Zero-Watermarking Algorithm for Medical Image Based on VGG19 Deep Convolution Neural Network

Table 4

The images under extrusion distortion attack.

	Medical image A	Medical image B	Medical image C	Medical image D	Medical image E
The smallest NC value	0.9354	0.7815	0.74818	0.78076	0.87566
The restored watermarking image
Medical image to be tested