On 6/21/2012 7:22 AM, Chuck Norcutt wrote:
> I'm not Moose and I don't know the answer but I can speculate that an
> RGB scan with conversion in PhotoShop might be better. My reasoning is
> that the scanner itself is an RGB device so the scan is happening in RGB
> to begin with.
In a sense, it is three panchromatic sensors, receiving the light in parallel,
but through different color filters.
> Either scanner firmware or scanner software is controlling the conversion to
> gray scale.
VueScan offers these options:
------------------------------------------
"Input | Make gray from
This option specifies how to make the gray color from the scanner's red, green,
blue and infrared sensors.
The default, "Auto", either uses the scanner hardware to convert from the color
CCD to gray, or converts in VueScan,
mostly from the green channel.
Otherwise, the gray color is taken from either the red, green, blue or infrared
channels. Using the red or infrared
channel can be useful when scanning older, degraded black/white negatives that
are silver based."
------------------------------------------
For an undamaged film neg, I can't see any point in an RGB scanner output.
> It might very well be that the individual color channels have more or less
> sensitivity to the light produced by the scanner and the manner in which they
> are combined might make a difference.
For that to be true, it would have to be quite a bad color scanner, unless the
differences were compensated in hardware
or in firmware. Certainly they wouldn't show up in the output available to the
scanning software.
All that I have read indicates that the actual sensors are highly linear over,
and beyond, the visual spectrum. Most
problems with color accuracy are down to imperfect filters in front of them.
> If I had a scanner setup at the moment I'd try it but I don't. Also, the
> results could well vary by scanner and control software. Perhaps Ken will be
> along soon to explain his reasoning.
As the ViewScan Guide says, damaged old negatives (or prints) may have color
casts from aging, poor storage, and so on,
such that scan quality would be maximized by choosing one channel or another.
For a new neg, there should be no
difference. OTH, for scanners that create all three channels in one pass, there
is no penalty for using all three.
I think it is a non-issue.
Channeling Moose
--
What if the Hokey Pokey *IS* what it's all about?
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