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0 pointsniels_olson10y ago0 comments

> higher bitdepths and sampling rates can be quite useful in mixing

That is really the central issue. It's much like imaging since the time of Ansel Adams: the sensor can capture more dynamic range than the human eye can experience. The producer may have use for that range when editing, but the audience will never know what was -- may have been -- missed. And we're not talking about limits of reproduction. We're talking about the human sensors both instantaneous and absolute upper and lower bounds.

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6 comments · 2 top-level

msandford10y ago· 4 in thread

> That is really the central issue. It's much like imaging since the time of Ansel Adams: the sensor can capture more dynamic range than the human eye can experience.

That's not really true. Dynamic range refers to the difference between the biggest value that isn't clipped and the smallest value that isn't rounded to zero. The human eye is a logarithmic detector, cameras are linear. The only reason HDR is a thing is because cameras DON'T have enough dynamic range.

http://photo.stackexchange.com/questions/21579/how-does-the-...

Sharlin10y ago

The instantaneous dynamic range of the human eye is estimated to be less than eight stops. Both film and modern camera sensors can capture much more than that. The reason we're able to adequately perceive scenes with 12+ stops of dynamic range is that our visual system does continuous integration and reconstructs an HDR "mosaic" in real time. HDR photography is required in situations where even the 12-14 stops that a modern sensor is capable of is not enough.

However, that's neither here nor there because the human eye is not the real bottleneck here. The media we use to display photos are. Printed photographs have approximately six stops of DR; typical monitors have eight. Modern cameras capture much more information than can be displayed, and the raw sensor data must be tone-mapped either by the camera software or in post-processing to produce a viewable image. There is a lot of latitude in deciding how to map 2^14 discrete values of input to a mere 2^8 values of output.

jacobolus10y ago

Nice photo prints can typically show something like 100:1 to 200:1 contrast (~6.5–7.5 stops) between white and black, or at the top end, some dye transfer prints under carefully controlled lighting can get up to about 500:1 (9 stops).

Nice computer displays (and mobile device displays) without glare and with the brightness cranked all the way up can get up to something like 9.5–10.5 stops.

Of course, that range still pales in comparison to the contrast between shadows and highlights on a sunny day, which can be more like 16+ stops.

niels_olsonOP10y ago

You're thinking about absolute range of a human system. Yes, I can look into shadows and my iris will imperceptibly dilate. Similarly, the stapedius muscle can dampen input to the oval window. So you can appreciate a wide dynamic range. But instantaneously, your retina is only good for about 7-8 EV steps. Modern imaging sensors deliver well over 10 EV, some deliver more than 14. Depending on which format you save to, you could be throwing away half the information! So, much like a artist should record 24/192, a photographer should be saving to RAW. But no monitor or film or the human eye will ever capture all that range in one instant. So, especially for temporal media, like audio and video, that space can be scoped down in the interest of space saving without any perceptible loss.

jamesfmilne10y ago

Define HDR. Almost all displays people have these days are not capable of reproducing the dynamic range that most cameras can capture. Hence why we have colour grading, which is the image equivalent of audio mastering.

jlarocco10y ago

I don't know about music and audio, but your photography comparison is incorrect for two reasons.

First, as msandford pointed out, the human eye has significantly better dynamic range than image sensors. Technically, our eyes have a lower range at any specific instant, but due to the way our eyes work we effectively see upwards of 20 stops of dynamic range. The best sensors available (in medium format cameras, pro-DSLRs, etc) can only capture 14-15 stops.

Second, some black and white films have a better dynamic range than digital sensors, so it's also not the case that digital is strictly better. 18-20 stops isn't unheard of for some types of film.

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