CDR Grady H. Tuell
National Oceanic and Atmospheric Administration, National Ocean Service, National Geodetic Survey

Optical Transfer Function (OTF) methodology is often used to analyze the geometric resolution of imaging systems. One possible implementation is based on direct measure of the Line Spread Function (LSF) obtained by isolating a sub-pixel linear pixel. The LSF is used to approximate the image derived Optical Transfer Function (OTF). Geometric resolution is then estimated by computing the Effective Instantaneous Field of View (EIFOV). The usual procedure requires observation of targets that have a constant contrast across the spectrum (such as black/white line pairs). In this experiment, direct measurements of the LSF were made (in an uncorrected AVIRIS image cube) which do not have constant spectral contrast due to the vary spectral separability of the foreground/background pair, coupled with atmospheric and adjacency effects. The resulting estimates do not definitively characterize the imaging system, but they are interesting in that they demonstrate the extent to which resolution for a particular foreground/background pair may vary across the spectrum. This type of analysis may be useful in choosing appropriate spectral bands for locating small targets against particular backgrounds, or in evaluating image processing treatments applied to the image cube.