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

Table 1

The value of correlation coefficients between different images.

Image	Brain	Lung	Spine	Abdomen	Elbow	Orbits	Knee	Coronary artery	Wrist
Brain	1.00	0.19	0.39	0.28	0.25	0.35	0.28	0.25	0.31
Lung	0.19	1.00	0.12	0.38	0.45	0.37	−0.05	0.17	0.15
Spine	0.39	0.12	1.00	0.23	0.37	0.33	0.41	0.19	0.46
Abdomen	0.28	0.38	0.23	1.00	0.18	0.17	0.07	0.18	0.12
Elbow	0.25	0.45	0.37	0.18	1.00	0.30	0.33	0.13	0.39
Orbits	0.35	0.37	0.33	0.17	0.30	1.00	0.17	0.30	0.39
Knee	0.28	−0.05	0.41	0.07	0.33	0.17	1.00	0.18	0.28
Coronary artery	0.25	0.17	0.19	0.18	0.13	0.30	0.18	1.00	0.39
Wrist	0.31	0.15	0.46	0.12	0.39	0.39	0.28	0.39	1.00