Table 3: Information entropy and average gradient in Figure 7.

Quantity figureInformation entropyAverage gradient

(a)7.116912.7524
(b)7.052718.5745
(c)7.554224.2284
(d)7.747921.3413
(e)6.70228.1590
(f)6.59459.9940
(g)6.919114.3697
(h)7.004212.3686
(i)7.069920.1335
(j)6.794921.9897
(k)7.217031.1642
(l)7.715828.0974
(m)7.01244.7013
(n)6.57314.9414
(o)7.16467.1624
(P)7.49535.5328