DIY gradient backgrounds for mobile phones

This is a mostly pointless, but marginally interesting idea I came up with. This works for an iPhone, and I assume any other cell phone with a built-in camera. All you do is put your finger over the camera lens, aim it at a strong light source, and then take the shot. By altering how much contact you make with the lens, how directly you point it at the light, and which finger you use (due to the various thicknesses of your fingers), the pictures will be in various colors. By making more contact with one edge of the lens than another, you get gradients. You can use them for backgrounds.

Here are just some samples I took when I discovered the technique. I was impressed by the range of different colors I could get.