A method for imaging an object is provided. The method includes acquiring image data of the object, wherein the image data includes a plurality of original voxels each having an original CT number, identifying, using a processing device, a subset of the original voxels based on at least one of an original CT number and a location of each original voxel, applying, using the processing device, an anisotropic smoothing filter to the identified original voxels in the subset to generate a set of smoothed voxels each having a smoothed CT number, generating, using the processing device, smoothed image data by combining the original voxels and the smoothed voxels, and analyzing the smoothed image data to determine whether the object contains contraband.