RE: Scanning & TWAIN

["Paul D. DeRocco" <pderocco@xxxxxxxxxxxxx>]

As long as you scan in 16-bit-per-channel mode, I recommend not obsessing
about the scan settings, and doing all the work in Photoshop, since it has
better controls. The only things you must do in the Twain software is make
sure you're not overexposing and clipping the highlights, make sure you've
got color management turned on (even in B&W mode), and make sure you're not
using any unexpected filters like descreening or sharpening.

As to what Epson Twain does in automatic mode, I expect that only the
programmer knows for sure. I recommend turning that off, and using Levels in
Photoshop to adjust the image by eye, watching the histogram to make sure
you don't accidentally clip anything from the extremes.

By the way, Twain is the generic term for the protocol used to interface
image applications like Photoshop to scanners. The software you're using is
Epson Twain. NikonScan is also a Twain driver. And as far as I know, it is
the nature of this protocol that control doesn't return to the application
until the Twain driver is closed.

The various source settings are, I believe, like presets for all the other
parameters. I'm not sure what the destination setting does, except preset
the dpi reported in the image (as opposed to the actual dpi of the scan);
I've never noticed any difference in the image quality with different
destination settings. But I could be wrong about that.

I also despise Silverfast Ai, mostly because it's user interface is
unbelievably bad. The indication of what focus mode you're in, for instance,
consists of about four pixels that change in a tiny icon; on my 2048x1536
monitor, that's just about invisible. Haven't they heard of radio buttons? I
haven't actually used Vuescan, but it's not a Twain driver; it's a complete
application that stores its scans in files and then invokes the editor
application, which you may prefer since both can be active at the same time.
Also, I've read here that its previous display isn't color managed, although
that's less of an issue with B&W scanning.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

> From: Michael Healy
>
> I am scanning with an Epson 2450, TWAIN, and PS 5.5, driven by a Pentium 3
> with 12-gigs and 96 megs of RAM. I am interested primarily in making
> high-quality scans of b&w negs for digital enlargement to be used
> in contact
> printing. My negs are 6x9 and 4x5. I am prepared to work my images in
> PhotoShop, but I want very much to maximize the scan quality in the first
> place so as to avoid excessive handling and "fixing" as a result of
> incompetent scans. Right now I am experimenting with TWAIN's gray scale --
> scanning, evaluating histograms, then rescanning with scale
> adjustments. I'm
> not only trying to master the options, but I want to nail down
> the variables
> so I know what I'm doing when I think I need to adjust one.
>
> That is the background. My trouble is that what I want requires
> more control
> than TWAIN seems willing to afford. Or rather I should say, more
> information
> than it will surrender. I frankly do not find TWAIN very forthcoming about
> what it's actually doing in there. EG, I can alter the scan's gray scale,
> but I cannot figure out what the gray scale actually is by
> "default" before
> I alter it. Does anyone know what TWAIN's "auto" gray scale
> values actually
> are? How about its "reset" scale? Do I need to hunker down and coax this
> information indirectly from histograms by experimenting?

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