Offset Print Analysis with Mathematical Regression Model

Abstract

The objective of this study is to analyze and compare the print quality by offset printing process on uncoated paper for matching the quality on par with ISO 12647 standards. A standard test form that contains different control strips for densitometric and colorimetric measuring has been used to define the optical density and color difference of the main process ink colors like cyan, magenta, yellow and black while printed on four-color Heidelberg CD102 sheet-fed offset printing press. The results are important from scientific and practical point of view. By applying the regression analysis methods, the correlation between the optical density deviations ΔD from the optimal values and color difference ΔEab represented by the following regression model of Quadratic equation: ΔEab = a + bΔD + cΔD2 (y = a + bx + cx2 ) has been ascertained. By using the mathematical regression model, identification of the suitable values of every color on the output in offset printing, can be easily done. The experimental result of print density and LAB values on uncoated paper is matching with ISO 12647-2 Graphic technology – process for the production print.