering the characteristic of the DEM images, the embedding position is selected in the relatively gentle terrains by analyzing the slope of the DEM image. The embedding intensity is optimized by an optimization model, of which the objective function is defined as the similarity between the original water mark and the abstracted watermark. The optimization model is then resolved with ant colony optimization algorithm, by which the precision of the data and robustness are guaranteed simultaneously. An example is then given to testify the method proposed which proves that the disturbing the elevation of DEM data is less than 5% and that the robustness of the watermark is high enough to immune 5% random noises. Simultaneously, the disturbing of the image is unnoticeable by human eyesight and the hiding of the watermark is also guaranteed.