Method for quantifying image quality in push-broom hyperspectral cameras

Abstract

We propose a method for measuring and quantifying image quality in push-broom hyperspectral cameras in terms of spatial misregistration—such as keystone and variations in the point-spread-function across spectral channels—and image sharpness. The method is suitable for both traditional push-broom hyperspectral cameras where keystone is corrected in hardware and cameras where keystone is corrected in post-processing, such as resampling and mixel cameras. We show how the measured camera performance can be presented graphically in an intuitive and easy-to-understand way, comprising both image sharpness and spatial misregistration in the same figure. For the misregistration we suggest that both the mean standard deviation and the maximum value for each pixel are shown. We also suggest a possible additional parameter for quantifying camera performance: probability of misregistration being larger than a given threshold. Finally, we have quantified the performance of a HySpex SWIR 384 camera prototype using the suggested method. The method appears well suited for assessing camera quality and for comparing the performance of different hyperspectral imagers, and could become the future standard for how to measure and quantify the image quality of push-broom hyperspectral cameras.