How to Remove Rings in Gradient

I have a gray plane with a light in front of it. I am rendering a 532x532 image of a gradient in the blender render engine. How do I remove these rings in the gradient? I am using this in a 2D game and this chopping gradient looks pretty bad I need to achieve a smooth gradient.
http://s28.postimg.org/z248wiqwd/gradient2.png