1. A system for inspecting an object, the system comprising a work surface providing an object plane on which, in use, the object to be inspected is located; and a camera having a focal point and a field of vision, the camera being arranged with respect to the work surface so that at least part of the work surface is within the camera's field of vision, the camera being arranged to capture an image of the object, the image comprising a plurality of image data components, the system further including an apparatus for processing the object image, the apparatus being arranged to receive image data components from a single image of the object from the camera and to generate, using said image data components of said single image, three dimensional data representing at least part of the object, and wherein in order to generate said three dimensional data the apparatus is arranged to identify a plurality of said image data components that represent the position of a respective edge component of the object in an image plane, wherein, during the capture of said single image by the camera, the camera and the object are fixed with respect to one another, the processing apparatus being arranged to project each image edge data component onto the object plane to produce a respective object edge data component in the object plane, the processing apparatus being further arranged to determine whether each object edge data component relates to a lower edge of the object that lies on the work surface or to an upper edge of the object that is offset above the work surface by an amount substantially equal to a thickness of the object at said upper edge, and wherein, only in respect of object edge data components that are determined to relate to an upper edge of the object, the processing apparatus is arranged to adjust the value of the respective object edge data component by an amount depending on the ratio of said thickness of the object at said upper edge to the perpendicular distance of the camera's focal point from the object plane, such that said object edge data components that are determined to relate to an upper edge of the object are adjusted with respect to the other object data components produced by said processing apparatus from said single image.