Characterizing unprinted paperboard surface for predicting optically induced halftone mottle

摘要

Optically induced mottle in halftone prints reduces perceived print quality. A new model is proposed to predict optically induced halftone mottle without requiring printing of the paper surface. It is based on Hotelling's multivariate paired T-2 statistic computed from colorimetric coordinates obtained from a knife edge shadow image response on unprinted paperboard surface. The proposed T-2 index is shown to characterize the paper surface's lateral light scattering variability. An analysis of the behavior of lateral light scattering of a paper or board surface at different spatial scales is presented here in conjunction with other potential contributing factors including fibre floc distribution, coating coverage uniformity and surface topography. The proposed T-2 index performs well in predicting the visual perception of primary greyscale mottle, and it is useful in analyzing the underlying papermaking causes that lead to halftone mottle induced by optical phenomena.