MTF assessment of high resolution satellite images using ISO 12233 slanted-edge method

Abstract

The MTF (modulation transfer function) has been used to evaluate the performance of optical systems. More accurate access to on-orbit MTF opens the way to enhance images so that we can deduce more information from the images of IKONOS, OrbView, or SPOT. Generally, the MTF was assessed using various methods such as the point source method and the knife-edge method etc. In this paper, the value of the slanted-edge method is investigated as a tool to assess the on-orbit MTF. The slanted-edge method is the ISO 12233 standard for the MTF measurement of electronic still-picture cameras. The method is adapted to estimate the MTF values of line-scanning telescopes. We applied the method to measure the MTF of high resolution satellite images and also, we compared the MTF measurement with that of the knife-edge method applied to EOS-C test images to increase the confidence on MTF measurement on EOS-C. EOS-C is a 2.5m resolution satellite sensor for SI-200 satellite which is under the development by Satrec Initiative. The MTF measured from this method is used for the MTF compensation of satellite images by generating the MTF convolution kernel based on the PSF (point spread function).