how do i do comparing 3 images about contrast in matlab

please guide me that how to write matlab code for this image

Answer 1

[Image Analyst]

Try looking at the standard deviation of the images. The lower the contrast, the lower the standard deviation

stdDev = std(double(grayImage));

[pegah esmaeilpour]

thanks for your answers but please get more matlab code for this image

[Image Analyst]

grayImage1 = imread(yourFileName1);
stdDev1 = std(double(grayImage1));
grayImage2 = imread(yourFileName2);
stdDev2 = std(double(grayImage2));
grayImage3 = imread(yourFileName3);
stdDev3 = std(double(grayImage3));