Objective Image Quality Assessment for High Resolution Photospheric Images by Median Filter Gradient Similarity

摘要

All next generation ground-based and space-based solar telescopes require agood quality assessment metric in order to evaluate their imaging performance.In this paper, a new image quality metric, the median filter gradientsimilarity (MFGS) is proposed for photospheric images. MFGS is ano-reference/blind objective image quality metric (IQM) by a measurement resultbetween 0 and 1 and has been performed on short-exposure photospheric imagescaptured by the New Vacuum Solar Telescope (NVST) of the Fuxian SolarObservatory and by the Solar Optical Telescope (SOT) onboard the Hinodesatellite, respectively. The results show that: (1)the measured value of MFGSchanges monotonically from 1 to 0 with degradation of image quality; (2)thereexists a linear correlation between the measured values of MFGS androot-mean-square-contrast (RMS-contrast) of granulation; (3)MFGS is lessaffected by the image contents than the granular RMS-contrast. Overall, MFGS isa good alternative for the quality assessment of photospheric images.