Feature Selection Based on Genetic Algorithm for CBIR

Automated techniques to optimize feature descriptor weights and select optimum feature descriptor subset are desirable as a way to enhance the performance of content based image retrieval system. In our system, all the MPEG-7 image feature descriptors including color descriptors, texture descriptors and shape descriptors are used to represent low-level image features. We use a real coded chromosome genetic algorithm (GA) and k-nearest neighbor (k-NN) classification accuracy as fitness function to optimize weights. Meanwhile, a binary one and k-NN classification accuracy combining with the size of feature descriptor subset as fitness function are used to select optimum feature descriptor subset. Furthermore, we propose two kinds of two-stage feature selection schemes for weight optimization and descriptor subset selection, which are the integration of a real coded GA and a binary one. The experimental results over 2000 classified Corel images show that with weight optimization, the accuracy of image retrieval system is improved; with the selection of optimum feature descriptor subset, both the accuracy and the efficiency are improved.