Light scattering and ink penetration effects on tone reproduction

Abstract

Light scattering, or the so-called Yule-Nielsen effect, and ink penetration into the substrate paper play important roles in tone reproduction. We develop a framework in which the influences of both of these effects on the reflectance and tristimulus values of a halftone sample are investigated. The properties of the paper and the ink and their bilateral interaction can be parameterized by the reflectance Rp(o) of the substrate paper, the transmittance Ti of the ink layer, the parameter gamma describing the ink penetration, and p describing the Yule-Nielsen effect. We derive explicit expressions that relate the reflectance of the ink dots (Ri), the paper (Rp) and the halftone image (R) as functions of these parameters. We also describe the optical dot gain as a function of these parameters. We further demonstrate that ink penetration leads to a decrease in optical dot gain and that scattering in the paper results in the printed image's being viewed as more saturated in color.

Reflectance and transmittance model for recto-verso halftone prints

“…(12)]. Each element of irradiance is reflected by the interface with a factor of R 10 ͑ 1 ͒ and traverses twice, before and after the reflection, a path of relative length 1 / cos 1 within the inked layer.…”

“…[10][11][12] Reflectance models accounting for the internal Fresnel reflections are extensions of the Clapper-Yule model [13][14][15] or of the Kubelka-Munk model. 16 Recent extensions of the Kubelka-Munk model [17][18][19] concern absorbing and inhomogeneous scattering media, such as prints in which the solid ink partially penetrates into the diffusing substrate.…”

Spectral reflection and dot surface prediction models for color halftone prints

“…[14][15][16] Since the point spread function can also be viewed as a probability density, probability models were proposed to describe the lateral scattering of light within the paper bulk. [17][18][19][20] The models described by Eq. ͑4͒ assume that light traverses the ink layer, is laterally scattered and reflected by the paper, traverses a second time the ink layer ͑at a different position due to lateral scattering͒, and exits from the printed paper.…”

Base Models for Color Halftone Reproduction

“…Some of them are described in this book. Let us mention hdi053 initially published in [23], [24], [25], hdi052, hdi054 published in [26], hdi055, initially published in [27], [28], [29], [30], the KubelkaMunk model, see hdi062, Section 7 initially published in [31], [32] as well as ink penetration models [33], [25].…”