1. A method for obtaining an image of a smoothed-out document from an image (I) of this document when it is crumpled (DO), said method comprising a step ( 100 ) of determining a three-dimensional geometric model (M3D) of the surface of the crumpled document (DO) by triangulation of three-dimensional points (u i ) defined from the pattern of a target (M) extracted from the image (I) of this document when it is crumpled, a step ( 200 ) of determining a projection (M2D) of the three-dimensional geometric model (M3D) on a so-called acquisition plane by minimisation of error (ERR) of this projection under constraints of preservation of the distances between the three-dimensional points (u i ) of the three-dimensional geometric model, wherein the error (ERR) in projection of the three-dimensional geometric model (M3D) is also minimised under constraints of preservation of the angles between the various edges that connect these three-dimensional points.