on 8/29/02 5:42 PM, Austin Franklin at darkroom@ix.netcom.com wrote:
> Roy,
>
>> I can't figure out why you and Austin have such a mental block about
>> ranges and ratios.
>
> And I can't figure out why you want to argue about this. Every reference
> I've cited (and others have cited) agrees with me completely...I still don't
> know what on earth you're trying to claim...as you keep changing it.
Austin,
I've never, never changed my claim. My Claim has always been pure and
simple: Dynamic (from the Greek dynamo: power) Range is the range of
possible power levels. The range has a maximum power and a minimum
power. The DyR equation calculates the SIZE of that power range --
that SIZE (of the Dynamic Range) is always specified as a ratio or
the log of that ratio.
--- the end, that's it ---
All the stuff about number of levels and resolution are artifacts of the
digital process and not part of the DyR concept which existed way before
the word digital was even coined. The digital world breaks things up
into discrete levels which you can count, but that in no way changes
the actually concept of Dynamic Range.
>
>> In all the situations we're talking about, they are
>> just plain one and the same. Dynamic Range is a ratio AND its a range --
>
> Can you point me to ANYWHERE on earth that says something to the effect "we
> have a dynamic range that goes from .01 to 3.2" or something like that? No,
> because dynamic range is ONE number, as clearly specified in EVERY dynamic
> range equation. It is NOT a RANGE of numbers.
The ONE number is the SIZE of the RANGE. Yes, a range has a max and a min.
But the SIZE of the range is ONE number -- and it can be mathematically
calculated with a subtraction OR with a ratio. In the dynamic range
case we always calculate the SIZE of the range with a ratio = max/min.
You don't seem to have trouble when someone says "density range" and
Dmax - Dmin. Why the hangup when the adjective is changed?
A specification of dynamic
> range, say, 92dB, does NOT give you ANY range,
Like I said it gives you the SIZE of the RANGE of power levels.
it merely gives you the
> information about the relationship over a (unknown) range.
>
> You are confusing that dynamic range IS calculated OVER a specified range,
> but it is NOT a range in and of it self, and simply because you calculate it
> FROM a specified range, does not make it a range. That's silly.
>
>> Similarly, Dmax - Dmin is a ratio and
>> its also a range
>
> How's that? That's a "MINUS" sign, not a "from - to" in the dynamic range
> equation. You certainly could SAY that something "over a range from dMin to
> dMax", there is nothing wrong with that, but that is NOT dynamic range,
> that's simply a density range.
>
>> -- looks like a density range (a range as well and its
>> a ratio). They are ALL the same kind of animal.
>
> Well, no...density and dynamic range are similar, only in that they are both
> represented typically in log values, but that's a so what, and doesn't make
> them the same.
>
>> Todd is reading and interpreting the ISO standard and that audio paper
>> entirely correctly. Listen to him.
>
> Todd is confused by this probably because you, and some others, have some
> real misunderstandings as to what dynamic range is, and you are simply so
> prolific, and so out of focus, and want to argue the minutiae instead of
> understand the overall concept, no wonder people are confused.
Well, there's a difference of opinion about who's mistaken.
>
> So much for your promise to not post any more on this...
>
> Austin
>
Roy Harrington
roy@harrington.com
Black & White Photography Gallery
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