How to sort the files obtained by ImageDatastore?

I used imageDatastore to obtain the directory of all the images in a folder.

Images = 'D:\Google Drive\MARYLAND\ENPM808 Independent Study\Independent Study\3D_map_poses\rgb';
rgb_image = imageDatastore(fullfile(Images),'IncludeSubfolders',false,'FileExtensions','.png','LabelSource','none');

But I realized that the order of the directories is not the same as the File Explorer and hence the generated video after processing the frames is erroneous.

Instead I need this to be in increasing order, (e.g. 1,3,7,9,10,16,...).

How can I do this? Thanks!

[KALYAN ACHARJYA]

Question is not clear for me.

[Stephen23]

"How to sort the directories obtained by ImageDatastore?"

I suspect that you really meant to write "...sort the files..."

Your screenshot shows .png files with different names that are not in numeric order. The directories appear to be all identical.

[Canberk Suat Gurel]

You are right, I edited the topic.

[Image Analyst]

So, did Stephen's utility, described below in his answer, work for you? (Did you even see it?) If so, you can mark it as "Accepted" to give him credit for helping you.

[Canberk Suat Gurel]

I have just got the chance to try it. I "Accepted" the answer.

Answer 1

[Stephen23]

I don't know if it is possible to sort the ImageDatastore object itself, but you can certainly sort the filenames yourself: one option is to download my FEX submission natsortfiles, which was written to solve the exact file-order problem that you are having:

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

natsortfiles has plenty of examples in its help, the online description, and the HTML documentation, so you should not have any problems using it. You will probably have to specify the order of the files when calling ImageFileStore, by supplying the first argument as the correctly sorted filenames, something like this (untested):

P = 'D:\Google Drive\MARYLAND\ENPM808 Independent Study\Independent Study\3D_map_poses\rgb';
S = dir(fullfile(P,'*.png'));
S = natsortfiles(S);
F = fullfile({S.folder},{S.name});
I = imageDatastore(F,...)

I don't have imageDatastore, so you will have to experiment with this yourself.

Note that you can avoid this whole problem by using sufficient leading zeros on all of the filenames, e.g. use (0001).png instead of (1).png, then the filenames will always be sorted into the correct order (for <10000 files).

[emirhan toprak]

it helped alot thnak you Stephen <3

Answer 2

[Stephen23]

A very neat and simple approach (from an answer by Pranay Koppula here) is to apply NATSORTFILES() to the FILES property of the IMAGEDATASTORE object:

obj = imageDatastore(..);
obj.Files = natsortfiles(obj.Files);

The function NATSORTFILES() can be downloaded here:

https://www.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort

As Pranay Koppula wrote, it is unclear if this affects other attributes of the object.

[Nazmul Hasan]

I also used the same appraoch and got perfect results.