Patent Document ID: 9497356
Application ID: 14747184
Patent Status: 1

Claim One:
1. A method for reproducing an input color image on a metallic layer with cyan, magenta, yellow and white inks, said reproduced color image providing a high quality appearance both under specular and non-specular observation conditions, the method comprising a preparation and a printing phase, where the preparation phase comprises the steps of: (i) creating and calibrating models for predicting colors obtainable with known surface coverages of cyan (c), magenta (m), yellow (y) and white (w) ink halftones under both specular and non-specular viewing conditions; (ii) computing optimal sub-gamuts under the specular and the non-specular viewing conditions containing colors that are printable and that provide the closest distance to input colors, both under the specular and the non-specular viewing conditions; (iii) mapping input RGB colors to the optimal specular and non-specular sub-gamuts, obtaining optimal surface coverages of the c, m, y, w inks by minimizing the distances between said mapped colors and printable colors both under the specular and the non-specular viewing conditions and filling a color reproduction table creating a correspondence between said input RGB colors and said optimal surface coverages of the c, m, y, w inks; said minimization of distances between said mapped and said printable colors providing the high-quality appearance under both the specular and the non-specular viewing conditions; and where the printing phase comprises the steps of (a) obtaining from input image RGB colors by accessing said color reproduction table the c, m, y, w ink surface coverages providing the high-quality appearance under both the specular and the non-specular viewing conditions and creating with said optimal c, m, y, w ink surface coverages cyan, magenta, yellow and white color separation layers; (b) halftoning said color separation layers and sending them to the printer.