DIGITAL WATERMARK EMBEDDING APPARATUS, DIGITAL WATERMARK EMBEDDING METHOD, AND DIGITAL WATERMARK DETECTION APPARATUS
First Claim
1. A digital watermark embedding apparatus comprising:
- an interface unit which acquires video data and digital watermark information; and
a processing unit which embeds the digital watermark information into the video data, whereinthe processing unit is adapted to cause the area of a watermark pattern formed by a plurality of pixels having a prescribed value, and superimposed on each image contained in the video data, to vary the area of the watermark pattern in periodic fashion over time according to the value of a symbol contained in the digital watermark information, andcorrect, using the prescribed value, the value of each pixel contained in a region where each image in the video data and the watermark pattern corresponding to the each image overlap each other.
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Abstract
A digital watermark embedding apparatus includes an interface unit which acquires video data and digital watermark information, and a processing unit which embeds the digital watermark information into the video data. The processing unit is adapted to cause the area of a watermark pattern formed by a plurality of pixels having a prescribed value, and superimposed on each image contained in the video data, to vary in periodic fashion over time according to the value of a symbol contained in the digital watermark information, and correct, using the prescribed value, the value of each pixel contained in a region where each image in the video data and the watermark pattern corresponding to that image overlap each other.
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Citations
13 Claims
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1. A digital watermark embedding apparatus comprising:
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an interface unit which acquires video data and digital watermark information; and a processing unit which embeds the digital watermark information into the video data, wherein the processing unit is adapted to cause the area of a watermark pattern formed by a plurality of pixels having a prescribed value, and superimposed on each image contained in the video data, to vary the area of the watermark pattern in periodic fashion over time according to the value of a symbol contained in the digital watermark information, and correct, using the prescribed value, the value of each pixel contained in a region where each image in the video data and the watermark pattern corresponding to the each image overlap each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A digital watermark embedding method comprising:
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acquiring video data and digital watermark information; causing the area of a watermark pattern formed by a plurality of pixels having a prescribed value, and superimposed on each image contained in the video data, to vary the area of the watermark pattern in periodic fashion over time according to the value of a symbol contained in the digital watermark information; and embedding the digital watermark information into the video data by correcting, using the prescribed value, the value of each pixel contained in a region where each image in the video data and the watermark pattern corresponding to the each image overlap each other.
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10. A computer readable recording medium having a digital watermark embedding computer program recorded thereon for causing a computer to execute the process of embedding digital watermark information into video data, and wherein the program causes the computer to carry out:
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causing the area of a watermark pattern formed by a plurality of pixels having a prescribed value, and superimposed on each image contained in the video data, to vary the area of the watermark pattern in periodic fashion over time according to the value of a symbol contained in the digital watermark information; and embedding the digital watermark information into the video data by correcting, using the prescribed value, the value of each pixel contained in a region where each image in the video data and the watermark pattern corresponding to the each image overlap each other.
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11. A digital watermark detection apparatus comprising:
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an interface unit which acquires video data in which digital watermark information is embedded; and a processing unit which detects the digital watermark information embedded in the video data, wherein the processing unit is adapted to calculate, for each image contained in the video data, an average pixel value for the entire image or for a reference region that contains a watermark pattern whose area varies in periodic fashion over time with a phase or period that matches the value of a symbol contained in the digital watermark information, calculate a spectrum depicting how the average pixel value varies over time, by frequency-transforming a set of the average pixel values contained in a time segment corresponding to one the symbol and arranged in time series order, and obtain the value of the symbol by extracting from the spectrum a frequency component corresponding to the periodic variation of the area of the watermark pattern and by calculating from the frequency component the phase or period of the periodic variation of the area of the watermark pattern.
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12. A digital watermark detection method comprising:
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acquiring video data in which digital watermark information is embedded; for each image contained in the video data, calculating an average pixel value for the entire image or for a reference region that contains a watermark pattern whose area varies in periodic fashion over time with a phase or period that matches the value of a symbol contained in the digital watermark information; calculating a spectrum depicting how the average pixel value varies over time, by frequency-transforming a set of the average pixel values contained in a time segment corresponding to one the symbol and arranged in time series order; and obtaining the value of the symbol by extracting from the spectrum a frequency component corresponding to the periodic variation of the area of the watermark pattern and by calculating from the frequency component the phase or period of the periodic variation of the area of the watermark pattern, and thereby detecting the digital watermark information embedded in the video data.
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13. A computer readable recording medium having a digital watermark detection computer program recorded thereon for causing a computer to execute the process of detecting digital watermark information embedded in video data, wherein the program causes the computer to carry out:
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for each image contained in the video data, calculating an average pixel value for the entire image or for a reference region that contains a watermark pattern whose area varies in periodic fashion over time with a phase or period that matches the value of a symbol contained in the digital watermark information; calculating a spectrum depicting how the average pixel value varies over time, by frequency-transforming a set of the average pixel values contained in a time segment corresponding to one the symbol and arranged in time series order; and obtaining the value of the symbol by extracting from the spectrum a frequency component corresponding to the periodic variation of the area of the watermark pattern and by calculating from the frequency component the phase or period of the periodic variation of the area of the watermark pattern, and thereby detecting the digital watermark information embedded in the video data.
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Specification