RE: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI

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

> Austin wrote:
> > That's the point, it isn't an argument!  It's like asking
> > why the number 9 is larger than the number 4.  It's just
> > the way it is.  It's just a fact of simple physics that a
> > pixel does not contain near the same amount of information
> > as a dye cloud.
>
> I suspected I should have chosen a word other than "argument".  The number
> 9 is larger than the number 4 because it is a convention that 9
> is 5 integer
> values larger than 4.  Other than that, the digit 9 or the word "nine" are
> simply labels to represent an idea.  Saying "it is because it is" does not
> constitute any sort of meaningful explanation.

Some things just are, and the truth is manifested in and of it self.  A
basket that has 25 eggs in it has MORE eggs than a basket with 4, right?
All semantics aside.

Here is (one of) your original question(s)/statement(s), which I have been
answering:

"> > > I don't see why stochastic or random dye clouds inherently
> provides more
> > > information than a pixel."

The point of contention appears to be "more information".  I believe we
agree on what "more" and "information" mean.  Pixels ONLY represent the
tonal value of the area which the sensor sees, which does NOT represent the
physical characteristics of the dye cloud, unless the dye cloud is perfectly
square and happens to line up perfectly in the field of view of that one
pixel.

In fact a pixel MAY represent many dye clouds, or only a portion of a single
dye cloud, but there is NO way you can represent the amount of information
in a single dye cloud by a single pixel, when A pixel ONLY contains tonal
information.

Dye clouds are irregular in shape, and dye clouds do NOT line up 1:1 with
pixels.  Even if you did characterize each and every dye cloud digitally,
you would need more than spot tonal information, You would also have to use
many pixels, or characterize the shape, because it's irregular.
Characterizing the shape will be very consuming (as in a lot of data) to
represent.

Given all that, I believe it is obvious why a dye cloud "provides inherently
more information than a pixel".  If you don't see that, I can't explain it
any further without sitting down at a white board and drawing it out step by
step...

> Claiming that a pixel has anything to do with physics is an odd thing to
> do.

Now that's an odd thing to do...claim a pixel has nothing to do with
physics...  I don't know about your scanner, but mine is not Gnostic.

> A pixel is a number or a set of numbers that represent a mixture and
> intensity of light.  It's not limited by physics.

A pixel has an analog to digital origin in our case.  This analog to digital
conversion has limitations, which ARE limitations of physics.  That's just a
fact.  If you created a drawing with Adobe Illustrator, then your pixels
would not have an analog origin.

> A dye cloud
> has a certain
> dimension and a certain behviour with light.  A pixel is not limited in
> the same way.

Er, a pixel is FAR more limited, since it is only representing a single
characteristic of a regular patterned point source (as in a single element
in a regular grid pattern of equal sized elements).

> A pixel could represent an area the size of an atom, or the
> size of a galaxy; *any* dimension

Except for the fact that we are talking about film scanners, and the are a
pixel can represent is limited by physics...

> and it may be an 8 bit number
> or you could
> pick any number of bits.

Yes, and it ONLY represents tonality, NO other characteristic at all is
represented by a pixel.

> How small would you like to make the
> area represented
> by the pixel and how many bits of RGB would you like to use until
> you exceed
> the data contained in a chemical representation of an image?

Then you said "it's just a matter of increasing the resolution of the
grid..."

Which is where the physical characteristics come in play.  There are
physical limitations as to how many pixels you can "practically" use in a
scanning system.  You can't just make a sensor of infinite density (or
infinite size and use optics), since these bring up physical limitations.
These are just facts of physics, and why physics is involved.

> I'm
> astonished
> that you could believe the "fact" you have stated above.

Because what I have stated ARE facts.  It would take MANY MANY pixels to
represent the physical characteristics of a single dye cloud, and one could
argue for quite some time what is the "correct" number of pixels to do
this...and NO, because of physical limitations on sensor element sizes (that
are NOT the same as faster processors, larger memory etc...those aren't
analog sensors, so advances in those areas are not entirely applicable to
advances in digital imaging sensors in this case) you can not just "increase
the resolution of the grid".