Figure 8.

The key sensitivity test: (a,e): the original image and corresponding histogram; (b,f): the encrypted image $E1$ with the security key set $k_{ey}\left(1\right)$ and corresponding histogram; (c,g): the encrypted image $E2$ with the security key set $k_{ey}\left(2\right)$ and corresponding histogram; (d,h): the pixel-by-pixel difference $|E1-E2|$ and corresponding histogram; (i): the decrypted image from $E1$ using the correct security key set $k_{ey}\left(1\right)$ ; (j): the decrypted image from $E2$ using an incorrect security key set $k_{ey}\left(1\right)$.