Method for detecting rotation and magnification in images
First Claim
1. A method for detecting an amount of rotation or magnification in a modified image, comprising the steps of:
- a) embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle α
in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image;
b) performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and
c) comparing the separation d'"'"' and orientation α
'"'"' of the autocorrelation peaks with the separation d and orientation α
of the features in the marker image to determine the amount of rotation and magnification in the modified image.
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Accused Products
Abstract
A method for detecting an amount of rotation or magnification in a modified image, includes the steps of: embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle α in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image; performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and comparing the separation d'"'"' and orientation α'"'"' of the autocorrelation peaks with the separation d and orientation α of the features in the marker image to determine the amount of rotation and magnification in the modified image.
204 Citations
7 Claims
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1. A method for detecting an amount of rotation or magnification in a modified image, comprising the steps of:
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a) embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle α
in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image;b) performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and c) comparing the separation d'"'"' and orientation α
'"'"' of the autocorrelation peaks with the separation d and orientation α
of the features in the marker image to determine the amount of rotation and magnification in the modified image. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer program product, comprising a computer readable storage medium having a computer program stored thereon for detecting an amount of rotation or magnification in a modified image, for performing the steps of:
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a) embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle α
in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image;b) performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and c) comparing the separation d'"'"' and orientation α
'"'"' of the autocorrelation peaks with the separation d and orientation α
of the features in the marker image to determine the amount of rotation and magnification in the modified image.
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Specification