Thanks for the informative response. I will use the new information to fill
up some of the empty crevices in my brain. I doubt if it will make me any
smarter but with enough information and fewer crevices, I will have a smooth
brain. :-)
In seriousness, I realize that a color enlarger print may take on a grainy
appearance as might the actual color film under a grain focuser, what I did
not really know was if it would act the same way with reguard to scanning
and some of the grain reduction methods currently being employed in the
scanner software. I think (but I could be wrong) that there is a real
difference between grain APPEARANCES and actual grain STRUCTURE and was not
sure how it might impact on scanning and scanner software.
-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Tony Sleep
Sent: Thursday, October 10, 2002 6:58 PM
To: laurie@advancenet.net
Subject: [filmscanners] Re: Grain aliasing: Thoughts, solutions?
On Thu, 10 Oct 2002 00:14:35 -0500 Laurie Solomon (laurie@advancenet.net)
wrote:
> (1) can one actually get grain alaising
> with these films such that the methods for dealing with that problem will
> work with those films and (2) does it act and respond to grain reduction
> functions in scanning software in the same way as true grain.
Chromagenic is no different from any colour film, the dye clouds are quite
capable of appearing grainy in an ordinary enlarger print. The grain
aliasing issue arises because some spatial frequencies of grain
distribution (micro-tonal variations) in the image are close to the spatial
frequency of the pixel matrix which comprises the scan. No different from
digital Moire, essentially, except grain pattern is random, not geometric.
With all aliasing the easy cure is to degrade the frequency of image
information so that it falls well within the Nyquist limit. Defocussing, or
antialiasing filters, do the job. I presume software that attempts to deal
with it relies on some sort of blur function, which is how you can attempt
to deal with it in PS. It could be clever and only act on areas where
aliasing occurs, but there is no way to deal with aliasing and retain the
HF info that causes it. Aliasing is just an inescapable property of pixels.
Regards
Tony Sleep -
Online portfolio & exhibit + film scanner info & comparisons
----------------------------------------------------------------------------
------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message title
or body
----------------------------------------------------------------------------------------
Unsubscribe by mail to listserver@halftone.co.uk, with 'unsubscribe
filmscanners'
or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or
body
