How to write U-Net Deep Learning code dealing with ".tiff" images?

[JenniferYingyiWu2020]

Hi,
I have read the supervised machine learning on the page of "https://rasterframes.io/supervised-learning.html", now I would like to implement U-Net (Semantic Segmentation) Deep Learning which is integrated with RasterFrames.
However, I am so confused about how to write U-Net Deep Learning code dealing with ".tiff" images? So, would you pls help to give me some suggestions? Many Thanks!