[Stiglr]

To resize a background image:

1) Make sure your mouse is in the viewport whose background image you're resizing, and that you've clicked the space (not selecting any object, just selecting "dead space" in the viewport).

2) Hold down the Shift + Alt keys.

3) Use the up and down arrow keys to scale the background image proportionally.

4) To move the image, hold only the Alt key down and use the left and right arrow buttons to move the background image.