Austin,
> I disagree that banding (in general) can't be caused by differences not
> accounted for in calibration between each of the LEDs, both of the same
> color, and between the different colors.
Just to make sure we are talking about the same thing: there is only
ONE LED of each colour in the LS-8000.
> Typical scanner calibration does calibrate all three colors, and calibrates
> each individual sensor for all three colors. Every scanner I've designed
> does that, and every one I've done work on does. I KNOW the Leafscan does
> it that way. I can't vouch for any other desktop scanners though, but it
> makes absolutely no sense that a competent programmer wouldn't do it that
> way, because not doing it that way gives less accurate results.
The Coolscans don't work this way. It's not necessary simply because
the CCDs have identical colour response, given by the semiconductor
material in use and independent of particularities of the microscopic
structures of the semiconductor device. Calibrating for each colour is
only necessary if your light source has different spatial profiles for
the three colours, which in the Coolscans is not the case.
> Something and/or someone is confusing/ed here. For example, you have an out
> LED, which does leave a gap...that is in the X direction, but the banding is
> in the Y direction, just like a clogged print nozzle. Film staging problems
> are what typically cause banding in the X direction on a film scanner.
I've never seen x banding on a Coolscan, and it can't even exist in
principle (that's what the CCD is calibrated for).
> LEDs in the hardware. There is a reason for doing it, as it can decrease
> smear and bloom, which can lead to a better scan. Now, they may have tuned
How does the intensity of the LEDs affect anything but exposure and
thus (indirectly) signal-to-noise ratio?
Andras
===========================================================================
Major Andras
e-mail: andras@users.sourceforge.net
www:
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