MATLAB: How to solve this batch process error: “Error using movefile The process cannot access the file because it is being used by another process”

Question

I'm trying to run this code to batch process some image stacks. I get an error code in the end, when I try to rename each 'test.tif' file I get at the end of the second for loop using a movefile function. I want to rename them as test_1.tif, test_2.tif as they are being processed within the first for loop. When I run the code using the Image-BatchProcess App, I get an error message "Error using movefile The process cannot access the file because it is being used by another process". I am not able to figure out which process is still using the 'test.tif' file that I generate at the end of the second for loop. I'd appreciate any thoughts/help here.

Here is my code:

Image_folder= uigetdir;
Diff_stack_folder=uigetdir;
Image_Dir=dir([Image_folder '/*.tif']);
total_images=size(Image_Dir, 1);
   for n= 1: total_images
    filename= Image_Dir.name;
    fid=fopen(filename);
    info = imfinfo(filename);
    num_images = numel(info);
         for k = 1:num_images - 1
             A = imread(filename, k, 'Info', info);
             B = imread(filename, k + 1, 'Info', info);
             Q = A - B;  
             imshow(Q, []); 
             imwrite(Q,'test.tif','WriteMode', 'append')
         end
   [~, f,ext] = fileparts(Image_Dir(n).name);
   rename = sprintf('test_%d.tif',n); 
   movefile(Image_Dir(n).name, rename);
   end

Answer 1

You have the file open with fid=fopen(filename)

run fclose() before you run movefile().