Head or tail detection

Hi,

I wish to detect from a set of images whether the coin is showing heads or tails. Assuming the background remains same, but coin position can vary, which detection algorithm would suit best ?

Also in case if the background is a box and there is chance for coin to be lying at an angle to a vertical wall of the box, will the same algorithm be fine ?

I'm relatively new to matlab, so please consider that while replying !!