How can I resize images and bounding boxes on dataset?

I'm trying to resize the images and bounding boxes of a combined datastore with a function to fit their size with resnet18 input size to create a YOLO object detector, but it displays an error when I execute it. This is the function (I'm sorry the names are in spanish):

function data = ReescalarDataset(data) 
    tamanio = [224 224 3]; %tamaño de entrada requerido por resnet18
    % data{1} es la imagen
    escala = tamanio./size(data{1},[1 2]);
    data{1} = imresize(data{1},tamanio);
    % data{2} contiene la bounding box
    data{2} = bboxresize(data{2},escala);
end

And when I execute this

dataEscalado = transform(data, @ReescalarDataset)
pruebaGroundTruth = preview(dataEscalado)

It displays this error

Invalid transform function defined on datastore.

The cause of the error was:

Arrays have incompatible sizes for this operation.

Error in ReescalarDataset (line 7)
    escala = tamanio./size(data{1},[1 2]);

Error in matlab.io.datastore.TransformedDatastore/applyTransforms (line 610)
                            data = ds.Transforms{ii}(data);

Error in matlab.io.datastore.TransformedDatastore/read (line 222)
            [data, info] = ds.applyTransforms(data, info);

Error in matlab.io.datastore.TransformedDatastore/preview (line 295)
            dataFromRead = read(copyds);

I don't know other way to do the scaling of both the image and the bounding box.

Answer 1

[Birju Patel]

The error is caused by dividing a three element vector with a two element vector. Make the follow change to your code:

escala = tamanio(1:2)./size(data{1},[1 2]);