1. A method comprising: using projection data acquired during a tomographic examination of a periodically moving object to reconstruct a plurality of image layers, wherein the image layers are generated from projection data segments having an angular extent less than that which is required to provide a complete tomographic data set; generating a first reference weighting function which corresponds to the first motion phase; calculating image layer weights which minimize the difference between a projection dependent weight profile and the first reference weighting function for each of a plurality of regions in an image volume; weighting the image layers according to the calculated image layer weights so that the weighting applied to the image layers approximates the first reference weighting function; combining the image layers to generate first image data indicative of the object at an arbitrary first motion phase; and displaying a human readable image indicative of the first image data.