  Image captioning is a challenging task and attracting more and more attention
in the field of Artificial Intelligence, and which can be applied to efficient
image retrieval, intelligent blind guidance and human-computer interaction,
etc. In this paper, we present a survey on advances in image captioning based
on Deep Learning methods, including Encoder-Decoder structure, improved methods
in Encoder, improved methods in Decoder, and other improvements. Furthermore,
we discussed future research directions.
