Digital watermark detecting device and method thereof
First Claim
1. A digital watermark detecting device comprising:
- a sequence generator configured to generate a predetermined sequence of numbers corresponding to a watermark which is to be detected;
a shift circuit configured to shift a detection objective content to obtain shifted content;
a first correlation calculator configured to divide the detection objective content and the shifted content into blocks, and calculate a first correlation value of blocks of the shifted content with the predetermined sequence of numbers and a second correlation value of blocks of the detection objective content with the predetermined sequence of numbers;
a second correlation calculator configured to calculate an estimated correlation value of blocks of an estimated original content in which no watermark is embedded with the predetermined sequence of numbers based on the first correlation value; and
a determination unit configured to determine whether the predetermined sequence of numbers is embedded in the detection objective content based on the estimated correlation value and the second correlation value.
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Abstract
A digital watermark detecting device comprises a sequence generator which generates a predetermined sequence of numbers corresponding to a watermark which is to be detected, a shift circuit which shifts the digital content in unit of a predetermined part of data in predetermined directions, and obtain a predetermined number of shifted contents, a correlation calculator which divides the digital content and the shifted contents into blocks, arranges predetermined data obtained from the blocks of the contents to form sequences of numbers for each of the digital content and the shifted contents, and calculates correlations between the predetermined sequence of numbers and the sequences of numbers, and a determination unit which determines whether the predetermined sequence of numbers exists in the digital content based on the correlations.
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Citations
19 Claims
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1. A digital watermark detecting device comprising:
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a sequence generator configured to generate a predetermined sequence of numbers corresponding to a watermark which is to be detected; a shift circuit configured to shift a detection objective content to obtain shifted content; a first correlation calculator configured to divide the detection objective content and the shifted content into blocks, and calculate a first correlation value of blocks of the shifted content with the predetermined sequence of numbers and a second correlation value of blocks of the detection objective content with the predetermined sequence of numbers; a second correlation calculator configured to calculate an estimated correlation value of blocks of an estimated original content in which no watermark is embedded with the predetermined sequence of numbers based on the first correlation value; and a determination unit configured to determine whether the predetermined sequence of numbers is embedded in the detection objective content based on the estimated correlation value and the second correlation value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A digital watermark detecting method comprising:
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generating a predetermined sequence of numbers corresponding to a watermark which is to be detected; shifting a detection objective content to obtain shifted content; dividing the detection objective content and the shifted content into blocks; calculating a first correlation value of blocks of the shifted content with the predetermined sequence of numbers and a second correlation value of blocks of the detection objective content with the predetermined sequence of numbers; calculating an estimated correlation value of blocks of an estimated original content in which no watermark is embedded with the predetermined sequence of numbers based on the first correlation value; and determining whether the predetermined sequence of numbers is embedded in the detection objective content based on the estimated correlation value and the second correlation value. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein, the computer readable program code means comprising:
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computer readable program code means for causing a computer to generate a predetermined sequence of numbers corresponding to a watermark which is to be detected; computer readable program code means for causing a computer to shift a detection objective content to obtain shifted content; computer readable program code means for causing a computer to divide the detection objective content and the shifted content into blocks; computer readable program code means for causing a computer to calculate a first correlation value of blocks of the shifted content with the predetermined sequence of numbers and a second correlation value of blocks of the detection objective content with the predetermined sequence of numbers; computer readable program code means for causing a computer to calculate an estimated correlation value of blocks of an estimated original content in which no watermark is embedded with the predetermined sequence of numbers based on the first correlation value; and computer readable program code means for causing a computer to determine whether the predetermined sequence of numbers is embedded in the detection objective content based on the estimated correlation value and the second correlation value.
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Specification