Secure and Efficient Image Compression-Encryption Scheme Using New Chaotic Structure and Compressive Sensing

Table 3

Correlation analysis.

Image		Direction	Correlation coefficient of plain image	Correlation coefficient of cipher image
				Chebyshev + Tent [14]	Our-Chebyshev + our-Tent	Sine + Logistic [17]	Our-Sine + our-Logistic
CS scheme [14]	Lena	Horizontal	0.9343	−0.0407	0.0098	−0.0568	−0.0251
		Vertical	0.9715	−0.0549	−0.0324	0.0943	0.0107
		Diagonal	0.9271	0.0343	−0.0047	0.0633	0.0624
	Boom	Horizontal	0.8544	−0.0195	−0.0011	0.0521	0.0372
		Vertical	0.8311	0.0402	0.0287	−0.0149	−0.0236
		Diagonal	0.7576	−0.0608	0.0293	0.0459	−0.0438
	Average	Horizontal	0.8944	−0.0301	0.0044	−0.0024	0.0061
		Vertical	0.9013	−0.0074	−0.0019	0.0397	−0.0065
		Diagonal	0.8424	−0.0133	0.0123	0.0546	0.0093
Our scheme	Lena	Horizontal	0.9278	0.0393	−0.0058	−0.0010	0.0012
		Vertical	0.9688	0.0352	0.0197	0.0428	−0.0306
		Diagonal	0.9031	0.0140	0.0246	−0.0023	−0.0197
	Boom	Horizontal	0.8685	−0.0125	−0.0105	−0.0123	−0.0126
		Vertical	0.8247	−0.0278	−0.0156	−0.0814	0.0181
		Diagonal	0.7623	−0.0173	−0.0149	0.0226	0.0344
	Average	Horizontal	0.8982	0.0134	−0.0082	−0.0067	−0.0057
		Vertical	0.8968	0.0037	0.0021	−0.0193	−0.0063
		Diagonal	0.8327	−0.0017	0.0049	0.0102	0.0074