"Robert E. Wright" wrote:
> ----- Original Message -----
> From: Rob Geraghty <harper@wordweb.com>
> To: <filmscanners@halftone.co.uk>
> Sent: Thursday, March 29, 2001 9:27 PM
> Subject: Re: filmscanners: Printing A3 from a 2700dpi scan
>
> > ...
> > I believe that for some reason there is more CCD noise in the blue channel
> > than other channels. It may be that the effect of Nikon's collimated
> light
> > is more pronounced in the blue channel than elsewhere - certainly shorter
> > wavelengths might show different focus than longer wavelengths. However,
> > the negative has the blue channel inverted doesn't it? :) I'm not hugely
> > concerned about what the source of the effect may be - the fact is that
> > on my LS30, all slide films scan far better in terms of apparent grain
> than
> > the neg films I've tried.
> > ...
> > Rob
> >
> >
> > Rob Geraghty harper@wordweb.com
> >
> >
> I think every reference I've seen regarding noise is scanned images
> identifies the Blue channel as being the most noisy. I have never seen an
> explanation of why this is so, but does not appear to be dependant on the
> light source or specific scanner. Maybe the noise isn't coming the film?
>
> Bob Wright
CCD's (Charged Couple Device) used in scanners and digital cameras are least
sensitive to blues, making it difficult for
them to interpret those colors correctly. File compression (such as with jpeg)
can also contribute to noise in the blue
channel.
--
Regards,
Joe Daugirdas
Personal: mailto:JDaugirdas@bellsouth.net
Business: mailto:JMD01@us.ibm.com
