Table 2. Correlation coefficients of the adjacent pixels in different directions for the original and encrypted images

Image	Correlation coefficients for encrypted images			Correlation coefficients for original images
	Horizontal	Vertical	Diagonal	Horizontal	Vertical	Diagonal
Lena	0.005794	0.005644	0.003480	0.968683	0.943269	0.933408
Airport	0.003446	-0.007657	0.002155	0.850811	0.800954	0.729673
Chemical plant	0.002155	-0.002842	0.000282	0.916546	0.947592	0.896024
Walter Cronkite	-0.000058	0.002272	0.001407	0.987105	0.987038	0.978499
Toy Vehicle	0.000192	-0.013196	-0.002466	0.943520	0.982781	0.933587