Calibrating the ink spreading curves enhanced Yule-Nielsen modified spectral Neugebauer model with the two-by-two dot centering printer model

Abstract

The Yule-Nielsen modified spectral Neugebauer model enhanced for accounting for ink spreading in the different ink superposition conditions (EYNSN) requires measuring the reflectances of halftone calibration patches in order to compute the ink spreading curves mapping nominal ink surface coverages to effective ink surface coverages. Spectral measurements of dozens of halftone patch reflectance spectra for each considered halftoning method, screen shape or screen frequency variant is cumbersome and time consuming. As an alternative, we compute automatically the reflectance of the calibration patches necessary to establish the ink spreading curves by making use of the two-by-two dot centering model (abbreviated "2-by-2"). The two-bytwo dot centering model requires its own set of calibration patches, among which a very small subset is necessary for predicting the reflectance of the EYNSN calibration patches. For a given combination of printer, paper and inks, using only 68 two-by-two calibration patches for the three CMY inks, respectively 118 twoby-two calibration patches for the four CMYK inks, we are able to predict the reflection spectra of most classical halftone screens and at many different frequencies. We compare the results of predictions where the EYNSN model calibration patches are measured or are predicted with the two-by-two dot centering model. For 125 (CMY) and 625 (CMYK) uniformly distributed patches printed with an ink-jet printer at three different screen frequencies (75lpi, 100lpi and 125lpi), the mean reflectance prediction accuracy is similar, i.e. the decrease in accuracy due to the two-by-two prediction of EYNSN calibration patch reflectance is less than ΔE 94 =0.4.

Specular color imaging on a metallic substrate

“…This model has been further improved by subdivision of the ink surface coverage space [14] and by accounting for ink spreading within each subspace. This yields for prints on paper very accurate predictions [15].…”

“…We presented a full reproduction workflow for printing color images on metallic substrates. This color reproduction workflow relies on the ink spreading enhanced cellular Yule-Nielsen modified spectral Neugebauer model [15]. The model is calibrated with 35 uniform color samples printed on the metal film measured under specular reflection.…”

“…For the characterization of the target printer, it would be tedious to follow the black box approach and to try to measure more than thousand samples in specular mode. We therefore made use of the cellular Yule-Nielsen modified spectral Neugebauer prediction model enhanced to account for ink spreading (IS-CYNSN), see [15].…”

Review of spectral reflectance models for halftone prints: Principles, Calibration, and prediction accuracy

“…Let us describe in detail the cellular Yule‐Nielsen model with one subdivision level . The subdomain primaries are formed by surface coverages at all combinations of 0%, 50%, and 100% surface coverages (3 3 = 27 combinations).…”

Gamut expanded halftone prints

“…The ink spreading enhanced cellular Yule-Nielsen spectral prediction model (IS-CYNSN) [6] is remarkably accurate for predicting the spectral reflectances of halftones comprising daylight fluorescent inks. It achieves a mean prediction error of ∆E 94 of 0.7 when predicting the total spectral reflectances of 125 uniformly distributed halftones comprising at least one daylight fluorescent ink.…”