14-bit vs 12-bit: A Comparison

Just stumbled upon <a href="http://www.earthboundlight.com/phototips/nikon-d300-d3-14-bit-

versus-12-bit.html">this comparison</a> of 12- and 14-bit modes on a Nikon D300. It's a long read,

but the illustrations speak for themselves. Note that a 14-bit image contains 4 times as much tonal

information as a 12-bit one (although it is not clear how much of this extra information is simply noise).

I think the benefit here isn't the difference between 12 and 14 bits but rather proper exposure

(expose to the right):

 

http://www.digitalphotopro.com/tech/exposing-for-raw.html

 

Yes, as you expose for the right, in 12 bits, you're essentially only describing that last stop with 64

levels with 6 stops of range best case scenario. Theoretically a 14 bit capture would have more

levels here. But the benefits are in exposing correctly such that you don't blow out highlight data

you wish to capture, the result being MORE steps in that last stop. In his example but using a 6 stop

range (typical of today's DSLRs), there's either 64 steps in 12 bit or 256 steps in 14 bits in the last

stop of shadows, and that's where all the noise lives anyway. Under expose just a bit, you're getting

even fewer levels and more noise.

Any thoughts as to how active D Lighting plays out here? It seems to me it would be more effective in 14bit mode, since more shadow detail/less noise is present.

In my understanding (I don't own a Nikon camera), Active D-Lighting is a post-processing

option, and as such has no effect at the time of capture/digitization. So it would not affect

the results.

Active D-Lighting leaves a lot of questions to be answered. I've seen claims of how good it is, but no explanation of how it works and what exactly it's advantages are, expressed in technical terms. Ellis Vener, I understand, is in the process of reviewing either the D3 or D300 and I hope he will understand and explain.

For Frans:

 

"I've seen claims of how good it is, but no explanation of how it works and what exactly it's advantages are, expressed in technical terms."

 

> Eugene is correct, Active D-lighting does not change how the D300 meters -- you get the same RAW data with or without it. Shooting in RAW, Active D-lighting just applies a tag to the file instructing NX to disable contrast and brightness controls and substitute the user selected Active D-lighting setting (I consider this an NX bug).

 

Regarding the advantages of 14 bits versus 12 bits as implemented in the D300 in particular, it is of negligible value most of the time. I see differences in files under extreme magnification mostly in Zone III.

Eugene, these may interest you:

 

http://nikonglass.blogspot.com/2008/01/d300-14-versus-12-bit.html

 

http://nikonglass.blogspot.com/2008/04/d300-12-versus-14-bit-pt2.html

 

http://nikonglass.blogspot.com/2008/01/active-d-lighting.html

 

Cheers

It's not surprising and has been discussed here in the past via plots of D300/D3

performance as a function of ISO and 12 vs 14 bit sampling...

 

Dynamic range is set by the sensor. ADC performance can only degrade - and that's

coupled with the fact that no ADC is perfect. And ALL ADCs have an effective number of

bits (ENOB) based on equivalent SNR which is always less that the physical number of

wiggling data bits.

 

If your sensor supports 12 bit of DR then one could sample the output with a 100 bit ADC

(if one existed) and derive no benefit.

 

You may see some benefit of greater number of bits at lower ISOs - for the reason that at

lower ISOs there's less noise from the sensor/amplifier - allowing a greater number of

ADC bits to provide benefit.

<p>Here is a comparison I created by under-exposing a picture of my black altec

lansing computer speakers to the point there was barely any information in the

jpeg. The camera was set to manual focus and I used nikon camera control to

change the settings, ensuring like for like images.

 

<p>Jpeg (auto exposure correction) vs 12-bit (auto exposure correction) and 14 bit

(auto exposure correction)

 

<p>The original image looked flat-black on my monitor.

 

<img src="http://www.mn-c.com/temp/D300-12-vs-14.jpg" width=800><br><br>

<a href="http://www.mn-c.com/temp/D300-12-vs-14.jpg">Full Size</a>