Multipurpose Watermarking Algorithm for Medical Images

Table 3

Similarity of the extracted watermark based on two algorithms.

Attacking mode	Robust watermark similarity (NC)
	Algorithm 1	Algorithm 2
No attack	1	1
Gaussian low-pass filter	0.938	0.937
Median filter [3, 3]	0.942	0.943
Gaussian noise (0.05)	0.952	0.949
Salt and pepper noise (0.03)	0.957	0.956
Shear (1/16)	0.921	0.921
JPEG compression Q = 20	0.924	0.922
JPEG compression Q = 50	0.965	0.964
Shrink 10%	0.985	0.985
Rotate 30°C	0.982	0.982