1. A method for cone beam CT imaging of an object, the method comprising: (a) acquiring projection images of the object taken at different view angles by using an imaging process that uses a polychromatic x-ray source, an energy-resolving detector having a plurality of energy channels, and a grating system; (b) said acquiring comprising acquiring, for each of the plurality of energy channels of the detector, a respective plurality of the projection images taken at different view angles; (c) performing three-dimensional (3D) computed tomography reconstructions of the object for each of the plurality of energy channels to produce a respective plurality of 3D reconstruction images; and (d) processing the plurality of 3D reconstruction images for each of the plurality of energy channels to produce one or more images of the object, wherein step (d) comprises assigning different weights to the images acquired from different energy channels.