A new MTF-based image quality assessment for high-resolution SAR Sensors

Synthetic aperture radar (SAR) is an active microwave sensor which is able to produce high-resolution images of the earth surface, with all-weather day and night capability. Conventionally, SAR image quality assessment is typically done by evaluating the signal of the corner reflectors which are positioned in the scenery, and a specialist is needed to extract some characteristic parameters (e.g. the 3-dB impulse response width, the PSLR and the ISLR) to assess the SAR image quality. But it is still an unsolved problem that whether the SAR image quality assessment based on current parameters can predict the reliable probabilities of target recognition from the high-resolution SAR images. For EO sensors (Electro Optical sensors), the image assessment is assessed by the evaluation of MTF (Modulation Transfer Function), with non-specialists. In this paper, a new concept for SAR image quality assessment is proposed to solve this problem. The definitions of spatial frequency and MTF are given to support the new concept. After giving the scene construction of a TEST Field used for measuring MTF, an MTF measuring algorithm is proposed. Experiment results show that the proposed assessment method can describe SAR image quality more accurately and effectively than traditional PSF assessment method.