A Hierarchical Entropy Based Representation for Medical Signals

In this chapter, we present a Hierarchical Entropy-based Representation (HER) for 1-dimensional signals. In fact, many 2-dimensional signals can be effectively encoded in a 1-D form that will allow the use of HER. This method represents the signal by a vector containing the energy values related to its local maxima and their locations along the time axis. Such a representation has been utilized as the feature extraction engine in an image retrieval system for medical image databases, with a K-d-tree based spatial access method.The data used for the experiments were contours and textures from various medical sources.The experiments show that HER performs very well in this respect.