MATLAB: How to find out Correlation between two image

Question

clc;

clear all;

close all;

a=imread('1.jpg');

b=imread('2.jpg');

corr2(a,b);

____________::Error Occured::_____________

Error using corr2

Error using corr2

Expected input number 1, A, to be two-dimensional.

Error in corr2>ParseInputs (line 35)

validateattributes(A, {'logical' 'numeric'}, {'real','2d'}, mfilename, 'A', 1);

Error in corr2 (line 21)

[a,b] = ParseInputs(varargin{:});

Error in featureExt (line 9)

corr2(a,b);

Answer 1

They're probably color. Do it on one color channel at a time, or use rgb2gray() to convert them to grayscale. Untested code:

grayImage1 = rgb2gray(a);
grayImage2 = rgb2gray(b);
out = corr2(grayImage1, grayImage2);