Best way to show icons over an arbitrary background image

I am newbie when it comes to design/ui. I am creating an android application for the phone. On one of the pages, there is going to be a random background image. I would like to put 4 image button icons on top of the background image. The icon buttons will be for "go to url", "share", "replay", "like".

However, I need some help. What's the best way to put these icons on top of the image? Should they be transparent? Should they be solid colors? Should there be an outline shadow?

The icons would look like this: