Underwater image enhancement by the Retinex inspired Contrast Enhancer STRESS

Underwater images are often affected by undesired effects, like noise, color casts and poor detail visibility, hampering the understanding of the image content. This work proposes to improve the quality of such images by means of STRESS, a Retinex inspired contrast enhancer originally designed to process general, real-world pictures. STRESS, which is based on a local color spatial processing inspired to the human vision mechanism, is here tested and compared with other approaches on the public underwater image dataset UIEB. The experiments show that in general STRESS remarkably increases the quality of the input image, while preserving its local structure. The images enhanced by STRESS are released for free to enable visual inspection, further analysis and comparisons.