1. A method of correcting for residual fixed pattern noise in a radiometric infrared (IR) camera, the method comprising: pointing the camera at a first scene external to the camera; generating sets of IR image data, while pointing the camera at the first scene, said sets of IR image data representative of IR energy received on a focal plane array (FPA) within the camera, the FPA including a plurality of IR detector elements; initiating a non-uniformity correction (NUC) routine, the NUC routing including: generating a first set of IR image data representative of the IR energy received on the FPA, and generating NUC data from the first set of IR image data, the NUC data for correcting fixed pattern noise in the first set of IR image data; pointing the camera at a second scene external to the camera to produce a scene that effectively is of uniform IR energy; triggering the camera, while pointing the camera at the second scene, and initiating an NUC refinement routine including; generating a second set of IR image data representative of IR energy received on the FPA from the second scene, generating NUC refinement data from the second set of IR image data, and generating normalized NUC refinement data by normalizing the NUC refinement data relative to IR image data in the second set of IR image data associated with at least one of a generally centrally positioned IR detector element from the plurality of IR detector elements; generating adjusted NUC data by adjusting the NUC data with the normalized NUC refinement data; adjusting at least one set of the IR image data with the adjusted NUC data to minimize fixed pattern noise in the at least one set of the IR image data; and calculating radiometric scene temperature data associated with at least a portion of the first scene based on at least a portion of at least one set of the IR image data, the NUC data, and the normalized NUC refinement data.