數位印刷機之色域表現分析

Color Gamut Analysis for Major Digital Presses in Taiwan

本研究將印刷機分三大類：傳統平版印刷機Heidelberg Speedmaster 102-5、混合型印刷機(Hybrid Press）Heidelberg Quickmaster DI46-4及數位印刷機Agfa Chromapress 50i、Indigo E-Print 1000、Xeikon DCP-50D、MGI Digital Carte Master Color，針對此三大類印刷機進行色域表現之分析。本研究採實驗法，使用X-Rite 528反射式濃度計量測每張樣本的YMCRGB色塊之L*a*b*值，並繪製各印刷機之全階調a*b*色域圖。本研究結果顯示六台印刷機在明調區域的a*b*色域圖差異最大，Agfa Chromapress 50i與Xeikon DCP-50D的a*b*色域圖較為相近，而MGI Digital Carte Master Color在明調、四分之一調的a*b*色域圖最小，在中間調、四分之三調及暗部調的a*b*色域圖最大，液態電子油墨的Indigo E-Print 1000其a*b*色域圖只有在四分之一調較乾式碳粉的數位印刷機小。同樣均使用傳統油墨的Heidelberg Quickmaster DI 46-4 與Heidelberg Speedmaster 102-5在色域的表現上有相當大的差異。

Due to the great demand of the digital process in the printing industry, there is an increasing market of the digital press in Taiwan. Digital printing technology does not only save printers production time and cost, but also provide flexibility on the short-run, on-demand, and variable-data printing. It has become a major technology trend in the printing industry. 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 the major digital presses in Taiwan. It intended to study the color gamut difference among digital, conventional sheetfed offset, and hybrid presses. The presses used to run the experiments for this study were Agfa Chromapress 50i, Indigo E-Print 1000, Xeikon DCP-50D, MGI Digital Carte master Color（digital presses）, Heidelberg QuickMaster DI 46-4（hybrid Press）, and Heidelberg SpeedMaster 102-5（conventional offset press）. A digital test form was used to run the experiment； the CIELAB readings were obtained by a X-Rite 528 and the data were used to draw the color gamut for each press. One hundred printed sheets were collected for each press after the press was determined to be at equilibrium, and 50 of them were systematically random sampled. The results of the color gamut for all presses are presented in the paper and their comparisons are also reported.