Apparatus and method for watermark data insertion and apparatus and method for watermark data detection
First Claim
1. A watermark data insertion method for inserting watermark data into an input original signal, comprising:
- a frequency transform step of applying a frequency transform to the original signal to form an intermediate signal;
a watermark data insertion step of inserting the watermark data into a first set of frequency components of the intermediate signal; and
a frequency inverse transform step of applying an inverse frequency transform to the intermediate signal, the watermark data having been inserted into the intermediate signal, thereby obtaining a signal containing the watermark data embedded therein, wherein the watermark data insertion step comprises;
determining, based on pseudo random numbers, the first set of frequency components of the intermediate signal into which the watermark data is inserted; and
using a second set of frequency components of the intermediate signal as a reference signal, the watermark data not being inserted into the second set of frequency components.
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Abstract
A watermark data insertion method for inserting watermark data into an input original signal is provided. The method includes: a frequency transform step for applying a frequency transform to the original signal to form an intermediate signal; a watermark data insertion step for inserting the watermark data into a first set of frequency component of the intermediate signal; and a frequency inverse transform step for applying an inverse frequency transform to the intermediate signal, the watermark data having been inserted into the intermediate signal, thereby obtaining a signal containing the watermark data embedded therein. The watermark data insertion step includes: determining, based on pseudo random numbers, the first set of frequency components of the intermediate signal into which the watermark data is inserted; and using a second set of frequency components of the intermediate signal as a reference signal, the watermark data not being inserted into the second set of frequency components.
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Citations
7 Claims
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1. A watermark data insertion method for inserting watermark data into an input original signal, comprising:
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a frequency transform step of applying a frequency transform to the original signal to form an intermediate signal;
a watermark data insertion step of inserting the watermark data into a first set of frequency components of the intermediate signal; and
a frequency inverse transform step of applying an inverse frequency transform to the intermediate signal, the watermark data having been inserted into the intermediate signal, thereby obtaining a signal containing the watermark data embedded therein, wherein the watermark data insertion step comprises;
determining, based on pseudo random numbers, the first set of frequency components of the intermediate signal into which the watermark data is inserted; and
using a second set of frequency components of the intermediate signal as a reference signal, the watermark data not being inserted into the second set of frequency components. - View Dependent Claims (2, 3, 4, 5, 6)
a weighting step of increasing or decreasing a signal amplitude of the watermark data in accordance with an amplitude of the first set of frequency components of the intermediate signal into which the watermark data is inserted.
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4. A watermark data insertion method according to claim 1, wherein the watermark data insertion step comprises determining the first set of frequency components of the intermediate signal into which the watermark data is inserted by using pseudo random numbers having frequency-dependent weights.
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5. A watermark data insertion method according to claim 1, wherein the watermark data insertion step comprises:
a weighting step of increasing or decreasing a signal amplitude of the watermark data in accordance with a frequency of the first set of frequency components of the intermediate signal into which the watermark data is inserted.
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6. A watermark data insertion method according to claim 1, wherein the watermark data insertion step comprises converting binary data representing the watermark data into predetermined positive and negative values, and thereafter inserting the converted binary data into the first set of frequency components of the intermediate signal.
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7. A watermark data insertion apparatus for inserting watermark data into an input original signal, comprising:
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a frequency transform section for applying a frequency transform to the original signal to form an intermediate signal;
a watermark data insertion section for inserting the watermark data into a first set of frequency components of the intermediate signal; and
a frequency inverse transform section for applying an inverse frequency transform to the intermediate signal, the watermark data having been inserted into the intermediate signal, thereby obtaining a signal containing the watermark data embedded therein, wherein the watermark data insertion section determines the first set of frequency components of the intermediate signal into which the watermark data is inserted based on pseudo random numbers, and uses a second set of frequency components of the intermediate signal as a reference signal, the watermark data not being inserted into the second set of frequency components.
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Specification