Document authentication by attitude-independent determination of surface appearance using controlled illumination

A method of determining whether a document is genuine, the method comprising:

• illuminating the document with a controlled illumination source which is in a fixed spatial relationship with a camera;
• changing the distance between the camera and a centroid of the document, wherein the distance change includes a change in a distance between the camera and the centroid of the document along an axis perpendicular to a plane of she document;
• using the camera to capture imagery of the document while changing the distance between the camera and the centroid of the document;
• analyzing the captured imagery to obtain information about changes in appearance of a surface of the document resulting from:
• changes in illumination incident on the document caused by changing a position of the controlled illumination source with respect to the document;
• and
• changes in a position of the camera with respect to the document caused by the changing of the distance between the centroid of the document and the camera;
• and
• analyzing the information about changes in appearance of the document to determine a likelihood that the captured imagery was captured from a genuine document.