[Leica] Film/Digital

[henningw at archiphoto.com (Henning Wulff)]

At 5:43 PM -0500 4/3/07, Eric wrote:
>  >http://www.luminous-landscape.com/essays/clumps.shtml
>
>"Not so fast! Here's the catch that many testers trip over. Grain particles
>are binary. An individual film grain can only be either black or not-black,
>on or off, exposed or not exposed. Sort of a binary device. A photo site
>(pixel), on the other hand, has a range of thousands of brightness levels,
>because it's an analog device. (Curious isn't it, that at this level film is
>binary and digital is analog?)"

The pixel location can be defined in a binary fashion, and the A/D 
converter will output a binary value for the photosite, but there is 
the usual chopping done to arrive at a binary value. Of course, in 
the end all is digital, as a photon of a specific wavelength has but 
one value, so whether the sum of photons gets trapped by a photosite 
which deals with the number of photons first as an analog value and 
then digitizes it again, or whether the photons interact with a 
number of silver salt grains to provide an analog value that is then 
'digitized' by the units of grains, the end result is that once 
digitized the pixels stay digital until print time, and the silver 
grain values travel through analog paths to the darkroom print, which 
is also analog.

Both paths have digital and analog portions, but the 'digital' path 
is more digital in the portion that we can influence...

>This is twisted logic, at best.  Comparing apples and oranges.  A pixel is
>analog?  Not by any definition of analog that I've ever seen.  True, a film
>grain is either there or not...but they can clump together.  Definitely not
>binary.
>
>I'd question any conclusions this guy reaches when he can't even define
>terms correctly.

Only if you demand narrow definitions for 'digital' and 'analog'.

-- 
    *            Henning J. Wulff
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