Commercial Printing Guidelines as a Printability Metric

摘要

The commercial printing guidelines in the USA are called GRACoL (General Requirements Applications in Commercial Offset Lithography) (1999). One of the guideline categories is SWOP (Specifications for Web Offset Publications), referring to printing on a No. 5 groundwood paper (1997). The guidelines indicate the expected or anticipated printing attributes in relation to prepress input and press output. Good printability is defined as meaning that output values are obtained which are near those in the guideline table. This paper describes the evolution of printing guidelines from early LTF/GATF recommendations for the web offset publication market to standards activities, and finally to the sheet-fed commercial printing market or GRACoL. In addition, a printing project is described involving the creation of a set of printed samples representative of each commercial printing category. Five commercial printing categories of GRACoL are compared, using four ink sets on seven different papers, all printed on the same 28in press. The categories include glossy and dull coated papers, matt coated paper, ar d premium uncoated paper. The samples are characterised according to paper and ink properties, tone reproduction, and colour gamut. The process can be characterised by the colour gamut achieved at a certain solid ink density and the tone value increase (TV1) or by an entire IT87/3 target map (ANSI/IT8, 1993). It is shown that conventional wisdom would predict these results, based upon density range. The authors make suggestions for future work, and explain why the industry needs it.