How to implement image preprocessing using imageDatastore?

I want to do image preprocessing before implementing deep lerning, MATLAB dosn't accept "transformed imageDatastor":

imds: imageDatastore

imds_T = transform(imds,@(x) medfilt2(x)); %imds_T: transformed imageDatastor

I tried to apply "splitEachLabel" and I got the following error:

Undefined function 'splitEachLabel' for input arguments of type 'matlab.io.datastore.TransformedDatastore'.

What is the problem?

How to implement image preprocessing using imageDatastore?

[Mohammad Sami]

Perhaps you can use splitEachLabel to separate your training and test datasets first, before you apply the transform.