Split image dataset into two separate folders

Hello all,

I need to split an image dataset folder into two seperate folders.

In general i use :

imds = imageDatastore(dataset,...

'IncludeSubfolders',true,'LabelSource','foldernames');

[trainingSet, testSet] = splitEachLabel(imds, 0.7, 'randomize');

but how can I get the two seperate folders, because I need them for other processing things ?

More precisely, I want to divide each category folder to two separate folders one for training and one for test with a definite percentage rate (for example 30% of the category folder images are saved in test folder and the other 70% in training folder).

Thank you for your help!

Answer 1

[Parag]

Hi @Andrea Daou,

Image dataset can be split into training and testing folders by physically copying the files into two separate directories for each class label. This method is useful when you need to use the separated folders for custom processing or external tools that expect a specific folder structure.

Please follow the below steps to achieve this:

• Use ‘ImageDatastore’ to read images and labels.
• Use ‘splitEachLabel’ to separate them.
• Physically copy the files into new train and test folders, preserving the label structure.

% Source dataset folder (with subfolders per label) 
sourceFolder = 'path_to_your_dataset'; 

% Destination folders 
trainFolder = 'path_to_train_folder'; 
testFolder  = 'path_to_test_folder'; 

% Create image datastore 
imds = imageDatastore(sourceFolder, ... 
    'IncludeSubfolders', true, ... 
    'LabelSource', 'foldernames'); 

% Split datastore (70% train, 30% test) 
[imdsTrain, imdsTest] = splitEachLabel(imds, 0.7, 'randomize'); 

% Function to copy files to new folder structure 
copyImagesToFolder(imdsTrain, trainFolder); 
copyImagesToFolder(imdsTest, testFolder); 

disp('Images successfully copied to training and test folders.'); 

%% ------- Helper Function -------- 
function copyImagesToFolder(imds, destFolder) 
% Ensure the destination folder exists 
if ~exist(destFolder, 'dir') 
    mkdir(destFolder); 
end 

% Loop through all files 
for i = 1:numel(imds.Files) 
    % Get image path and label 
    srcFile = imds.Files{i}; 
    label = string(imds.Labels(i)); 
    
    % Create subfolder if needed 
    destSubFolder = fullfile(destFolder, label); 
    if ~exist(destSubFolder, 'dir') 
        mkdir(destSubFolder); 
    end 
    
    % Copy image 
    [~, name, ext] = fileparts(srcFile); 
    destFile = fullfile(destSubFolder, [name ext]); 
    copyfile(srcFile, destFile); 
end 
end 

You can refer to MATLAB documentation of ‘copyfile’ for more details:

https://www.mathworks.com/help/matlab/ref/copyfile.html

Hope it helps!