Re: Blue CCD Banding: A Little Test

["dickbo" <dickbo@xxxxxxxxxxxxxxx>]

Noise on the yelllow channel is never going to be a problem a problem
because the eye cannot see it on the printed output.

----- Original Message -----
From: "Phil.Lippincott" <phil.lippincott@worldnet.att.net>
To: <scan@leben.com>
Sent: Thursday, April 11, 2002 5:20 PM
Subject: Blue CCD Banding: A Little Test


> Paul and Friends
>
>    The blue CCD channel is generally the weakest of the three color
channels for
> the sensor.  On especially negative film the blue channel is the densest
or
> darkest channel.  Thus there is a conflict between the least sensitive
channel
> needing to scan the most difficult darkest film densities on negative
films.
> This both why a yellow posterization cast exists on a lot of CCD scanning
of
> negatives and why the scanner engineers like to turn up the blue channel
gain,
> integration time and sensitivity in blue.  Yet if they turn up the
sensitivity
> it also pushes the CCD into a noise condition of over modulation and yes
banding
> in the blue channel distinguishable from the others.  This whole process
is a
> catch 22 which is very frustrating to CCD scanner designers, engineers and
> software developers.  We need better CCDs or PMT (photo multiplier) / drum
> scanners to avoid these issues.
>
> Phil Lippincott
> www.aztek.com
>
> "Paul D. DeRocco" wrote:
>
> > I don't think it could be, because then it wouldn't be able to do
superfine
> > mode with a single line. It sounds like it's three lines, each of which
has
> > RGB sensors, whose only purpose is to be able to capture three scan
lines at
> > a time. I don't think the fact that there are three lines has anything
to do
> > with the fact that there are three primary colors--they could have used
a
> > four-line CCD and made it four times as fast as superfine mode.
> >
> > Or maybe I'm missing something.
> >
> > --
> >
> > Ciao,               Paul D. DeRocco
> > Paul                mailto:pderocco@ix.netcom.com
> >
> > > From: orafe.bustin@verizon.net
> > >
> > > On 9 Apr 2002 at 21:37, gary wrote:
> > >
> > > > So it is tri-line but monochrome (i.e. no color mask), right?
> > >
> > > yup, you got it.
> >
> > -
> > Turn off HTML mail features. Keep quoted material short. Use accurate
> > subject lines. http://www.leben.com/lists for list instructions.
>
> -
> Turn off HTML mail features. Keep quoted material short. Use accurate
> subject lines. http://www.leben.com/lists for list instructions.

-
Turn off HTML mail features. Keep quoted material short. Use accurate
subject lines. http://www.leben.com/lists for list instructions.