Method of authenticating digital-watermark pictures
First Claim
1. A method of authenticating a digital-watermark picture by execution of:
- an embedding process to create a digital-watermark picture as a picture obtained by embedding information for authentication into an original picture;
an extraction process to extract information corresponding to said information for authentication from a picture being inspected; and
an authentication process to authenticate legitimacy of said picture being inspected on the basis of said information extracted in said extraction process, wherein said extraction process comprises the steps of;
carrying out geometric transformation on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture;
creating a plurality of degraded original pictures with different types by degradation of said original picture;
creating a plurality of differential pictures each representing differences between said picture being inspected with a transformed size and said degraded original pictures; and
extracting information corresponding to said information for authentication from each of said differential pictures.
1 Assignment
0 Petitions
Accused Products
Abstract
An extraction process includes the steps of carrying out a geometric transformation on a picture being inspected to transform the size of the picture being inspected into a reduced scale of an original picture; creating a plurality of degraded original pictures with different types each obtained as a result of degradation of the original picture; creating a plurality of differential pictures by subtraction of the degraded original pictures with different types from the picture being inspected with a transformed size to cancel degradation components in the picture being inspected with a transformed size; and extracting the information corresponding to the authentication information.
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Citations
11 Claims
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1. A method of authenticating a digital-watermark picture by execution of:
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an embedding process to create a digital-watermark picture as a picture obtained by embedding information for authentication into an original picture;
an extraction process to extract information corresponding to said information for authentication from a picture being inspected; and
an authentication process to authenticate legitimacy of said picture being inspected on the basis of said information extracted in said extraction process, wherein said extraction process comprises the steps of;
carrying out geometric transformation on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture;
creating a plurality of degraded original pictures with different types by degradation of said original picture;
creating a plurality of differential pictures each representing differences between said picture being inspected with a transformed size and said degraded original pictures; and
extracting information corresponding to said information for authentication from each of said differential pictures. - View Dependent Claims (2, 3, 4, 5)
computing geometric-transformation coefficients required for geometric transformation of said original picture to transform the size of said original picture into a reduced scale of said picture being inspected; and
using a plurality of interpolation techniques of different types each prepared in advance to carry out geometric transformation on said original picture to transform the size of said original picture into a reduced scale of said picture being inspected on the basis of said geometric-transformation coefficients to transform said transformed size back into an original size on the basis of said geometric-transformation coefficients.
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3. A method of authenticating a digital-watermark picture according to claim 2, wherein said step of carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture in said extraction process comprises the sub-steps of:
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computing geometric-transformation coefficients required for geometric transformation of said picture being inspected from a plurality of tie points determining tie positions between said picture being inspected and said original picture; and
carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture on the basis of said computed geometric-transformation coefficients.
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4. A method of authenticating a digital-watermark picture according to claim 1, wherein said step of carrying out geometric information on said picture being inspected to transform the size of said picture being inspected in to a reduced scale of said original picture in said extraction process comprises the sub-steps of:
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computing geometric-transformation coefficients required for geometric transformation of said picture being inspected from a plurality of tie points determining tie positions between said picture being inspected and said original picture; and
carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture on the basis of said computed geometric-transformation coefficients.
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5. A method of authenticating a digital-watermark picture according to claim 4 wherein said picture being inspected with a transformed size obtained as a result of said geometric transformation carried out on said picture being inspected and said original picture are at least displayed, and a position on said displayed picture being inspected with a transformed size or said displayed original picture which is specified externally is accepted as a tie point.
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6. A method of authenticating a digital-watermark picture by execution of:
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an embedding process to create a digital-watermark picture as a picture obtained by embedding information for authentication into an original picture;
an extraction process to extract information corresponding to said information for authentication from a picture being inspected; and
an authentication process to authenticate legitimacy of said picture being inspected on the basis of said information extracted in said extraction process, wherein said extraction process comprises the steps of;
carrying out geometric transformation on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture;
creating a plurality of degraded original pictures with different types by degradation of said original picture;
creating a plurality of differential pictures each representing differences between said picture being inspected with a transformed size and said degraded original pictures;
displaying said differential pictures to be externally selected; and
extracting information corresponding to said information for authentication from said externally selected differential picture. - View Dependent Claims (7, 8)
computing geometric-transformation coefficients required for geometric transformation of said original picture to transform the size of said original picture into a reduced scale of said picture being inspected; and
using a plurality of interpolation techniques of different types each prepared in advance to carry out geometric transformation on said original picture to transform the size of said original picture into a reduced scale of said picture being inspected on the basis of said geometric-transformation coefficients to transform said transformed size back into an original size on the basis of said geometric-transformation coefficients.
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8. A method of authenticating a digital-watermark picture according to claim 6, wherein said step of carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture in said extraction process comprises the sub-steps of:
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computing geometric-transformation coefficients required for geometric transformation of said picture being inspected from a plurality of tie points determining tie positions between said picture being inspected and said original picture; and
carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture on the basis of said computed geometric-transformation coefficients.
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9. A method of authenticating a digital-watermark picture by execution of:
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an embedding process to create a digital-watermark picture as a picture obtained by embedding information for authentication into an original picture;
an extraction process to extract information corresponding to said information for authentication from a picture being inspected; and
an authentication process to authenticate legitimacy of said picture being inspected on the basis of said information extracted in said extraction process, wherein said extraction process comprises the steps of;
carrying out geometric transformation on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture;
creating a plurality of degraded original pictures with different types by degradation of said original picture;
creating a plurality of differential pictures each representing differences between said picture being inspected with a transformed size and said degraded original pictures;
computing an error statistic for each of said differential pictures; and
extracting information corresponding to said information for authentication from one of said differential pictures with a smallest error statistic. - View Dependent Claims (10, 11)
computing geometric-transformation coefficients required for geometric transformation of said original picture to transform the size of said original picture into a reduced scale of said picture being inspected; and
using a plurality of interpolation techniques of different types each prepared in advance to carry out geometric transformation on said original picture to transform the size of said original picture into a reduced scale of said picture being inspected on the basis of said geometric-transformation coefficients to transform said transformed size back into an original size on the basis of said geometric-transformation coefficients.
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11. A method of authenticating a digital-watermark picture according to claim 9, wherein said step of carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture in said extraction process comprises the sub-steps of:
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computing geometric-transformation coefficients required for geometric transformation of said picture being inspected from a plurality of tie points determining tie positions between said picture being inspected and said original picture; and
carrying out geometric information on said picture being inspected to transform the size of said picture being inspected into a reduced scale of said original picture on the basis of said computed geometric-transformation coefficients.
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Specification