Fig. 1. Box filter. (a) x-scale; (b) y-scale; (c) xy-scale

Fig. 2. Multi-channel spectral original image and image after SURF registration. (a) Target image and multi-channel spectral image to be registered; (b) target image and multi-channel spectral image after SURF registration

Fig. 3. Block diagram of MSM-SURF algorithm

Fig. 4. Effect image of superposition

Fig. 5. Flow chart of maximum submatrix algorithm

Fig. 6. Maximum submatrix

Fig. 7. Multichannel spectral images after MSM-SURF registration. (a) 580 nm; (b) 620 nm; (c) 715 nm

Fig. 8. 6-channel multi-spectral images of murals. (a) Mural A; (b) mural B

Fig. 9. Test results with three inscribed rectangle detection methods. (a) T-SURF; (b) CD-SURF; (c) MSM-SURF