International Business Machines Corporation

William Chesley Decker

Jack Louis Zable

Ho Chong Lee

Toner/ink is saved while still being able to print any given color value within the full color gamut of a given printer. Combinations of varying percentages of a printer's toners/inks (cyan, magenta, yellow and black) are determined for maximum black substitution with varying percentages of under color addition (UCA) (e.g., 0%, 50%, 80%, and 100%). Patches of varying combinations of CMYK using maximum black substitution and a given percentage of UCA are printed out, and the color value (L*a*b*) of each patch is measured. Tables are generated having the percentage amounts of C,M,Y, and K and the corresponding measured color value. A first table represents maximum black substitution with 0% UCA. If a desired color value falls within this table, the corresponding CMYK combination represents the most toner/ink that can be saved. If a desired color value does not fall within the first table, subsequent tables representing increasing percentage amounts of UCA are examined. If the color is not found in any of the tables, the requested CMYK is unaltered. When the table is found, the corresponding CMYK combination, found through inversion and interpolation, saves some toner/ink while still being able to print the desired color value contained within that particular color gamut. The method is typically used to build a CMYK-to-CMYK transform table which the printer can use to print multi-color images with the minimum possible toner/ink usage and without sacrificing the image quality.

System, method, and program for saving toner/ink in a color printer without sacrificing image quality

A unique combination of four colorants (C&prime;M&prime;Y&prime;K&prime;) of a given printer that is equivalent to an externally defined four colorant combination (CMYK) by having the same color values (e.g., L*a*b* values). A fourth colorant, e.g., black, (K) of the externally defined four colorant combination is mapped to an equivalent fourth colorant (K&prime;) of the printer by matching optical density, reflectance, L* or similar color value. The L* value is found for various percentages of the fourth colorant of the printer by printing varying percentages of the fourth component and measuring its L*a*b* values and, assuming a* and b* are near zero, using the L* value. These values are inputted into an interpolation program. Then, patches of varying percentages of each one of the three color components of the printer (CMY) are printed out at varying percentages. The L*a*b* values for each patch are measured and inputted into an inversion/interpolation program along with the corresponding percentages of colorants of each patch. The externally defined four component colorant having L*a*b* values also used in the inversion/interpolation program, which creates a color transform table from CMY with various percentages of K of the externally defined four dimensional colorant to C&prime;M&prime;Y&prime; with various percentages of K&prime; of the four dimensional colorant of the printer by matching L*a*b* values.

Enhanced system, method and program for converting an externally defined four dimensional colorant (CMYK) into an equivalent four dimensional colorant defined in terms of the four inks (C&prime;M&prime;Y&prime;K&prime;) that are associated with a given printer

The system, method, program, and print pattern of this invention allows print misregistration to be detected and controlled through density measurements. A special print pattern is used for which a correlation between a density measurement of the print pattern and an amount of misregistration can be made. Initially, for a given printer, and for each printing station within the printer, the special print pattern is printed using two printing stations at varying amounts of misregistration of one of the printing stations. The density of each special print pattern printed at the varied amount of misregistration is measured. A correlation is made between density and amount of misregistration of the one printing station relative to the other printing station. Whenever misregistration is desired to be determined, the special print pattern is printed, the density is measured, and the correlation is applied to the measured density to determine a misregistration amount.

System, method, program, and print pattern for performing registration calibration for printers by measuring density

A method and apparatus for controlling the density of the printed medium of a printer is provided and comprises the following steps. First a control strip is printed on the print medium having at least two coverage patches having a first and second different standard density. Next, the optical density of each of the patches are measured. Next a first and second tolerance limit is determined for the first and second patch, respectively. The next step is to determine whether the measured optical density of the first patch is within a first tolerance of the first standard density. If the first measured optical density is not within tolerance of the first standard density, then a change of at least one printer parameter is calculated such that the first density is corrected within the first tolerance. Then the effect of the change of the printer parameters on the second optical density is determined. If the second optical density with the effect is not within the second tolerance, then a change of at least one other printer parameter is calculated so that the second optical density with the effect is within the second tolerance, while the first optical density is still within its tolerance. Next, new printer parameter settings are calculated from the printer parameter changes. Last, the printer parameters are automatically adjusted to the new settings.

Density control for a printer

Disclosed is a method, system, and program for converting an externally defined four dimensional colorant, e.g., CMYK, to an equivalent four dimensional colorant, e.g., C'M'Y'K, having components of a printer. A measurement is made of first color values, e.g., L.sup.* a.sup.* b, of a first set of patches having predetermined combinations of varying percentages of three primary colors, e.g., CMY, printed by the printer. Each combination of known CMY values are correlated with corresponding color values, e.g., L.sup.* a.sup.* b, as input to a first inversion program for determining CMY values for any given color value (L.sup.* a.sup.* b). A measurement is also made of second color values, e.g., L.sup.* a.sup.* b, of a second set of patches having predetermined varying percentages of a fourth colorant (K) printed by the printer. The first inversion program is used to determine CMY values corresponding to the color values, L.sup.* a.sup.* b, for the varying percentages of the fourth colorant (D). These determined CMY values corresponding to the second set of patches (D) and the known CMY values of the first set of patches are used to determine an equivalent fourth colorant substitution for the first patches having new CMY (C'M'Y') values and a corresponding percentage of the fourth colorant (D). Each combination of the C'M'Y' and K are correlated with associated color values as input to a second inversion program for determining C'M'Y'K values for any given color values or equivalent values.

System, method and program for converting an externally defined colorant

The system, method, and program of this invention is capable of taking as input a three dimensional colorant (e.g., CMY, L*a*b*) and determining an equivalent combination of colors made up of four or more colorants that are used by a given printer. A plurality of patches are printed having predetermined known combinations of varying percentages of three primary colors (e.g., CMY). Another set of patches are printed having predetermined varying percentages of a fourth color (e.g., black). The L*a*b* of these patches are measured. An inversion program is used to determine equivalent CMY component percentage values for the varying percentages of the fourth component based upon similar actually measured L*a*b* values. These determined CMY component percentage values and the known percentages of CMY are used to substitute the fourth colorant (K) for each of the original CMY combinations, known as fourth colorant substitution or black substitution.

System, method, and program for converting three dimensional colorants

A system, method, and program of the invention determine a unique combination of four colorants (C'M'Y'K') of a given printer that is equivalent to an externally defined four colorant combination (CMYK) by having the same color values (e.g., L*a*b* values). L*a*b* values associated with each three component combination (CMY) with the fourth component value (K) equal to zero of the externally defined four colorant combination (CMYK) are used in an inversion/interpolation program The printer also prints out a matrix of predetermined varying combinations of the three colorants of the printer (CMY)p with the fourth colorant K equal to zero. L*a*b* values are measured for each patched. These values and the corresponding three colorant combination values are inputted into the inversion/interpolation program. For any given externally defined three colorant combination (CMY), or L*a*b* value, a corresponding three colorant combination (C'M'Y') of the printer can be determined from the inversion/interpolation program by matching L*a*b* values. Then, a fourth colorant, e.g., black, (K) of the externally defined four colorant combination is mapped to an equivalent fourth colorant (K') of the printer by matching color values (e.g., L*). For example, the L* value is found for various percentages of the fourth colorant through standard tables where C=0, M=0, Y=0. The L* value is found for various percentages for the fourth colorant of the printer by printing varying percentages of the fourth component and measuring its L*a*b* values and, assuming a* and b* are near zero, using the L* value. As such, the conversion takes place in two steps, from CMY to C'M'Y' and from K to K'.

System, method and program for converting an externally defined four

A system, method, and program for generating a color rendering dictionary file or look-up table for an equivalent device dependent four component colorant combination for a given printer from a given device independent three dimensional color space. First input parameters are comprised of varying percentage amounts of an additional fourth colorant and corresponding measured color values for varied percentage amounts of the additional fourth colorant. Second input parameters are comprised of varying percentage amounts of three base colorants and corresponding measured color values for varied percentage amounts of the three base colorants. Percentage amounts of the three base colorants (three colorant values) for each varied percentage amount of the additional fourth colorant are determined from the sets of measured color values. The percentage amounts of the three base colorants with the additional fourth colorants are determined, such that the fourth colorants are equivalent to the varied percentage amounts of the base colorants. The determined four colorant values are then correlated with the measured color values of each of the equivalent varied amounts of the three base colorants. A look-up or color dictionary is used to find correlated four colorant values for any given color.

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Longmont, CO, United States of America

William Chesley Decker