Three-dimensional image quality measurement for the benchmarking of 3D watermarking schemes

Three-dimensional image quality assessment causes new challenges for a wide set of applications and particularly for emerging 3-D watermarking schemes. First, new metrics have to be drawn for the distortion measurement from an original 3-D surface to its deformed version: this metric is necessary to address distortions that are acceptable and to which a 3-D watermarking algorithm should resist. In this paper, we focus on distortion energy evaluation extending works on distortion minimization for planar and spherical parameterization. Secondly, a key perceptual assessment of 3-D geometrical transforms is their impact on the various 2-D views that can be extracted from the object. As a matter of fact, most of the applications (games, avatars, ...) are targeting users owning 2-D screens. In this paper we restrict our study to 3-D shape distortion analysis, assuming standard lighting conditions and we do not address the textures distortion issues. We analyze how to automatically select relevant pairs of 2D projections which needs an initial registration between both shapes to compare. We use a mutual information criterion to assess the distortion for each projection pair and eventually derive a global score by weighting the contributions of each view.