Patent ID: 6128736
Filing Date: 2000-10-03
Classification: G06T

Abstract:
A method for inserting a watermark signal into unwatermarked data, the watermark signal being extracted by application of a given watermark extraction process, the method comprising the steps of:(a) applying a part of the watermark extraction process to the unwatermarked data for generating a first set of intermediate extracted values;(b) identifying a first set of target values that are to replace the intermediate extracted values by;(i) applying a transform to the first set of intermediate extracted values;(ii) applying a further part of the watermark extraction process to the transformed first set of intermediate extracted values to obtain a second set of intermediate extracted values;(iii) identifying a second set of target values that are to replace the second set of intermediate extracted values;(iv) computing the difference between the second set of target values and the second set of intermediate extracted values;(v) adding the computed difference throughout the transformed first set of intermediate extracted values to obtain a transformed first set of target values; and(vi) applying an inverse transform to the first set of transformed target values to obtain the first set of target values;(c) computing the difference between the first set of target values and the first set of intermediate extracted values; and(d) adding the computed difference throughout the unwatermarked data.