A Strong Robust Zero-Watermarking Scheme Based on Shearlets’ High Ability for Capturing Directional Features

Table 5

The values of distorted host images and values of extracted watermarks under Gaussian noise.

Host image
	SSIM/NC	SSIM/NC	SSIM/NC	SSIM/NC	SSIM/NC
Boat	0.72/1.0000	0.43/0.9980	0.32/0.9974	0.13/0.8728	0.08/0.6977
Goldhill	0.76/0.9922	0.45/0.9876	0.31/0.9830	0.11/0.8644	0.07/0.8870
Baboon	0.85/0.9941	0.61/0.9719	0.48/0.9562	0.20/0.6668	0.13/0.7733
Barbara	0.77/0.9974	0.50/0.9961	0.39/0.9941	0.17/0.9915	0.11/0.9683
Peppers	0.70/0.9987	0.38/0.9987	0.26/0.9993	0.10/0.9922	0.06/0.8675
Man	0.75/0.9961	0.45/0.9902	0.33/0.9823	0.12/0.8182	0.08/0.8577