Methods and apparatus for embedding watermarks
View Patent ↗Methods and apparatus for embedding a watermark are disclosed. An example method for embedding a watermark disclosed herein comprises identifying a transform coefficient associated with a compressed digital data stream, obtaining a mantissa code, and modifying the transform coefficient based on the mantissa code to embed the watermark.
1. A method for embedding a watermark, the method comprising:
identifying a transform coefficient associated with a compressed digital data stream;
obtaining a mantissa code; and
modifying the transform coefficient based on the mantissa code to embed the watermark, wherein the mantissa code is a first mantissa code, and wherein modifying the transform coefficient comprises substituting the first mantissa code for a second mantissa code associated with the transform coefficient.
2. A method for embedding a watermark, the method comprising:
identifying a transform coefficient associated with a compressed digital data stream;
obtaining a mantissa code; and
modifying the transform coefficient based on the mantissa code to embed the watermark, wherein obtaining the mantissa code comprises:
selecting a code signal frequency to encode to the transform coefficient based on data to be embedded;
obtaining a masking energy associated with the code signal frequency to be encoded to the transform coefficient;
selecting a magnitude for a watermarked transform coefficient associated with the mantissa code based on the masking energy; and
determining the mantissa code based on the magnitude.
3. A method as defined in claim 2 wherein the code signal frequency comprises one or more sinusoidal components, and wherein each sinusoidal component includes a frequency based on a desired code.
4. A tangible article of manufacture, excluding propagating signals and storing machine readable instructions which, when executed, cause a machine to at least:
identify a transform coefficient associated with a compressed digital data stream;
obtain a mantissa code; and
modify the transform coefficient based on the mantissa code to embed a watermark, wherein the mantissa code is a first mantissa code, and wherein the machine readable instructions, when executed, further cause the machine to modify the transform coefficient by substituting the first mantissa code for a second mantissa code associated with the transform coefficient.
5. A tangible article of manufacture, excluding propagating signals and storing machine readable instructions which, when executed, cause a machine to at least:
identify a transform coefficient associated with a compressed digital data stream;
obtain a mantissa code; and
modify the transform coefficient based on the mantissa code to embed a watermark, wherein the machine readable instructions, when executed, further cause the machine to obtain the mantissa code by:
selecting a code signal frequency to encode to the transform coefficient based on data to be embedded;
obtaining a masking energy associated with the code signal frequency to be encoded to the transform coefficient;
selecting a magnitude for a watermarked transform coefficient associated with the mantissa code based on the masking energy; and
determining the mantissa code based on the magnitude.
6. A tangible article of manufacture as defined in claim 5 wherein the code signal frequency comprises one or more sinusoidal components, and wherein each sinusoidal component includes a frequency based on a desired code.
7. An apparatus for embedding a watermark, the apparatus comprising:
an identifier to identify a transform coefficient associated with a compressed digital data stream; and
a modifier to obtain a mantissa code and modify the transform coefficient based on the mantissa code to embed the watermark, wherein the mantissa code is a first mantissa code, and wherein the modifier is to modify the transform coefficient by substituting the first mantissa code for a second mantissa code associated with the transform coefficient.
8. An apparatus for embedding a watermark, the apparatus comprising:
an identifier to identify a transform coefficient associated with a compressed digital data stream; and
a modifier to obtain a mantissa code and modify the transform coefficient based on the mantissa code to embed the watermark, wherein the modifier is to obtain the mantissa code by:
selecting a code signal frequency to encode to the transform coefficient based on data to be embedded;
obtaining a masking energy associated with the code signal frequency to be encoded to the transform coefficient;
selecting a magnitude for a watermarked transform coefficient associated with the mantissa code based on the masking energy; and
determining the mantissa code based on the magnitude.