US Patent 11587212 Target-less calibration of turbid media

A submersible vehicle comprising: an image sensor; a first illuminator; at least one hardware processor operatively coupled with said image sensor and first illuminator, and the at least one hardware processor being configured to: acquire a first image of a scene inside a medium, when there is no object along the line-of-sight (LOS), under illumination from a first location or orientation, acquire a second image of the scene inside the medium, when there is no object along the LOS, under illumination from a second, different location or orientation, and compute attenuation coefficients, one per color channel, based on backscatter in the first and second images.