Fig. 1. HTM formed by extrapolating from the blue band with different window sizes. (a) Original image; (b) $\omega$ = 3; (c) $\omega$= 5; (d) $\omega$ = 7

Fig. 2. Judgment results of different window sizes for thin cloud masks. (a) Original image; (b) $\omega$ = 11; (c) $\omega$= 21; (d) $\omega$ = 31

Fig. 3. Effect of different window sizes on the final image for each band. (a) Original image; (b) $\omega$ = 3; (c) $\omega$ = 11; (d) $\omega$= 21

Fig. 4. Normalized spectral response curves of each spectrum segment for each CCD camera. (a) CCD 1; (b) CCD 2; (c) CCD 3; (d) CCD 4

Fig. 5. Technical route for thin cloud removal in multispectral remote sensing images

Fig. 6. Highlighted object area in area A. (a) Original image; (b) highlighted area

Fig. 7. Area A and its HTM image. (a) Original image; (b) HTM image

Fig. 8. Cloud mask image of area A. (a) Original image; (b) cloud mask image

Fig. 9. HTM_i calculation results of each band in area A. (a) Band 1; (b) band 2; (c) band 3; (d) band 4; (e) band 5

Fig. 10. Linear regression coefficient of each band in area A. (a) Band 1; (b) band 2; (c) band 3; (d) band 4; (e) band 5

Fig. 11. The images for area A-D before and after thin cloud removal. (a) Original images; (b) images after removing thin clouds

Fig. 12. Comparison of clarity before and after thin cloud removal in area A-D. (a) Area A; (b) area B; (c) area C; (d) area D

Fig. 13. Comparision of image contrast before and after thin cloud removal in area A-D. (a) Area A; (b) area B; (c) area C; (d) area D

Fig. 14. Comparison of image standard deviation before and after thin cloud removal in area A-D. (a) Area A; (b) area B; (c) area C; (d) area D

Fig. 15. Histogram area selection of cloud-free area before and after thin cloud removal in area A. (a) Original image; (b) after thin cloud removal

Fig. 16. The histogram results of the cloud-free area for different bands before and after thin cloud removal in area A. (a) Original images; (b) after removing thin clouds