Digital Cinema Watermarking for Estimating the Position of the Pirate
Many illegal copies of digital video productions for cinema release can be found on the Internet before their ofﬁcial release. During the illegal copying of cinema footage, composite geometric distortions commonly occur due to the angle of the camcorder relative to the screen. We propose a novel video watermarking based on spread spectrum way that satisﬁes the requirements for protecting digital cinema. It enables the detector to not only extract the embedded message but also estimate the position where the camcorder recording is made. It is sure that the proposed position estimating model (PEM) can judge the seat in a theater with a mean absolute error (MAE) of (33.84, 9.53, 50.38) cm. Experimental results using various types of ﬁlms show that the presented method provides the mathematical model for detecting and investigating the position of the pirate.
MANY illegal copies of movies can be found on the Internet or on the street markets before their ofﬁcial release. Over 90% of these copies were made by recording ﬁlms with camcorders in movie theaters . These illegal acts inﬂict a great loss on motion picture industries. Many entertainment companies use copy protection technologies as countermeasures against illegal recording. Moreover, a digital cinema system, which uses of digital technology to distribute and project motion pictures, is published and has come into wide use. Digital Cinema Initiatives (DCI) deﬁnes a forensic marking system in their standards in order to protect their copyrights . Digital watermarking technology seems to match the requirements of both conventional ﬁlm and digital cinema in terms of copyright protection. According to the speciﬁcations of DCI, the forensic mark data payload should contain the following information about movie playback: time stamp and location information. It works for warning the designated theater against camcorder piracy and preventing the piracies. However, only identifying when and where the illegal recording happens is not sufﬁcient to the original purpose of copyright protection and traitor tracing. It is better to identify the pirate or limit the number of pirate suspects. A scenario for the purpose of identifying the pirate proposed in  is considered. Fig. 1 describes the scenario in detail. The pirate records the movie during playback in the theater. In the movie, the information about when and where the movie is playing is embedded as a watermark by using our proposed scheme. The pirate illegally puts the captured movie in circulation on the Internet. Then, the forensic marking system ﬁnds the illegally captured movie in the Internet and tries to ﬁnd out the pirate. Our proposed detection scheme extracts the watermark and decodes the embedded watermark as the time and the theater. Also, another advantage of our scheme can estimate the approximate position of the pirate. Then it needs to match each seat with its corresponding person. The extracted information from the embedded watermark determines when and where the pirate is made, and also it helps to match the persons who illegally recorded a movie to the databases stored in the electronic ticket ofﬁces or in payment system. Finally, the number of piracy suspects is restricted and it helps to ﬁnd out the pirate.
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