1. An aerothermal radiation correction method, the method comprising: (1) filtering out noise and details in an original aerothermal radiation image Z, thus obtaining a filtered image {circumflex over (Z)}, to overcome the adverse effects of noise in thermal radiation field estimation process; (2) through estimation of the filtered image {circumflex over (Z)}, obtaining an aerothermal radiation field B 1 of the original aerothermal radiation image Z, and further obtaining an initially corrected image S 1 =Z−B 1 ; (3) solving a central region of the aerothermal radiation field B 1 , and according to the central region of the aerothermal radiation field B 1 , dividing the original aerothermal radiation image Z and the initially corrected image S 1 into correspondingly equal-sized image-blocks; (4) calculating the contrast values of the image-blocks of the original aerothermal radiation image Z and the contrast values of the image-blocks of the initially corrected image S 1 , respectively, thus obtaining the variation of the contrast values of the image-blocks of the original aerothermal radiation image Z relative to the corresponding image-blocks of the initially corrected image S 1 ; (5) comparing the variation of the contrast values of the image-blocks corresponding to the central region of radiation and the variation of the contrast values of the image-blocks corresponding to non-central regions of radiation, if the difference is less than or equal to a predetermined threshold value, then taking the initially corrected image S 1 as the final correction result, otherwise sequentially proceeding to step (6); and (6) obtaining an image 1 ={circumflex over (Z)}−B 1 from the filtered image {circumflex over (Z)} and the aerothermal radiation field B 1 and taking the portion of the image corresponding to the radiation central region of the aerothermal radiation field B 1 as a new filtered image {circumflex over (Z)}, and through estimation of the new filtered image {circumflex over (Z)}, obtaining a residual aerothermal radiation field B 2 at the radiation central region of the initially corrected image S 1 , and further obtaining a secondarily corrected image S 2 =S 1 −B 2 .