Do not apply a model trained on smaller images to directly segment large images -will not work!!! (Code shared to prove this point).
Divide images into patches of smaller sizes and then perform the prediction.
Code generated in the video can be downloaded from here:
https://github.com/bnsreenu/python_for_microscopists
Dataset info: Electron microscopy (EM) dataset from
https://www.epfl.ch/labs/cvlab/data/data-em/
To annotate images and generate labels, you can use APEER (for free):
www.apeer.com
To install patchify: pip install patchify