SIMPLIFIED HYPERSPECTRAL CAMERA CALIBRATIONFOR ACCURATE RADIOMETRIC MEASUREMENTS

摘要

Hyperspectral imaging has enhanced radiometric and colorimetric analysis of complex scenes by offering a continuous spectrum for every pixel in the entire scene. Nevertheless, hyperspectral image acquisition and spectral calibration still remain a challenging task. We propose a simplified methodology to enable accurate and reliable characterisation of a commercial hyperspectral camera and spectral calibration of its output data. A calibration coefficient was determined for the spectral acquisition range (400 nm-1000 nm) and native resolution (every 2,7 nm) to transform the raw hyperspectral data into spectral radiance in SI units (W·m~(-2).sr per nm). This calibration curve, along-with a linear relation between exposure values and corresponding raw radiance values, was used to automatically determine exposure values that might over/under expose the camera sensors. Different spectral resolutions were also tested to minimize the data size and maintain spectral accuracy. These characterisations and the spectral calibrations were validated under LED and fluorescent sources within a 2300 K-6500 K range of correlated-colour temperatures.