Array handling

I am new to this field. While I am working on deep learning algorithms at a certain juncture in my program I needed use ImageClassifierData.from_arrays() of fastai.
Can someone help create an array of (10000,256,256,3) dims where 10000 images data (of size 2562563) can be loaded.

The array of size (10000,256,256,3) will be fed to ImageClassifierData.from_arrays()