Digital BW, The Print

> Austin,
>
> The Merriam definition takes this into account as the "weakest sound
> intensity" would be the sound just greater than the noise floor.

Hi Martin,

Weakest is not the same as noise.

> > > Calculated using Dmax and Dmin:
> > > Inkjet dynamic range:  23 to 85
> >
> > No...that's the point.  Density ratio values are NOT the same as dynamic
> > range.
>
> That's not what the definition says.

What definition says what?  Seriously, it's not debatable that density ratio
values are not the same as dynamic range, it simply is a fact...  All
density ratio values are, are ratios of, well, density, there is nothing in
the density ratio value scale that has anything to do with noise (minimum
measurABLE signal).

>  The value of 1 is the step size of density ration values, but NOT of
> > dynamic range.
>
> Density variation is step-less in an analog system. A silver print is a
> continuous tone image.

Not true.  Analog systems are not stepless, there is noise in any system!
If they WERE stepless, the dynamic range would be infinite, by definition.

>  "1" is nothing but a ratio value, as in, 2:1 is twice as
> > dark...  Technically, something can be 1.223456:1 times as dark, but the
> > density ratio value system is based on :1, and does not accommodate
> this...
> >
> > Dynamic range requires you know the noise in the system,
>
> This is true in audio and electronics but seems to have little to
> do with a
> step wedge of tones on a piece of paper.

Noise (minimum measurable signal is the same as noise for the purposes of
this discussion) is required by the definition of dynamic range!  Dynamic
range is the ratio of the largest measurable signal to noise!  Without
noise/smallest measurable signal, you can not determine dynamic range.

> >  density ratio
> > values do not, they are only relative to themselves in intensity, where
> > dynamic range is not.  As the example I gave in my other post, you can
> have
> > a really high density value of, say 4, but no tones in
> between...and that
> > has poor dynamic range, but you can have a dMax of 1.8 and a dMin if .1,
> but
> > have a whole lot of tones in between...that has a high dynamic range.
>
> Dynamic range does not tell you anything about what is in between
> the end of
> the scale it simply defines its scope.

No, the endpoints define it's "scope" (range).  Dynamic range IS the number
of steps between the minimum measurable signal and the largest signal, since
you can only measure in increments of noise.

> If it is analog you can
> stop anywhere
> within the range an find a point and those are infinite in number. Silver
> printing is stepless.

Not true.  In an analog system, you can only measure to noise, so your
measurement will have a +- range, and that range is noise.  You can not
measure .0000001 volts in a system that has .1V noise!

> No max:min density ratios are dynamic range.

Absolutely not.  Because you measured a minimum value of X does not mean
that value is the noise floor!

> I will stick to the
> dictionary
> definition. You are arguing less is more.

I don't understand what you mean "I am arguing less is more"...please
explain.  BTW, I have been designing signal processing systems for a long
time.  The definition of dynamic range I know very very well.  You are
missing the concept of noise not being the same as the minimum measurED
signal, as opposed to the minimum measurABLE signal.  This is a very
important distinguishing point.

> > > Since a silver print and an inkjet
> > > print are both
> > > analog, there is an infinite number of tones between the minimum and
> > > maximum.
> >
> > Well, no.  The silver print is finite, since noise will overcome your
> > ability to discern tones.  That's what limits silver prints
> dynamic range.
> > The number of steps that can be discerned (in a range) is dynamic range.
>
> Okay, if it is finite how many tones can be produced in a silver gelatin
> print?
>
> Silver is not finite. Silver emulsion exposure and development produce
> reactions that can proceed to any point and provide an infinite number of
> tones.

I take it you don't understand the concept of noise in an analog system, or
you would understand why the tones are limited.

> I understand, I just don't agree.

Then you don't understand some things...and that is what I am trying to
explain to you.  Please put down your beliefs, and listen to me.  I've been
doing this stuff for a long time, and I know what I am saying is absolutely,
unmistakably correct.

> I think that you are redefining dynamic
> range in light of your electronics and digital background that are not
> completely applicable to a paper print.

Dynamic range IS dynamic range, period, what ever the application!  It is
completely applicable.  As I've said, this is a point of confusion that has
been around for some time, understanding the difference between density
ratio values and dynamic range, and that they are not interchangeable terms.
The term dynamic range is typically misused.  It is similar to the
misunderstanding that because positive film has a wider density range, that
it has a higher dynamic range, and it does not.  Negative film has more
discernable tones than positive film, and yet it has a shorter density
range.

> I agree that Density Range and Density Dynamic Range are not
> interchangeable. Range is the max minus min difference and
> Dynamic Range is
> the max:min ratio.

As I've said, you are confusing what min means in each case, and in each
case, they are different.  Min in the sense of dynamic range is the noise in
the system, min in the sense of density ratio values is the minimum you
measured in THAT image...and is NOT the same as the noise in the system.

Again, the minimum measurED signal is entirely different than a minimum
measurABLE signal.  Density ratio values are based on measureED signal, and
dynamic range is based on measurABLE signal.

> In any case, neither value places a limit on the ability to make a fine
> print with the materials chosen, either ink or silver.

True, but misunderstanding only confuses the ability to understand how this
stuff really works ;-)

Austin