ANTI-COUNTERFEITING AND DIFFUSIVE SCREENS

Anti-counterfeiting marking for documents, which marking may be disguised as an incidental or artistic feature of overall marking on the documents is adapted to be read by a complementary reading device. In one embodiment the marking may be a one, two or three-dimensional statistically fractal marking and is representative of an array of digits in which the value of each digit is represented by the fractal dimensions over a corresponding region or set of regions of the document bearing the marking. Corresponding apparatus for reading the anti-corresponding marking is also provided.