MATLAB: Problem with image size for AlexNet

Question

Hello everyone!

I'm trying to train an AlexNet model to Feature Extraction and i'm getting the following problems:

I have the following imageDatastore:

    imds = imageDatastore(fullfile(path),...
    'IncludeSubfolders', true, 'LabelSource', 'foldernames',...
    'ReadFcn', @preProcess);

As you can see, i'm using the 'ReadFcn' to make resize over all the images from the data set.

My 'preProcess' function:

    image = imread(imgFile);
    image = imresize(image, [227, 227]);

And my AlexNet model:

    net = alexnet;
    layers = net.Layers;
    layers(end-2) = fullyConnectedLayer(102);
    layers(end) = classificationLayer;
    options = trainingOptions('sgdm', ...
        'MaxEpochs', 6, 'MiniBatchSize', 64, 'ExecutionEnvironment', 'GPU');
    [mynet, netinfo] = trainNetwork(imds, layers, options);

I'm getting the following error:

    Caused by:
    Error using nnet.internal.cnn.MiniBatchDatasourceDispatcher>iCellTo4DArray (line 328)
    Unexpected image size: All images must have the same size.

Someone can help me?

Thank you for the support!

Answer 1

Hi everyone! On MATLAB 2017b version, i solved my problem with:

    imageSize = [277 277 3];
    auimds = augmentedImageSource(imageSize, imds);