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This algorithm removes water from underwater photos, and they look incredible

by 14 Comments

Oceanographer and engineer Derya Akkaynak from MIT has developed an algorithm that “removes water” from underwater images. As a result, it makes the underwater world look exactly as it would if we were to see it on dry land. And it’s not only useful for scientists. For us “common folks,” it’s amazing to see the underwater world in a completely new context.

Derya developed the algorithm named Sea-thru in collaboration with Tali Treibitz from the University of Haifa. In the video above, you can hear her explaining how the algorithm works and how it was trained. Basically, she would place a color chart at the base of a coral reef and swim away about 15m (~50 feet). She would then start swimming towards the reef and take photos from different distances and different angles. In a post on Reddit, Derya clarified that the method does not require the use of a color chart. “All you need is multiple images of the scene under natural light, no color chart necessary,” she explains. In case you need a more detailed and scientific explanation, you can find it in the paper here.

The thing with underwater images is that there’s a layer of backscatter (haze). The further you are from the object in the scene, the more “haze” you’ll have. In addition, the light gets absorbed and scattered as it travels through the water. That’s why underwater images can look dull and distorted, and without accurate representation of colors. Sea-thru solves these problems, making us see the underwater world just like we would on the surface. Here are a few screenshots to give you an idea:

 

 

It’s worth noting that the algorithm can’t simply be replaced by Photoshop. While it does correct the color cast, it’s more than just enhancing the image. “It’s a physically accurate correction, rather than a visually pleasing modification,” Derya explains.

This technique could help marine biologists study the underwater world. It would also be valuable to scientists who are trying to understand how climate change affects coral reefs and other marine systems. And it terms of photography, it’s simply interesting. It’s definitely a unique and unusual experience to see the underwater world as we would see it on the surface.

[via PetaPixel, Scientific American]

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  • It’s an underwater xrite colorchecker passport

  • Erik Gonzalez Hermosillo Jensen

  • Valerija Butorac

  • But if you remove the water, all the fish will die!!!

  • Shaun McDougle

    Can you reverse it and make everything else look like it is under water?

  • Can you reverse it and make everything else look like it is under water?

  • Easier to not take photos underwater

  • Get the color balance right in the first place

    • David

      Actually, it is almost impossible to have an accurate white balance underwater as the colours change both on depth and distance to subject where both you and the subject can be moving. Rare to have underwater tripods :-)
      Basically for anything under 10m, you need to shoot in raw and post process for accurate white balance correction. The colour intensity also decrease with that depth/subject distance (reds first etc leaving only blues to black). The sun’s intensity above water also impacts the colour depth unless underwater flash/strobes are used to add additional light. An overcast day (or night!) shows the difference :-)
      In terms of backscatter, off axis strobes can light the foreground (depending on size/quantity of strobes) but on-camera flash has bad backscatter with particles in the water. The turbidity of the water (“vis”) also impacts the effective viewable distance.
      The dehaze tool in lightroom is great to enhance the clarity of the underwater seascapes when used judiciously.
      Lastly on a subjective basis, a little blue can show that a shot is taken underwater. Shipwrecks can look more realistic/ghostly when no white balance change is made ie only blues left or converted to black and white.

  • Annick Beaulne Perso bientôt…..

  • Simple

  • Timothyf7

    It doesn’t help with the focus! All pictures are soft. Rather have the water in the picture to explain why it isn’t sharp.

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