Digital watermarking apparatus and its method and digital watermark reproducing apparatus and its method
First Claim
1. A digital watermarking apparatus comprising:
- area specifying means for specifying a predetermined area in which a digital watermark is to be embedded, said predetermined area being included in received image signals;
encryption data generating means for encrypting the digital watermark and for outputting encryption data; and
mixing means for comparing an average of intensity values or color difference values of all pixels in a first area in the predetermined area in the received image signals with an intensity value or a color difference value of each pixel in a second area that is an area other than the first area in the predetermined area to find, for all pixels in the second area, a first counter value and a second counter value, said first counter value indicating a number of pixels each of which has an intensity value or a color difference value larger than the average, said second counter value indicating a number of pixels each of which has an intensity value or a color difference value smaller than the average, for transforming the intensity value or the color difference value of each pixel in the second area such that a relation between the first counter value and the second counter value becomes a preset relation according to a first value or a second value of the encryption data from said encryption data generating means, and for outputting the received image signals as watermarked image signals.
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Accused Products
Abstract
An encryption mixer transforms the intensity values of image signals in a predetermined area, specified by an area specifier, based on encryption data from an encryption data generator. To do so, for an odd-numbered line and an even-numbered line in the predetermined area, the encryption mixer calculates the average of the intensity values of the image signals in the even-numbered line and compares the average with the intensity value of each pixel in the odd-numbered line. The encryption mixer increments CNTpos1 by 1 when the average is smaller, and increments CNTnega by 1 when the average is larger. Then, the encryption mixer modifies the intensity values of the image signals in the odd-numbered line such that CNTpos1>CNTnega when the bit to be embedded is “1” and such that CNTpos1<CNTnega when the bit to be embedded is “0”.
58 Citations
8 Claims
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1. A digital watermarking apparatus comprising:
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area specifying means for specifying a predetermined area in which a digital watermark is to be embedded, said predetermined area being included in received image signals;
encryption data generating means for encrypting the digital watermark and for outputting encryption data; and
mixing means for comparing an average of intensity values or color difference values of all pixels in a first area in the predetermined area in the received image signals with an intensity value or a color difference value of each pixel in a second area that is an area other than the first area in the predetermined area to find, for all pixels in the second area, a first counter value and a second counter value, said first counter value indicating a number of pixels each of which has an intensity value or a color difference value larger than the average, said second counter value indicating a number of pixels each of which has an intensity value or a color difference value smaller than the average, for transforming the intensity value or the color difference value of each pixel in the second area such that a relation between the first counter value and the second counter value becomes a preset relation according to a first value or a second value of the encryption data from said encryption data generating means, and for outputting the received image signals as watermarked image signals. - View Dependent Claims (2)
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3. A digital watermarking method comprising:
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a first step for specifying a predetermined area in which a digital watermark is to be embedded, said predetermined area being included in received image signals;
a second step for encrypting the digital watermark and for outputting encryption data; and
a third step for comparing an average of intensity values or color difference values of all pixels in a first area in the predetermined area in the received image signals with an intensity value or a color difference value of each pixel in a second area that is an area other than the first area in the predetermined area to find, for all pixels in the second area, a first counter value and a second counter value, said first counter value indicating a number of pixels each of which has an intensity value or a color difference value larger than the average, said second counter value indicating a number of pixels each of which has an intensity value or a color difference value smaller than the average, and a fourth step for transforming the intensity value or the color difference value of each pixel in the second area such that a relation between the first counter value and the second counter value becomes a preset relation according to a first value or a second value of the encryption data and for outputting the received image signals as watermarked image signals. - View Dependent Claims (4)
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5. A digital watermark reproducing apparatus comprising:
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area specifying means for receiving digitally watermarked image signals as input signals and for specifying a predetermined area, said digitally watermarked image signals being generated by transforming signals in the predetermined area of the image signals according to a value of encryption data generated by encrypting a digital watermark;
extracting means for comparing an average of intensity values or color difference values of all pixels in a first area in the predetermined area in the digitally watermarked image signals with an intensity value or a color difference value of each pixel in a second area that is an area other than the first area in the predetermined area to find, for all pixels in the second area, a first counter value and a second counter value, said first counter value indicating a number of pixels each of which has an intensity value or a color difference value larger than the average, said second counter value indicating a number of pixels each of which has an intensity value or a color difference value smaller than the average, and for extracting from the predetermined area the encryption data which is determined to be a first value or a second value according to a relation between the first counter value and the second counter value; and
a decrypting means for decrypting the extracted the encryption data to an original watermark for output. - View Dependent Claims (6)
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7. A digital watermark reproducing method comprising:
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a first step for receiving digitally watermarked image signals as input signals and for specifying a predetermined area, said digitally watermarked image signals being generated by transforming signals in the predetermined area of the image signals according to a value of encryption data generated by encrypting a digital watermark;
a second step for comparing an average -of intensity values or color difference values of all pixels in a first area in the predetermined area in the digitally watermarked image signals with an intensity value or a color difference value of each pixel in a second area that is an area other than the first area in the predetermined area to find, for all pixels in the second area, a first counter value and a second counter value, said first counter value indicating a number of pixels each of which has an intensity value or a color difference value larger than the average, said second counter value indicating a number of pixels each of which has an intensity value or a color difference value smaller than the average;
a third step for extracting from the predetermined area the encryption data which is determined to be a first value or a second value according to a relation between the first counter value and the second counter value; and
a fourth step for decrypting the extracted encryption data to an original watermark for output. - View Dependent Claims (8)
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Specification