Comparison of print mottle and surface topography testing methods

Mottling is one of the most important indicators affecting offset print overall quality. This paper presents the results of mottling evaluation using two techniques of measurement. The dynamic technique of mottling assessment is based on image sequence processing of moving printed area that calculates mottling using an analysis of the spectral image. The static technique evaluates an original image after printing. The quality sequence of coated papers in term of mottling obtained from full-scale printing in a printing machine was in good agreement with laboratory printing tests. Microtopography of paper surface has a significant effect on print quality. The contactless method of surface roughness measurement of paper is comparable to Parker permeability method. Evaluation of surface topography using the photoclinometric method is able to predict a print mottling of offset coated paper.