Study of Pigment and Optical Response Distributions in Newsprint.

The quality of the printed screen dots is one of the critical factors that determine the over all quality of a printed halftone image. In this paper the spatial distribution of pigment is recorded and its relation to optical response and local paper grammage in printed screen dots on newsprint is analyzed. It is shown that light scattering inside the paper structure to some extent hide large irregularities in the pigment distribution. It is also shown that a hole in a screen dot will be optical mitigate by the paper structure as a result of multiple light scattering inside the bulk. We also show experimentally the hue shift in the border zone of the screen dot. A halo of light around the pigment area, which shifts from cyan toward green, has been determined around a cyan screen dot. Influence from the cyan pigment can be spotted in the optical response up to a distance of at least 20 (m from the measured pigment particle.