Fernando Gonzalez Gentile wrote:
> .......
>
> Wonder if the mirror inside the scanner needs some dusting-off, since I
> always need to turn up the unsharp mask (intensity and halo width) in
> Nikon Scan 4.x .... hate the idea to send it to the local Nikon service,
> I simply don't trust them. Would like to know how to clean it myself,
> but first I'd like to diagnose if the small amount of dust I can see on
> the mirror is the cause of the softening I consistently get. (hint: lo
> look at the mirror inside the scanner, a pair of small concave mirrors,
> those used by dentists, are very useful)
>
I don't know the theoretical reasons, but my experience is that ALL
digitally captured images, including scanned images, require some
sharpening and/or LCE to make the detail that has actually been captured
apparent to the human vision system. I know I've read the same thing
said by various experts on their web sites. So you shouldn't be
concerned that there is something wrong with the scanner unless you have
noticed a deterioration over the time you've had it. I personally doubt
that even a fair amount of dust on the mirror makes any difference at
all, even if it is in the image path, rather than, as I suspect, it is
in the illumination light path, where it certainly won't matter at all.
You think the film scanner output needs sharpening, you should see what
a flatbed with film capability needs!
With digital cameras, the default settings always include sharpening.
With a scanner, I believe the software will usually default to some
sharpening, too. I personally use no sharpening on my Canon FS400 with
VueScan. With icc profiles, the images come out looking pretty sharp
anyway and sharpen up nicely in PS when I need it. but that has been
empirically determined for my specific scanner, scanning software and
workflow.
When using film with significant grain or digital with noise, it's
better to use no sharpening at all until after any application of noise
filtering. Sharpening also sharpens the edges of the noise/grain, adding
to the the work the noise filtering has to do and making it less
effective at reducing noise without losing detail. Here, in addition to
my own experience, I can refer to a specific acknowledged expert, Bruce
Fraser, in Image Sharpening With Adobe Photoshop CS2.
Moose
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