Method for identifying soiling and/or colour fading in the region of colour transitions on documents of value, and means for carrying out the method

摘要

A method for detecting color transitions in at least one portion of a document of value by determining for each image elements whether color coordinate values in the color space that are allocated to the image element correspond to a reference color distribution, which is given by at least one predetermined, closed reference surface in the color space, that is given by at least one linear segment predetermined for the document of value and a predetermined distance of the points of the reference surface from the at least one linear segment. The method further has the steps comparing the positions of the image elements whose color coordinate values are disposed inside or outside of the reference surface to predetermined reference positions on the document of value and detecting in dependence on the result of the comparison a presence or an absence of a color transition caused by soiling or color wear.