In order to cover one-copy application, the copy control status is required to be changed, i.e. from “one-copy (allowed)” to “no-more copy”. This status change can be done by removing the pre-attached copy permission data. The advantages of this approach are, (1) simple and low cost implementation, and (2) no impact to the image quality. The basic idea of this approach is to attach a copy permission (TOKEN) to the content to represent the permission of copying. When the watermark detector detects (1,0), the detector will then, verify the TOKEN. If the TOKEN is a valid one, the copy will be allowed and the TOKEN will be removed or destroyed when the copy is made. Because the lack of the TOKEN to be represent “No More Copy”, and it is hard to re-generate the valid TOKEN without the knowledge of the secret function, the changed status will remain as long as the pre-embedded CCI is detectable. The representation of the copy control status is shown below;
pre-embedded CCI Copy Control Status
(1,0) + TOKEN One Copy (Allowed)
(1,0) without TOKEN No More Copy
By: N. Morimoto et. al.
Published in: RT0307 in 2002
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