  Underwater object detection is a crucial and challenging problem in marine
engineering and aquatic robot. The difficulty is partly because of the
degradation of underwater images caused by light selective absorption and
scattering. Intuitively, enhancing underwater images can benefit high-level
applications like underwater object detection. However, it is still unclear
whether all object detectors need underwater image enhancement as
pre-processing. We therefore pose the questions "Does underwater image
enhancement really improve underwater object detection?" and "How does
underwater image enhancement contribute to underwater object detection?". With
these two questions, we conduct extensive studies. Specifically, we use 18
state-of-the-art underwater image enhancement algorithms, covering traditional,
CNN-based, and GAN-based algorithms, to pre-process underwater object detection
data. Then, we retrain 7 popular deep learning-based object detectors using the
corresponding results enhanced by different algorithms, obtaining 126
underwater object detection models. Coupled with 7 object detection models
retrained using raw underwater images, we employ these 133 models to
comprehensively analyze the effect of underwater image enhancement on
underwater object detection. We expect this study can provide sufficient
exploration to answer the aforementioned questions and draw more attention of
the community to the joint problem of underwater image enhancement and
underwater object detection. The pre-trained models and results are publicly
available and will be regularly updated. Project page:
https://github.com/BIGWangYuDong/lqit/tree/main/configs/detection/uw_enhancement_affect_detection.
