I want to measure entropy and PSNR to N number of images

clc
clear all
srcFiles = dir('----\*.jpg');  % the folder in which ur images exists
for i = 1 : length(srcFiles)
    filename = strcat('----',srcFiles(i).name);
    I = imread(filename);
end
E = entropy(I);

It returns to me one value only.

Answer 1

[Image Analyst]

Yes that's true. You're only calling it on the very last image you read in. If you want a value for every image, put it in the loop and index it.

for i = 1 : length(srcFiles)
    filename = strcat('----',srcFiles(i).name);
    I = imread(filename);
    E(i) = entropy(I);
end

If you want a value for every pixel in the image, use entropyfilt() instead of entropy().

entropyImage{i} = entropyfilt(I);

You can compute PSNR with the Image Processing Toolbox function called psnr().