Calibrating the Yule–Nielsen Modified Spectral Neugebauer Model with Ink Spreading Curves Derived from Digitized RGB Calibration Patch Images

“ b h o f t M d c 0 o t t p t d t d bstract. The Yule–Nielsen modified spectral Neugebauer model YNSN) enhanced for accounting for ink spreading in the different nk superposition conditions requires a spectrophotometer to meaure the reflectances of halftone calibration patches in order to comute the ink spreading curves mapping nominal ink surface coverge to effective ink surface coverage. Instead, as a first step owards the “on the fly” characterization of printers, we try to deduce he ink spreading curves from digitized RGB images of halftone caliration patches. By applying the Yule–Nielsen broadband formula to he average RGB intensities, we deduce the effective dot surface overages of halftone calibration patches. We then establish the ink preading curves mapping nominal dot surface coverages to effecive dot surface coverages. By weighting the contributions of the ifferent ink spreading curves according to the ratios of colorant urface coverages, we predict according to the YNSN model the eflectance spectra of the test patches. We compare the prediction ccuracy of the YNSN model calibrated by digitized RGB intensities f the calibration patches with the prediction accuracy of the same odel calibrated by the spectral reflectances of these calibration atches. The decrease in spectral prediction accuracy due to GB model calibration is about 30% for ink jet prints and 10% for hermal transfer prints. © 2008 Society for Imaging Science and echnology. DOI: 10.2352/J.ImagingSci.Technol. 2008 52:4 040908