On-board non-uniformity correction calibration methods for a microbolometer focal plane array in a thermal camera are disclosed. The methods include performing first calculations in the processor unit of the thermal camera to generate and apply a set of coarse correction bias voltages to the detector elements. The method also includes performing calculations in the external computer based on image data collected by the thermal camera with the coarse correction bias voltages applied to the detector elements to generate a set of fine correction bias voltages. The method also includes downloading the fine correction bias voltages to the thermal camera and applying the fine correction voltages to the detector elements to establish a fine calibration of the microbolometer focal plane array.