Retrieving Shapes Efficiently by a Qualitative Shape Descriptor: The Scope Histogram

Efficient image retrieval from large image databases is a challenging problem. In this paper we present a method offering constant time complexity for the comparison of two shapes. In order to achieve this, we extend the qualitative concept of positional-contrast by 86 new relations describing the position of a polygon w. r. t. its line segments. On this basis a histogram of the relations’ frequencies is computed for each shape. A useful property of our approach is that, due to the underlying concept of positional-contrast, it can be intuitively decided whether its combination with other features is promising. Especially, retrieval results of about 64% are achieved in the MPEG test with constant time complexity.