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[filmscanners] Re: scanning at less than optical res


I sent that reply to someone on another list who was using large-format film
but then scanning it at one-quarter of the optical resolution of his scanner
since he didn't want large files. There was some doubt as to whether I was
correct, so I thought I would see what this filmscanners list had to say.

Bob Frost.

----- Original Message -----
From: "LAURIE SOLOMON" <laurie@advancenet.net>

>If you scan at 1200dpi, the scanner usually either samples all the 4800
>possible data points per inch and throws three out of every four away, or
>only samples every fourth possible point. So you are only getting one
>quarter of the possible data from the film. So why scan at large format if
>you are throwing three quarters of the film data away?

Bob, I beliee you are correct; but I do not understand your question. What
do you mean by "scan at large format" in this case?  I must have missed
something in the discussion.  The first method,which you note, involves the
actual sampling of original data using sampling algorithms and does result
in a loss of ortiginal data; but the second method, which you speak of with
respect to Vuescan and is available in almost all other scnning
applications, involves resampling of the original sample data using formulas
for combining and recombining data on the basis of all existing data and the
formulas.  Both methods, however, would involve the scanner reading during
the scan all 4800 points; so both would involve a "scan at large format" -
using your terms - or whatever optical format is used by the scanner.  After
the scan, everything else by way of sampling or resampling is either digital
conversion via hardware or software generated.

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