You mean the poster on the left hand side, (frasier)?
If so, as far as I know those images cannot be rounded off in the same way, masks can only be applied to facades. (if it can be done, i dont know how)
The only way to round those off is with an overlay, like what it done in fanart views.
yes , i mean the poster in left side ..... and is can be down as Holzi explain ...