Generation of spot colors with reduced ink subsets
View Patent ↗Optimization of ink recipes for spot colors in printers. Often, ICC Profiles are optimized for smooth rendering of images; thus, color recipes often contain more inks than are required for matching a color when generated from a Profile. When transitioning from one color to another, it is better to make smaller changes in inkings. This goal is not served when printing spot colors. Spot colors are often single, solid colors that do not vary in gradients from one to another. Herein is a discussion including dividing an N-ink set into subsets, generating an ink recipe for a desired recipe in each ink subset, and selecting a subset based on predetermined criteria. Where a spot color is out of Gamut, that color is mapped to the Gamut.
1. A method for selecting a spot color formula in a printer, the method comprising:
dividing a set of inks into ink subsets, each ink subset having at least one less ink than the set of inks and where each ink in each subset is order-specific, the subsets including a CMYK subset;
determining a dominant ink to each ink subset, wherein cyan, magenta, and yellow are each considered dominant inks in the CMYK subset;
receiving a particular color identified by a color characterization value;
calculating ink recipes for each ink subset to generate the particular color;
rejecting from selection ink subsets that cannot generate the particular color within a predetermined range of variance, wherein the predetermined range of variance is no greater than 0.5 from the color characterization value; and
selecting a preferred ink subset for printing the particular color, where a preferred ink subset is that ink subset within the remaining non-discarded ink subsets wherein at least one of the calculated ink recipes calls for the maximum usage of the dominant ink, and wherein cyan, magenta, and yellow are each considered dominant inks in the CMYK subset.
2. The method of claim 1 , further comprising:
selecting a preferred ink recipe from those calculated for the preferred ink subset.
3. The method of claim 1 , wherein each ink subset includes the same number of inks.
4. The method of claim 1 , wherein the dominant ink is assigned based upon the position of that ink relative to other inks within the ink subset with the exception of black ink.
5. The method of claim 4 , wherein said dividing step includes:
organizing chromatic inks available in the set of inks in a circular, linked order;
generating the first ink subset from a predetermined of number of consecutive chromatic inks, and adding black to the end when available in the set of inks;
generating subsequent ink subsets by rotating the predetermined number of consecutive inks around the circular linked order of chromatic inks one at a time and adding black to the end; and
wherein the dominant color is assigned as an ink within each ink subset that is in the middle of the consecutive chromatic inks.
6. The method of claim 2 , wherein ink recipes calculated for each ink subset vary based on predetermined schemes of black ink usage.
7. The method of claim 6 , wherein the schemes of black usage include:
min-k; and
max-k.
8. A printer system for using reduced subsets of inks available to produce spot colors, comprising:
a set of inks which is divided into a plurality of ink subsets, each ink subset having at least one less ink than the set of inks and where each ink in each subset is order-specific, the subsets including a CMYK subset, each ink subset having an assigned dominant ink and wherein cyan, magenta, and yellow are each assigned dominant inks for the CMYK subset;
a job receipt module which receives print requests for the printer including a particular color identified by a color characterization value other than an ink recipe; and
a recipe calculator which generates ink recipes for each ink subset to generate the particular color and selects a preferred ink subset for printing the particular color, where the recipe calculator is configured to determine a preferred ink by discarding ink subsets that cannot generate the particular color within a predetermined range of variance and then subsequently selecting a non-discarded calculated ink recipe that calls for the maximum usage of the dominant ink, wherein the predetermined range of variance is no greater than 0.5 from the color characterization value.
9. The system of claim 8 , wherein the recipe calculator additionally selects a preferred ink recipe from those calculated for the preferred ink subset.
10. The system of claim 8 , wherein each ink subset includes the same number of inks.
11. The system of claim 8 , wherein the dominant ink is assigned based upon the position of that ink relative to other inks within the ink subset with the exception of black ink.
12. The system of claim 11 , wherein the set of inks is divided into ink subsets by:
organizing chromatic inks available in the set of inks in a circular, linked order;
generating the first ink subset from a predetermined of number of consecutive chromatic inks, and adding black to the end when available in the set of inks;
generating subsequent ink subsets by rotating the predetermined number of consecutive inks around the circular linked order of chromatic inks one at a time and adding black to the end; and
wherein the dominant color is assigned as an ink within each ink subset that is in the middle of the consecutive chromatic inks.
13. The system of claim 9 , wherein ink recipes calculated for each ink subset vary based on predetermined schemes of black ink usage.
14. The system of claim 13 wherein the schemes of black usage include: min-k; and max-k.
15. A method for selecting a spot color formula in a printer, the method comprising:
dividing a set of inks into ink subsets, each ink subset having at least one less ink than the set of inks and where each ink in each subset is order-specific, the subsets including a CMYK subset;
determining a dominant ink to each ink subset, wherein cyan, magenta, and yellow are each considered dominant inks in the CMYK subset;
receiving a particular color identified by a color characterization value;
calculating ink recipes for each ink subset to generate the particular color;
determining that the particular color is outside of a gamut for each of the ink subsets;
re-mapping the particular color to the gamut of the printer such that the particular color is in-gamut for at least one of the ink subsets;
rejecting from selection ink subsets that cannot generate the particular color within a predetermined range of variance, wherein the predetermined range of variance is no greater than 0.5 from the color characterization value; and
selecting a preferred ink subset for printing the particular color, where a preferred ink subset is that ink subset within the remaining non-discarded ink subsets wherein at least one of the calculated ink recipes calls for the maximum usage of the dominant ink.
16. The method of claim 15 , wherein the predetermined range of variance is determined with respect to said color characterization value.
17. The method of claim 16 , wherein the range of variance of each ink recipe is calculated from the color characterization value prior to re-mapping the gamut.
18. The method of claim 16 , wherein the range of variance of each ink recipe is calculated from the color characterization value after the re-mapping of the gamut.