Robust invisible watermarking of volume data using the 3D DCT

Proposes a novel watermarking algorithm for 3D volume data based on the spread-spectrum communication technique, which is invisible and robust. "Invisible" means that the 2D rendered image of this watermarked volume is perceptually indistinguishable from that of the original volume. "Robust" watermarking implies that the watermark is resistant to most intentional or unintentional attacks. We have implemented the algorithm in a software package and have conducted experiments showing that the watermark is invisible in the volume-rendered 2D images. This is further confirmed by computing the signal-to-noise ratio (SNR) and the peak signal-to-noise ratio (PSNR) of the 3D watermarked volume data. We addressed different attacks, putting more emphasis on those attacks that are most commonly performed by attackers. The experiments show that the watermarking scheme is robust.