Spectral imaging data have been acquired with the Navy HYDICE (the hyperspectral digital imagery collection experiment) instrument from an aircraft. Similar data will soon be collected with the NASA HSI instrument from the Lewis spacecraft. The majority of users of imaging spectrometer data are interested in studying surface properties. Therefore, atmospheric absorption and scattering effects must be removed from imaging spectrometer data, so that surface reflectance spectra can be derived. Previously, an operational atmosphere removal algorithm, which used the 5S code for modeling the atmospheric scattering effects and the Malkmus narrow band model for modeling atmospheric gaseous transmittances, was specifically designed for deriving surface reflectances from spectral imaging data collected by the NASA JPL airborne visible/infrared imaging spectrometer (AVIRIS). We have recently updated this algorithm by replacing the 5S code, which requires that the sensor be at the top of the atmosphere, with the 6S code, which accommodates sensors at any altitudes. The updated algorithm allows processing of imaging spectrometer data acquired from low- and high-altitude aircraft platforms, and from satellite platforms. We are currently developing another algorithm that uses a line-by line code to calculate atmospheric gaseous transmittances for processing imaging spectrometer data with spectral resolution between approximately 0.5 and 10 nm.