1. A method for correcting projection data generated from a computed tomography (CT) examination of an object, comprising: acquiring the projection data of the object; generating a CT image of the object based upon the projection data; segmenting the CT image to identify a set of sub-objects within the object, wherein the set of sub-objects comprises a first sub-object and a second sub-object; determining a first z-effective value for the first sub-object and a second z-effective value for the second sub-object; and performing a beam hardening correction upon the projection data using at least one of the first z-effective value or the second z-effective value to obtain corrected projection data.