Re: Blue CCD Banding: A Little Test

["Phil.Lippincott" <phil.lippincott@xxxxxxxxxxxxxxxx>]

Hi Art,

   Very insightful suggestion.  The answer is absolutely yes a density range tailored
scanner is possible..  I am currently writing artificial intelligence some advanced
firmware for calibration of a single CCD scanners light source temperature,
integration time, bias and gain for different films density ranges.  Our new Aztek Pro
level Plateau CCD scanner will automatically tune itself to the film density it is
scanning on the fly.  It's my effort to get a CCD scanner to try to simulate the
dynamic range that I and our customers have grown to expect from drum scanners.  By
the way simulate is the operative word nothing can do it.
   Meanwhile suggestion of simply designing and building a relatively low end scanner
with one good lens, tuned light source, video CCD circuit design tailored to a film
type and density range is totally feasible.  You mentioned chromes.  Most CCD scanners
are designed with video gamma 2.2 and chrome transparency or reflective circuitry
because it's easy.  Yet the film is not a gamma at all it's an "S" shaped curve with
specific film density spectral highlight and shadow range.  So a better design is to
tailor the scanner for the media not the monitor or printer.  This exactly what Aztek
is about.  Unfortunately our products are relatively high-end for a lot of peoples
budgets.

Phil,
www.aztek.com

Arthur Entlich wrote:

> Hi Phil,
>
> Very interesting slant on this issue...
>
> This may seem either silly or obvious or both.
>
> If a scanner could be optimized for just transparency work could a
> better film scanner result?
>
> I shoot almost no neg film, personally.  If a manufacturer made a
> scanner that was optimized for slides only, and as a result made a much
> more neg scan,  I could live with it, or buy a cheap scanner that was
> optimized for negs should I require it.  I would be willing to give up
> scanning color negs completely for a 20% improvement in slides scanning.
>
> I wonder if there are others who would make the same decision if it was
> an option?
>
> Art
>
> Phil.Lippincott wrote:
>
> > 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.
> >>
> >>--
> >
>
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