Exportgraphics is not overwriting

I have a set of figures that I'm saving using exportgraphics, after making some changes to the programm i get a new set of figures but exportgraphics is not overwriting it. I have been using this to export images for a long time and it used to overwrite, but since yesterday it isn't doing so. Any ideas about what may be causing this?

[DGM]

It would help to know how you're using it. A concrete code example, for instance.

Are you double-checking the file timestamps? Are they untouched, are or they simply rewritten with an identical content? Is it possible that something was changed with the code and now they're being written to a different location and you're looking at the old set of outputs?

[Vivek]

This is how i'm using it,

clc
clear
close all

f2 = "D:\DesiredFolder\";
x = 1:100;
y = 100:-1:1;
fig = figure;
plot(x,y)
fig.Units='inches';
fig.Position=[0,0,8,8.5];
filenameEN = fullfile(f2,"xyz.jpg");
exportgraphics(fig, filenameEN,'Resolution', 120);

Yes, I have checked timestamps,it is not changing. It is saving images only when I delete previous images, so location is not a problem.

[DGM]

f2 = ""; % just for forum testing
filenameEN = fullfile(f2,"xyz.jpg");

x = 1:100;
y = 100:-1:1;
fig = gcf;

% i'm going to repeatedly plot and save the screenshot
for k = 1:3
    plot(x,y)
    fig.Units='inches';
    fig.Position=[0,0,8,8.5];
    exportgraphics(fig, filenameEN,'Resolution', 120);
    imfinfo(filenameEN).FileModDate % check the timestamp
    pause(3)
end

ans = '13-Jul-2024 08:19:06'

ans = '13-Jul-2024 08:19:09'

ans = '13-Jul-2024 08:19:13'

I'm not sure why the forum editor dumps the figure twice here, but all I'm looking for are the timestamps, which do change.

My point in testing this here on the forum isn't strictly demonstrative; it's simply that I run R2019b, which doesn't have exportgraphics(), so the forum is where I'd have to test it.

From my vantage point, I don't see a good reason why exportgraphics() wouldn't write the file, though I think there's probably an explanation that I simply can't see from where I'm at. For example, I've had scenarios where my file manager simply stopped updating the contents of the directory I was looking at. It might be worth trying to use imfinfo() as above to programmatically check the file for changes.

That said, I would hope that someone else can chime in with more insight on newer versions.

One last note which is completely unrelated to the main problem:

I strongly recommend using PNG for capturing line plots like this. JPG will produce a visually degraded copy and a larger file size than a PNG. Unless you need JPG for compatibility reasons, it's best avoided for simple synthetic images. Again, that shouldn't be affecting the file-overwriting issue at all. Just general advice.

Answer 1

[Sandeep Mishra]

Dear Vivek,

Upon running the code snippet in MATLAB R2022a, I noticed that the ‘exportgraphics’ function is working properly and overwriting the file when executed multiple times.

To address the issue, consider the following troubleshooting steps:

1. Use the ‘clear all’ command to remove any existing variables that might interfere with your script.
2. Make sure the file you are trying to overwrite is not open in another application, which can prevent overwriting.

Additionally, a practical solution can be to delete the existing file before exporting the new image.

You can achieve this with the following MATLAB code snippet:

if exist(filenameEN, 'file')  
   delete(filenameEN);  
end  
exportgraphics(gca, filenameEN); 

I hope this helps.