Barn Door transition (Swinging)

I like the new Barn Door transition, since combined with a Zoom you can have the barn doors open and zoom into the next image (kinda like walking down a hallway).

BUT – I noticed that the “hinges” (the left and right side of the stage) is where the Barn Door effect is based, and it only really looks good if the image extends to fill the stage both left and right. If the image is narrower than the horizontal dimensions of the stage, then there’s an unsightly and unexplainable “gap” that appears at the top and bottom of the image as the swinging doors open inward.

I tried to think of a way around that, but I couldn’t come up with anything off hand. If the transition is used, the only optimal solution is to choose an image that presents itself in landscape mode and is sized to fit the stage left and right.