Let's create a background option! A background would be an advantage for when a user uploads a small image that doesn't fit the viewport. So instead of rejecting the image cause it's too small OR zooming the pixels, a background layer fills out the remainder of the output resolution.

Of course, the user can specify the background color so it matches their graphic.

This would also be great for those uploaded graphics that have an extreme aspect ratio. So if your desired output resolution is 200x200 and a user uploads a 500x100 image, they can just resize it down and then choose a background color to fill out the remainder of the height.