Remove water from underwater photos using this algorithm

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Taking pictures underwater can be quite an adventure, as many scuba diving enthusiasts have discovered. However, it’s impossible to capture the true, vivid colors of a scene underwater because the water casts a darker shade over everything. Now an oceanographer and engineer has developed an algorithm that can remove the water from underwater photos, bringing out the true colors of a scene as if they were taken on land.

Removing water from underwater photos

Derya Akkaynak developed the algorithm and published details about it in a paper for IEEE Xplore, which was reproduced digitally by the Computer Vision Foundation. She calls her technology Sea-thru, and she believes it could revolutionize underwater photography.

Technically, the algorithm doesn’t actually remove water from underwater photos, although it does negate the effects that water has on the visuals of underwater scenes. As light travels through water, it’s absorbed and scattered, which is why colors look so faded underwater.

Scientific American interviewed Akkaynak for a video posted on YouTube. You can watch the video in its entirety below. She explained that the algorithm isn’t like Photoshop, which changes the appearance of a photo. It doesn’t enhance the image or brighten the colors. Instead, it offers a “physically accurate correction rather than a visually pleasing modification” like Photoshop does.

Akkaynak designed her algorithm with scientists in mind. She said that currently, scientists who study the underwater depths for the purpose of examining different species must catalogue each species by hand because photos can’t capture the vivid hues that help them tell different species apart.

However, she also believes recreational divers or underwater photographers will also find it to be interesting. The algorithm will enable them to remove the degrading effects of the water so the true colors can be seen.

According to PetaPixel, in developing and training the algorithm on a coral reef, Akkaynak placed a color chart at the base of the reef and then swam away about 15 meters. Then she started swimming toward the reef and the color chart and photographed it from different angles until she gets to the reef. After the algorithm was trained, the color chart was no longer needed. She explained on Reddit that the only thing that’s needed is multiple images of the same scene under natural light.

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