Does more DR require more bits?

Started Mar 19, 2012 | Discussions thread
DSPographer Senior Member • Posts: 2,464
Re: No Re: Does more DR require more bits?

rhlpetrus wrote:

akin_t wrote:

Johan01 wrote:

I am curious if having more DR has any trade off in regards to the amount of data captured?

It seems like I am able to PP the 5D files quite a lot before I get artifacts between color gradations. I would imagine that a lower DR sensor could capture finer gradients for a given EV range?

I have also noticed the 5d meters itself strangely and I meter to the right more than my 60d without clipping highlights. How much of the 5d2 DR is hidden up in the highlights? Is the 100 iso of the 5d really closer to 50 iso? It always seems to want longer exposures.

All things being equal, yes.

You will need more bits (containers) to capture more dynamic range (data).

Not really, you are mixing the size of ladder with number of stairs. DR is the difference between noise floor and saturation point and has nothing to do with number of bits used to reproduce it in some gradation scale.

Yes, it does have an effect if there are too few bits: the stair spacing has to be close enough to properly record details in the deep shadows. Rounding to the nearest available level introduces an error called quantization noise that limits the DR attainable with a given number of bits. A good rule of thumb is that for a linear scale you need as many bits per pixel as you want stops of DR per pixel. In previous postings I have explained the details of what happens when this isn't true and the fact you can do slightly better than this with a perfect A-D converter, but this simple rule works well for normal camera raw data.

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