re:Digital vs Analog (might be backwards!)

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

Michael Kersenbrock writes

>In a digital camera, *each* pixel can be not only black or white, but
>in most cases least 254 brightness values inbetween, which seems a lot
>higher tonality than a singular minimum-sized silver spec.  And as such, 
>it takes an area of the film to provide the tonal range that an equivalent 
>digital-camera pixel has.  This is why it seems that the silver specs are 
>acting like dithered/halftoned binary representation of the image.  One
>then can conclude that silver-based film is more digital than a digital
>camera because on the microscopic scale, each pixel in a digital camera
>*is* roughly ananalog representation, while each "pixel" of silver film is
>roughly binary.

Gregory J. Wageman writes
>This can't be right (about film, I mean).  In order for film to behave
>as you say (with light-darkened silver halide crystals acting like a
>halftone), then adjacent crystals would have to have knowledge of what
>their neighbor is doing (i.e., "this area is supposed to be 50% grey,
>and my neighbor is on, so I should be off").  In the digital halftoning
>world, this knowledge is present in the computer program which is
>approximating a true grayscale value by turning on and off a certain
>ratio of pixels in a given area.

It seems to me that film probably behaves more like halftoning rather than
dithering. Halftoning reproduction basically would be the crystal
represented by a large black "dot" and light gray with a smaller area black
"dot", to represent the different shades of gray. I would assume the
opacity of the crystal would also probably be a factor. 
Dithering, I would think would not come into play in film photography thou
and is basically taking the ratio of the area of black and white to simulate
the different shades of gray. (of course there is also color dithering)
This is done on monitors and printing. 
Thus if halftoning (and not dithering) is at play with film, then there
might be some truth that the resolution of film is not as stated. The
increase of real-estate (black spots) taken up by the film layer would
reduce the resolution of the film. Another stab (wild guess) is that, this
is why slow speed film has hi-contrast. The smaller crystals can only
"grow" black in area thus don't have a large grey scale depth. This would
also explain why high speed film doesn't look necasarilly poorer. It has
less resolution but lower contrast due to x-all real-estate. I won't go
into depth on this topic unless warranted and would have to go into some
length. This can get quite confusing but really is not.

P.S. It might sound confusing that lower contrast would be desirable.
This is thou the case if the subject has low contrast and the film
can only render high contrast. The film would not faithfully reproduce
the view. If the subject has high contrast then there is no problem.
If the subject has low contrast and the film has low contrast, the film
would reproduce it faithfully. Or in other words hi-speed film can better
reproduce low contrast situations due to it's low contrast capabilities.
There are good analogies of this in digital picture manipulation. 

WARNING These are not based on fact but from personal observationS and 
conclusions. So it is not entirely based on fact. To be taken with a 
grain of salt and call me in the morning.

Gabriel


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