A survey of the low-level descriptors used for content based multimedia retrieval

This paper provides a comprehensive survey of the technical achievements in the research area of image retrieval, especially content-based image retrieval, an area that has been so active and prosperous in the past few years. In order to improve the retrieval accuracy of content-based image retrieval systems, research focus has been shifted from designing sophisticated low-level feature extraction algorithms to reducing the 'semantic gap' between the visual features and the richness of human semantics. The main objective of visual descriptors is to pro vide a standardized description of streamed or stored images or video for visual low - level features that helps users or applications identify, categorize or filter images or video. The general visual descriptors include: color, texture, shape and motion feature.