抄録
Digital watermark is a technology that protects digital intellectual property from being illegally copied and distributed by embedding it with information such as copyrights. By presenting the copyrights, digital watermarks serve as available technology for protecting the rights governing use of intellectual property. Recently, distribution of images taken from CRTs or other kinds of screens has become a problem. This is because current methods have difficulties detecting digital watermarks in the re-shot images. We present a method that can detect digital watermarks in moving images taken with a consumer camera from a CRT monitor connected to an NTSC signal system. The method can embed information in both temporal and spatial domains. It is embedded for a relatively long time and in low spatial frequencies to avoid degradation of images. The method can also detect digital watermarks in re-shot images that degrade in high frequencies. In addition, it can detect digital watermarks in real time without using the original images. This paper describes the method, presents an experimental system based on it, and verifies its effectiveness with various types of moving images. We also examine various aspects of the robustness needed for watermarks embedded with this method.
