1. A method for authenticating a feature of a document, the method comprising: providing a document authentication system comprising: at least one electromagnetic radiation emitter for selectively illuminating the document with at least two frequencies of electromagnetic ration, at least one image sensor for capturing images of the document when subjected to electromagnetic radiation from the at least one electromagnetic radiation emitter, and a computing device for controlling the at least one electromagnetic radiation emitter and the at least one image sensor, wherein the computing device includes a document authentication application having a image capturing module, a training module, an image analysis module, and a comparison module; subjecting a region of the document to different first and second wavelengths of electromagnetic radiation emitted from the at least one electromagnetic radiation emitter and capturing with the at least one image sensor a first image and a second image of the region of the document corresponding to the first and second wavelengths of electromagnetic radiation, respectively, the region comprising at least a portion of the document; determining a first intensity value associated with the first image of the region and determining a second intensity value associated with the second image of the region; using the comparison module to compare the first intensity value with a first training intensity value of a region of a training document, the first training intensity value obtained using the first wavelength of electromagnetic radiation, and comparing the second intensity value with a second training intensity value of the region of the training document, the second training intensity value obtained using the second wavelength of electromagnetic radiation; and determining whether the document is authentic at least partially based on the comparison between the first intensity value and the first training intensity value and using the comparison between the second intensity value and the second training intensity value.