Abstract: A computer-implemented method for training an artificial intelligence based neural network is provided. At least one digital image of at least one security document is provided as a reference. A set of digital training images is provided, wherein these are altered compared to the digital image of the security document. The set of digital training images includes a first subset of positive digital training images having a visual impact of an alteration such that an unbiased human observer would consider a reproduction of the respective digital training image to represent the security document or multiple security documents. The set of digital training images includes a second subset of negative digital training images. Ground truth is provided to the neural network as to whether a reproduction of the respective digital training image is to be considered representing the security document or multiple security documents or not.

Abstract: A computer-implemented method for preventing unauthorized processing of a digital representation of at least a portion of a document, a device for data processing, and a computer program product are provided, wherein in particular the document is a banknote. The method comprises providing data, wherein the data is based on the digital representation of at least a portion of a test element. The digital representation may be an image file corresponding to the at least one portion of the test element. The method also involves analyzing the data with regard to data representing at least one characterizing feature of the at least one portion of the document. The method further comprises activating prohibiting means if the data being based on the digital representation of the at least one portion of the test element is similar to the data representing the at least one characterizing feature.