9. The apparatus of claim 8 , wherein the angle detector is adapted to, for each two edges detected, determine whether the two edges have an intersection, and if the two edges have an intersection, determine an angle between the two edges.
8. A apparatus, comprising: an optical device for obtaining a two-dimensional image of the document; an edge detector for performing edge detection within the two-dimensional image to identify edges of the document; an angle detector for determining angles between detected edges; a three-dimensional position calculator for calculating, based on the detected edges and the angles determined, a three-dimensional position of the document relative to a position of the apparatus; a three-dimensional position correction calculator for calculating correction information to correct, by relative movement, the three-dimensional position of the document relative to the position of the apparatus; a guidance feedback processor for deriving first guidance information from the correction information, wherein the first guidance information is provided to a user of the apparatus, prompting the user to perform the relative movement such that the three-dimensional position of the document is correct relative to the position of the apparatus; and a document capture processor for capturing the document.