Most region based shape image retrieval techniques in literature are complex to implement. As the result of their complex computations, the retrieval performance of these techniques is not robust. In this paper, we propose a new approach to use contour based method for region based shape representation and retrieval. Specifically, we compute a one dimensional signature function from a two dimensional region shape and use it for region shape representation and retrieval. The proposed region shape feature is much more efficient to compute than conventional region shape techniques. The retrieval performance of the technique has been evaluated using a standard region shape database. Experimental results show that the proposed technique is efficient and robust, and outperforms the widely used shape methods in literature.