Li, XY, Gu, XF, Yu, T (2009). In-flight MTF measurement and compensation for the CBERS-2 WFI. INTERNATIONAL JOURNAL OF REMOTE SENSING, 30(4), 829-839.
The Wide-Field Imager (WFI) is one of three payloads onboard the China-Brazil Earth Resources Satellite (CBERS). Limited knowledge of its radiometric characteristics has limited use of its data in China. In this study, our aim was to evaluate the in-flight modulation transfer function (MTF) of the WFI and restore the images. Using the high ground spatial resolution images obtained with the charge-coupled device (CCD) camera also onboard CBERS, a two-image comparison approach was applied to determine the MTF of the WFI, with three pairs of images acquired on different dates. The MTF values measured on different dates were different, especially in the along-orbit direction. As subimage pairs of the Korean scene had the richest information and low relief, MTF values determined from the Korean scene were applied to calculate the half-bandwidths of the WFI and perform the MTF compensation for the WFI images. The results demonstrated that the instant fields of view of the WFI were 317 m, 304m and 320m in the cross-orbit, along-orbit and 45 degrees-orbit directions, respectively. As expected, the restored images contained more detail than the original ones.