ImageList assumes the data contains a filename in the get method. See https://github.com/fastai/fastai/blob/master/fastai/vision/data.py#L269:
def get(self, i):
fn = super().get(i) # In your case, returns data/10x10
res = self.open(fn). # <- Here, instead of opening an image, you need to create it.
self.sizes[i] = res.size
return res
If it doesn’t work, you may need a custom ItemType. See https://docs.fast.ai/tutorial.itemlist.html. In this case, you may want to try fastai v2 (it’s in development). A good starting point is [muellerzr course].(A walk with fastai2 - Vision - Study Group and Online Lectures Megathread)
Finally, regarding data types and dimensions, I don’t know. Keep in mind that all images have to be same size in order to collate them in a batch.