Digital Proofing of Gravure Spot-Color Printing

Spot color is widely used in gravure printing to obtain a colorful appearance. With new developments in printers, inks, and media, an inkjet printer can be treated as a digital proofer for gravure printing, providing significant time and cost savings compared to conventional procedures for job approvals. The implementation of digital proofing is integrally related to color management. In the digital proofing process, a third-party RIP can be employed to interpret raster and vector data files for a specific printer, distributing the right amount of ink on the substrate, therefore, providing better control for accurate digital color reproduction. The objective of this work was to establish a digital proofing system for gravure spotcolor printing. An Epson Stylus Pro 4000 digital printer combined with two commercially available RIPs (CGS ORIS RIP and GMG ColorProof RIP) were tested and compared. ICC profiles were generated for the Epson Stylus Pro 4000 using the actual production printing substrate. The quality of spot-color reproduction was evaluated in terms of the ∆E in L*a*b* color space for selected spot colors. The overall results suggested that the shadow area of each spot-color test chart has relatively high ∆E values due to some spot colors in the test charts being out of the color gamut of the test printer. Overall, the printer with RIP software offers better spot-color reproduction resulting in lower ∆E values than printing without RIP. The Epson 4000 printer with the CGS RIP delivered better color reproduction in Yellow spot colors, while the Epson 4000 printer with the GMG RIP had better color reproduction in Blue-347, Black-392, and Red-314 spot colors. Among the seven selected spot colors, Yellow-385 is the hardest one to reproduce.