Method of judging digital watermark information
AssigneeHitachi, Ltd.
InventorsHiroshi Yoshiura, Kousuke Anzai, Yutaka Kurosu
Life of this patent
Estimating the term…
Abstract
A digital watermark information judging method is provided for detecting digital watermark information which is embedded in at least one element of digital data by altering at least one data value of the element. The method first estimates the data value of the element by using data values of at least two neighboring elements of data located near the element, then compares the estimated data value with an actual data value of the element to detect the amount of the alteration, and judges the presence and value of the digital watermark information based on the amount of the alteration.
Claims6
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.
A storage medium for storing therein a digital watermark information judging program 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, wherein said program causes a computer to execute 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 the step of estimating includes (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.
A digital watermark information judging device 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:
- means for estimating a data value of said element by using data values of at least two neighboring elements of data located near said element;
- means for comparing said estimated data value with an actual data value of said element to detect the amount of the alteration thereof;
- and
- means for judging the presence and value of said digital watermark information based on the detected amount of the alteration;
- wherein said means for estimating includes means for (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.
Dependencies are inferred from the claim text.