Analysis of histogram descriptor for image retrieval in DCT domain

International audienceMany researches of content-based image retrieval appear in transform domain. We analyze and enhance a histogram method for image retrieval in DCT domain. This approach is based on block DCT. After pre-processing, AC and DC Patterns are extracted from DCT coefficients. After various experiments, we propose to use zig-zag scan with fewer DCT coefficients to construct the AC-Pattern. Moreover adjacent patterns are defined by observing distances between them and merged in AC-Pattern histogram. Then the descriptors are constructed from AC-Pattern and DC-Pattern histograms and the combination of these descriptors is used to do image retrieval. Performance analysis is done on two common face image databases. Experiments show that we can get better performance by using our proposals