Color Zero-Watermarking Algorithm for Medical Images Based on BEMD-Schur Decomposition and Color Visual Cryptography

Table 5

NC values under geometric rotation attacks.

Attack type	Attack intensity	Fundus1	Fundus2	Fundus3	Fundus4	Cerebral1	Cerebral2	Cerebral3	Cerebral4
Rotation	5°	0.9940	0.9877	0.9940	0.9886	0.9631	0.9735	0.9780	0.9697
	10°	0.9898	0.9837	0.9934	0.9827	0.9461	0.9591	0.9648	0.9553
	15°	0.9876	0.9780	0.9899	0.9786	0.9340	0.9472	0.9692	0.9465