Details:
Summary:
Due to the great demand of the digital process in the printing industry, there is an increasing market for digital presses in Taiwan. Digital printing technology cannot only save printers' production time and cost, but also provide them with flexibility on the short-run, on-demand, and variable-data printing. It has become a major technology trend in the printing industry lately. Print quality is always an important issue associated with the technical development of any printing machine. One of the major quality concerns for most printers is the characteristic of the color reproduction for digital presses.
The purposes of the study were twofold: (1) it intended to investigate the print color differences (DEab) among the four digital presses commonly used by Taiwan's printers, Agfa Chromapress 50i, Indigo E-Print 1000, Xeikon DCP- 50D, and MGI Digital Carte Master. (2) It also tried to compare the print color differences among VI digital, conventional (analog) offset (Heidelberg SpeedMaster 102-5), and hybrid (FI digital) presses (Heidelberg Quickmaster DI46-4). A digital test form was designed for the experiment. An experiment was conducted to investigate the values of L*a*b* in Y(Yellow), M(Magenta), C(Cyan), and K(Black) on the sampled sheets, which were printed by the six presses, respectively, and then, CIELab readings on those color patches at various tint values were obtained by an X-Rite 530 and the data were entered onto SPSS and Minitab for computing the color difference (DEab) for the presses. Fifty sheets were systematically random sampled from 100 printed sheets collected from each of the six presses after the presses were determined to be at equilibrium.
The main conclusions are: (1) t-test results show that the AE values of all 12-press pairs in the tonal range from 50% to 90% tints are higher than those in other areas. Generally speaking, the greatest color difference (maximum (DE) occurred at the 75% tint and the (DE values increase as the tint values increase. (2). The mechanical design of the Agfa Chromapress 50i and Xeikon DCP 50D are very similar. The result shows that their color difference in YMCK is not significant. (3) The color difference between the hybrid press QuickMaster DI and MGI Digital Carte Master Color is much greater than that between the other press pairs. (4) The color difference performance of the four digital presses is not necessarily inferior to that of the traditional press, Speedmaster l02-5; in fact, in some cases the color difference performance of the digital presses is comparable with that of the Speedmaster.