How to join or merge two Image Data Stores?

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kowshik Thopalli
kowshik Thopalli on 26 Feb 2017
Edited: Matt J on 28 Jun 2022
If I have two image datastores and I wish to concatenate them. How can I do that?
  1 Comment
Sherin Aly
Sherin Aly on 13 Jan 2018
It was a bit tricky but I was able to merge 2 datastores as follows:
imds1 = imageDatastore(location of DS 1,'IncludeSubfolders',true,'LabelSource','foldernames');
imds2 = imageDatastore(imds2 location,'IncludeSubfolders',true,'LabelSource','foldernames');
% create a dummy dataset with the same size of the combined datastores (if ds1 has 100 images and ds2 has 100 images then dummy has 200 images. I made a folder with some photos with equal number of the 2 datastores)
dummy = imageDatastore('Dummy data store locaation','IncludeSubfolders',true,'LabelSource','foldernames');
% note: below this line you can use any datastore variable you want to merge including the ones you get after splitting training and testing
% Now dummy is the new combined datastore and you can use all datastore functions

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Accepted Answer

Zhiqiang Qiu
Zhiqiang Qiu on 22 Jan 2018
I know it is an ancient problem, but I just to make it a better reference for other people.
imds1 = imageDatastore('imds1 location', ...);
imds2 = imageDatastore('imds2 location', ...);
imds_combine = imageDatastore({'imds1 location', 'imds2 location'}, ...);
Just combine the address of these two locations. The following parameters are all the same.
  1 Comment
habtamu miheretie
habtamu miheretie on 7 Sep 2018
that is cool answer! i have very similar problem. when i create the data store the files are not in the same order as in the folder. how can i make that possible? i need it because the label i use is coming from another .csv file. so i need to match the order to process the images easily. can anyone help me on this please?

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More Answers (5)

Hana on 18 Jan 2018
I met the same problem and saw your post. Finally I find out a way:
imds = imageDatastore(cat(1,imds1.Files,imds2.Files))
imds.Labels = cat(1,imds1.Labels,imds2.Labels)
It works for me.

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berkan on 22 May 2017
allImages.Files=[test1.Files;test2.Files]; allImages.Labels=[test1.Labels;test2.Labels];
  1 Comment
Sascha D. Krauß
Sascha D. Krauß on 3 Jul 2017
Unfortunately, this produces a struct instead of a new datastore - and I could not find a way to convert it back. This means, that you cannot use the datastore specific functions like "countEachLabel" etc. Does anyone know another solution?

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KSSV on 27 Feb 2017
A = imread('ngc6543a.jpg');
B = imread('peppers.png');
%%resize the images so that they have same dimensions
A_resize = imresize(A,[size(B,1) size(B,2)]) ;
%%join them
AB = [A_resize B] ;
imshow(AB) ;
  1 Comment
kowshik Thopalli
kowshik Thopalli on 27 Feb 2017
Hi, Thanks for the answer, however I am looking to merge two

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Aasim Khurshid
Aasim Khurshid on 30 Dec 2020
Edited: Matt J on 28 Jun 2022
There is a better way to do this,
imds = imageDatastore({fullfile(imgFolder1Adress),fullfile(imgFolder2Adress),fullfile(imgFolder3Adress)},...

Matt J
Matt J on 28 Jun 2022
Edited: Matt J on 28 Jun 2022
Perhaps by wrapping them in a TransformedDataStore (R2019a and higher),
imdsnew = transform(imds1,imds2, @(x) x)

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