1. A method for detecting soiling and/or color wear in the area of color transitions in at least one portion of a document of value of a predetermined type of document of value on the basis of processing data reproducing color coordinate values of image elements in a color space in dependence on the position of the areas in the portion of the document of value that correspond respectively to the image elements, and of reference data reproducing for a type of documents of value a predetermined color reference distribution of color coordinate values in the color space in dependence on reference positions on a document of value of the type of document of value, comprising the steps: determining for each of the image elements whether the color coordinate values in the color space that are allocated to the image element correspond to the color reference distribution, wherein the color reference distribution is given by at least one predetermined, closed reference surface, wherein the closed reference surface is defined by at least one linear segment predetermined for the type of document of value and a predetermined distance of predetermined points from the at least one linear segment; comparing the positions of the image elements whose color coordinate values were determined as corresponding to the reference distribution 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 soiling and/or color wear in the area of a color transition.