How to Read animated gif Perfectly

when i use the code like [imgs,map]=imread('xx.gif','frames','all'); and then show it with imshow(imgs(:,:,:,1),map); there are stains on the frame of the gif, I think it may because the GIF disposalMethod is leaveinplace.

How to deal with it? thx

[Geoff Hayes]

Frank - is it possible to include the gif that exhibits this behaviour? I took the 2to1.gif that you embedded in the answer (should really have attached it to a comment), loaded it in MATLAB and "ran" it as

 [imgs,map]=imread('2to1.gif','frames','all'); 
 for k=1:7
     imshow(imgs(:,:,:,k),map);
 end

There were no streaks or stains in this animation. Though this animated gif is different from the one that does show the stains (as shown in your other photo).

[Frank]

Thanks Geoff Hayes! I used your exact code, but still have the same problem.

[Geoff Hayes]

What version of MATLAB are you using? What operating system? If you just extract individual frames as

 for k=1:7
     [img,map] = imread('2to1.gif','frames',k);
     figure;
     imshow(img,map);
 end

do you still see the stains?

[Frank]

Yes, I still saw the streaks,Matlab Version 7.11 2010b,Operating system: Windows 7, Does it matter?

[Geoff Hayes]

I'm not sure. I'm running 2014a on a Mac, and do not see any streaks in any frame. How did you generate the animation? Through MATLAB?

Frank - since the last set of code showed the streaks, could you attach one or more of the images as mat files along with the map? Just change the code to

 for k=1:7
     [img,map] = imread('2to1.gif','frames',k);
     save(sprintf('img%d.mat',k),'img');
     save('map.mat','map');
     figure;
     imshow(img,map);
 end

and return one or more of the imgX.mat and the map.mat files. Just curious as to what the contents of these files are. Do they include the streaks/stains?

[Frank]

There's no difference among the methods you suggested. I will try update the matlab. thank you anyway. ^_^

[Kiana Maillet]

have you found a solution?

[DGM]

@Kiana Maillet

Unless you are having issues reading the exact same image, please explain your exact issues. There are common and easily-made mistakes that many users make when first trying to read animated gifs, but there are also various bugs which have affected the process throughout different versions, up to and including R2018b-R2020b (idk about R2021a/b). If you are trying to read a complicated color gif, the chances that you're running into one of these problems is high.

This thread explains the most recent issue in depth and also describes common mistakes with colormap handling and offers examples of typical usage for reading gifs prior to R2018b.

https://www.mathworks.com/matlabcentral/answers/654298-nonsensical-imread-behavior-with-multiframe-gifs-in-r2019b

If you are running into problems due to that bug, we may have to discuss what workarounds are possible.

EDIT: Preliminary testing with R2021a via the online version suggests that there may be even more egregious bugs now. I don't know if that's just the online version or not. If it affects regular installations, then imread() may simply no longer be able to correctly read GIF files. If you're using R2021a/b, then we'll have to verify that first.

It would be best if you can describe the exact problems you're having, and what version you're using. If possible, you may attach a copy of a test gif and I can see what I can do.