System and method for accurately reproducing color
View Patent ↗A method of determining the OD of a printed colorant, comprising: determining a visible wavelength region in which the color is at or near saturation; and if a portion of a determination of saturation is found, determining the OD in a wavelength region at which the color is not at or near saturation.
1. A method of determining the optical density (OD) of a printed colorant, comprising:
determining a visible wavelength region in which the color is at or near saturation; and
if a portion of a determination of saturation is found, determining the OD in a wavelength region at which the color is not at or near saturation.
2. A method according to claim 1 and including, if none of the visible wavelength region is at or near saturation:
determining the OD in a wavelength region at which the spectrum of light reflected from the colorant is a minimum.
3. A method according to claim 2 and comprising:
acquiring a reflection spectrum of the printed colorant including at least a wavelength region in which the color is not at or near saturation, wherein the OD is determined based on a reflectance measurement at a wavelength in which the color is not at or near saturation.
4. A method according to claim 1 and comprising:
acquiring a reflection spectrum of the printed colorant including at least a wavelength region in which the color is not at or near saturation, wherein the OD is determined based on a reflectance measurement at a wavelength in which the color is not at or near saturation.
5. A method according to claim 2 wherein determining the OD comprises:
filtering light reflected from the colorant through a filter which passes at least a portion of the wavelength region in which the color is not at or near saturation; and
measuring the filtered reflected light.
6. A method according to claim 1 wherein determining the OD comprises:
filtering light reflected from the colorant through a filter which passes at least a portion of the wavelength region in which the color is not at or near saturation; and
measuring the filtered reflected light.
7. A method according to claim 6 , and including choosing the filter from a plurality of filters, wherein choosing comprises:
determining which of the filters in the plurality of filters blocks a maximum amount of the reflected light without saturation of the measurement.
8. A method according to claim 5 , and including choosing the filter from a plurality of filters, wherein choosing comprises:
determining which of the filters in the plurality of filters blocks a maximum amount of the reflected light without saturation of the measurement.
9. A method according to claim 8 , wherein the colorant is a process color and wherein the plurality of filters comprise a filter associated with each of the process colors, each said filter selectively passing only wavelengths for which the colorant has a high absorption and including:
determining which of the filters that do not cause a saturation condition in the measurement of OD, blocks a maximum of the reflected light; and
utilizing the thus determined filter to filter the reflected light prior to measurement.
10. A method according to claim 7 , wherein the colorant is a process color and wherein the plurality of filters comprise a filter associated with each of the process colors, each said filter selectively passing only wavelengths for which the colorant has a high absorption and including:
determining which of the filters that do not cause a saturation condition in the measurement of OD, blocks a maximum of the reflected light; and
utilizing the thus determined filter to filter the reflected light prior to measurement.
11. A method according to claim 10 wherein the filter is a filter other than the filter associated with the process color.
12. A method according to claim 9 wherein the filter is a filter other than the filter associated with the process color.
13. A method for determining the diffuse reflection from the surface of a printed colorant comprising;
printing the colorant with a thickness such that the color is saturated in a given wavelength band; and
measuring the diffuse reflection of light from the printed colorant in said wavelength band.
14. A method according to claim 13 wherein measuring the diffuse reflection comprises measuring the diffuse reflection of light from the surface through a filter that selectively passes light only in the given wavelength band.