DIFFERENCE BETWEEN USING COLOURIMETRIC VALUES (L*a*b*) OR OPTICAL DENSITY FOR RANDOM PRINT NONUNIFORMITY QUANTIFICATION

Abstract

Surface nonuniformity can appear at a print in two forms: random or as a systematic variation. Both types appear in digital printing, but in this study, an only random variation on the digital prints was analyzed. We used two methods for quantification of the nonuniformity: M Score and ISO methods, which are based on physical measurement of the prints, using one of the measuring instruments that measure the colourimetric (L*a*b* values) and densitometric (optical density) values. Samples used in this paper were generated using the software MATLAB Macro Uniformity Toolbox add-in that is printed on the same paper using ink jet printing machine Epson Stylus PRO 7800. We used spectrophotometer Eye One Pro2 and software Measure Tool to measure samples. Other calculations are done in a software application in Microsoft Excel. Based on the results obtained in the research, it is concluded that both methods can be used to measure the random variation of the print nonuniformity.