1. A method of correcting cone beam artifacts in circular computed tomography, comprising the steps of: a) reconstructing a reference image from measured data at a predetermined circular source trajectory, the reference image being obtained based upon a filtered-backprojection algorithm by filtering along predetermined filtering directions, the predetermined filtering directions being given by Cseg+z/cos (gamma), where gamma is a cone angle, z is a vertical distance from Cseg, which is defined by a number of detector rows—1 divided by 2; b) generating synthetic data by forward projection of the reference image along a predetermined source trajectory, which supplements the circular source trajectory to a theoretically complete trajectory; c) reconstructing a correction image from the synthetic data; and d) substantially reducing the cone beam artifacts by generating a corrected image using the reference image and the correction image.