Systems and methods for assisting in the determination of the authenticity of security documents based on known characteristics of similar but authentic security documents. The system and methods use digital processing to capture a digital image of the document being examined and they use a feature localization or detection technique to search for a specific feature in the document based on a stored image of a similar feature from an authentic document. Once the feature on the subject document has been found, the digital image of the localized feature is transformed, by applying mathematical transforms or other image/mathematical operators, such that the result will have distinguishing characteristics that can be derived or analyzed. When the distinguishing characteristics have been analyzed, these are then compared to the stored distinguishing characteristics of similar features from known authentic documents. Based on the comparison, a score is then generated that is indicative of how similar or how different the distinguishing characteristics of the feature being examined are from the features from known authentic documents. The system may also be used such that multiple features from a single document are assessed and scored separately from one another with a final aggregate or weighted score being provided to the user for the whole document.