Abstract
Relationship between pre-printing and post-printing topographies of paper surfaces in both electrophotography and offset printing was discussed. The correlation coefficient of Pearson between two-dimensional profiles of paper surface and its printed surface at the same location was calculated by using four kinds of coated paper of different gloss. The correlation coefficient was high for every coated paper except cast coated paper for offset printing.,but it was low for every coated paper for electrophotography. Even rough low-gloss paper resulted in a low correlation coefficient, therefore paper surface profile does not influence printed surface profile greatly for electrophotography. Then, transfer function analysis was applied to surface profiles as paper surface profiles were input and printed surface profiles were output. Two differences were found between the two printing methods. One is the printed surface topography formed by toners or inks at lower frequencies. The other is the level to which roughness of paper surface is filled by toners or inks at higher frequencies. Moreover,for electrophotography,reduction in amount of toners gives a better correlation coefficient between paper surface and printed surface profiles.
