how to compute correlation coefficient of rgb image

i have 256*256*3 image and i want to find horizontal,vertical,diagonal of it which can give me only 1 value

[Walter Roberson]

Can you explain that further?

[aaru sri]

Correlation coefficients of two adjacent pixels in two images.

Plain image Ciphered image

Horizontal 0.91765 0.01183

Vertical 0.95415 0.00016

Diagonal 0.90205 0.01480

where plain image is 256*256*3 colour image

[Walter Roberson]

How are you calculating pixel correlation for color images? Correlation of brightness? Correlation of hue?

[aaru sri]

adjacent correlation between ciphered and original image

[Walter Roberson]

We need your code.