Color Zero-Watermarking Algorithm for Medical Images Based on BEMD-Schur Decomposition and Color Visual Cryptography

Table 9

Comparison of the robustness (NC) between the proposed scheme and schemes [13, 15–17].

Attack type	Scheme [13]	Scheme [15]	Scheme [16]	Scheme [17]	Proposed scheme
Gaussian noise (σ = 0.01)	0.9470	0.9609	0.9264	0.9609	0.9914
Salt and pepper noise (σ = 0.01)	0.9600	0.9531	0.9416	0.9424	0.9961
Median filtering (3 × 3)	0.9818	0.9500	0.9817	0.6200	0.9996
Median filtering (5 × 5)	0.9541	0.9600	0.9708	0.4500	0.9992
Gaussian filtering (3 × 3)	0.9946	0.9629	0.9803	0.9629	0.9990
Average filtering (3 × 3)	0.9785	0.9600	0.9774	0.9721	0.9995
JPEG compression (QF = 30)	0.9762	0.9000	0.9540	0.9000	0.9974
Rotation with 5°	0.9892	0.9100	0.8851	0.8076	0.9874
Rotation with 10°	0.9845	0.8700	0.8503	0.5996	0.9833
Scaling 0.75	0.9991	0.8652	0.9901	0.7076	0.9991
Scaling 1.5	0.9878	0.8891	0.9861	0.7900	0.9993
Left distance (0, 30)	0.8203	0.5781	---	0.8900	0.9459
Cropping (30%) Y direction	0.9768	0.7500	0.9839	0.7200	0.9547

--- means no item.