Load image to docker without dockerd

I want to load docker image without dockerd. (like docker load -i image.tar ) I see that when I load docker image there are files that added to only 2 directories: overlay2,image How can I set the desire files there from my image.tar without running docker/dockerd? (I just want to understand the Docker filesystem layout. So I looking for a way to simulate the loading image in a shell script)