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

Table 5

The NC value of the proposed algorithm is compared with other algorithms.

Type of attacks	Intensity	NC
		DCT	DTCWT-DCT [27]	Proposed
Gaussian noise	5%	0.90	0.91	0.83
	25%	0.71	0.78	0.65
JPEG compression	4%	0.89	0.82	0.90
	8%	1.00	0.91	0.90
Median filter (10 times)	3 × 3	1.00	0.91	0.79
	7 × 7	0.88	0.63	0.63
Rotation (clockwise)	5°	0.79	0.87	0.90
	20°	0.62	0.78	0.81
Scaling	0.3	0.79	0.71	0.54
	1.2	1.00	1.00	1.00
Translation (down)	8%	0.71	0.81	1.00
	22%	0.10	0.52	1.00
Cropping (Y-axis)	2%	0.89	1.00	1.00
	40%	0.36	0.65	0.90