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

Table 7

The NC value of the proposed algorithm is compared with the algorithm based on SURF-DCT.

Type of attacks	Intensity	NC
		SURF-DCT	Proposed
Gaussian noise	5%	0.71	0.83
	25%	0.63	0.63
JPEG compression	4%	0.81	0.90
	8%	0.72	0.90
Median filter (10 times)	3 × 3	0.63	0.79
	7 × 7	0.81	0.63
Rotation (clockwise)	5°	0.74	0.90
	44°	0.57	0.64
Scaling	0.5	0.34	0.68
	2.0	0.42	0.81
Translation (down)	8%	0.81	1.00
	38%	0.72	0.81
Cropping (Y-axis)	2%	0.90	1.00
	38%	0.72	0.90

Bold values show the best data.