Table 2. Comparison of correlation coefficients of two adjacent pixels in different directions using the proposed algorithm with some other algorithms.

	Correlation direction
	Horizontal	Vertical	Diagonal
The original Lena image	0.92473	0.96053	0.83092
The proposed algorithm	-0.00368	0.00014	-0.02298
Ref. [26]	0.1257	0.0581	0.0504
Ref. [28]	0.0681	0.0845	-
Ref. [30]	0.0042	0.0033	0.0024
Ref. [37]	-0.00124	0.00176	0.00193
Ref. [45]	-0.0018	0.00033	0.00427