Effect of Printing Ink Sequence (KCMY vs. YMCK) of Multicolor Offset Printing on the Color Gamut and Overall Print (image) Quality

摘要

This research utilized an experimental research method. The purpose of this research study was to determine the effect of ink sequence (KCMY vs. YMCK) of multicolor offset printing on the color gamut and over print quality. The experiment was conducted in a CTP based workflow for offset printing. A custom layout of 17.5" × 23" test target was used and linear plates were produced by using the CTP device. After the plates were made for the KCMY and YMCK printing sequence respectively, a pilot test was conducted to achieve the target solid ink density (SID) values according to GRACOL SID standard (or in-house SID standard). During the pilot test of KCMY printing, 500 sheets were printed. This pilot test of printing is only to bring the SID values to a standard level. Once density values had been achieved according to the standard ink density (SID) values, the press was run continuously without operator interference and another 100 (N) test sheets were printed, from which a total of 80 (n) sheets were randomly selected for the analysis. The sample size was selected in order of the specific confidence interval (α = 0.05). A random sampling technique was used to identify the sample size because of the large size (N = 100) of total population. The findings of this research, comparing color gamut volume of KCMY vs. YMCK ink sequences revealed that there is no significant major difference of which ink sequence is better over the other. However, in comparing, the YMCK sequence gamut consists of higher gamut volume, and smoother gamut shape than the KCMY sequence. The findings make it difficult to draw conclusions regarding dot gain, because each printing sequence was executed by using the same printing conditions (press, paper, inks, etc.).