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 from the compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a first set of exponents, respective ones of the first set of mantissa codes being represented by a first number of bits;
determining a second set of mantissa codes based on the first set of mantissa codes and the watermark, respective ones of the second set of mantissa codes being represented by the same first number of bits as the respective ones of the first set of mantissa codes; and
replacing the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark in the compressed data stream 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
18 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 from the compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a first set of exponents, respective ones of the first set of mantissa codes being represented by a first number of bits; determining a second set of mantissa codes based on the first set of mantissa codes and the watermark, respective ones of the second set of mantissa codes being represented by the same first number of bits as the respective ones of the first set of mantissa codes; and replacing the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark in the compressed data stream without uncompressing the compressed data stream. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer readable storage device or storage disc comprising computer readable instructions which, when executed, cause a computer to at least:
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obtain a set of transform coefficients from a compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a first set of exponents, respective ones of the first set of mantissa codes being represented by a first number of bits; determine a second set of mantissa codes based on the first set of mantissa codes and a watermark, respective ones of the second set of mantissa codes being represented by the same first number of bits as the respective ones of the first set of mantissa codes; and replace the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark in the compressed data stream without uncompressing the compressed data stream. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A watermark embedding device comprising:
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an unpacking unit to obtain a set of transform coefficients from a compressed data stream, the set of transform coefficients comprising a first set of mantissa codes and a first set of exponents, respective ones of the first set of mantissa codes being represented by a first number of bits; and a modification unit to; determine a second set of mantissa codes based on the first set of mantissa codes and a watermark, respective ones of the second set of mantissa codes being represented by the same first number of bits as the respective ones of the first set of mantissa codes; and replace the first set of mantissa codes in the compressed data stream with the second set of mantissa codes to embed the watermark in the compressed data stream without uncompressing the compressed data stream. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification