IR specialty imaging methods and systems

1. A method of printing an image encoded with an IR watermark on a substrate associated with a printing device including a plurality of colorants, the method comprising:

a) generating a first device dependent multidimensional color space representation of the printing device using a first constant value of one or more of the plurality of colorants as an input to a calibration process, the first device dependent multidimensional color space representation defining a first gamut associated with the printing device;

b) generating a second device dependent multidimensional color space representation of the printing device using a second constant value of the one or more of the plurality of colorants as an input to the calibration process, the second constant value of the one or more of the plurality of colorants offset from the first constant value of the one or more of the plurality of colorants, the second device dependent multidimensional color space representation defining a second gamut associated with the printing device;

c) defining an effective gamut associated with the printing device formed by the intersection of the first gamut and second gamut;

d) defining a third device dependent multidimensional color space representation of the printing device including only the first device dependent multidimensional color space representation of the printing device using the first constant value of one or more of the plurality of colorants within the effective gamut;

e) defining a fourth device dependent multidimensional color space representation of the printing device including only the second device dependent multidimensional color space representation of the printing device using the second constant value of one or more of the plurality of colorants within the effective gamut;

f) generating a device dependent multidimensional color space representation of the image encoded with the watermark by encoding the watermark using a metameric pair of device dependent multidimensional color space representations of the image color associated with the watermark location, the metameric pair including a first metamer of the image color derived from the third device dependent multidimensional color space representation of the printing device to generate a first fixed infrared response and a second metamer of the image color derived from the fourth device dependent multidimensional color space representation of the printing device to generate a second fixed infrared response, whereby the differential infrared response of the metameric pair is substantially constant; and

g) printing the device dependent multidimensional color space representation of the image encoded with the watermark on the substrate using the associated printing device.

2. The method according to claim 1 , wherein the first constant value of one or more of the plurality of colorants is associated with a substantially black colorant K, and the second constant value of one or more of the plurality of colorants is associated with the substantially black colorant K offset from the first constant value.

3. The method according to claim 2 , wherein the first constant value of K is within the range of 0-5%, and the second constant value of K is within the range of 20-35%.

4. The method according to claim 2 , wherein K is associated with one of a black colorant and process black including a mixture of nonblack colorants.

5. The method according to claim 1 , wherein the plurality of colorants are two or more of C (Cyan), M (Magenta), Y (Yellow), K (Black), O (Orange), V (Violet), R (Red), G (Green) and B (Blue).

6. The method according to claim 1 , wherein the IR watermark is a barcode or other machine readable code.

7. The method according to claim 1 , wherein the first, second, third and fourth device dependent multidimensional color space is CMYK.

8. The method according to claim 1 , wherein the first and second device dependent multidimensional color space representation of the printing device transform from a trichromatic color space to CMYK color space.

9. A printing system comprising:

a printing device including a plurality of colorants, the printing device configured to receive device dependent data representative of an image encoded with an IR watermark and the printing device configured to print the image encoded with the IR watermark on a substrate; and

a controller operatively connected to the printing device, the controller configured to execute controller readable instructions to perform a method of printing an image encoded with an IR watermark on a substrate operatively associated with the printing device, the method comprising:

a) generating a device dependent multidimensional color space representation of the image encoded with the watermark; and

b) printing the device dependent multidimensional color space representation of the image encoded with the watermark on the substrate,

wherein the device dependent multidimensional color space representation of the image encoded with the watermark is generated by a method comprising:

aa) generating a first device dependent multidimensional color space representation of the printing device using a first constant value of one or more of the plurality of colorants as an input to a calibration process, the first device dependent multidimensional color space representation defining a first gamut associated with the printing device;

bb) generating a second device dependent multidimensional color space representation of the printing device using a second constant value of the one or more of the plurality of colorants as an input to the calibration process, the second constant value of the one or more of the plurality of colorants offset from the first constant value of the one or more of the plurality of colorants, the second device dependent multidimensional color space representation defining a second gamut associated with the printing device;

cc) defining an effective gamut associated with the printing device formed by the intersection of the first gamut and second gamut;

dd) defining a third device dependent multidimensional color space representation of the printing device including only the first device dependent multidimensional color space representation of the printing device using the first constant value of one or more of the plurality of colorants within the effective gamut;

ee) defining a fourth device dependent multidimensional color space representation of the printing device including only the second device dependent multidimensional color space representation of the printing device using the second constant value of one or more of the plurality of colorants within the effective gamut; and

ff) generating the device dependent multidimensional color space representation of the image encoded with the watermark by encoding the watermark using a metameric pair of device dependent multidimensional color space representations of the image color associated with the watermark location, the metameric pair including a first metamer of the image color derived from the third device dependent multidimensional color space representation of the printing device to generate a first fixed infrared response and a second metamer of the image color derived from the fourth device dependent multidimensional color space representation of the printing device to generate a second fixed infrared response, whereby the differential infrared response of the metameric pair is substantially constant.

10. The printing system according to claim 9 , wherein the first constant value of one or more of the plurality of colorants is associated with a substantially black colorant K, and the second constant value of one or more of the plurality of colorants is associated with the substantially black colorant K offset from the first constant value.

11. The printing system according to claim 10 , wherein the first constant value of K is within the range of 0-5%, and the second constant value of K is within the range of 20-35%.

12. The printing system according to claim 10 , wherein K is associated with one of a black colorant and process black including a mixture of nonblack colorants.

13. The printing system according to claim 9 , wherein the plurality of colorants are two or more of C (Cyan), M (Magenta), Y (Yellow), K (Black), O (Orange), V (Violet), R (Red), G (Green) and B (Blue).

14. The method according to claim 9 , wherein the IR watermark is a barcode or other machine readable code.

15. The method according to claim 9 , wherein the first, second, third and fourth device dependent multidimensional color space is CMYK.

16. The method according to claim 9 , wherein the first and second device dependent multidimensional color space representation of the printing device transform from a trichromatic color space to CMYK color space.

17. A method of printing a first image not encoded with an IR watermark on a substrate, and printing a second image encoded with the IR watermark on the substrate, the substrate associated with a printing device including a plurality of colorants, the method comprising:

a) generating a device dependent multidimensional color space representation of the first image not encoded with the watermark within a first gamut associated with the printing device;

b) generating a device dependent multidimensional color space representation of the second image encoded with the IR watermark within a second gamut associated with the printing device, the second gamut a subset of the first gamut; and

c) printing the device dependent multidimensional color space representation of the first image and second image on a common substrate,

wherein step b) includes:

aa) generating a first device dependent multidimensional color space representation of the printing device using a first constant value of one or more of the plurality of colorants as an input to a calibration process, the first device dependent multidimensional color space representation defining a first gamut associated with the printing device;

bb) generating a second device dependent multidimensional color space representation of the printing device using a second constant value of the one or more of the plurality of colorants as an input to the calibration process, the second constant value of the one or more of the plurality of colorants offset from the first constant value of the one or more of the plurality of colorants, the second device dependent multidimensional color space representation defining a second gamut associated with the printing device;

cc) defining an effective gamut associated with the printing device formed by the intersection of the first gamut and second gamut;

dd) defining a third device dependent multidimensional color space representation of the printing device including only the first device dependent multidimensional color space representation of the printing device using the first constant value of one or more of the plurality of colorants within the effective gamut;

ee) defining a fourth device dependent multidimensional color space representation of the printing device including only the second device dependent multidimensional color space representation of the printing device using the second constant value of one or more of the plurality of colorants within the effective gamut; and

ff) generating the device dependent multidimensional color space representation of the image encoded with the watermark by encoding the watermark using a metameric pair of device dependent multidimensional color space representations of the image color associated with the watermark location, the metameric pair including a first metamer of the image color derived from the third device dependent multidimensional color space representation of the printing device to generate a first fixed infrared response and a second metamer of the image color derived from the fourth device dependent multidimensional color space representation of the printing device to generate a second fixed infrared response, wherein the differential infrared response of the metameric pair is substantially constant.

18. The method according to claim 17 , wherein the first constant value of one or more of the plurality of colorants is associated with a substantially black colorant K, and the second constant value of one or more of the plurality of colorants is associated with the substantially black colorant K offset from the first constant value.

19. The method according to claim 18 , wherein K is associated with one of a black colorant and process black including a mixture of nonblack colorants.