1. A camera movement correction apparatus for use in a system which detects a position of a sporting projectile within a scene, the apparatus comprising: circuitry configured to: receive a first image of the scene and a second image of the scene captured by a camera; determine a position of a reference marker within the first image of the scene and a position of the reference marker within the second image of the scene, the reference marker being static within the scene; determine a difference between the position of the reference marker in the first image of the scene and the position of the reference marker in the second image of the scene; and apply a corrective transform, that corrects for the difference between the position of the reference marker in the first image of the scene and the position of the reference marker in the second image of the scene, to pixels of the second image of the scene to create a corrected second image of the scene on the basis of said determined difference.