Ink set with expanded color gamut and process for using same
View Patent ↗A four-color ink set capable of printing an expanded color gamut has a cyan ink that prints on a reference substrate with CIELAB colorimetric aim values of L*=54, a*=−41, and b*=−45, within a ΔE* ab ≦8; a magenta ink that prints on the reference substrate with CIELAB colorimetric aim values of L*=52, a*=79, and b*=−9, within a ΔE* ab ≦8; a yellow ink that prints on the reference substrate with CIELAB colorimetric aim values of L*=90, a*=−7, and b*=102, within a ΔE* ab ≦10; and a black ink. Obtaining a profile for the expanded gamut ink set, for example an International Color Consortium (ICC) profile, that relates tone values for the ink set to colorimetric values for the printed ink allows the printer to obtain the maximum benefit of the expanded color gamut. The profile for the ink set is applied in a color separation process prior to printing the image on press.
1. A four-color ink set, comprising:
a cyan ink that prints, as measured on a reference substrate, with CIELAB colorimetric aim values of L*=54, a*=−41, and b*=−45, within a ΔE* ab ≦8;
a magenta ink that prints, as measured on the reference substrate, with CIELAB colorimetric aim values of L*=52, a*=79, and b*=−9, within a ΔE* ab ≦8;
a yellow ink that prints, as measured on the reference substrate, with CIELAB colorimetric aim values of L*=90, a*=−7, and b*=102, within a ΔE* ab ≦10;
and a black ink.
2. A four-color ink set according to claim 1 , wherein the inks have Status T optical densities of about 1.5 for the cyan ink, about 1.5 for the magenta ink, and about 1.15 for the yellow ink.
3. A four-color ink set according to claim 1 , wherein the inks are heat set inks.
4. A four-color ink set according to claim 1 , wherein the inks are cold set inks.
5. A four-color ink set according to claim 1 , wherein one or more of the inks comprise one or more fluorescent materials.
6. A four-color ink set according to claim 1 , wherein the four-color ink set has an increase in color gamut area over the SWOP four-color ink set of about 20% or more, as measured on a CIELAB Diagram.
7. A four-color ink set according to claim 1 , wherein the four-color ink set has an increase in color gamut area over the SWOP four-color ink set of about 25% or more, as measured on a CIELAB Diagram.
8. A four-color ink set according to claim 1 , wherein the four-color ink set has a color gamut area at least about 85% of the color gamut area available with the Hexachrome ink set, as measured on a CIELAB Diagram.
9. A four-color ink set according to claim 1 , wherein the four-color ink set has a color gamut area at least about 88% of the color gamut area available with the Hexachrome ink set, as measured on a CIELAB Diagram.
10. A four-color ink set according to claim 1 , wherein the four-color ink set has a color gamut area of from about 85% to about 90% of the color gamut area available with the Hexachrome ink set, as measured on a CIELAB Diagram.
11. A method of printing a color image, comprising
providing a color separation of the image based on a four-color ink set comprising:
a cyan ink that prints, as measured on a reference substrate, with CIELAB colorimetric aim values of L*=54, a*=−41, and b*=−45, within a ΔE* ab ≦8;
a magenta ink that prints, as measured on the reference substrate, with CIELAB colorimetric aim values of L*=52, a*=79, and b*=−9, within a ΔE* ab ≦8;
a yellow ink that prints, as measured on the reference substrate, with CIELAB colorimetric aim values of L*=90, a*=−7, and b*=102, within a ΔE* ab ≦10;
and a black ink,
and printing the color image with the four-color ink set according to the color separation.
12. A method according to claim 11 , wherein the step of providing a color separation of the image based on the four-color ink set comprises a step of applying a color profile in the color separation process.
13. A method according to claim 12 , wherein the color profile is a profile on a substrate on which the color image is printed.
14. A method according to claim 12 , wherein the color profile is obtained by printing a color target using the same press conditions that are used to print the color image.
15. A method according to claim 11 , wherein the printing step comprises printing by a lithographic, flexographic, gravure, or digital printing process.
16. A method according to claim 11 , wherein the printing step comprises sheet fed printing.
17. A method according to claim 11 , wherein the printing step comprises web printing.
18. A method according to claim 11 , wherein the color image comprises a color that cannot be obtained using a standard SWOP ink set but that is within the color gamut of the four-color ink set.
19. A four-color ink set, comprising a cyan ink, a magenta ink, a yellow ink, and a black ink, wherein the ink set comprises at least one member selected from the group consisting of:
a cyan ink that prints, as measured on a reference substrate, with CIELAB colorimetric aim values of L*=54, a*=−41, and b*=−45, within a ΔE* ab ≦8,
a magenta ink prints, as measured on a reference substrate, with CIELAB colorimetric aim values of L*=52, a*=79, and b*=−9, within a ΔE* ab ≦8, and
a yellow ink prints, as measured on a reference substrate, with CIELAB colorimetric aim values of L*=90, a*=−7, and b*=102, within a ΔE* ab ≦10.