Method and apparatus for recording and reproducing electronic watermark information, and recording medium
First Claim
1. A recording medium having a record of a video signal, electronic watermark information which is embedded in the video signal, and a reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
- wherein the reference signal includes a first reference signal and a second reference signal, the first reference signal having an amplitude equal to a peak white level, the second reference signal having an amplitude smaller than the amplitude of the first reference signal.
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Accused Products
Abstract
When a video signal having electronic watermark information embedded therein is recorded on a recording medium, a reference signal is inserted in the video signal at a position different from a position of embedment of the electronic watermark information. The electronic watermark information is embedded in the video signal by alteration of a luminous value of a luminance signal included in the video signal. When the video signal is reproduced from the recording medium, a luminous value of the electronic watermark information is modified based on the reference signal.
158 Citations
7 Claims
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1. A recording medium having a record of a video signal, electronic watermark information which is embedded in the video signal, and a reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
wherein the reference signal includes a first reference signal and a second reference signal, the first reference signal having an amplitude equal to a peak white level, the second reference signal having an amplitude smaller than the amplitude of the first reference signal.
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2. A method of recording electronic watermark information comprising the steps of:
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embedding electronic watermark information in a video signal so as to cause a minimal disturbance to the video signal; and
recording a reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
wherein the reference signal includes a first reference signal and a second reference signal, the first reference signal having an amplitude equal to a peak white level, the second reference signal having an amplitude smaller than the amplitude of the first reference signal.
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3. A method of reproducing electronic watermark information comprising the steps of:
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detecting a reference signal for detecting electronic watermark information from a recording medium having recorded thereon a video signal, the electronic watermark information which is embedded in the video signal by alteration of a luminous value of a luminance signal included in the video signal, and the reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
modifying a luminous value of the electronic watermark information based on the reference signal;
calculating a gain drift based on the reference signal;
modifying the luminous value of the luminance signal based on the calculated gain drift; and
detecting the electronic watermark information from the luminance signal having the modified luminous value.
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4. A method of reproducing electronic watermark information comprising the steps of:
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detecting a reference signal for detecting electronic watermark information from a recording medium having recorded thereon a video signal, the electronic watermark information which is embedded in the video signal by alteration of a luminous value of a luminance signal included in the video signal, and the reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
modifying a luminous value of the electronic watermark information based on the reference signal;
calculating a gain drift based on the reference signal;
detecting the electronic watermark information from the luminance signal; and
modifying an amplitude of the detected electronic watermark information based on the calculated gain drift.
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5. An apparatus for recording electronic watermark information comprising:
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a permissible alteration range detecting circuit which calculates a permissible alteration range of a luminous value depending on a luminous value of a luminance signal included in a video signal;
an electronic watermark information embedment processing circuit which embeds electronic watermark information in the video signal by altering the luminous value of the luminance signal at a predetermined position in the video signal if the altered luminous value is within the calculated permissible alteration range; and
a reference signal adding circuit which inserts a reference signal in the video signal at a position different from a position of embedment of the electronic watermark information;
wherein the reference signal includes a first reference signal and a second reference signal, the first reference signal having an amplitude equal to a peak white level, the second reference signal having an amplitude smaller than the amplitude of the first reference signal.
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6. An apparatus for reproducing electronic watermark information comprising:
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detection means for detecting electronic watermark information for reproduction based on a reference signal from a recording medium having recorded thereon a video signal, the electronic watermark information which is embedded in the video signal so as to cause a minimal disturbance to the video signal, and the reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
wherein the detection means includes;
a detection signal generating circuit which generates a detection signal for detecting the reference signal from a sync signal;
a sample-holding circuit which samples and holds an amplitude of the reference signal in response to the detection signal;
a gain drift calculating circuit which calculates a gain drift based on the amplitude of the reference signal provided by the sample-holding circuit;
a modification circuit which modifies a luminance signal included in the video signal based on the calculated gain drift provided by the gain drift calculating circuit; and
an electronic watermark information detecting circuit which detects the electronic watermark information from the modified luminance signal by using the detection signal.
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7. An apparatus for reproducing electronic watermark information comprising:
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detection means for detecting electronic watermark information for reproduction based on a reference signal from a recording medium having recorded thereon a video signal, the electronic watermark information which is embedded in the video signal so as to cause a minimal disturbance to the video signal, and the reference signal which is inserted in the video signal at a position different from a position of embedment of the electronic watermark information;
wherein the detection means includes;
a detection signal generating circuit which generates a detection signal for detecting the reference signal from a sync signal;
a sample-holding circuit which samples and holds an amplitude of the reference signal in response to the detection signal;
a gain drift calculating circuit which calculates a gain drift based on the amplitude of the reference signal provided by the sample-holding circuit;
a detection circuit which detects the electronic watermark information from a luminance signal included in the video signal by using the detection signal; and
a modification circuit which modifies an amplitude of the detected electronic watermark information based on the gain drift calculated by the gain drift calculating circuit.
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Specification