An
image retrieval system is a computer system for browsing, searching and retrieving images from a large
database of
digital images. Most traditional and common methods of image retrieval utilize some method of adding
metadata such as
captioning',
keywords, or descriptions to the images so that retrieval can be performed over the annotation words. Manual image annotation is time-consuming, laborious and expensive; to address this, there has been a large amount of research done on
automatic image annotation. Additionally, the increase in social
web applications and the
semantic web have inspired the development of several web-based image annotation tools.