Yes, finally it is doable, for real and it gets smaller too :-)
Not really a problem maybe, but when the ref image gets bigger and bigger for every time you create one and you KNOW that it is just old patches and new code that consumes the space, you really want to get rid of all the junk. There has been some “do this, it works but it is not really sported”, but now we really have a solution for this.
Using dism with the new /resetbase it is now possible to cleanup the image and remove all the old patches, however, there is one downside here, when you cleanup, there is NO way to uninstall a patch, since that patch is now “base”. So you should only do this when your image is stable and have no issues at all.
Note: the /resetbase only works on a Windows 8.1 or Windows Server 2012 R2 image, there are other solutions for older legacy systems, like Windows 8 and such, and yes, I’m working on posts for that too.
Dism /Online /Cleanup-Image /StartComponentCleanup /ResetBase
DISM /Image:C:\MyDir\Mount /Cleanup-Image /StartComponentCleanup /ResetBase
In the TaskSequence: