[filmscanners] Re: Dynamic range

["Julian Robinson" <jrobinso@pcug.org.au>]

There's a large number of ways you can write down numbers to define a
range.  There is only one way in common use to express a range in a single
number that is independent of gain and other things that are irrelevant -
as a ratio.

You can express that ratio in a number of ways, dimensionless plain number
or as a log value etc.

Julian

At 12:55 30/08/02, you wrote:

>"Julian Robinson" <jrobinso@pcug.org.au> writes:
>
> >>>>>>>>>>>
>...  It is not hard to understand - 1dB is a small range (about 1.26 to 1),
>100dB is a big range (10000000000 to 1). The range we are discussing is the
>range from MDS to max signal, which in scanner case is Dmax to Dmin.
><<<<<<<<<<
>
>There are _two_ ways to talk about "Dmax to Dmin", you can talk about their
>absolute values (transmittances in the range 0 to 1, for example) as a
>density range or you can talk about the ratio of Dmax to MDS (or Dmin to MDS
>depending on the definitions) as the dynamic range. If you claim that these
>are equivalent, then Austin and I disagree, but if you think they are
>different, then we all agree. That's all there is here.
>
>David J. Littleboy
>davidjl@gol.com
>Tokyo, Japan
>
>
>
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