Title
Unpaired Image Captioning With semantic-Constrained Self-Learning
Abstract
Image captioning has been an emerging and fast-developing research topic. Nevertheless, most existing works heavily rely on large amounts of image-sentence pairs and therefore hinder the practical applications of captioning in the wild. In this paper, we present a novel Semantic-Constrained Self-learning (SCS) framework that explores an iterative self-learning strategy to learn an image captioner with only unpaired image and text data. Technically, SCS consists of two stages, i.e., pseudo pair generation and captioner re-training, iteratively producing "pseudo" image-sentence pairs via a pre-trained captioner and re-training the captioner with the pseudo pairs, respectively. Particularly, both stages are guided by the recognized objects in the image, that act as semantic constraint to strengthen the semantic alignment between the input image and the output sentence. We leverage a semantic-constrained beam search for pseudo pair generation to regularize the decoding process with the recognized objects via forcing the inclusion/exclusion of the recognized/irrelevant objects in output sentence. For captioner re-training, a self-supervised triplet loss is utilized to preserve the relative semantic similarity ordering among generated sentences with regard to the input image triplets. Moreover, an object inclusion reward and an adversarial reward are adopted to encourage the inclusion of the predicted objects in the output sentence and pursue the generation of more realistic sentences during self-critical training, respectively. Experiments conducted on both dependent and independent unpaired data validate the superiority of SCS. More remarkably, we obtain the best published CIDEr score to-date of 74.7\% on COCO Karpathy test split for unpaired image captioning.
Year
DOI
Venue
2022
10.1109/TMM.2021.3060948
IEEE Transactions on Multimedia
Keywords
DocType
Volume
Encoder-decoder networks,image captioning,self-supervised learning
Journal
24
ISSN
Citations 
PageRank 
1520-9210
0
0.34
References 
Authors
25
7
Name
Order
Citations
PageRank
H Ben100.34
Yingwei Pan235723.66
Yehao Li3758.57
Ting Yao484252.62
Richang Hong54791176.47
M Wang600.34
Meng Wang73094167.38