[filmscanners] RE: Density vs Dynamic range

["Austin Franklin" <darkroom@ix.netcom.com>]

Hi Laurie,

> >It does, you are right...but only to the point of reaching the
> noise level.
> >Once you have resolved down to the noise, resolving any further simply
> >doesn't give you any more information.
>
> Here is where I tend to get myself in trouble; but here it goes.  As a
> practical empirical matter of pragamtic significance, I agree and in my
> comments have sort of taken that as a given eventhough logically,
> analytically, and theoretically you could extend the descrete segments
> beyond the noiseless portions of the density range into the noise.  If one
> did so, it would be meaningless from an empirical and practical
> standpoint.

Correct.

> That is my thinking and why I could not visualize noise in the equation (I
> suppose one could just define as a matter of definition the
> density range as
> being only the noiseless portion of the density spectrum ignoring that
> portion which lies below; but I guess I am reluctant to do this for
> analytical reasons of defining a phenomenon like the density range which
> often extends beyond the clean, noiseless, visable - taken
> metaphorically -
> elements of that phenomenon). But with respect to my conceptual
> understanding as it is, am I incorrect about this?

Hum.  I believe I understand what you are saying, I just have to think about
it a bit.  You are talking about noise, say in the shadows...where it
becomes quite non-linear (increases)...  If that's what you're saying, I
agree.

> >Simply put, dynamic range is the number of steps within the
> density range.
> >I believe we have no problem with the definition of density
> range...right?
>
> That is my generic understanding of what you have been saying,
> and one with
> which I understand and agree.  To carry it further, I also
> understand you to
> be saying in general terms that the bit depth (number of bits) has no
> bearing on the size of the density range, but it does determine the number
> of steps or segments that that density range is divided into (not
> necessarily the size of any of those steps or segments).

Bingo!

> Or to put it
> another way, the bit depth describes the structure of the dynamic
> range and
> not the size of the density range.  Am I off base or close to what your
> understanding is.

Nope, right on the dot!

Regards,

Austin

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