6 ms·

actual project site with more detailed description and before+after images: https://www.deryaakkaynak.com/sea-thru https://www.deryaakkaynak.com/sea-thru paper

actual project site with more detailed description and before+after images: https://www.deryaakkaynak.com/sea-thru https://www.deryaakkaynak.com/sea-thru paper [pdf]: http://openaccess.thecvf.com/content_CVPR_2019/papers/Akkaynak_Sea-Thru_A_Method_for_Removing_Water_From_Underwater_Images_CVPR_2019_paper.pdf http://openaccess.thecvf.com/content_CVPR_2019/papers/Akkayn...

2bitencryption 7y ago
that's fascinating, and a lot more involved than what I expected (my guess was something more like off-the-shelf color correction)
- loeg 7y ago
  The palette cards they carry around remind me of white-balancing.
  - mstade 7y ago
    If I understand things correctly it's not entirely different to white balancing either, just that the difference between white balancing a monitor or camera is that you don't really have to correct for the scattering of light through air because it's negligible at the distances you're likely to work with. The trick here – again, if I understand correctly – is that this method also finds the light scattering/absorption characteristics and corrects for those as well. It might seem obvious, but I think it's more involving than it seems, because light scatters differently in different environments and I think – again, I might be wrong, this is just my understanding – this method accounts for that by using multiple images at different distances to gather the parameters to find the scattering and absorption characteristics. This is what makes it physically accurate and not just "make these colors mostly look good" which is really quite cool and useful!
    - kd5bjo 7y ago
      If I remember correctly, the percentage of light that passes through a column of water exponentially decays with distance, like stacking a bunch of fixed-percentage optical filters on top of each other. They’re using parallax shift between multiple images to generate a depth map, so they have a measure of the amount of water obscuring each pixel. I’m not sure how they’re finding the optical properties of the water; there’s something about using the darkest pixels in the image for calibration that I didn’t quite follow.
  - planetmaker 7y ago
    It's actually exactly that. Her set of skills is to do that actually accurately with setpoints for both distance to the objects as well for different wavelengths simulataneously.
Groxx 7y ago
"Sea-thru" is such a great name for this. Also I'm always glad to see things that aren't "we threw a neural net at it and it looks pretty good"
- nuclx 7y ago
  Soundtrack: https://youtu.be/NWB02uS2Gow https://youtu.be/NWB02uS2Gow
- chias 7y ago
  The company name ("SeaErra") is pretty amusing too :)
andromeduck 7y ago
So it seems like it's just MVS > depth map + recovery of haze characteristics by sampling a color reference at a bunch of distances. That seems blindingly obvious unless I missed something.
- SmellyGeekBoy 7y ago
  Don't tell me, you could have done it yourself in your basement in a couple of hours? Well done.
- ancarda 7y ago
  This is the most Hacker News comment I've seen in a really long time Good job, dude
  - flir 7y ago
    It's so HN it's almost /.?
- crazygringo 7y ago
  First of all, you're wrong. "It works without a color chart, or any information about the optical qualities or depth of the water body." Secondly, if you think it's "blindingly obvious", read the paper linked in the parent's comment. Even a quick skim will show you're wrong. In conclusion: yes, you missed something.
- moralsupply 7y ago
  You missed something: the huge amounts of effort required to make it work and produce acceptable results
  - jvagner 7y ago
    And that no one had done it before (apparently).
toastal 7y ago
I just wish that site didn't require JavaScript just to view these images. How is this Wix behavior acceptable?
- gnagatomo 7y ago
  Common users don't care or don't even know about javascript.
ComodoHacker 7y ago
On the first example corrected image reveals some details in shadows but also burns out some highlights.

2bitencryption 7y ago

that's fascinating, and a lot more involved than what I expected (my guess was something more like off-the-shelf color correction)

loeg 7y ago
The palette cards they carry around remind me of white-balancing.
- mstade 7y ago
  If I understand things correctly it's not entirely different to white balancing either, just that the difference between white balancing a monitor or camera is that you don't really have to correct for the scattering of light through air because it's negligible at the distances you're likely to work with. The trick here – again, if I understand correctly – is that this method also finds the light scattering/absorption characteristics and corrects for those as well. It might seem obvious, but I think it's more involving than it seems, because light scatters differently in different environments and I think – again, I might be wrong, this is just my understanding – this method accounts for that by using multiple images at different distances to gather the parameters to find the scattering and absorption characteristics. This is what makes it physically accurate and not just "make these colors mostly look good" which is really quite cool and useful!
  - kd5bjo 7y ago
    If I remember correctly, the percentage of light that passes through a column of water exponentially decays with distance, like stacking a bunch of fixed-percentage optical filters on top of each other. They’re using parallax shift between multiple images to generate a depth map, so they have a measure of the amount of water obscuring each pixel. I’m not sure how they’re finding the optical properties of the water; there’s something about using the darkest pixels in the image for calibration that I didn’t quite follow.
- planetmaker 7y ago
  It's actually exactly that. Her set of skills is to do that actually accurately with setpoints for both distance to the objects as well for different wavelengths simulataneously.

Groxx 7y ago

"Sea-thru" is such a great name for this. Also I'm always glad to see things that aren't "we threw a neural net at it and it looks pretty good"

nuclx 7y ago
Soundtrack: https://youtu.be/NWB02uS2Gow https://youtu.be/NWB02uS2Gow
chias 7y ago
The company name ("SeaErra") is pretty amusing too :)

andromeduck 7y ago

So it seems like it's just MVS > depth map + recovery of haze characteristics by sampling a color reference at a bunch of distances. That seems blindingly obvious unless I missed something.

SmellyGeekBoy 7y ago
Don't tell me, you could have done it yourself in your basement in a couple of hours? Well done.
ancarda 7y ago
This is the most Hacker News comment I've seen in a really long time Good job, dude
- flir 7y ago
  It's so HN it's almost /.?
crazygringo 7y ago
First of all, you're wrong. "It works without a color chart, or any information about the optical qualities or depth of the water body." Secondly, if you think it's "blindingly obvious", read the paper linked in the parent's comment. Even a quick skim will show you're wrong. In conclusion: yes, you missed something.
moralsupply 7y ago
You missed something: the huge amounts of effort required to make it work and produce acceptable results
- jvagner 7y ago
  And that no one had done it before (apparently).

toastal 7y ago

I just wish that site didn't require JavaScript just to view these images. How is this Wix behavior acceptable?

gnagatomo 7y ago
Common users don't care or don't even know about javascript.

ComodoHacker 7y ago

On the first example corrected image reveals some details in shadows but also burns out some highlights.