Patent Document ID: 8085434
Application ID: 12052909
Patent Status: 1

Claim One:
1. A method for predicting the appearance of a color print viewed under UV illumination, said method comprising the steps of: using a multi-colorant digital printer to print a multi-colorant target comprising a plurality of color patches each printed using a known coverage of one or more of a plurality of printer colorants; illuminating the target using a UV light source; capturing an electronic image of the multi-colorant target while illuminated with the UV light source, wherein said electronic image comprises a plurality of color signals acquired for each color patch of said multi-colorant target; using at least one of the plurality of color signals for each color patch to compute a prediction of luminance under UV light for each color patch of said multi-colorant target; from the prediction of luminance under UV light for each color patch, deriving a UV printer characterization model that relates any arbitrary combination of said printer colorants to a predicted UV luminance, said predicted UV luminance for said combination of printer colorants indicating a relative luminance ordering resulting from printing a document using such combination of printer colorants and viewing the document while the document is illuminated with a UV light source; correcting said UV printer characterization model based upon input received from human observers performing a visual matching task, wherein said visual matching task comprises: printing a visual matching target comprising solid color regions including: (i) a 100% colorant coverage region for each of said printer colorants; and, (ii) a 100% colorant coverage overprint region for each two color combination of said printer colorants; printing a plurality of black regions of respectively varying black colorant coverages adjacent to each of said solid color regions; illuminating said visual matching target with a UV light source; while said visual matching target is illuminated with said UV light source, and for each solid color region, receiving input from a human observer identifying one of said black regions that most closely matches the luminance of the solid color region; for each solid color region, deriving a solid color correction factor based on the luminance predicted by the UV printer characterization model for the solid color region and the luminance predicted by the UV printer characterization model for the corresponding matching black region according to the equation: 
 CF =B k / B where CF is the correction factor, B is the luminance of the solid color region as predicted by the UV printer characterization model, and B K is the luminance of the corresponding matching black region as predicted by the UV printer characterization model; for an arbitrary colorant coverage combination of said printer colorants in said UV printer characterization model, deriving an arbitrary coverage correction factor based upon the solid color correction factors, and; applying the arbitrary coverage correction factor to obtain a corrected predicted luminance for the arbitrary colorant coverage combination in said UV printer characterization model by multiplying the arbitrary coverage correction factor derived for that colorant combination by the luminance predicted by the UV printer characterization model for that colorant combination.