How to read multiple dicom image files from a folder ? This is the code. I am trying to calculate psnr and store it in excel, but i am getting blank sheet. Thanks in advance

clc;

clear all;

img_folder = 'C:\Users\COMSOL\Documents\MATLAB\2XXX00';

dicomlist = dir(fullfile(img_folder,'Images','*.dcm'));

a = zeros(100, 'int8');

for I = 1 : numel(dicomlist)

f = dicomread(fullfile(img_folder,'Images',dicomlist(cnt).name));

gray = rgb2gray(f);

M = medfilt2(gray, [3,3]);

nr = psnr(gray,M);

a(1i,:) = nr;

end

xlswrite('psnr.xlsx',a);