1. A method of providing an image to be displayed comprising the steps of: providing captured scene data representing one or more images of a real scene and providing illumination data representing real illumination impinging on the real scene; providing a virtual reality image of a theoretical object by modeling said theoretical object using said illumination data to define illumination impinging on the theoretical object; and providing a combined image including elements of the real scene based on said captured scene data and including said virtual reality image; wherein said real illumination impinging on the scene changes with time, said step of providing illumination data includes providing successive sets of illumination data representing changes in illumination with time, and said step of providing a virtual reality image includes providing successive virtual reality images based on said successive sets of illumination data; wherein illumination data generated either directly or indirectly by the virtual reality object within said scene is used to modify the combined image.