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

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

>
> "Austin Franklin" <darkroom@ix.netcom.com> wrote:
> >Rob wrote:
> > > I don't see why stochastic or random dye clouds inherently
> provides more
> > > information than a pixel.
> > Actually, FAR more.  It's their position and size, not their color, that
> is
> > far more information than pixels are.  Pixels (in current
> implementations)
> > must fall on a grid pattern, and are a fixed size.
>
> But the information in a pixel is limited only by the number of
> bits used to
> represent the colour.

But a dye cloud is more than color.  It is ALSO shape and position.  Those
characteristics (information) are NOT represented by color.

> Can you explain your claim in some way that shows me how one is better
> than the other?  If you're comparing say a 2700dpi pixel grid with a film
> emulsion, then I agree.  But as far as I can tell, it's just a matter of
> increasing
> the resolution of the grid and/or the number of bits in each pixel and you
> should be able to meet or exceed the amount of information stored in the
> film.

Yes, but increase it to what?  You would need to be able to scan the exact
edges of every randomly placed dye cloud...it's about three orders of
magnitude more information than is currently possible.

> For practical purposes there has to be a point where the
> difference becomes
> irrelevent, or people wouldn't use scanning back cameras or
> really high res
> CCD cameras in professional situations.

Well, there's yet another problem.  You can only make a CCD (or CMOS)
"pixel" just so small, and you are limited also by size of the array.  This
is a physics limitation.  Each and every pixel has to have wires running to
and from it.  That is not the case with dye clouds ;-)  Also, the smaller
you make them, the more noise you get.  This is the reason the cheapo
digital cameras use the small pixel arrays and they are not as good as the
larger arrays (physical size, not more pixels) as far as picture quality.
Hence, the Canon D30 is FAR better than a same or more sized cheapo digital
camera.