Certain embodiments of the present invention provide a method and system for improved calibration of an image acquisition device. Certain embodiments of the system include an image acquisition device for obtaining at least one image of an object and a calibration fixture positioned in relation to the image acquisition device. The calibration fixture includes a radiotranslucent material providing low frequency content for characterizing the image acquisition device. In an embodiment, the calibration fixture includes a plurality of peaks and valleys to create a low frequency signal for characterizing the image acquisition device. The calibration fixture may be positioned between the image acquisition device and an energy source such that a distance between the image acquisition device and the calibration fixture is minimized. In certain embodiments, a grating or other calibration fixture may be used to generate a moire pattern to calibrate the image acquisition device.