An Analysis of the Current Status of Process Control for Color Reproduction in Newspapers

摘要

This study on the current status of process control for color reproduction in newsprint is presented in three parts. The first part is a fresh analysis of data gathered from 102 U.S. newspapers that printed a test form to apply for certification of conformance to the SNAP specifications. The data from these pressruns were used by the CGATS committee in calculating color characterization data for newspaper printing. On examination, this data revealed that only 6 of 102 newspapers were in compliance with the SNAP specifications for solid densities and 50% dot gains. It also revealed high levels of variability in the color values of the 928 patches in the ANSI/IT. 8.7/3-2005across the 102 newspapers.The second part of the study examined the current process control specifications for newspaper printing from the SNAP Committee and the proposed specifications from ISO TC 130/SC/WG 3. The values being specified were contrasted against the production measurement practices of a sample of newspapers from various countries. It was found that none of the papers regularly print the targets that would be required to test conformance with the specifications. The most common process control target used by newspapers in daily production was the three-color gray bar. The third part of the study addressed the question of whether control of solid densities, dot gains, or three-color gray is an effective way to predict the color appearance of a printing system. It was shown through correlation matrix analysis that there were only weak relationships between the specified process control attributes and the overall color appearance of a printing system. This study proposed that a practical avenue for color control in newspaper printing is measurement within the pictorial images themselves. The bases for this recommendation were that measurements of solid inks, dot gains, and three-color gray are not sufficiently predictive of color appearance, and, due to the absence of trim space in which to run process control targets, it is impractical for newspapers to make multiple measurements within each ink-key zone, as would be required for compliance with existing specifications.