System and methods for encoding information for printed articles

1. A method for generating a color design for a printed article comprising:

obtaining data associated with a first spot color S a , the first spot color S a comprising a component of a color design;

determining a plurality of substitute spot color candidates S b1 -S bi , where i is an integer, by evaluating—for each substitute spot color candidate—color distance metrics between data associated with the substitute candidate spot color and the data associated with the first spot color S a ;

determining a Cyan (C), Magenta (M) and Yellow (Y) tint for each of the plurality of substitute spot color candidates S b1 -S bi ;

using one or more electronic processors, simulating an overprint of each of the plurality of substitute spot color candidates S b1 -S bi with its respective CMY tint, and for each of the overprinted substitute spot color candidates, generating an Lab or Chroma distance metric relative to the first spot color S a ;

based on generated distance metrics, determining final spot color candidates;

for at least one of the final spot color candidates, and using one or more electronic processors, transforming its respective CMY tint with a digital watermark signal; and

substituting the at least one of the final spot color candidates plus its transformed CMY tint for the first spot color S a in the color design.

2. The method of claim 1 in which the data associated with the substitute candidate spot color comprises Lab data.

3. The method of claim 1 in which the data associated with the substitute candidate spot color comprises RGB or CMYK data.

4. The method of claim 1 in which said determining final spot color candidates comprises determining Lab distance values relative to the first spot color S a for each of the plurality of substitute spot color candidates S b1 -S bi .

5. The method of claim 1 in which said determining final spot color candidates comprises determining Chroma distance values relative to the first spot color S a for each of the plurality of substitute spot color candidates S b1 -S bi .

6. A system for encoding information for a printed article comprising:

memory for storing i) data representing a first color (S 1 ), ii) data representing second color data (S 2 ), and iii) data representing third color data (S 3 ), in which encoded information is provided by modulating the data representing third color data (S 3 ) with max (positive) and min (negative) tweaks;

one or more processors configured for:

determining a color error between S 1 and a combination of S 2 and S 3 , the combination including the max and min tweaks;

determining an information modulating error associated with the max and min tweaks; and

optimizing the combination of S 2 and S 3 , including minimizing the color error and minimizing the information modulating error; and

an output for providing the optimized combination of S 2 and S 3 for use in a design to be printed on the printed article.

7. The system of claim 6 in which the optimizing includes determining color weights and a global signal strength, the color weights to be applied to the data representing third color data (S 3 ) and the global signal strength for regulating the modulating.

8. The system of claim 7 in which the optimizing is constrained by spectral reflectance between 630 nm to 680 nm.

9. The system of claim 7 in which the optimizing is constrained by spectral reflectance between 655 nm to 670 nm.

10. The system of claim 7 in which the data representing third color data (S 3 ) comprises data representing two (2) or more process colors, and the data representing second color data (S 2 ) represents a second color.

11. The system of claim 10 in which the second color comprises a screened-back version of the first color.

12. The system of claim 6 in which the max and min tweaks correspond to a 2-dimensional image digital watermark tile.

13. The system of claim 6 further comprising a display, in which said one or more processors are configured for providing a graphical user interface through which a user can select embedding options.

14. A system for transforming color data to include an information signal embedded therein, comprising:

memory storing spot color data, and system constraint information, the system constraint information including at least one spectral dependency; and

one or more processors configured as an optimizer bounded by the system constraint information, the optimizer generates C (Cyan), M (Magenta), Y (Yellow) process color data to be combined with a screen of the spot color data to yield a minimized color error approximation of the spot color data, the optimizer generates tweak values in terms of at least ΔC, ΔM, ΔY for modulating the C, M, Y process color data to carry the information signal, the tweak values optimized based on an error metric; and

one or more processors configured as an embedder that transforms the C, M, Y process color data with the tweak values.

15. A method for generating a design for a printed article comprising:

minimizing: i) a color match error between a first color (S 1 ) and a combination of data representing second color data (S 2 ) and data representing third color data (S 3 ), the combination including auxiliary encoded information in the data representing third color data, and ii) an information modulating error associated with modulations of the data representing third color data (S 3 ) that carry the auxiliary encoded information,

said minimizing being constrained by a spectral component associated with an anticipated information detector,

in which said minimizing yields color percentage values associated with at least the data representing third color data (S 3 ) and a signal strength value for regulating the modulations; and

outputting the color percentage values and signal strength value for use in a design to be printed on the printed article.

16. The method of claim 15 in which spectral component comprises a metric associated with a spectral reflectance between 630 nm to 680 nm.

17. The method of claim 15 in which the modulations correspond to a 2-dimensional image digital watermark tile.