can you explain this code?

%Lung Mask Creation

croped = [];
croped = i(10:end-10,10:end-10) ;
figure(2)
subplot(221);imshow(mat2gray(croped));title('Croped Image');
binaryImage = croped < 120;
subplot(222),imshow(binaryImage, []),title('Original Binary Image');
se = strel('disk',6);
lungMask = zeros(m,n);
lungMask(10:end-10,10:end-10)= imclose(binaryImage,se);
subplot(223);imshow(lungMask);title('Lung mask');

Answer 1

[Stalin Samuel]

croped = [];%empty matrix created
croped = i(10:end-10,10:end-10) ;% we going to crop first 10 rows and and 10 columns of the image
figure(2)
subplot(221);imshow(mat2gray(croped));%croped region displayed
title('Croped Image');
binaryImage = croped < 120;%binaryImage contains  pixel value less than 120 from the croped image
subplot(222),
imshow(binaryImage, []),%binary image displayed
title('Original Binary Image');
se = strel('disk',6); %Create a disk-shaped structuring element
lungMask = zeros(m,n);
lungMask(10:end-10,10:end-10)= imclose(binaryImage,se);%se shape fills the gap with structuring element
subplot(223);
imshow(lungMask);
title('Lung mask');

[Stalin Samuel]

imclose strel

[Reyhaneh ST]

Hi

I want to use this code to create a lungmusk, but i'm get this error!

can you say me what should i do?