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Comment by Maursault | Hacker News Reader

All of the colors we see, whether accurate or not, are digital post-processing lies. It's just not possible to capture images with colors like that underwater. The image of the spotted handfish, however, does seem to be the most honest of the bunch, except for its saturated blue eye.

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Why not? I mean, in total darkness you're not capturing anything. But it looks like the human has a light for navigation, and the camera gear presumably has the ability to emit light. And that light interacts with the matter in the fish and some of it comes back to the camera. How is it any different that taking a picture with the flash on at night?

And if you're referring to the water, can't you just seal a heavy duty camera and use that? Is there something about Deep water that desaturates all light that passes through even less than a meter of it?

I agree with you. Let's face it, perception is largely subjective. We can measure and agree a wavelength, frequency and magnitude of something that we call light with an instrument with a given specification.

We perceive the world with a set of instruments which are not something you would design from scratch! However they are exquisitely refined for the job in hand. They are also bloody odd.

Your eyes constantly wizz around (a sort of directed scanning) to paint a picture of what is going on around you - generally in front. Your fovea is hi res (that's what you see in focus) and the rest is a bit peripheral, so "fuzzy". The periphery is highly tuned to look for broad signs of threats and will go ping for any sort of movement. If the periphery goes ping then the fovea will be deployed to look for more detail.

Now we get to rods and cones ...

You also have rather more sensors - sound, and touch and more. The whole thing is a right old complicated mess - some bits work well and some don't.

Yes, deep water adds a bluish haze to photos, which is caused by the fact that only certain wavelengths penetrate that far down compared to others. Most people postprocess to make photos at that depth appear as if they were taken in air, which IMO is harmless.

>> Is there something about Deep water that desaturates all light that passes through even less than a meter of it?

> Yes, deep water adds a bluish haze to photos, which is caused by the fact that only certain wavelengths penetrate that far down compared to others

Something's gone badly wrong here. By definition, the light has passed through less than a meter of water. How can you be talking about "only certain wavelengths penetrat[ing] that far"?

It also sucks out contrast and color saturation. Most diving lights are LED these days, and manufacturers go for "brightness" rather than accurate color rendition, so the blue in these cool white inaccurately color rendering LEDs only adds to the problem. But I wonder if a diving photographer zagged instead, and used a bright but very warm, sub 3000K High CRI light source if the problem could be mitigated, reducing the temptation of digital color monkeying. Hard to find old film underwater images online shot with tungsten filament-burning incan light sources, but I would bet my salt that those images looked better and more color-accurate than anything a modern DSLR and post-color processing can produce.

You don't rely on the natural light for these photos, you use a very powerful strobe/flash which allows reds etc.. to come through.

> You don't rely on the natural light for these photos

That's only because natural light isn't available. Modern diving lights use inaccurate color-rendering cool white LEDs heavy in the blue spectrum. To get the reds, a diver would actually need a second light source that has red LEDs. So much depends on the narrow color spectrum profile of these shitty LEDs. But incan light sources, no longer made and sold but for vintage collectables, burn tungsten, so the color spectrum is wide and very much like that of the sun, though warmer than the sun at noon, and they always produce a perfect color rendition. High CRI LEDs from Nichia and Cree are getting closer to natural light, with 93+ CRI and warmer color temperatures with pinker tints, but dive light manufacturers have not discovered these yet. So the best a diving photographer can do is to search for and find a bright halogen light source around 3200K. But instead, they shoot washed-out RAW digital images and use digital color post-processing resulting in something that can't ever be seen with human eyes in the real world because it doesn't exist. So, lies.

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