Fig. 1. Photos of YOGIS

Fig. 2. Coronal imaging system of YOGIS

Fig. 3. Objective imaging system of YOGIS

Fig. 4. Conjugate image of coronagraph objective lens

Fig. 5. Data of Group 1

Fig. 6. Data of Group 2

Fig. 7. Dust scattering background

Fig. 8. Image of SDO/AIA satellite at 21.1 nm

Fig. 9. Images obtained by processing SDO/AIA satellite data in the same way as ground-based coronal data

Fig. 10. Radial pixel value change of Fig. 9

Fig. 11. Least-squares fitting of radial distribution of Scatteri

Fig. 12. Least square fitting of k，b and I'

Fig. 13. The corrected coronal image of Group 1

Fig. 14. The corrected coronal image of Group 2

Fig. 15. The distribution of the mean intensity of corona of Group 1 in the low latitude region

Fig. 16. The distribution of the mean intensity of corona of Group 2 in the low latitude region