Digital watermarking in data representing color channels
View Patent ↗The present disclosure relates to digital watermarking. One claim recites a method to detect two or more different digital watermarks in media. The method includes: receiving captured imagery of the media, the captured imagery comprising a plurality of image frames; for a first image frame applying a first watermark detector to search for a first digital watermark hidden within the first image frame, in which an electronic processor is programmed as the first watermark detector; and for a second image frame applying a second, different watermark detector to search for a second, different watermark hidden within the second image frame, in which an electronic processor is programmed as the second watermark detector. Other claims and combinations are provided too.
1. A method comprising:
receiving optically captured data associated with printed media, wherein the received captured data represents a blue channel, a green channel and a red channel, and wherein a first digital watermarking is embedded in the printed media;
scaling the blue channel with a first factor;
scaling a sum of the red channel and the green channel with a second factor;
subtracting the scaled sum of the red channel and the green channel from the scaled blue channel and adding a shift factor to yield a detection signal; and
searching, using a processor, for the first digital watermarking in the detection signal.
2. The method of claim 1 , wherein scaling the blue channel, scaling the sum of the red channel and the green channel, subtracting and adding are related according to:
first factor*blue channel−second factor*(red channel+green channel)+shift.
3. The method of claim 1 , wherein the first factor is in a range of 0.3-0.75, the second factor is in a range of 0.15-0.375, and the shift factor is in a color value range of 64-192.
4. The method of claim 1 , wherein the first factor comprises 0.5, the second factor comprises 0.25 and the shift factor comprises 128.
5. The method of claim 1 , wherein the detection signal represents chrominance characteristics.
6. The method of claim 1 , further comprising searching for a second digital watermarking from luminance characteristics associated with the blue channel, the green channel and the red channel.
7. An apparatus comprising:
a processor configured to:
receive optically captured data associated with printed media, wherein the received captured data represents a blue channel, a green channel and a red channel, and wherein a first digital watermarking is embedded in the printed media;
scale the blue channel with a first factor;
scale a sum of the red channel and the green channel with a second factor;
subtract the scaled sum of the red channel and the green channel from the scaled blue channel and adding a shift factor to yield a detection signal; and
search for the first digital watermarking in the detection signal.
8. The apparatus of claim 7 , wherein the processor is configured to calculate the detection signal according to:
first factor*blue channel−second factor*(red channel+green channel)+shift.
9. The apparatus of claim 7 , wherein the first factor is in a range of 0.3-0.75, the second factor is in a range of 0.15-0.375, and the shift factor is in a color value range of 64-192.
10. The apparatus of claim 7 , wherein the first factor comprises 0.5, the second factor comprises 0.25 and the shift factor comprises 128.
11. The apparatus of claim 7 , wherein the detection signal represents chrominance characteristics.
12. The apparatus of claim 7 , wherein the processor is further configured to search for a second digital watermarking from luminance characteristics associated with the blue channel, the green channel and the red channel.
13. A non-transitory tangible computer-readable medium having instructions stored thereon, the instructions comprising:
instructions to receive optically captured data associated with printed media, wherein the received captured data represents a blue channel, a green channel and a red channel, and wherein a first digital watermarking is embedded in the printed media;
instructions to scale the blue channel with a first factor;
instructions to scale a sum of the red channel and the green channel with a second factor;
instructions to subtract the scaled sum of the red channel and the green channel from the scaled blue channel and adding a shift factor to yield a detection signal; and
instructions to search for the first digital watermarking in the detection signal.
14. The tangible computer-readable medium of claim 13 , further comprising instructions to calculate the detection signal according to:
first factor*blue channel−second factor*(red channel+green channel)+shift.
15. The tangible computer-readable medium of claim 13 , wherein the first factor is in a range of 0.3-0.75, the second factor is in a range of 0.15-0.375, and the shift factor is in a color value range of 64-192.
16. The tangible computer-readable medium of claim 13 , wherein the first factor comprises 0.5, the second factor comprises 0.25 and the shift factor comprises 128.
17. The tangible computer-readable medium of claim 13 , wherein the detection signal represents chrominance characteristics.
18. The tangible computer-readable medium of claim 13 , further comprising instructions to search for a second digital watermarking from luminance characteristics associated with the blue channel, the green channel and the red channel.