1. INTRODUCTION
Similarity analysis, performed over a large amount of images or large data sets is very important step in the procedure for classification of different types of pictorial or process information. This is a very specific area of activity, where in many cases the experienced human performs better and produces more plausible solutions than the currently available computerized systems. One reason for this is the complexity and the vagueness in the definition of the problem. Obtaining a “better” and “more plausible” solution to the problem of similarity is a key factor for success in many applications such as quick search through a large amount of image or process data information, and its proper sorting and classification. The results of this similarity analysis and classification are often used for a proper fault or medical diagnosis and for discovering different abnormalities in the observed systems.