1. A method for checking the authenticity of security documents, in particular banknotes, wherein authentic security documents comprise security features printed, applied or otherwise provided on the security documents, which security features comprise characteristic visual features intrinsic to the processes used for producing the security documents, wherein the method comprises the steps of: acquiring a sample image of at least one region of interest of the surface of a candidate document to be authenticated, which region of interest encompasses at least part of said security features; digitally processing said sample image by performing a decomposition of the sample image into at least one scale sub-space containing high resolution details of the sample image and extracting classifying features from said scale sub-space; and deriving an authenticity rating of the candidate document based on the extracted classifying features.