Patent ID: 7423778
Filing Date: 2008-09-09
Classification: G06K,H04N

Abstract:
1. A method for the control of printer actuation parameters relying on the computation of differences between initial values of relative ink thicknesses and inferred values of relative ink thicknesses obtained at printing time from polychromatic halftones, said relative ink thicknesses being deduced by using a spectral prediction model, said spectral prediction model comprising single ink transmittance spectra computed from measured solid ink patch reflection spectra, and transmittance spectra of superposed inks expressed as multiplications of contributing single ink transmission spectra raised to the power of their respective relative thicknesses, the method comprising the steps of: (a) calibrating the spectral prediction model by calculating from spectral reflectance measurements of paper printed with a single solid ink said single ink transmittance spectra and by deducing from spectral measurements of ink halftones mappings of nominal surface coverages of ink halftones to effective surface coverages of ink halftones; (b) inferring from measurements of paper printed with superposed solid inks using said spectral prediction model said initial values of relative thicknesses of said superposed solid inks; (c) acquiring at printing time a triplet of color coordinates of a polychromatic halftone element; (d) using said triplet of color coordinates for deducing from the calibrated spectral prediction model said inferred values of relative thicknesses; (e) comparing the initial values of relative thicknesses with the inferred values of relative thicknesses; and (f) according to said comparison, acting on the printer actuation parameters.