Theme-related keyword extraction from free text descriptions of image contents for tagging

This paper discusses a method for automatic theme-related keyword extraction from users' natural language comments on their photographs and videos. `Theme' indicates the concepts circumscribing and describing the content of the photos and videos such as pets, natural sites, palaces and places. The method employs a deep learning algorithm, RNN(Recurrent Neural Network) that is good at recognizing implicit patterns of sequential data. The method has been applied to the construction of a place-related image content DB, and delivers reasonably good performance even in case the measure (i.e. themes of image contents) is abstract and vague.