Mark, if these are different hardware scans (and not different scans - from disk - of the same raw file), the fact that the "noise" has exactly the same pattern in both pictures indicates that it is *not* noise (which is random), and it is more visible in the picture with bp=1% simply because that picture is a bit brighter (or, at least, it appears brighter on my monitor). If they are not, I'd recommend to make two separate scans of the film an check again...
Alessandro Pardi > -----Original Message----- > From: Mark T. [mailto:[EMAIL PROTECTED]] > Sent: venerd� 15 febbraio 2002 12.22 > To: [EMAIL PROTECTED] > Subject: [filmscanners] Blackpoint & noise, was grain > > > Now I'm confused (so what's new).. > > Why would adjusting the black point *up* cause noise to > appear, given that the adjustment I'm making isn't sufficient > to affect the deep shadow detail? This seems backward to me > - if I increase the black point, am I not telling the scanner > to throw away some of my deepest blacks (ie shadow detail), > and therefore some of the noise (if there was any) should go > with it..? > > I'm seeing the reverse. Well, it's Friday, late, and maybe > my mind is going.. > > Anyway, if anyone wants to see what I mean, and can then > humour me and explain in words of few syllables :-), the > samples and more info are here: > > http://members.ozemail.com.au/~markthomasz/problems/blackpt.htm > > (As it may affect your decision to visit, it's about a 270K > download altogether.) > > Thanks for any enlightenment.. > > mark t > > Tony wrote: > >> (markthomasz..) wrote: > > > >> I've noticed that on some transparency films, I get a > grain-like effect > >> in shadows when I use a black point other than zero (in > Vuescan). I > >> haven't yet looked into exactly what is happening, but the 'noise' > >> vanishes as soon as I set bp to 0. > >> > >> So it is obviously not CCD noise > > > >What you describe is very likely CCD noise. On well behaved > scanners most > >of it is below the black point on any film you want to scan, on less > >fortunate models it climbs up toward the midtones and you > can't just chop > >it off without sacrificing shadow detail. > > > >Regards > > > >Tony > > > -------------------------------------------------------------- > -------------------------- > Unsubscribe by mail to [EMAIL PROTECTED], with > 'unsubscribe filmscanners' > or 'unsubscribe filmscanners_digest' (as appropriate) in the > message title or body > ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
