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

[SKID Photography <skid@bway.net>]

Austin,
Most of what you are saying in this latest missive was brought up before and 
rejected by Rob.  It was at that
point that I gave up.  But, kudos to you for your tenacity and deep knowledge 
on this subject.  I feel like
I've been vindicated, and by someone with far more skill than I.

Harvey Ferdschneider
partner, SKID Photography, NYC



Austin Franklin wrote:

> > 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".