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Re: Digital Negatives with enough Tones for Pt/Pd
On Thu, 6 Jul 2000, Jeffrey D. Mathias wrote:
> FDanB@aol.com wrote:
> > ... Dynamic Range - Bit Depth
>
> For all practical purposes dynamic range and bit depth are tied
> together, the greater the bit depth the greater the dynamic range. The
> only way to get a large dynamic range is to have a correspondingly large
> bit-depth. See:
> http://www.scantips.com/basics14.html
No, that isn't really correct. The dynamic range is a measure of the
sensitivity of the detector and scanner electronics. The limiting feature
here would be the signal to noise ratio of the detector circuitry. The
bit depth on the other hand only determines the number of discrete levels
that the dynamic range can be split into.
An analogy would be to consider two sticks of different length. The
length of the sticks would be analogous to the dynamic range. In either
case you can divide the sticks into 256 sections (8 bit sampling) or
65,536 sections (16 bit sampling). More bit depth just means that you
get a finer scale. The dynamic range tells you the length of the scale.
Bit depth and dynamic range are NOT dependent on each other. Of course
the noise in the A/d converter will force a practical limit on the maximum
bit depth that makes sense for a given dynamic range.
- Wayde
(wallen@boulder.nist.gov)