Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., "Austin Franklin" <
> > I don't know about 3.2 drange, but how about the Microtek 300Z or the
> > Apple One Scanner.
> 
> Got the specs for them?

They could probably be found on the internet somewhere. I'm sure they 
are pretty bad. I don't think they rated dynamic range for them back 
then.


> > > It IS possible, I've already "figured it out", but, as you say, it just
> > > isn't necessary.  It's actually very simple.  The data out of
> > the A/D does
> > > not represent integer density ratio values, but fractional density ratio
> > > values.
> >
> > Why do they have to be integers?
> 
> Because that's what ratio values typically are.  Ratios are relative to 1.
> You set 1 to some density value, and when something is twice as dark, that
> gets a value of 2, as in 2:1.

I ask because if they were't, according to you, that would allow us to 
get a smooth, longer histogram out of the same d-range negative.

> 
> >
> > > > I have taken issue with the term dynamic range. Scanner companies use
> > > > it to mean their scanners capture more information.
> > >
> > > The term "dynamic range" has been around long before scanners, and has a
> > > fixed meaning in the engineering community.  Because it is
> > > misrepresented/misunderstood by some does not change the
> > definition of it.
> >
> > The dynamic range of sound does not relate to the intensity (volume)
> 
> Actually, it does.  It's typically measured just below clipping.  Dynamic
> range is very simple.  It is the largest signal over the smallest
> discernable signal.

That doesn't mean they are the same.

> > > > If a
> > > > scanner could really capture 4.5 density-range in a 12 bit space,
> > >
> > > As I've said, you CAN capture (if you design a scanner to do
> > so) any density
> > > range into 2 or more bits...BUT...the values you get are NOT
> > integer density
> > > ratio values.
> >
> > Who says they have to be integers?
> 
> See above, and that's the way they are designed.  What advantage would you
> get by not using integer density ratio values?

So that we could scan a negative of 3.2 d-range into a 12 bit space 
(something you can't do with scanner capable of 4.0, 12 bits)

> > > > then
> > > > a normal negative's range would have to fit into a much smaller space
> > > > than 12 bits.
> > >
> > > For that particular scanner, IF that scanner was designed to
> > operate that
> > > way, that could be true.  Perhaps the scanner could expand the
> > data to fit
> > > the entire 12 bits.
> > >
> >
> > Wouldn't this be something we would want?
> 
> No, not if YOU wanted to manually set the setpoints.

But it wouldn't be clipping, so I would always like it to fill more of 
the histogram and get more tonality. I could always compress it myself 
if that is what I wanted.

> 
> > > > Which would mean that, with that negative, that scanner
> > > > would actually capture less information than a 3.3 d-range, 12 bit,
> > > > scanner.  Does this make sense?
> > >
> > > Only if the scanner was designed to operate that way.
> >
> > I am thinking that this would be true with the scanners on the market
> > now, yes?
> 
> No.

why not?

> > >
> > > > That is one of the reasons I think they should have called it density
> > > > range. And left the term dynamic range to something more along the
> > > > lines of bit depth.
> > >
> > > But they are both the exact same thing.  Density is a ratio, just like
> > > dynamic range is.
> >
> > Yes and no, density is a ratio compared to the darkest one can see.
> > Dynamic range is a ratio compared to the sublest change one can see.
> > Because of the way scanners are made, they end up being the same.
> 
> It isn't because of the way scanners are made...it's because of the way CCDs
> measure light, as well as being convenient and make sense.  What the heck is
> the problem with using integer density ratio values?  Can you propose some
> other methodology that can be standardized so all data files pretty much
> "mean" the same thing?  Your arguing about why car wheels are round IMO.
> You could make them something else, but why and to what advantage?

ideally, to get a smooth, full, 16bit histogram from a negative with 
less dynamic range than 4.8 or whatever it would take using current 
methodologies.

-mikeH