I'm trying to scale the image x,y but there is no way to do it. A quick google search shows a stretch/fit/crop option which I do not see even after scaling and scrolling through the panel. They are suppose to show up under the Back/Front buttons.
According to the Blender manual, the stretch/fit/crop apply to the camera view only. They do not apply to the Top, Left, Right, or Bottom views in the 3D view-port.
I don't have Blender in-front of me to be able to check, however, I suspect those options will only appear when your image is set to display in the camera view (on your screenshot, your image is set to display in the Top view). They might only appear when you are looking through the camera (
I will verify next time I have access to Blender.