Diffuse attenuation coefficient Kd(490)retrieval model for nearshore area of Bohai sea
渤海近岸水体漫衰减系数Kd(490)遥感反演模型

In this paper, a method to evaluate the in-flight MTF (Modulate Transfer Function) of the WFI (Wide Field Imager) on CBERS-02B is presented and the WFI images are restored. The CCD is another payload on CBERS-02B with high spatial resolution. Using the CCD images as high resolution images, the two-image comparison approach is applied to determine the MTF of the WFI with a pair of images acquired over Beijing on Nov. 10, 2007. As the results, MTF values in three directions are derived. The MTF values at Nyquist frequency in cross-track, in-track and 45° directions were respectively about 0.43, 0.52 and 0.35 for red band and 0.30, 0.46 and 0.36 for near-infrared band. Image-derived MTF values are applied to calculate the half bandwidths of the WFI. The results indicate that the instant fields of view of the WFI in the cross-track, in-track and 45o-track directions were respectively 1.188 pixels, 1.165 pixels and 1.281 pixels for red band, and respectively 1.258 pixels, 1.195 pixels and 1.326 pixels for near-infrared band. Weiner filter model is used to perform the MTF compensation for WFI images. The results show that the restored image seemed clearer and contained more detailed information.