Todd,
> >
> >
> >"largest" is shown on this diagram to be the maximum signal
> level minus the
> >minimum signal level, and is the largest range or absolute range that the
> >signal can go from <=> to. Example, maximum signal level is 5, minimum
> >signal level is 2, the absolute range/largest range is (5 - 2) or 3.
>
> Hi Austin,
>
> Above is the part of your explanation I don't have the background to
> understand. What type of signal will have a max signal level of 5
> and a min
> signal level of 2?
A DC measured signal that has a voltage of 5V tops and a minimum of 2 volts
on the low end. Not ALL signals are relative to 0V, or are A/C.
>I understand that some signals may be +/-3v, or
> something like that, but are there really signals that are +5-2?
It really doesn't matter, it's merely an example. You can add a voltage
offset to ANY D/C signal...there is nothing mysterious about this. Take two
batteries and put them in series...the first battery is 0-1.5V and the
second is 1.5-3V...
> If we are feeding a range of signal levels through a device to
> determine the
> device's DyR, isn't it done in a way that starts with a signal of zero, or
> so close to zero as to surely be below the noise of the device?
No. As I've said, most A/D converters used in scanners have +-3V input
requirement, and therefore, they are NOT zero based. There is absolutely no
requirement at all for a signal to have ANY particular voltage, or voltage
range.
> I'm having trouble to imagine the scenario where one has a device that
> produces a Largest/Peak Level/Dmin of 5-2, but I accept that is due to my
> lack of understanding. Please explain.
I really can't explain it any better than I have, it's also just SO simple
and so irrelevant. I don't know why you don't understand it, but I believe
your lack of experience in electronics may giving you trouble.
> This gets to my comparison of the Higgins diagram to fig 5, which you
> dismissed because ""One diagram is in log (the paper), and one is
> in non-log
> (Higgins). You can not compare the two."
>
> I take issue with that, those are mathematical differences, but I'm
> discussing this conceptually and via the terms of the definition, and how
> the diagrams illustrate those terms.
Well, you'll have to take my word for it, they ARE different, and mean and
show different things. It would take another hundred hours probably to
explain why they are different...if I know how these discussions go. For
starters, in the Higgins diagram, noise is EVERYWHERE over the entire signal
range, anywhere the signal is, there is also noise, in the log diagram,
noise is shown on the bottom.
I think you NEED to back off from the minutia. You're asking for an EE
degree in a newsgroup. You keep asking for explanation for every little
thing to do with this...and I don't know that it's going to help you, if
it's even relevant or that you are really going to understand it to the
level (it appears) you believe you want to...without a LOT of previous
background knowledge. Don't take this the wrong way, but this has just kept
going on and on and on...and the questions just keep getting more and more,
and as I said, I don't believe these questions are going to get you
anywhere. It's just not that complicated to understand dynamic range in a
way that it means something useful to you. You're really overly
complicating something that is just very simple.
Austin
----------------------------------------------------------------------------------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or
body
