It would be valuable to have options for the background image.
1. Original: no change to image
2. Tile: Fill the screen with multiple replications of the image. Useful for symetrical patterns
3. Stretch: A single image stretched to fill the entire screen.
4. Crop: To fill the projection screen with the image maintaining the aspect ratio.
5. Letter box: Showing the full image at maximum zoom buffering the short sides to fill the screen with the image again maintaining the aspect ratio.