Method and system for determining image transformation
First Claim
Patent Images
1. A method of watermark decoding that includes:
- providing a set of input image data;
applying an edge detection algorithm to the image data to yield a processed image;
sensing linear energy in the processed image along more than two different angles;
identifying an angle yielding an extrema of energy; and
decoding a watermark from the input image data by reference to said angle.
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Abstract
A watermark decoding method makes use of a line-finding algorithm (e.g., the Radon transform) to determine rotation of an image from an initial orientation. Once rotation has been characterized, differential scaling of the image can readily be determined.
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Citations
6 Claims
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1. A method of watermark decoding that includes:
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providing a set of input image data;
applying an edge detection algorithm to the image data to yield a processed image;
sensing linear energy in the processed image along more than two different angles;
identifying an angle yielding an extrema of energy; and
decoding a watermark from the input image data by reference to said angle. - View Dependent Claims (2, 3, 5)
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4. A method of decoding a watermark from an image, including:
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providing a set of data representing the image in the frequency domain;
compensating said set of data for a rotation factor;
correlating said compensated set of data with a reference signal; and
determining, based on said correlation, differential scaling of said image; and
by reference to said determined differential scaling, decoding a watermark from the image. - View Dependent Claims (6)
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Specification