| 摘要 |
<p>A method of applying a security code to a moving picture comprises recording a plurality of separate coded symbols, each symbol being recorded in a separate frame of the moving picture. The coded symbols may comprise marks which look like defects or artefacts in the picture. Each of the symbols may represent one digit of a multi-digit print identification number. A different identification number may be used for each copy and a record may be kept of the identification number for each copy and the destination to which it was sent. The origin of a counterfeit copy can therefore be traced by determining the identification number of the copy. Also described is a method of identifying a copy of an audio-visual program by selecting locations in each copy of the program such that the locations form a unique pattern in each copy and altering images appearing in the selected locations.</p> |
