Methods and apparatus for calibrating a digital color imaging device that uses multi-hue colorants
AssigneeElectronics for Imaging, Inc.
InventorsMario Kühn, Samer Mady
Life of this patent
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Abstract
Methods and apparatus are provided for calibrating a digital color imaging device to a printing press by determining a total colorant limit, per-channel colorant limits, and channel linearization tables using colorimetric and/or spectrophotometric techniques. In addition, for digital color imaging devices that use multi-hue colorants, methods and apparatus are provided for determining distribution functions for the multi-hue colorants as a function of input values.
Claims20
A method for calibrating a digital color imaging device to a printing press by determining a plurality of distribution functions for a plurality of multi-hue colorants, the method comprising:
- printing a test pattern comprising a plurality of patches, each patch comprising a plurality of colorimetric values;
- measuring a plurality of colorimetric values for each patch including at least a first shade of a colorant and at least one additional shade of said colorant;
- calculating a first tonal response of said range of hues of said colorant from said measured colorimetric values;
- calculating at least one additional tonal response of said at least one additional range of hues of said colorant from said measured colorimetric values;
- calculating a tonal response of said printing press;
- calculating a first distribution over a first range of input values;
- calculating a second distribution over a second range of input values;
- creating a table of tonal responses including said first range of input values and said second range of input value;
- and
- calculating a normal distribution including the full range of input values.
A system for calibrating a digital color imaging device to a printing press by determining a plurality of distribution functions for a plurality of multi-hue colorants comprising:
- a color output device for printing a test pattern comprising a plurality of patches, each patch comprising a plurality of colorimetric values;
- a measurement device for measuring a plurality of colorimetric values for each patch including at least a first shade of a colorant and at least one additional shade of said colorant;
- a processor for calculating a first tonal response of said range of hues of said colorant from said measured colorimetric values and for calculating at least one additional tonal response of said at least one additional range of hues of said colorant from said measured colorimetric values;
- a processor for calculating a tonal response of said printing press from 0 to 100%;
- a processor for calculating a first light distribution from 0% to a lower limit;
- a processor for calculating a second light distribution from a lower limit to 100%;
- a processor for creating a table of light-normal tonal responses from a lower limit to 100%;
- and
- a processor for calculating a normal distribution.
Dependencies are inferred from the claim text.