Restoration of time-of-flight (ToF) underwater images using TV regularization

This paper investigates a total variation (TV) regularization image processing algorithm to restore underwater range images taken with a modified commercial time-of-flight (ToF) camera. The ToF camera illuminator was modified to support 532 nm flood illumination for underwater operation. This approach can produce highresolution amplitude and range images while rejecting a significant amount of ambient light. However, scattering due to the water turbidity adversely impacts image quality by introducing high amounts of image noise and image blurring that affect both the amplitude and range images. The TV regularization algorithm is applied to experimental images taken in a small test tank in the presence of a scattering agent to simulate a range of practical turbidities. Algorithm details are provided, and baseline and processed images are presented. The processed images demonstrate image restoration that retains the downrange edge features of the object being imaged is possible for a range of practical turbidities.