Animated GIF contains offset in consecutive timestamps

I have an animated GIF that contains offsets from timestamp to timestamp, which is not desired.

The relevant code snippet is as follows:

for iter = 1 : 100
    % Create an animated GIF image to illustrate the evolution of
    % material distribution of optimized design
    frame = getframe(axMatDist);
    im = frame2im(frame);
    [imind, cm] = rgb2ind(im, 256);
    if (iter == 1)
        imwrite(imind, cm, 'myanimation.gif', 'gif', 'Loopcount', inf);
    else
        imwrite(imind, cm, 'myanimation.gif', 'gif', 'WriteMode', 'append');
    end
end

What could be the problem?

[hmhuang]

Any ideas?

Answer 1

[DGM]

To be more precise, the file does not contain any frame offsets. All the frames are positioned at [1 1]. The problem is that the frame sizes differ. This is an issue with the way the figures are drawn and captured.

h = imfinfo('https://www.mathworks.com/matlabcentral/answers/uploaded_files/860820/myanimation.gif');
unique([h.Top])

ans = uint16 1

unique([h.Left])

ans = uint16 1

unique([h.Height])

ans = 1×3

245 248 252

unique([h.Width])

ans = 1×3

491 495 504

Since I don't know how the figure is being drawn, I'll just suggest that it may suffice to explicitly set the axes geometry with xlim() and ylim(). If the axes position keeps changing (e.g. due to tick labels changing), or if the figure size keeps changing, that will change the output size. If so, removing extraneous objects from the figure and explicitly setting object sizes may make things more consistent.

If that's not an option, perhaps the captured images can be resized or padded to a fixed geometry using imresize(), but that's probably the less attractive option, as it's unclear whether there's a scale difference between frames or not. It's also unclear what the correct registration would be.