Digital BW, The Print

>> I've always heard the "need" for sharpening explained something like, "all
>> CCD scans require some kind of sharpening to compensate for the softening
>> effects of scanning, it's just part of the analog to digital
>> conversion, as
>> optics are involved which can soften and image, and CCDs are prone to blur
>> and smear."
> 
> Todd,
> 
> I thought about this a bit.  Remember, the Leafscan (which is the scanner I
> have) only uses a neutral density filter for B&W scans, therefore
> eliminating the smear and bloom characteristics of using red and blue
> filters with CCDs.  That may be the real reason why I don't sharpen, aside
> from the fact my images are shot with high quality glass, exposed and
> developed for sharpness and tonality.

Austin,

I really don't disagree, per se. My sharper films and images do "require"
less sharpening. I guess it boils down to what we want from sharpening.

In the case of the Leaf, in my tests, which were by no means exhaustive,
(maybe 8 comparisons), my grayscale scans were always the 2nd sharpest
choice short of choosing the singularly sharpest of the three color
channels. IOW, usually just the green channel would be slightly sharper than
the grayscale scan (though sometimes blue, and once even red). But I'm
really talking on the level of grain sharpness - nothing you'd see at normal
magnification. I decided it wasn't a sufficient difference to merit the
longer scan time, and if I wanted the additional sharpness I could get it
with USM. But which channel is the right sharpness? I also look at dust
specks and decide how sharp they should be. It's really purely subjective as
to how sharp that little edge should be, no?

I'm guessing the tradition of sharpening has come about for two reasons:

A) Perhaps through a microscope they measure the performance of a particular
lens/film/dev combo, at reproducing a resolution test chart. They'd then
scan that film and measure the performance on the monitor, and decide that
in order to match the films performance on the monitor, or for a given
output, sharpening needs to be employed. That's my guess. For real images
more subjective reasons might prevail in deciding whether sharpening is
worthwhile or not.

B) As I understand it, traditional offset half tone screening breaks up
image sharpness, and printers have found some "over sharpening" of an image
prior to printing could counteract that effect. In my case I've found that
my 1160/Epson Driver prints actually come out looking sharper than my
monitor image! So again, different rules may apply here.

I think it's all subjective. USM is just another tool to be used and abused.
;-)

Todd