Blind Detection for Digital Cinema

Method of extracting a payload from a motion image signal, the method comprising:

• receiving an image signal including a first watermark and at least a second watermark, the first and the at least second watermarks being representing by at least a first sequence of watermark samples;
• providing the first and at least second watermarks to be detected in the image signal;
• determining a first and at least a second global property of an image of the signal in the signal;
• extracting the first watermark by comparing a sequence of first global properties with the first watermark to be detected;
• extracting the at least second watermark by comparing a sequence of at least second global properties with the at least second watermark to be detected;
• comparing the first and the at least second watermark so as to determine a shift of the at least second watermark with respect to the first watermark;
• extracting from the shift a payload.

Watermark embedder comprising:

• signal unit (1) for receiving a motion image signal;
• watermark sample unit (7) for representing a first and an at least second watermark by at least a first sequence of watermark samples;
• global property unit (9) for determining a first and at least a second global property of an image of the signal;
• embedding unit (2) for embedding the first and the at least second watermark in the signal, so that a shift of the at least second watermark with respect to the first watermark represents a payload;
• wherein the first and the at least second watermarks are embedded in the embedding unit by modifying the first and the at least second global property in the image in accordance with the corresponding watermark samples.

Watermark detector comprising:

• signal unit (30) for receiving a motion image signal, the image signal including a first watermark and at least a second watermark, the first and the at least second watermarks being representing by at least a first sequence of watermark samples;
• watermark unit (36) for providing the first and at least second watermarks to be detected in the image signal;
• global property unit (40) for determining a first and at least a at least second global property of an image of the signal;
• extractor unit (34) for extracting the first watermark by comparing a sequence of first global properties with the first watermark to be detected, and for extracting the at least second watermark by comparing a sequence of at least second global properties with the at least second watermark to be detected;
• comparator unit (35) for comparing the first and the at least second watermark so as to determined a shift of the at least second watermark with respect to the first watermark;
• payload unit (39) for extracting from the shift a payload.