Table 11.

The SSIM of the algorithms on the deep crack images.

Level	AEO	EO	HHO	ChOA	SSA
2	0.7437	0.7415	0.7389	0.7072	0.7308
3	0.7420	0.7396	0.7374	0.7046	0.7287
4	0.7404	0.7385	0.7363	0.7055	0.7281
5	0.7423	0.7403	0.7378	0.7065	0.7297

Significant values are in bold.