1. A method for checking the authenticity of security documents, 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, the method comprising the step of digitally processing a sample image of at least one region of interest (R.o.I.) of the surface of a candidate document to be authenticated, which region of interest encompasses at least part of the security features, the digital processing including performing a decomposition of the sample image by means of wavelet transform (WT) of the sample image, wherein the decomposition of the sample image is based on a wavelet packet transform (WPT) of the sample image.