A method of determining the amount of mis-alignment in one direction of an image of a scene, the image captured by a first camera is described. The method comprising the steps of: defining a line between a first point in the image and a second point in the image, the line extending in the direction of mis-alignment; defining a reference section in the scene to which the image is to be aligned, the reference section of the scene having a reference image characteristic; identifying an image characteristic at different points along the line in the image; and comparing the image characteristic at each point along the line with the reference image characteristic, and determining the amount of mis-alignment by determining the distance between the position of the reference image characteristic of the reference section captured in the image and the defined reference section in the scene.