Computing the PSF with high-resolution reconstruction technique

Abstract

Point spread function (PSF) is a very important indicator of the imaging system; it can describe the filtering characteristics of the imaging system. The image is fuzzy when the PSF is not very well and vice versa. In the remote sensing image process, the image could be restored by using the PSF of the image system to get a clearer picture. So, to measure the PSF of the system is very necessary. Usually we can use the knife edge method, line spread function (LSF) method and streak plate method to get the modulation transfer function (MTF), and then use the relationship of the parameters to calculate the PSF of the system. In the knife edge method, the non-uniformity (NU) of the detector would lead an unstable precision of the edge angle; using the streak plate could get a more stable MTF, but it is only at one frequency point in one direction, so it is not very helpful to get a high-precision PSF. In this paper, we used the image of the point target directly and combined with the energy concentration to calculate the PSF. First we make a point matrix target board and make sure the point can image to a sub-pixel position at the detector array; then we use the center of gravity to locate the point targets image to get the energy concentration; then we fusion the targets image together by using the characteristics of sub-pixel and get a stable PSF of the system. Finally we use the simulation results to confirm the accuracy of the method.