A docker host has the kernel + file system + libraries (e.g. ubuntu)
A docker image has no kernel, only the file system + libraries but may be in a different os's structure, e.g. redhat's file system.
A docker container starting from a docker image calls the kernel of the host system to get things running.
On a windows host there has to be a linux os kernel installed with the docker client to be able to provide the kernel for a container to run.