Retrieval by spatial similarity: an algorithm and a comparative evaluation

We present an algorithm for retrieval by spatial similarity of symbolic images. The proposed algorithm is based on graph-matching and is invariant to scaling, rotation and translation, recognizes multiple rotation variants and can deal with multiple instances of a symbolic object in an image. It is particularly suitable for a query by sketch approach, in that it requires that at least objects in the query have to be present in the database image. Our approach is proposed in comparison with other two well-known algorithms. Peculiarities are analyzed and motivated. Results of a comparative evaluation on a test dataset of symbolic images are presented and discussed.