1. An image generation method, comprising: obtaining a plurality of 2D images through an object to be imaged; obtaining a 3D image data set of the object to be imaged; registering, if required, the 2D images with the 3D image data set; processing the plurality of 2D images to remove clutter features therefrom; defining within the 3D image data set an image reconstruction plane, being the plane of an image to be reconstructed from the plurality of 2D images; for a pixel in the image reconstruction plane, mapping corresponding pixel values from the plurality of 2D images thereto, and combining the mapped pixel values into a single value to give a value for the pixel in the image reconstruction plane, wherein the clutter removal comprises, for a 2D image: obtaining, from the 3D data set, a synthetic image of the clutter to be removed; and subtracting the synthetic image from the 2D image to give a clutter free 2D image.