Patent ID: 6665417
Filing Date: 2003-12-16
Classification: G06T,H04N

Abstract:
A digital watermark information judging method for judging the presence and value of digital watermark information which is embedded in at least one element of digital data by altering at least one data value of said element, comprising the steps of:estimating a data value of said element by using data values of at least two neighboring elements of data located near said element; comparing said estimated data value with an actual data value of said element to detect the amount of the alteration thereof; and judging the presence and value of said digital watermark information based on the detected amount of the alteration; wherein said estimating step comprises (a) calculating a variance based upon data values of at least two neighboring elements along a first direction extending through said element to be estimated, (b) repeating the calculation of variance based upon data values of at least two neighboring elements along at least one other direction extending through said element to be estimated different than said first direction, (c) selecting a direction with minimum variance from the calculated variances of said first direction and said at least one other direction extending through said element to be estimated, and (d) estimating said data value of said element to be estimated by using data values of elements included in a set of elements along the selected direction.