In this paper, a method of copyright monitoring or tracing using invariants of contents is proposed. We first define certain feature parameters of color images which are invariant under arbitrary bicontinuous or smooth transforms, called topological or differentially topological invariants. To extract the topological invariants robustly, we introduce scale-space of invariant features. By selecting topologically stable features with respect to scale transform, noise-robust invariants of images are obtained. These invariants can be applied to copyright tracing or monitoring and protection due to their robustness against various deformation attacks.