Perceptual evaluation of single image dehazing algorithms

Images captured in outdoor scenes often suffer from poor visibility and color shift due to the presence of haze. Although many algorithms have been proposed to remove the haze, not much effort has been made on quality assessment of dehazed images. In this paper, we first build a database that contains 25 hazy images as well as dehazed images created by eight dehazing algorithms. A subjective user study is then carried out based on the database, from which we have several useful findings. First, considerable agreement between human subjects on the perceived quality of hazy and dehazed images is observed. Second, not a single dehazing algorithm performs the best for all test images. Third, existing objective image quality assessment (IQA) models are very limited in providing proper quality predictions of dehazed images.