METHOD OF PROVIDING A COVERT SECURITY FEATURE

摘要

A method of providing a covert security feature on an article. The method comprises generating data defining indicia to be provided on a substrate of the article, the indicia comprising a plurality of elements, wherein the data defines a security feature constituted by a characteristic of the elements which varies in a predetermined manner. Providing the indicia on a substrate of the article using a marking material and in accordance with the data, wherein the providing step causes the characteristics of the elements to vary so that the security feature cannot be determined from a visual inspection of the indicia on the substrate but the presence of the security feature can be deduced following a statistical analysis of the variation in the said characteristic of the elements of the indicia on the substrate using the predetermined manner in which the security feature was defined.