In a paper published in Optics Express, researchers have demonstrated the ability to produce clear images through murky water – an advancement that will pave way for rescue operations of drowning victims and submerged vehicles to be much more fruitful.
While imaging is definitely a huge challenge when it comes to dirty water as particles in murky water scatter light, this scattering of light itself has paved way for the new tech. Scientists say that because scattered light is partially polarized, it is possible to use an imaging camera that is sensitive to polarization can be used to suppress scattered light in underwater images.
Researchers have shown in the study that their method is capable of enhancing image contrast while preserving image details without introducing considerable noise. The new method even works in dense turbid water, which is so cloudy it is almost impossible to see through.
Imaging underwater
Scientists say that traditional approaches to underwater imaging requires prior knowledge of the imaging area or the background of an image to calculate and remove scattered light. These methods have limited utility in the field because they typically require manual processing, images do not always have visible backgrounds, and prior information is not always available.
To overcome these challenges, the researchers combined a traditional polarized imaging setup with a new algorithm that automatically finds the optimal parameters to suppress the scattering light. This not only significantly improves image contrast to achieve clear imaging but can be used without any prior knowledge of the imaging area and for images with or without background regions.
Seeing through murky water
The researchers tested their new technique by acquiring images in turbid liquid mixtures in the laboratory. They started with a transparent tank filled with water and then blended in different amount of milk to mimic an underwater environment with different turbidities. They imaged various objects made from a variety of materials, such as wood, plastic and ceramic.
Now that the method has been demonstrated in the lab, the researchers plan to test it in a practical underwater environment such as in the ocean. They also plan to improve the imaging distances to make it more useful in a real-world underwater environment.