Windows Image File are used to store boot-up images (for example, images that run Windows Setup from CD or USB, or Network Boot), Windows PE (again, from CD, USB or Network boot) or entire operating system images.
Example: Most bootable media - CD drives and USB drives - will contain a WIM file called BOOT.WIM in the Sources folder.
WIM files can be manipulated using systems such as MDT or WDS, to add drivers or distribute them out to clients.
On occasion, it can be necessary to manually mount a WIM file to add drivers, or to inspect the contents. This article will cover the basics.
You will need the Windows Assessment and Deployment Kit (ADK) to load images. For some image functions - for example, adding drivers, your ADK version must match, or be greater, than the version of the operating system contained inside the image. Sometimes the version of operating system you are running also matters. For example, the Windows 10 versions of the ADK are operating system specific. The 1511 version of the kit requires Windows 10, version 1511.
Windows ADK Page here.
You can do this without mounting, or extracting, the WIM file.
dism /get-wiminfo /wimfile:"boot.wim"
dism /mount-wim /wimfile:"boot.wim" /index:1 /mountdir:"d:\mount"
dism /mount-wim /wimfile:"boot.wim" /index:1 /mountdir:"d:\mount" /readonly
You can add drivers to an image using the DISM command.
dism /Image:"d:\mount" /Add-Driver /Driver:"e:\drivers\video\mydriver.inf"
dism /Image:"d:\mount" /Add-Driver /Driver:"e:\drivers\video"
dism /Image:"d:\mount" /Add-Driver /Driver:"e:\drivers" /recurse
When you are finished, the Image must be unmounted, even if you do not wish to save any changes.
dism /unmount-Wim /MountDir:"d:\mount" /discard
dism /unmount-Wim /MountDir:"d:\mount" /commit