Digital BW, The Print

Mike, I forget, which software version are you scanning with?

Anyway, try this;

In PS, open a new file, @ 364 DPI, 20x20, GS- file size will be 50.6M @8bit;
change to 16 bit and the file size is 101.2M, right?

Now go to Image size, and you will see that the file is 7280 pixels.

How did you get 7280 pixels from a 2.36" (6 cm) negative? Do the math, or
use the Image size dialog box to convert, and you find that you are scanning
at 3082 PPI.

Scanning software was developed for the pre-print market, where all they
cared about was the final image size and DPI.  The final print size and
resolution, in your case, has nothing to do with your scanning resolution.
When I scan, therefor, I always scan at 100% at the film size (i.e.,
whatever my crop size of the film is), and set my resolution to a scanner
native resolution, depending on what I expect my largest final print size
and resolution will be.

When you resample, you smooth out (read blur) the image; you are doing this
at about the grain resolution (I know, my terms aren't exactly correct
here), so it makes sense that it might reduce the presence of the grain.  It
might be interesting to scan @ 4000DPI, resample to 3082 DPI in PS, and
compare it to your scan.

Bill Morse
PhotoProspect
Cambridge, MA 02139



on 3/21/02 9:25 PM, Michael Kravit wrote:

Bill,

I set the scanner resolution to scan at 364dpi, the Q-Factor to 1.0, and I
set the output size at 20x20. The file becomes roughly 101mb or there
abouts.  The Howtek D400 has 364dpi as a native optical resolution. Unless I
am missing something Howtek states that this is still considered an optical
resolution and does not resample.

As I am not an electrical engineer I do not profess to be knowledgeable on
the subject of scanner theory. However, I have been told by Howtek that as
long as one sticks to on of the optical resolutions (As provided in the
chart with the scanner) all will  be safe in the universe.

Mike


----- Original Message -----
From: "Bill Morse" <willym@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Thursday, March 21, 2002 9:02 PM
Subject: Re: [Digital BW] Re: scan vs. printer resolution (WAS: combingcure)


> Mike, I'm not sure I'm following you.  Are you scanning the negative @364
> DPI or is the 20x20 print @ 364 DPI?
>
> If 20x20, then the actual scanner resolution is 3081 DPI - (20x364)/2.36 -
> not exactly optimal if what you are trying for is scanner optical
> resolution- although, come to think of it, maybe that's why you're seeing
> less grain? [g]
>
> There must be something really simple I'm not getting...
>
> Bill
>
>
>
> on 3/21/02 7:59 PM, Michael Kravit wrote:
>
> Austin is 100% right. Run these tests and you will see the results
clearly.
>
> One other thing that I have found is regarding grain. I find that by
> scanning at the lowest possible optical resolution of the scanner will
> reduce prominence of grain. That is on my Howtek D4000 if I scan at 4000
dpi
> at 1:1 the negative grain is very clearly evident.
>
> If I choose a lesser opticacal scanner resolution (Howtek provides a chart
> of the native optical resolutions) the PMT does not scan the grain and my
> images exhibit less grain in the final print. For example a 6x6 negative
> scanned at 364dpi (A Howtek D4000 Native Optocal Resolution) at a final
> print size of 20"x20".
>
> Mike
>
>
> Austin Franklin Wrote:
> > The best image out you are going to get is to scan at the optical
> resolution
> > of your scanner, and size the print (not interpolating) and let the PPI
> fall
> > where it may, providing it's above a certain point.  I've done dozens to
> > probably near hundreds of comparison tests, and the overwhelming
> conclusion
> > is that this gives the best image.  Also, everyone I've suggested this
> > methodology to, has said the same thing.
> >
> > The reasoning is pretty obvious.  Decimating the image information means
> > that you are changing the image data that the halftone algorithm is
basing
> > its decisions on, and that will degrade your output tonality and
> sharpness.
> > Now, this isn't true with EVERY image on earth, but as a general rule of
> > thumb, for me, it has held true.
> >
> > It is a very easy test you can do for your self.  Scan an image, resize
to
> > your output size in PS NOT allowing decimation to take place, and let
the
> > PPI fall where they may to 240PPI.  Print the image.  Take the same
image
> > and check the little box in re-size to allow decimation, and then change
> the
> > PPI to 240.  Print it out.  See for your self ;-)
>
>
>
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