Spatially resolved analysis of print through and ink penetration of printed matters
2015 (English)Conference paper (Other academic)
Print through is an often encountered defect of printed maters, especially on paper grades of low and medium grammages. Print through phenomena have two contributing components, show through and strike through, resulting from insufficient paper opacity and ink penetration, respectively. The existing measurement method of print through and its components are calculated from a set of spectral reflectance values of printed and non-printed paper samples. These reflectance values are from rather big areas that equal to the opening of the employed spectrophotometer (say 33 mm in diameter). Thus, the calculated print through, show through and strike through, are only average values of the measured areas. This method has intrinsic weaknesses as paper is an inhomogeneous medium whose structure and materials compositions vary from one position to another, leading to inhomogeneous show through and strike through (opacity and ink penetration) across the measured areas, especially for papers of low and medium grammages.In this report we present a new method that enables one to take into account of variations in print through across the measured areas. The method employs a scanner that scans the printed and unprinted samples into RGB images of desired spatial resolutions. With the help of calibration patches that are simultaneously scanned as the measured samples, the RGB image signals can be converted into reflectance values. These reflectance values are then used to compute the print through, show through and strike through. Moreover, by means of Kubelka-Munk model, the depth of ink penetration at each spatial position can also be obtained. The developed method has been implemented in Matlab and successfully been applied to printed samples of newsprint and office papers. Comparative studies between instrumental measurements and perceptual evaluations confirm that the print through variations across the printed areas have strong influences on the print quality assessments. It is also found that using internal size agents in paper making is helpful for reducing ink-penetration.
Place, publisher, year, edition, pages
print quality, analysis, ink penetration, printed matter, print through
Paper, Pulp and Fiber Technology
IdentifiersURN: urn:nbn:se:ri:diva-29141OAI: oai:DiVA.org:ri-29141DiVA: diva2:1083166
9th International paper and coating chemistry symposium, Tokyo, Japan, Oct 29