I finally developed a solution. For the benefit of those still reading this thread. There is a solution involving adding a new key to the registry but that was not feasible for an application to be distributed to others. However, I discovered that you can import the picture without specifying the shape, use that import to obtain the shape of the image, delete the previous import and reimport specifying the expanded dimensions you need to fit to the frame correctly and it will then import enough pixels to permit filling the frame to whichever dimension is limiting.