Why region_seg_demo is not working for the imcrop size of my preference?

Hi

I use the below code I found in the Mathworks community

S = uigetfile('*');
 
Img= imread(S);
Img = double(Img(:,:,1));
Img = imcrop(Img,[253.25 158.25 447 132]);
 
 
 
I = Img;
m = zeros(size(I,1),size(I,2));          %-- create initial mask
m(5:80,80:550) = 1;
 
I = imresize(I,.5);  %-- make image smaller 
m = imresize(m,.5);  %     for fast computation
 
subplot(2,2,1); imshow(I); title('Input Image');
subplot(2,2,2); imshow(m); title('Initialization');
subplot(2,2,3); title('Segmentation');
 
figure
 
seg = region_seg(I, m, 3000); %-- Run segmentation
 
subplot(2,2,4); imshow(seg); title('Global Region-Based Segmentation');

And I get the below error when I choose my preffered cropping size window

Index exceeds the number of array elements (15008).
Error in region_seg (line 51)
    u = sum(I(upts))/(length(upts)+eps); % interior mean
Error in region_seg_demo (line 30)
seg = region_seg(I, m, 3000); %-- Run segmentation 

Any idea the cause of this error?

Thanks

[Stelios Fanourakis]

Let me know if I have to upload anything such as the image I am trying to crop or the region_seg code.