[filmscanners] Re: Nikon Coolscan

["David J. Littleboy" <davidjl@gol.com>]

"Laurie Solomon" <laurie@advancenet.net> wrote:
>>>>>>>>
First, even if you interpret him as not saying that, you are left with
accepting his assertion that it's pointless.
>>>>>>>>

No, he's asking if it's pointless, and then pointing out that if it is, it's
a rather moot point.

>>>>>>>>>
  Thus, he is deciding for
someone else what is pointless and what is not.
<<<<<<<<<

No, we're both _asking_ if it's pointless. Everything I've heard about GF,
and my experience scanning, indicates that it is pointless.

>>>>>>>>>>>
>I don't understand the point of GF in a scanner

I am not sure you really understand what GF is and how it functions - let
alone the point of it in a scanner.  There is not point to having GF in a
scanner because that is not where it goes.  It is an image editing
application plugin and not the substitute for or an addition to the scanner
software which it may be bundled.  Typically it is bundled with Photoshop
for which it is a plugin and Photoshop happens to be bundled with the
scanner and its native scanning software.
<<<<<<<<<<<<

I understand that GF is a program that runs on a PC/Mac and that accepts
images at one resolution and spits them out at another, and that it's claim
to fame is that it upsamples better than photoshop for radical upsampling.

>>>>>>>>>>>>
> Does someone want to explain what's wrong with my logic???

It does not make sense to me; that is what I find wrong with it.  I am not
sure why you are comparing digital camera images with scanned images for
starters in determining the usefulness of GF.
<<<<<<<<<<<<<<

I'm pointing out that GF is useful in certain contexts. And identifying what
I consider the conditions under which it might be useful. (The main
condition being that you actually have some sharp edges worth preserving
when you go to outrageous print sizes.)

>>>>>>>>>>>>>>
>Which is to say, in some sense, scanner images are already upsampled. So it
doesn't make sense _to me_ to use GF on scanner images.

Scanners only upsample or downsample if you set the scanner software to do
so; and the software only does so after the scanning function has been
completed and the raw scan has been obtained.
<<<<<<<<<<<<<<

I wrote "in some sense". What I was trying to say is that a scanned image
has a lower ratio of information to pixels than a D60 image. In that sense,
a scanned image is further upsampled (from some theoretical maximum
information content) than a D60 image is.

Because of the softness of scanner images, it's possible to have a lower
resolution file with more real information. Example: a Kodak ProPhotoCD scan
at 1800 dpi looks a lot better than an Epson 2450 scan at 2400 dpi. The
Kodak scan captures more of the detail on the slide than the Epson does.
Epson can scream 2400 at the top of their lungs till the cows come home, but
that doesn't make the scans anything other than fuzzy mush.

>>>>>>>>>>>>>
  Scanners have maximum optical
resolutions that they can scan at.  If you scan at that resolution you are
obtaining the best scan resolution wise with anything below that resolution
or above it being less than optimal and involving interpolation or
downsampling which involves the creation of artificial pixels or the
deleting of actual existing pixels from the raw scan.  The typical workflow
for most people is to scan images at the scanner's optical resolution and to
leave image editing and enhancement to external third party software like
Photoshop.  Typically such operations as resampling and resizing are left to
that stage of the workflow and even toward the end of that stage.
<<<<<<<<<<<<<<

Yup. That's the way I work to.

>>>>>>>>>>
  Any
resizing and resampling that one might do will depend for the most part on
the final output and use (.e., web monitor display, inkjet prints,
Chromira/Lightjet prints, offset printing) as large wide format hardcopies,
small wallet prints, snapshots, 8x10s. If after you scanned your medium
format film, you decided that you needed to have a 24x36 Lightjet print made

which requires a 300 dpi file; how do you propose to resize the captured
scanner image to 20x24 dimensions with a 300 dpi resolution without using
Photoshop or the GF plugin?  Are you going to go back and rescan the image
at that size and resolution?
<<<<<<<<<<<<<<

Both Photoshop and Picture Window Pro resample images quite nicely. But now
we're actually getting somewhere: I take it that you're claiming that for
small changes in resolution, GF does a better job than Photoshop's bicubic
interpolation. Have you tested this? In what cases is it significant?

David J. Littleboy
davidjl@gol.com
Tokyo, Japan



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