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RE: Digital Negatives with enough Tones for Pt/Pd

I'll butt in just long enough to make a comment about bit depth, dynamic
range, and software.....

The actual limitation on the scanner is the noise in the system.  That means
dust noise, movement noise, detector noise, electronic noise, eitting light
noise, and probably a lot of other noise sources.  To complicate matters,
there is a technique that could be used that allows the scanner to change
the range of the maximum, keeping the number of recorded bits the same.
 think of a digital meter wherethe range could be 1.99 or 19.9 or 199.)
Putting THAT complication aside,::::

The problem is that in every scanner, there is a truncation of bits that are
passed through to the computer program.  That could be 8 bits per color, or
more or less.

Bit depth is the number of bits of informnation that are produced digitally.
Yes it has no bearing at this stage on the dynamic range, but shortly it
will have a different effect.....

Dynamic range is usually defined, in electronic terms, as the ratio of
maximum signal to minimum signal.  The problem is that you don't know what
the maximum or minimum range of the signal is actually scanned, then
truncated, to produce a computer image.  In realistic practical terms, for
producing a negative, one COULD say the dynamic range is the signal that the
computer sends to the printer in terms of bit depth.  Typically, for a B+W
image,  8 BITS or a dynamic range of 8 ZONES.  However, now that we have a
set number of bits of depth of our pixel, and knowing that those bits are
evenly set apart on a scale, the maximum dynamic range is now set by the
number of bits available to the printer.  8 bits in my example, or 256:1
dynamic range.

Ditto all this confusion again when you take into account the issue of what
the printer is programmed to do ( bit depth, ink ooutput linearity, ink dot
size, dithering) , its noise sources ( ink spitters, ink itself, paper
absorption, lots of other sources) and you can see why this whole issue is a
mess.....

Simply put: we're on the cutting edge asking these questions.  The problem
is that we represent a 0.00001% of the audience for picture printers
connected to a computer.  Bottom line... we are on ourt own to get
stupendous results from our images.0

Frank Filippone
red735i@earthlink.net