Method of producing secure images using inks comprising modified pigment particles

摘要

The present invention describes a method of producing an image which is visually distinct from its reproductions. This method comprises the steps of formulating an ink composition comprising a liquid vehicle and at least one modified pigment having attached at least one organic group and applying this ink composition to a substrate. Methods of determining the authenticity of an image and of verifying the date of creation of an image is also described.