Multiresolution watermarking for MPEG-4 2D mesh animation

Although watermarking techniques have been extensively developed for natural videos, little progress is made in the area of graphics animation. Following the former successful MPEG-1 and MPEG-2 coding standards that provide efficient representations of natural videos, the emerging MPEG-4 standard incorporates new coding tools for 2D mesh animation. Graphics animation information is crucial for many applications and may need proper protection. In this paper, we develop a watermarking technique suitable for MPEG-4 2D mesh animation. The proposed method is based on the multiresolution analysis of 2D dynamic mesh. We perform wavelet transform on the temporal sequence of the node points to extract the significant spectral components of mesh movement, which we term the "feature motions." A binary watermark invisibly resides in the feature motions based on the spread-spectrum principle. Before watermark detection, a spatial-domain least-squares registration technique is used to restore the possibly geometrically distorted mesh data. Each watermark bit is then detected by hard decision with cryptographically secure keys. We have tested the proposed method with a variety of attacks, including affine transformations, temporal smoothing, spectral enhancement and attenuation, additive random noise, and a combination of the above. Experimental results show that the proposed watermarks can withstand the aforementioned attacks.