Save figure as image to folder with continuous numbering

if i use this code all the picture that were there previously are overwritten by the last one. i would like that it names the files like this 1.jpg,2.jpg, and so on . . . and not overwrite the files!

 %   
 filename = fullfile(folder, baseFileName);
img = getframe(gcf);
    folder = 'C:\Users\Taiko\Desktop\FalseColor\';
ImageFiles = dir(folder);
    a = length(ImageFiles)-1;
    for Index = 1:a
        baseFileName = [num2str(Index),'.jpg'];
        imwrite(img.cdata,fullfile(folder,baseFileName));
    end
   if exist(filename, 'file')
   promptMessage = sprintf('%s already exists.\nDo you want to overwrite it', filename);
   titleBarCaption = 'Overwrite?';
  buttonText = questdlg(promptMessage, titleBarCaption, 'Yes', 'No', 'Yes');
   if strcmpi(buttonText, 'Yes')
      imwrite(img.cdata,filename);
   end
else
     imwrite(img.cdata,filename);
end

i got the code from this post put it got never resolved: https://de.mathworks.com/matlabcentral/answers/289707-how-to-prevent-image-that-has-been-stored-not-overwrite-using-imwrite

edit: i have a script that makes false color images and i would like to whenever i run the script that it saves the output image in that folder and labeling them continuously 1.jpg and so on

[Walter Roberson]

It is not clear why you have a loop that writes sequential files 1.jpg, 2.jpg, etc., one for every existing file (with any name) inside the folder (skipping the last one), with all of the files having the same content. And then that, having been done, a test is made about overwriting a completely different file name ??

[franz binder]

i am new to matlab i was looking for question with similar problem and this one seemd to do what i was looking for excpt it doesn't. i just copied the code from the other question.

for me it is alright if you have a differnt way of doing it. i tried it with and without the test. both didn't not do what i wanted.

basically i have a script that make a false color image (one at a time) and i want that it saves the images to that folder and labeling them 1.png and so on whenever i run the script.(even better would be if it could be labled with the date it was made)

[franz binder]

i now have this code:

 %
img = getframe(gcf);
folder = 'C:\Users\Taiko\Desktop\FalseColor\';
ImageFiles = dir(folder);
a = length(ImageFiles)-1;

 for Index = 1:a

    baseFileName = [num2str(Index),'.jpg'];
    filename=[folder,baseFileName];

    kk=Index;
    while exist(filename,'file')    %  keep trying new filenames, each increased by 1 integer, until you find one that doesn't already exist
        kk=kk+1;
        filename=[folder,num2str(kk),'.jpg'];
    end

    imwrite(img.cdata,filename);
end

but i now get: 1.jpg(first image) 2.jpg(second image) 3.jpg(second image) 4.jpg(third image) 5.jpg(third image) 6.jpg(third image) 7.jpg(third image)

for the next one i get 8 copys

Answer 1

[Walter Roberson]

All of this gets easier if you can set up conditions first and then loop doing the getframe and writing files sequentially, instead of each time having to independently figure out which file to write.

But to handle your situation as-is, and presuming that there are no other jpg files in the directory:

img = getframe(gcf);
nowstr = datestr(now, 'yyyymmddHHMM');

folder = 'C:\Users\Taiko\Desktop\FalseColor\';
ImageFiles = dir( fullfile(folder, '*.jpg') );
if isempty(ImageFiles)
   next_idx = 1;
else
  lastfile = ImageFiles(end).name;
  [~, basename, ~] = fileparts(lastfile);
  file_number_str = regexp('(?<=.*_)\d+$', basename, 'match' );
  if isempty(file_number_str)
     error('There is a .jpg file present that does not follow the expected naming pattern: "%s", lastfile);
  end
  last_idx = str2double(file_number_str);
  next_idx = last_idx + 1;
end

newfilename = fullfile( folder, sprintf('%s_%04d.jpg', nowstr, next_idx) );

imwrite(img.cdata, newfilename);

Note: if you expect to write more than 9999 frames in one series, then change the %04d to %05d or larger. Make sure that you keep the 0 after the % though. Not %4d for example.

Most this code could be eliminated if it was permitted to initialize some variables first and then write files in a loop instead of having to figure out what the next file is independently each time.

[Oliver Horrobin]

Hi there,

I've tried implamenting this but it keeps getting stuck on

error('There is a .jpg file present that does not follow the expected naming pattern: "%s", lastfile);

What does '(?<=.*_)\d+$' do?

Cheers,

Ollie

[Oliver Horrobin]

The 1st Image saves as 20210211336_0001