Study on Color Simulating between Offset Printing and Digital Printing

Color output capability and output accuracy of digital printing machine used for simulating the offset printing were analyzed. A digital machine, Hp Indigo 1050, was used in this study. The colorimetric values of its primaries, cyan, magenta, yellow and black, were not the same as that primaries used in the offset printing, and the differences between them could not be removed by adjusting the maximal output ink level. The Hp Indigo's color gamut, consequently, could not completely meet the offset print requirement, typically presenting the absence of some colors equal to or close to the offset's color gamut. So, color management technique was accepted in our experiment, and the offset's CMYK values wore translated into the digital machine's CMYK values with the relative intent color simulation through these two machine's profiles. The results showed that the color output accuracy within the offset color gamut was raised on the whole, and the big color differences only happened on these colors outside the digital machine's gamut. Numerically, for 928 colors in IT8.7/3 chart, the CIELAB average/maximal color differences dropped from 4.98/13.90 to 3.13/13.13 respectively corresponding to the cases before and after color management accepting. Specially, for gray colors, the average/maximal color differences changed from 4.91/5.59 to 0.92/2.00, improving the gray balance dramatically.