| 摘要 |
The picture has a certain number of zones identified on it and numbered. According to a secret code, a weighting is attached to each zone, the weighting being between -1 and +1 and preferably taking only one of the values -1,0,+1. The individual weightings are such that their sum is zero. - In order to apply the coded markings a slight alteration in intensity or colour is introduced in the specified zones. Although detectable by machine the variation is below the threshold of perception by eye and does not impair normal use. The technique allows original and authorised copy films to be identified to combat illegal copying.(0/10)
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