Data hiding for spot colors on substrates
The present disclosure relates generally to data hiding for retail product packaging and other printed objects such as substrates. One embodiment embeds an information signal in a spot color for printing on various substrates. The spot color is screened, and overprinted with process color tint. The tint is modulated prior to overprinting with optimized signal tweaks. The optimization can include consideration of a detector spectral dependency (e.g., red and/or green illumination). Many other embodiments and combinations are described in the subject patent document.
1. A substrate comprising:
a first printed area, the first printed area comprising a combination of i) data representing a first color (S1), and ii) data representing a second color (S2), in which encoded information is provided on said substrate through modulation of the data representing the second color (S2) with max (positive) and min (negative) tweaks, in which the encoded information is detectable from chrominance values;
in which the combination has been optimized by:
determining a color error between data representing third color data (S3) and a combination of S1 and S2,
determining an information modulating error associated with the max and min tweaks; and
finalizing the combination of S1 and S2, including minimizing the color error and minimizing the information modulating error; and
a second printed area including a barcode;
a third printed area including text information printed thereon.
2. The substrate of claim 1 in which the combination has been optimized by a process which included determining color weights and a global signal strength, the color weights applied to the data representing the second color (S2) and the global signal strength for regulating the modulation.
3. The substrate of claim 2 in which the combination has been optimized by a process constrained by spectral reflectance between 630 nm to 680 nm.
4. The substrate of claim 2 in which combination has been optimized by a process constrained by spectral reflectance between 655 nm to 670 nm.
5. The substrate of claim 2 in which the data representing the second color (S2) comprises data representing two or more process colors, and the data representing the third color data (S3) represents a third color.
6. The substrate of claim 1 in which the second color comprises a screened-back version of the first color (S1).
7. The substrate of claim 1 in which the max and min tweaks correspond to a 2-dimensional image digital watermark tile.
8. An image processing system for generating a design for a substrate comprising:
memory storing data representing a first color (S1);
one or more multi-core processors configured for:
minimizing: i) a color match error between (S1) and a combination of data representing second color data (S2) and data representing third color data (S3), the combination including auxiliary encoded information in (S3), and ii) an information modulating error associated with modulations of (S3) that carry the auxiliary encoded information,
said minimizing being constrained by a spectral component associated with an anticipated information detector,
obtaining color percentage values associated with at least (S3) and a signal strength value for regulating the modulations;
an output configured for outputting the color percentage values and signal strength value;
a signal encoder configured for encoding a signal in the design using the color percentage values and signal strength value, said signal encoder generating an encoded design; and
a signal detector configured for determining signal robustness associated with the encoded design, in which the auxiliary encoded information is detectable from chrominance values.
9. The image processing system of claim 8 in which the spectral component comprises a metric associated with a spectral reflectance between 630 nm to 680 nm.
10. The image processing system of claim 8 in which the modulations correspond to a 2-dimensional image digital watermark tile.
11. The image processing system of claim 8 further comprising a display, in which said one or more multi-core processors are configured for providing a graphical user interface through which embedding options can be selected.
12. The image processing system of claim 8 in which the combination is optimized by determining color weights and a global signal strength, and in which the signal encoder is configured to apply the color weights the data representing the third color data (S3) and configured to regulate the modulation with the global signal strength.
13. An image processing method comprising:
obtaining color data representing a spot color ink;
obtaining data representing a process color ink tint, the process color ink tint including at least a Cyan (C) component, a Magenta (M) component and a Yellow component (Y);
determining from the data representing a process color ink tint an overprinting of the process color ink tint with the color data;
decomposing the process color ink tint into a maximum signal tweak and a minimum signal tweak, each of the maximum signal tweak and the minimum signal tweak having a Cyan (C) component, a Magenta (M) component and a Yellow component (Y);
minimizing a color error metric of the overprinting relative to the data representing the spot color ink;
optimizing the maximum signal tweak and the minimum signal tweak according to at least a spectral dependency, in which said optimizing comprises determining color weights and a global signal strength;
transforming the process color ink tint with the maximum signal tweak and the minimum signal tweak to represent an information signal, the color weights for application to the process color tint, and the global signal strength for application to the maximum signal tweak and the minimum signal tweak, said transforming yielding a transformed process color ink tint;
determining a robustness associated with the transformed process color ink tint;
outputting the transformed process color ink tint for overprinting with the color data.
14. The image processing method of claim 13 in which the spectral component comprises a metric associated with a spectral reflectance between 630 nm to 680 nm.
15. The image processing method of claim 13 in which the information signal corresponds to a 2-dimensional image digital watermark tile.
16. The image processing method of claim 13 further comprising providing a graphical user interface through which embedding options can be selected.
17. The image processing method of claim 13 further comprising outputting robustness associated with the transformed process color ink tint.
18. A non-transitory computer readable medium comprising instructions stored thereon that, when executed by one or more multi-core processors, cause the one or more processors to carry out the following acts:
obtaining color data representing a spot color ink;
determining from the data representing a process color ink tint an overprinting of the process color ink tint with the color data;
decomposing the process color ink tint into a maximum signal tweak and a minimum signal tweak, each of the maximum signal tweak and the minimum signal tweak having a Cyan (C) component, a Magenta (M) component and a Yellow component (Y);
decomposing the process color ink tint into a maximum signal tweak and a minimum signal tweak, each of the maximum signal tweak and the minimum signal tweak having a Cyan (C) component, a Magenta (M) component and a Yellow component (Y);
minimizing a color error metric of the overprinting relative to the data representing the spot color ink;
optimizing the maximum signal tweak and the minimum signal tweak according to at least a spectral dependency, in which the optimizing comprises determining color weights and a global signal strength;
transforming the process color ink tint with the maximum signal tweak and the minimum signal tweak to represent an information signal, the color weights for application to the process color tint, and the global signal strength for application to the maximum signal tweak and the minimum signal tweak, said transforming yielding a transformed process color ink tint;
determining a robustness associated with the transformed process color ink tint;
outputting the transformed process color ink tint for overprinting with the color data.
19. The non-transitory computer readable medium of claim 18 in which the spectral component comprises a metric associated with a spectral reflectance between 630 nm to 680 nm.
20. The non-transitory computer readable medium of claim 18 in which the information signal corresponds to a 2-dimensional image encoding tile.
21. The non-transitory computer readable medium of claim 18 further comprising instructions which cause the one or more multi-core processors to carry out the following act: providing a graphical user interface through which embedding options can be selected.
22. The image processing method of claim 18 further comprising instructions which cause the one or more multi-core processors to carry out the following act: outputting robustness associated with the transformed process color ink tint.