  Shape is one of the main features in content based image retrieval (CBIR).
This paper proposes a new shape signature. In this technique, features of each
shape are extracted based on four sides of the rectangle that covers the shape.
The proposed technique is Fourier based and it is invariant to translation,
scaling and rotation. The retrieval performance between some commonly used
Fourier based signatures and the proposed four sides distance (FSD) signature
has been tested using MPEG-7 database. Experimental results are shown that the
FSD signature has better performance compared with those signatures.
