Underwater image captioning: Challenges, models, and datasets

We delve into the nascent field of underwater image captioning from three perspectives: challenges, models, and datasets. One challenge arises from the disparities between natural images and underwater images, which hinder the use of the former to train models for the latter. Another challenge exists in the limited feature extraction capabilities of current image captioning models, impeding the generation of accurate underwater image captions. The final challenge, albeit not the least significant, revolves around the insufficiency of data available for underwater image captioning. This insufficiency not only complicates the training of models but also poses challenges for evaluating their performance effectively. To address these challenges, we make three novel contributions. First, we employ a physics-based degradation technique to transform natural images into degraded images that closely resemble realistic underwater images. Based on the degraded images, we develop a meta-learning strategy specifically tailored for underwater tasks. Second, we develop an underwater image captioning model based on scene-object feature fusion. It fuses underwater scene features extracted by ResNeXt and object features localized by YOLOv8, yielding comprehensive features for underwater image captioning. Last but not least, we construct an underwater image captioning dataset covering various underwater scenes, with each underwater image annotated with five accurate captions for the purpose of comprehensive training and validation. Experimental results on the new dataset validate the effectiveness of our novel models. The code and datasets are released at https://gitee.com/LHY-CODE/UICM-SOFF.