Methods and apparatus for embedding watermarks
First Claim
1. A method to embed a watermark in a compressed data stream, the method comprising:
- obtaining a set of transform coefficients included in the compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a set of exponents, the first set of mantissa codes associated with a respective set of step sizes;
identifying a first transform coefficient from the set of transform coefficients having a smallest magnitude among the set of transform coefficients;
determining a second set of mantissa codes based on the first transform coefficient and the set of step sizes; and
replacing the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark without uncompressing the compressed data stream.
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Abstract
Methods and apparatus for embedding a watermark are disclosed. An example method disclosed herein to embed a watermark in a compressed data stream comprises obtaining a set of transform coefficients included in the compressed data stream, the set of transform coefficients having a respective first set of mantissa codes and a respective set of exponents, the first set of mantissa codes associated with a respective set of mantissa step sizes, identifying a first transform coefficient from the set of transform coefficients having a smallest magnitude among the set of transform coefficients, determining a second set of mantissa codes based on the first transform coefficient and the set of step sizes, and replacing the first set of mantissa codes included in the compressed data stream with the second set of mantissa codes to embed the watermark without uncompressing the compressed data stream.
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Citations
20 Claims
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1. A method to embed a watermark in a compressed data stream, the method comprising:
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obtaining a set of transform coefficients included in the compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a set of exponents, the first set of mantissa codes associated with a respective set of step sizes; identifying a first transform coefficient from the set of transform coefficients having a smallest magnitude among the set of transform coefficients; determining a second set of mantissa codes based on the first transform coefficient and the set of step sizes; and replacing the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark without uncompressing the compressed data stream. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A tangible machine readable storage device or optical disk, storing machine readable instructions which, when executed, cause a machine to at least:
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obtain a set of transform coefficients included in a compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a set of exponents, the first set of mantissa codes associated with a respective set of step sizes; identify a first transform coefficient from the set of transform coefficients having a smallest magnitude among the set of transform coefficients; determine a second set of mantissa codes based on the first transform coefficient and the set of step sizes; and replace the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed a watermark in the compressed data stream without uncompressing the compressed data stream. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system to embed a watermark in a compressed data stream, the system comprising:
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an interface to receive a compressed data stream; and a processor to; obtain a set of transform coefficients included in a compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a set of exponents, the first set of mantissa codes associated with a respective set of step sizes; identify a first transform coefficient from the set of transform coefficients having a smallest magnitude among the set of transform coefficients; determine a second set of mantissa codes based on the first transform coefficient and the set of step sizes; and replace the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark without uncompressing the compressed data stream. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification