局所記述子に基づく幾何学的変換にロバストな画像著作権保護

Abstract

In recent years, illegal copies on the Internet have become a serious social problem. As a method of copyright protection, digital watermarking is a well-known mean which embeds copyright information to digital contents to be protected. However, for the case of digital still images, for example, there exist image falsification attacks (e.g., Stirmark ) which change images to make it difficult to read the embedded copyright information. In particular, robustness against geometric transformation becomes an important issue. In this paper, we propose a method for solving this problem by using “local descriptors” of images. Local descriptors have a property insensitive to geometric transformation, they have a potential to solve the problem. The characteristic feature of the proposed method is that it can sequence local regions defined by local descriptors for embedding information. This indicates that the amount of information increases as compared to independent embedment on each local region. From the experimental results, we show that the sequence of local regions can be correctly read and embedded information can be successfully decoded from most of images that undergo the Stirmark attack.

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