Abstract: A method of characterizing an imaging system is described includes printing a color chart having a plurality of predetermined color patches; measuring the color patches to obtain colorimetric data; initializing a Neugebauer model with the Neugebauer solids of said colorimetric data; optimizing the global parameters of the Neugebauer model; optimizing the parameters associated with Demichel terms based on the Neugebauer primary associated with the Demichel term; optimizing parameters that vary with device coordinates; creating a characterization file for the imaging system.

Abstract: A method of characterizing an imaging system is described includes printing a color chart having a plurality of predetermined color patches; measuring the color patches to obtain colorimetric data; initializing a Neugebauer model with the Neugebauer solids of said colorimetric data; optimizing the global parameters of the Neugebauer model; optimizing the parameters associated with Demichel terms based on the Neugebauer primary associated with the Demichel term; optimizing parameters that vary with device coordinates; and creating a characterization file for the imaging system.

Abstract: A method for compensating for effects of illumination when comparing soft proofs to hard copy proofs viewed under non-standard illumination comprises adjusting a standard illumination display profile until estimates of device independent colors produced by the display based on the adjusted profile match the colors corresponding to the non-standard illumination within a predefined tolerance.

Abstract: A method of characterizing an imaging system is described includes printing a color chart having a plurality of predetermined color patches; measuring the color patches to obtain colorimetric data; initializing a Neugebauer model with the Neugebauer solids of said colorimetric data; optimizing the global parameters of the Neugebauer model; optimizing the parameters associated with Demichel terms based on the Neugebauer primary associated with the Demichel term; optimizing parameters that vary with device coordinates; and creating a characterization file for the imaging system.

Abstract: A method for matching colors including comparing the appearance of a first white color associated with a first color imaging system and a second white color associated with a second color imaging system, wherein the tristimulus values of the first and second white color are similar; determining a fixed correction to the tristimulus values of the second white color to achieve a visual match to the first white color; measuring a first set of spectral values for a first color associated with the first color imaging system; determining a first set of tristimulus values from the first set of spectral values; measuring a second set of spectral values for a second color associated with the second color imaging system; determining a second set of tristimulus values from the second set of spectral values; applying a correction to the tristimulus values of the second color; determining a difference between the tristimulus value of the first color and the corrected tristimulus value of the second color; and adjusting th

Abstract: A method for forming a color transform for a color printing device having a plurality of colorant channels that includes applying a tone scale adjustment function and a total colorant load limit. An optimization process is used to optimize a merit function including a tone scale reproduction accuracy term and a gamut shape term. The method involves determining an initial merit function value responsive to an initial total colorant load limit and an initial set of tone scale adjustment parameters for a tone scale adjustment function. Modified tone scale adjustment parameters and a modified total colorant load limit are determined that provide an improved merit function value subject to a constraint that an average total colorant load is no more than a predefined threshold for a predefined distribution of input colors.

Abstract: A method for applying gamut mapping to an input digital image having an associated input color gamut, to produce an output digital image having an associated output color gamut, which includes: defining a gamut mapping color transform which embodies the operations of transforming input color values from the input color space to linear RGB color values for a linear RGB color space, wherein the linear RGB color space has desirable hue preserving characteristics; transforming the linear RGB color values to determine nonlinear RGB color values; applying a 3×3 matrix transformation to the nonlinear RGB values to an opponent color space; applying a gamut mapping function to map opponent color values within the input color gamut to produce modified opponent color values within the output color gamut; and transforming the modified opponent color values to produce the output color values in the output color space.

Abstract: A method for forming a color transform for a color printing device having a plurality of colorant channels that includes applying a tone scale adjustment function and a total colorant load limit. An optimization process is used to optimize a merit function including a tone scale reproduction accuracy term and a gamut shape term. The method involves determining an initial merit function value responsive to an initial total colorant load limit and an initial set of tone scale adjustment parameters for a tone scale adjustment function. Modified tone scale adjustment parameters and a modified total colorant load limit are determined that provide an improved merit function value subject to a constraint that an average total colorant load is no more than a predefined threshold for a predefined distribution of input colors.

Abstract: A method for matching colors including comparing the appearance of a first white color associated with a first color imaging system and a second white color associated with a second color imaging system, wherein the tristimulus values of the first and second white color are similar; determining a fixed correction to the tristimulus values of the second white color to achieve a visual match to the first white color; measuring a first set of spectral values for a first color associated with the first color imaging system; determining a first set of tristimulus values from the first set of spectral values; measuring a second set of spectral values for a second color associated with the second color imaging system; determining a second set of tristimulus values from the second set of spectral values; applying a correction to the tristimulus values of the second color; determining a difference between the tristimulus value of the first color and the corrected tristimulus value of the second color; and adjusting th

Abstract: A method for forming a color transform for a color printing device having a plurality of colorant channels that includes applying a colorant control value transformation function characterized by a set of transformation function parameters. An optimization process is used to optimize a merit function including a gamut shape term. The method involves determining an initial merit function value responsive to an initial gamut shape determined using the initial set of transformation function parameters. Modified transformation function parameters are determined that produce a modified gamut shape and provide an improved merit function value.

Abstract: A method for matching colors including comparing the appearance of a first white color associated with a first color imaging system and a second white color associated with a second color imaging system, wherein the tristimulus values of the first and second white color are similar; determining a fixed correction to the tristimulus values of the second white color to achieve a visual match to the first white color; measuring a first set of spectral values for a first color associated with the first color imaging system; determining a first set of tristimulus values from the first set of spectral values; measuring a second set of spectral values for a second color associated with the second color imaging system; determining a second set of tristimulus values from the second set of spectral values; applying a correction to the tristimulus values of the second color; determining a difference between the tristimulus value of the first color and the corrected tristimulus value of the second color; and adjusting th

Abstract: A method for reproducing an image on an imaging device, including measuring a set of spectral data for each of a plurality of colors from a set of color device values with a spectral measurement device; determining a first set of tristimulus values corresponding to each set of spectral data; defining a set of human observer color matching functions for each set of tristimulus values; determining a second set of tristimulus values for each set of spectral data using the human observer color matching functions; creating a first map from device-dependent coordinates to device-independent color coordinates; creating a second map from device-independent coordinates to device-dependent color coordinates based on the first map; obtaining image data comprising device-independent color coordinates; converting the image data coordinates into device color coordinates; and reproducing the image on the color device using the device color coordinates.

Abstract: A method for matching colors includes providing a first source of a first color and a second source of a second color; measuring a set of spectral values for first color stimuli associated with the first color; calculating a first set of tristimulus values; defining a first set of human observer color matching functions; calculating a first set of corrected tristimulus values from the first set of spectral values using the first set of human observer color matching functions; measuring a second set of spectral values for second color stimuli associated with the second color; calculating a second set of tristimulus values; defining a second set of human observer color matching functions; calculating a second set of corrected tristimulus values from the second set of spectral values; determining a difference between the first and second set of corrected tristimulus values; and adjusting one of the sources to reduce the difference.

Abstract: A method of characterizing an imaging system is described includes printing a color chart having a plurality of predetermined color patches; measuring the color patches to obtain colorimetric data; initializing a Neugebauer model with the Neugebauer solids of said colorimetric data; optimizing the global parameters of the Neugebauer model; optimizing the parameters associated with Demichel terms based on the Neugebauer primary associated with the Demichel term; optimizing parameters that vary with device coordinates; creating a characterization file for the imaging system.

Abstract: A method of characterizing an imaging system is described includes printing a color chart having a plurality of predetermined color patches; measuring the color patches to obtain colorimetric data; initializing a Neugebauer model with the Neugebauer solids of said colorimetric data; optimizing the global parameters of the Neugebauer model; optimizing the parameters associated with Demichel terms based on the Neugebauer primary associated with the Demichel term; optimizing parameters that vary with device coordinates; and creating a characterization file for the imaging system.

Abstract: A method of characterizing an imaging system is described includes printing a color chart having a plurality of predetermined color patches; measuring the color patches to obtain colorimetric data; initializing a Neugebauer model with the Neugebauer solids of said colorimetric data; optimizing the global parameters of the Neugebauer model; optimizing the parameters associated with Demichel terms based on the Neugebauer primary associated with the Demichel term; optimizing parameters that vary with device coordinates; and creating a characterization file for the imaging system.

Abstract: A method for characterizing a color in terms of tristimulus values, the method includes providing a source of a color; measuring a set of spectral values for color stimulus associated with the color using a spectral measurement device controlled by a digital processing system; calculating a first set of tristimulus values from the set of spectral values; defining a set of human observer color matching functions, the set of human observer color matching functions being functions of the tristimulus values; and determining a second set of tristimulus values from the set of spectral values using set of human observer color matching functions.

Abstract: A method for characterizing the color response of an imaging device, the method includes reproducing a color on the imaging device based on a set of device color coordinates; measuring spectral values for the reproduced color with a spectral measurement device controlled by a digital processing system; calculating a first set of tristimulus values from the spectral values; defining a set of human observer color matching functions, the set of human observer color matching functions being functions of the first set of tristimulus values of the reproduced color; calculating a second set of tristimulus values from the spectral values using the defined set of human observer color matching functions; and associating the reproduced device color coordinate with the second set of tristimulus values.

Abstract: A color measurement device includes an aperture for obtaining light from a color sample to be measured; a plurality of sets of color filters associated with human observer functions at different regions of color space; at least one detector for measuring the intensity of filtered light; an analog to digital converter for converting voltage signals from the at least one detector to digital values representative of tristimulus values associated with each of the sets of color filters; and a processor to combine the sets of tristimulus values in order to calculate a final set of tristimulus values, the combining being a function of at least one of the sets of tristimulus values.

Abstract: A method for applying gamut mapping to an input digital image having an associated input color gamut, to produce an output digital image having an associated output color gamut, which includes: defining a gamut mapping color transform which embodies the operations of transforming input color values from the input color space to linear RGB color values for a linear RGB color space, wherein the linear RGB color space has desirable hue preserving characteristics; transforming the linear RGB color values to determine nonlinear RGB color values; applying a 3×3 matrix transformation to the nonlinear RGB values to an opponent color space; applying a gamut mapping function to map opponent color values within the input color gamut to produce modified opponent color values within the output color gamut; and transforming the modified opponent color values to produce the output color values in the output color space.