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Comment by Ma8ee | Hacker News Reader

That is exactly what is happening when you lack dynamic range.

Say that your eye is sensitive from light intensity 0 to 100 in some units, but your camera sensor only handles 40 to 60. That means that everything under 40 will be mapped to black, and everything above 60 will be mapped to white.

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No, that does not make any sense. That should result in 40, and everything darker resulting in 40, while 60 and everything brighter resulting in 60. But what you can see is that 40 results in 0, and 60 resulting in 100. That should never happen unless there is an error in processing.

Only the picture file format should limit what range you can save with any modern camera.

It does make sense. 40 is black, and 60 is white.

No it doesn't make sense. You should not be able to capture anything darker than 40, or brighter than 60 if you are limited to 40-60. (actually by the file format, not the sensor, sensors today have higher dynamic ranges than 8 bit sRGB) It should not turn 40 into 0 and 60 into 100.

In real life, a logarithmic brightness scale (which is how human perception works) goes from negative infinity (zero energy) to positive infinity (infinite energy) – excluding both endpoints. 0 is not the bottom, and 100 is not the top.

In real life, photographs are printed on paper. The brightness of light reflecting off paper depends not only on the colour of the paper, but on the brightness of the illumination. (Likewise, photographs displayed on a computer monitor depend on the screen's brightness.)

In real life, human brightness perception depends on the brightness of the environment. An LED can look bright in the dark and dim in sunlight, and range dim to medium to bright on a cloudy day without anyone really noticing that the clouds between them and the sun are thicker or thinner.

In real life, there is no 0. There is no 100. Your comment doesn't make any sense.

Right. Metering is even now with scene programs and AI still basically a complicated negotiation about establishing middle grey -- when there may be no perceptual middle grey in the scene at all (black cat in coal bin, polar bear in snow)

The narrow band of sensitivity of a film or sensor has to be sort of moved to where it is needed (by controlling how much light gets in or for how long) according to the result the photographer is likely to want from their photo.

Even the most basic of film dead-reckoning methods -- Sunny 16 -- relies on subjective input from the photographer:

https://en.wikipedia.org/wiki/Sunny_16_rule

And it's up against the nature of human perception of light and dark, which as this classic page demonstrates, is complex:

https://scienceinfo.net/video-chessboard-illusion-confuses-p...

It's trivial to take an image editor and any existing image that is as you describe, and adjust the black point to 40 "percent" and white to 60%. It won't look more correct or realistic at all.

That of course depends on how you show it on the screen. You can of course show those part of the sensor that didn’t register anything (less than 40) as grey, and everything than saturated the sensor as a bit lighter grey. But people don’t tend to like the look of those pictures very much, and they definitely don’t look more natural than the conventional processing.

The main limitation isn’t the file format. The main limitation is the sensor. On the lower end, it is noise in different forms that overwhelm the very weak signal from dark areas. On the higher end, the sensors get saturated, that is, the semi-conductor bucket for the charges that is released by the photons get full.

And then the experience of the picture is of course limited by the medium that is used to display it. Even the best screens can’t show even a small fraction of the contrast that the eye experiences outdoors on a sunny day. And don’t mention printed media.

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