公开(公告)号：GB2324669A

公开(公告)日：1998-10-28

申请号：GB9708192

申请日：1997-04-23

Applicant: IBM

Inventor： CHAPMAN SYDNEY GEORGE ,  JONES JULIAN H

IPC: G06T1/00 ,  H04N7/16 ,  H04N7/24

Abstract: Display of video or image data is controlled in dependence on content classification information which is integrated within the data by means of invisible digital watermarking techniques. A controller decodes the watermarked content codes and then prevents display of certain material, by overlaying the display with blanking data, if the codes match certain stored codes which the controller has been set to respond to. The codes are more difficult for unauthorised persons to detect and remove than other embedded codes would be.