  We address personalization issues of image captioning, which have not been
discussed yet in previous research. For a query image, we aim to generate a
descriptive sentence, accounting for prior knowledge such as the user's active
vocabularies in previous documents. As applications of personalized image
captioning, we tackle two post automation tasks: hashtag prediction and post
generation, on our newly collected Instagram dataset, consisting of 1.1M posts
from 6.3K users. We propose a novel captioning model named Context Sequence
Memory Network (CSMN). Its unique updates over previous memory network models
include (i) exploiting memory as a repository for multiple types of context
information, (ii) appending previously generated words into memory to capture
long-term information without suffering from the vanishing gradient problem,
and (iii) adopting CNN memory structure to jointly represent nearby ordered
memory slots for better context understanding. With quantitative evaluation and
user studies via Amazon Mechanical Turk, we show the effectiveness of the three
novel features of CSMN and its performance enhancement for personalized image
captioning over state-of-the-art captioning models.
