A method for determining a correction for beam hardening in CT images includes obtaining air scans at a plurality of kVp's, determining detection efficiencies for detector elements of the CT imaging apparatus, and estimating projection values through a combination of at least two different materials of different thicknesses. The method further includes determining a transfer function that translates the estimated projection values into ideal projection values for at least two of the different materials and storing the transfer function as the beam hardening correction for images of the CT imaging apparatus.