The disclosure relates generally to methods and apparatus for spectral calibration of a spectroscopic system which includes a fiber array spectral translator. One embodiment relates to a method for obtaining a first image of a known substance using a photon detector and a fiber array spectral translator having plural fibers, wherein the first image comprises at least one pixel; providing a second image of the substance wherein the second image comprises at least one pixel; comparing the first image with the second image; and adjusting at least one pixel of the first image based on the comparison of images to thereby obtain an adjusted image.