| 摘要 |
<p>An item requiring verification comprising a substrate printed with a first printed ink image visible to the human eye under normal white light irradiation through the reflection of colours produced by the subtractive process and a second printed ink image only visible to the human eye under irradiation by radiation of non-visible wavelengths by additive emission of lights of visible wavelength, characterised in that the second printed ink image is a record of a polychromatic reference composition recorded in the colours of said reference composition, and in that the pixels of the second printed ink image are each comprised of one or more inks which are colourless under visible light irradiation and which contain one or more dopants which have a coloured fluorescent response to said radiation of non-visible wavelength, said pixels collectively forming said record of said polychromatic reference composition having a reference quality, whereby mental comparison by an observer between said polychromatic reference quality image and the colour composition of a remembered image of the polychromatic reference composition enables the observer to determine that the item is authentic. Preferably the item requiring verification is a bank note comprising further security features and preferably the pixels of the second printed ink image each comprise varying amounts of three inks having fluorescence responses in the red, green and blue colour ranges.</p> |
