An Image Retrieval System Based on Region Classification

Abstract

In this study, a content based image retrieval (CBIR) system to query the objects in an image database is proposed. Images are represented as collections of regions after being segmented with Normalized Cuts algorithm. MPEG-7 content descriptors are used to encode regions in a 239-dimensional feature space. User of the proposed CBIR system decides which objects to query and labels exemplar regions to train the system using a graphical interface. Fuzzy ARTMAP algorithm is used to learn the mapping between feature vectors and binary coded class identification numbers. Preliminary recognition experiments prove the power of fuzzy ARTMAP as a region classifier. After training, features of all regions in the database are extracted and classified. Simple index files enabling fast access to all regions from a given class are prepared to be used in the querying phase. To retrieve images containing a particular object, user opens an image and selects a query region together with a label in the graphical interface of our system. Then the system ranks all regions in the indexed set of the query class with respect to their L ₂ (Euclidean) distance to the query region and displays resulting images. During retrieval experiments, comparable class precisions with respect to exhaustive searching of the database are maintained which demonstrates effectiveness of the classifier in narrowing down the search space.