Overwritting problem in for loop

I simply crop images and save them with a number.For example i have Grain #1,Grain #2,Grain #3.If i move to another image and crop further images i cannot create images Grain #4 ,Grain #5 etc and instead there are overwritten images...Here is my code.Where is my mistake??

clear all;
clc;

addpath(genpath('C:\Users\User\Desktop\TEI'));
imtool close all; 
k=input('How many times do you want to repeat the cropping?');
IMAGE = uigetfile('*.jpg','Pick an image');
A=imread(IMAGE);
figure,imshow(IMAGE);
folder=('C:\Users\User\Desktop\TEI\BEE_POLLEN _PROJECT\Scripts');
for i=1:k
  f = sprintf('Select a ROI and double click to crop #%d',i);
  uiwait(warndlg(f));
  [B, rect] = imcrop(A);
  baseFileName = sprintf('Grain #%d.jpg',i);
  fullFileName = fullfile(folder, baseFileName);
  baseFileName2 = sprintf('Grain #%d .jpg', (i+1));
  fullFileName2 = fullfile(folder, baseFileName2);
  if exist(fullFileName)     
    imwrite(B, fullFileName2);
  else
    imwrite(B, fullFileName);
  end
  if i==k
    f=sprintf('FINISHED!!');
    uiwait(warndlg(f));
  end
end

[dpb]

You base the file number on the 1:k loop index variable i so it starts all over from the beginning every time you run the script.

You would need to keep a persistent variable that retains its value to continue numbering from the last case to just keep making more files of the same base name.

BUT, I'd suggest you should probably go to a more expressive naming scheme where you build a name for the set of cropped image files for a given input image that reflects that input file as well as just a sequence number.

Also, when you create sequentially-numbered files such as this, unless it is absolutely certain that there will never be more than 1 thru 9 for a given base name, you shoule use a format that writes leading zeros for the numeric part -- otherwise they will not sort numerically, but alphabetically.

fmt='Grain #%03d.jpg'  ;
baseFileName = sprintf(fmt,i);

[DIMITRIOS THEODOROPOULOS]

can you suggested me the full corrected code?

[dpb]

At least give it a go with the supplied hints..."nothing ventured, nothing gained!"

Specific Q? if/when you have a specific problem, sure; just write code for another's job?, "not so much"...

[Jan]

The clear all will impede the method of using a persistent variable. Because this brute clearing of everything has other severe disadvantages also, omitting it is a good idea in general.

Adding a set of folders automatically to Matlab's path can cause problems, when any of the included folders contain M-files:

addpath(genpath('C:\Users\User\Desktop\TEI'));

Do you do this only to access the images in these folders? Then leave the path untouched. You are using absolute file names already, so do not pollute the path without needs.

Answer 1

[Jan]

nExisting = numel(dir(fullfile(folder, 'Grain #*.jpg')));
for i = 1:k
  f = sprintf('Select a ROI and double click to crop #%d',i);
  uiwait(warndlg(f));
  [B, rect] = imcrop(A);
  baseFileName = sprintf('Grain #%d.jpg', i + nExisting);
  fullFileName = fullfile(folder, baseFileName);
  if exist(fullFileName, 'file')  % with 'file' !!!
      error('Collision with filename: %s', fullFileName);
  end
  imwrite(B, fullFileName);
end
f = 'FINISHED!!';  % without sprintf
uiwait(warndlg(f));

Or use https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort (link) tofind the largest index in the file names and start counting there. (I'd prefer this.)

Another idea is to check the existence of a file name dynamically:

count = 1;
for i = 1:k
  ...
  isFree = false;
  while ~isFree
    baseFileName = sprintf('Grain #%d.jpg', count);
    fullFileName = fullfile(folder, baseFileName);
    if ~exist(fullFileName, 'file')  % with 'file' !!!
       isFree = true;
    end
    count = count + 1;
  end
end

It is not tricky, as you can see.

[DIMITRIOS THEODOROPOULOS]

Thank you very much!!!!!I.Very clever!II couldnt not find how to count the existing files and the first command in the first solution was the answer!!

...Now i will try the others!

[Jan]

You are welcome.