[rollei_list] Re: SCANNING MF

  • From: Walker Smith <doubs43@xxxxxxx>
  • To: rollei_list@xxxxxxxxxxxxx
  • Date: Sat, 31 Jan 2009 13:34:02 -0500

I don't know why the information didn't come through that I copied and pasted but I'll try again:


RE: [Spotmatic] VueScan vs SilverFast

Good Morning!

As I think the ability to do high-quality, affordable scanning is a real
asset for those of us who would like to continue using our great old film
cameras, I'd like to offer a bit of advice on this subject.

I've retired after a twenty-year career doing imaging work for an archives.
Half way through I made the transition from large format film copying to
digital for most purposes.

I've digitized many thousands of images, black and white and colour, in a
wide assortment of formats using quite an assortment of scanners as well as
digital cameras.

SilverFast and Vuescan are very different products. In my view Silverfast
is intended to emulate the multiple functions of sofware usually associated
with high-end pre-press scanning systems, while Vuescan is intended to give
photographers a simple,high-qulaity tool for basic scanning. Hence the
differences in complexity and price.

One important lesson I've learned working with large numbers of images often
with short deadlines is to keep things simple.

In my view Photoshop is a much better tool than scanner software for making
image corrections. All I expect of scanner software is to produce files that
aren't screwed up for Photoshop.

There are three key screwups to avoid.

The first screwup is inadequate bit depth. For best results, always scan
black and white negs in 16-bit mode and colour negs and slides in 48-bit
mode. This gives you far more information for making tonal and colour
corrections, which will help you avoid problems like blown-out highlights.
(In Vuescan you must select bit depth in two places- Bits per Pixel on the
Input tab and TIFF File Type on the Output tab.)

The second screwup is scanning your files as JPEGs. Always save your scans
as TIFFs. Google "JPEG compression artifact" if you want to know why.

The third screwup to avoid is "clipping" of highlights and shadows.

By default, most scanning software is set up to cut off a certain amount of
highlight and shadow information. The intent is to produce "brilliant",
punchy images. Unfortunately this also throws away information that can
greatly improve the tonal range and richness of images. The throwing away
process is called "clipping".

One of the strengths of Vuescan is that it allows you to take control over
clipping very simply. Most other software packages are a pain in the butt
for this particular function.

I'll cut to two basic methods that work well for me. You'll need to switch
on the advanced "more" interface options in Vuescan to use them.

Method 1- suitable for scanning large numbers of images in a hurry.

Settings: Under the Color tab, select Auto Levels. Enter 0 for Black Point
and 0.1 for White Point. Select "generic" film type. Set Output Color
Space to Adobe RGB or Gray as appropriate. You can leave all other settings
under Color at their defaults, as other corrections are better made in
Photoshop.

Method 2- suitable for somewhat better individual scans.

Settings: Start with settings as in Method 1. Activate histogram by going
to the Prefs tab and selecting "linear" as the histogram option.

Adjust the sliders on the histogram so that they are positioned just outside
the top and bottom of the curve. This will give you maximum image
information without clipping. You will have to do this for every image.
Note that the numbers in the Black Point and White Point boxes will change
as you do this.

Comments: I came up with these methods after considerable trial and error
with Vuescan. They have worked well for me over a good many versions of the
software.

The resulting files may not be that great in terms of brightness, colour
balance or contrast. The important thing thing is that they will contain
the information needed to make those corrections most effectively in
Photoshop.

Questions welcome.

John Poirier
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