[Retracted] Robust and Secure Zero-Watermarking Algorithm for Medical Images Based on Harris-SURF-DCT and Chaotic Map

Table 4

The test data under geometric attacks.

Geometric attacks	Intensity	PSNR (dB)	NC
Rotation (clockwise)	4°	17.40	0.90
	19°	12.52	0.89
	44°	11.08	0.64
Rotation (counterclockwise)	4°	17.41	1.00
	21°	12.42	0.90
	46°	10.97	0.64
Scaling	0.3	—	0.54
	0.5	—	0.68
	0.8	—	0.88
	1.2	—	1.00
	2.0	—	0.81
	3.4	—	0.66
Translation (left)	3%	12.39	1.00
	17%	8.40	0.89
	38%	6.20	0.90
Translation (up)	3%	13.05	1.00
	16%	9.65	0.88
	38%	7.57	0.81
Cropping (X-axis)	8%	—	1.00
	16%	—	1.00
	30%	—	0.79
Cropping (Y-axis)	10%	—	1.00
	24%	—	1.00
	38%	—	0.90