Method for generating customized ink/media transforms

1. A method of generating an ink/media transform for a target device, comprising the steps of:

selecting an ink type;

selecting a color set;

selecting a media type;

selecting an ink saturation level;

generating a set of linearization ramps;

measuring the linearization ramps;

generating a set of target patches, wherein each generated patch has corresponding Lab values;

measuring the target patches;

screening the measured target patches and generating a boundary surface of a gamut for the target device, wherein the step of screening each target patch comprises the steps of:

accepting a patch having a threshold maximum lightness value (L) value for a preselected ink coverage value and discarding patches having an ink coverage value that is higher than the threshold maximum lightness value (L);

implementing under-color removal and black generation; and

building the transform.

2. The method as claimed in claim 1 , including the step of:

converting the Lab values for each patch to CIEXYZ values, and subsequently resetting them to back to CIELab values.

3. The method as claimed in claim 1 , including the step of eliminating patches that contain an ink coverage amount that is inconsistent with a specified hue value.

4. The method as claimed in claim 3 , including the steps of:

(a) identifying and discarding patches that satisfy criterions of both containing 100% of a non-primary color and containing less than 100% of a non-primary ink that comprises the color;

(b) identifying and discarding patches tat satisfy criterions of both containing 75% of the non-primary color and containing less than 75% of the non-primary ink that comprises the color; and

repeating steps (a) and (b) for all non-primary color ink levels of the color set.

5. The method as claimed in claim 1 , including the steps of:

(a) identifying and discarding patches that satisfy criterions of both containing 100% of a non-primary color and containing less than 100% of a non-primary ink that comprises the color;

(b) identifying and discarding patches that satisfy criterions of both containing 75% of the non-primary color and containing less than 75% of the non-primary ink that comprises the color; and

repeating steps (a) and (b) for all non-primary color ink levels of the color set.

6. The method as claimed in claim 5 including the steps of:

eliminating patches with color values that include pure black ink.

7. The method as claimed in claim 1 , wherein the step of screening each generated target patch comprises the steps of:

accepting a patch having at least a threshold chroma value for a preselected ink coverage value and discarding patches having an ink coverage value that is higher than the threshold chroma value.

8. A method of generating an ink/media transform for a target device in which an ink type, a color set media type and an ink saturation level have all been selected, a set of linearization ramps have been generated and measured, and a set of target patches have been generated and measured, the method comprising the steps of:

screening the set of target patches, wherein each generated patch has corresponding Lab values, wherein the step of screening each generated target patch comprises the steps of:

(a) accepting a patch having a threshold maximum lightness value (L) value for a preselected ink coverage value and discarding patches having an ink coverage value that is higher than the threshold maximum lightness value (L);

(b) accepting a patch having at least a threshold maximum chroma value for a preselected ink coverage value and discarding patches having an ink coverage value that is higher than the threshold maximum chroma value;

(c) eliminating patches that contain an ink coverage amount that is inconsistent with a specified hue value;

(d) identifying and discarding patches that satisfy criterions of both containing 100% of a non-primary color and containing less than 100% of a non-primary ink that comprises the color;

(e) identifying and discarding patches that satisfy criterions of both containing 75% of the non-primary color and containing less than 75% of the non-primary ink that comprises the color; and

(f) repeating steps (d) and (e) for all non-primary color ink levels of the color set;

(g) eliminating patches with color values that include pure black ink;

determining in-gamut and out-of-gamut colors for the transform by using a 3-dimensional Delauney Tessellation, wherein each vertice corresponds to a coordinate point position of a target patch, and a final gamut boundary re-shaping method used in a profile building process;

performing 3-dimensional interpolation from nearby vertices when transforming color values for colors that are not directly represented in the LUT data set; and

building the transform includes the steps of:

constructing a hypercube of dimensions 15×15×15 uniformly spaced points in a CIELab color space;

creating a look-up table containing a transformation value for each of the selected color patch values by indexing the corresponding Lab values to corresponding coordinates in the color space;

implementing a baricentric interpolation and gamut-mapping procedure to fill out the transform LUT with a complete set of values.

9. The method as claimed in claim 8 , including the step of extending the 15×15×15 hypercube to a 100×100×100 hypercube to create a transform file by using a tri-linear interpolation wherein a color point is found from vertices of a tetrahedron that fall within a color space tessellation.

10. The method as claimed in claim 9 , including the step of interpolating the ink values from the tessellation by using a gamut-mapping algorithm for Lab points outside the tessellation, in which a gamut-mapping algorithm attempts to locate a position on the gamut edge that is at a same hue angle and provides a desired result.

11. A method of generating an ink/media transform for a target device, comprising the stops of:

selecting an ink type;

selecting a color set;

selecting a media type;

selecting an ink saturation level;

generating a set of linearization ramps;

measuring the linearization ramps;

generating a set of target patches;

measuring the target patches;

screening the measured target patches and generating a boundary surface of a gamut for the target device, wherein the step of screening each generated target patch comprises the steps of accepting a patch having at least a threshold maximum chroma value for a preselected ink coverage value and discarding patches having an ink coverage value that is higher than the threshold maximum chroma value;

implementing under-color removal and black generation; and

building the transform.

12. The method as claimed in claim 11 , including the step of eliminating patches that contain an ink coverage amount that is inconsistent with a specified hue value.

13. The method as claimed in claim 11 , including the steps of:

(a) identifying and discarding patches tat satisfy criterions of both containing 100% of a non-primary color and containing less than 100% of a non-primary ink that comprises the color;

(b) identifying and discarding patches that satisfy criterions of both containing 75% of the non-primary color and containing less than 75% of the non-primary ink that comprises the color; and

repeating steps (a) and (b) for all non-primary color ink levels of the color set.

14. A method of generating an ink/media transform for a target device, comprising the steps of:

selecting an ink type;

selecting a color set;

selecting a media type;

selecting an ink saturation level;

generating a set of linearization ramps;

measuring the linearization ramps;

generating a set of target patches;

measuring the target patches;

screening the target patches and generating a boundary surface of a gamut for the target device, and determining in-gamut and out-of-gamut colors for the transform by using a 3-dimensional Delauney Tessellation, wherein each vertice corresponds to a coordinate point position of a target patch;

implementing under-color removal and black generation; and

building the transform.

15. The method as claimed in claim 14 , including the step of performing 3-dimensional interpolation from nearby vertices when transforming color values for colors that are not directly represented in a LUT data set.

16. A method of generating an ink/media transform for a target device, comprising the steps of:

selecting an ink type;

selecting a color set;

selecting a media type;

selecting an ink saturation level;

generating a set of linearization ramps;

measuring the linearization ramps;

generating a set of target patches, wherein each generated patch has corresponding Lab values;

measuring the target patches;

screening the target patches and generating a boundary surface of a gamut for the target device;

implementing under-color removal and black generation; and

building the transform, including the steps of:

constructing a hypercube of dimensions 15×15×15 uniformly spaced points in the CIELab color space;

creating a look-up table containing a transformation value for each of the selected color patch values by indexing the corresponding Lab values to corresponding coordinates in the color space; and

implementing a baricentric interpolation and gamut-mapping procedure to fill out the transform LUT with a complete set of values.

17. The method as claimed in claim 16 , including the step of:

extending the 15×15×15 hypercube to a 100×100×100 hypercube to create a transform file using a tri-linear interpolation wherein a color point is found from vertices of a tetrahedron that fall within a color space tessellation.

18. The method as claimed in claim 17 , including the steps of providing correspondence between an ICC profile and a custom transform by creating a cube the size of the ICC cube and then scaling it up linearly.

19. The method as claimed in claim 18 , including the step of interpolating the ink values from the color space tessellation by using a gamut-mapping algorithm for Lab points outside the tessellation, in which the gamut-mapping algorithm attempts to locate a position on the gamut edge that is at a same hue angle and provides a desired result.

20. The method as claimed in claim 17 , including the steps of providing correspondence between an ICC profile and a custom transform by creating a cube the size of the ICC cube and then scaling it up linearly.