Method and device for inserting and detecting a watermark in digital data
AssigneeCanon Kabushiki Kaisha
InventorsIoana Donescu, Eric Majani
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Abstract
The invention concerns a method of inserting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed, characterized in that it comprises the steps of extracting a subset of low-frequency coefficients, from the set of data, entropic decoding of the coefficients of the subset, modulation of the decoded coefficients by a signal representing the additional information item, so as to form quantized watermarked coefficients, entropic coding of the watermarked coefficients, and insertion of the watermarked encoded coefficients in place of the coefficients of the subset, in the set of data.
Claims48
A method of inserting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed, said method comprising the steps of:
- extracting a subset of low-frequency coefficients from the set of data,
- entropic decoding of the coefficients of the subset,
- modulation of the decoded coefficients by a signal representing the additional information item, so as to form quantized watermarked coefficients,
- entropic coding of the watermarked coefficients, and
- insertion of the watermarked encoded coefficients in place of the coefficients of the subset, in the set of data.
A device for inserting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed, said device comprising:
- means for extraction of a subset of low-frequency coefficients from the set of data,
- means for entropic decoding of the coefficients of the subset,
- means for modulation of the decoded coefficients by a signal representing the additional information item, so as to form quantized watermarked coefficients,
- means for entropic coding of the watermarked coefficients, and
- means for insertion of the watermarked encoded coefficients in place of the coefificients of the subset, in the set of data,
A method for detecting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed prior to the insertion of the additional information item, said method comprising the steps of:
- extracting a subset of low-frequency coefficients from the set of data,
- entropic decoding of the coefficients of the subset,
- calculation of the correlation between the subset and a signal representing the additional information item, and
- comparison of the result of the correlation with a threshold.
A method for detecting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed prior to the insertion of the additional information item, the data next having been decompressed, said method comprising the steps of:
- transforming the set of data,
- quantizing the transformed set of data,
- extracting a subset of low-frequency coefficients of the set of transformed and quantized data,
- calculating the correlation between the subset and a signal representing the additional information item, and
- comparing the result of the correlation with a threshold.
A device for detecting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed prior to the insertion of the additional information item, said device comprising:
- means for extraction of a subset of low-frequency coefficient, from the set of data,
- means for entropic decoding of the coefficients of the subset,
- means for calculation of the correlation between the subset and a signal representing the additional information item, and
- means for comparison of the result of the correlation with a threshold.
A device for detecting an additional information item in a set of digital data representing physical quantities, the data having been processed by transformation, quantization and entropic coding in order to be compressed prior to the insertion of the additional information item, said device comprising:
- means for transforming the set of data,
- means for quantizing the transformed set of data,
- means for extracting a subset of low-frequency coefficients of the set of transformed and quantized data,
- means for calculating the correlation between the subset and a signal representing the additional information item, and
- means for comparing the result of the correlation with a threshold.
Dependencies are inferred from the claim text.