Reasons and Ways for the Revision of the International Standard for Four Colour Offset Printing

The colorimetric characteristics of a set of printing inks for multi-colour offset printing are specified in the International Standard ISO 2846:1975. This standard evolved from the European Colour Scale which on its part served for national standardization in ten European countries. Although the standard was drafted for the production of offset inks it has gained significance also in the prepress area, in colour managing and computer publishing. However, since a couple of years, it has become apparent that the colour values of commercial cyan, magenta, and yellow inks had drifted away from those specified in the standard. Therefore, revision of the standard was set about by a joint working group ISO TC 130 WG 3/4 aiming at colorimetric specifications which are representing worldwide commercial inks for four colour offset printing within reasonable tolerances. The paper will show the background, methods of testing and actual colorimetric data such as SWOP, JAPAN COLOUR and EUROPEAN COLOUR SCALE serving as basis for the revision.