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[filmscanners] remove


  • To: lexa@www.lexa.ru
  • Subject: [filmscanners] remove
  • From: "" <tibor@home.se>
  • Date: Tue, 08 Apr 2003 05:23:07 +0200
  • Unsubscribe: mailto:listserver@halftone.co.uk

-----Original Message-----
From: <filmscanners_Digest_owner@halftone.co.uk>
To: tibor@home.se
Date: Tue, 8 Apr 2003 00:00:02 +0100
Subject: [filmscanners_Digest] filmscanners Digest for Tue 8 Apr, 2003 

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Topic: [filmscanners] archives?
==========================
Date: Mon, 7 Apr 2003 10:56 +0100 (BST)
From: TonySleep@halftone.co.uk (Tony Sleep)
----------------------------------------
Barbara White wrote:

> I can't remember where to find the archives for this list - does anyone
> know? Thanks!

http://www.mail-archive.com/filmscanners@halftone.co.uk

Regards 

Tony Sleep - http://www.halftone.co.uk
Online portfolio & exhibit + film scanner info & comparisons

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Topic: [filmscanners] vuescan: IT8 calibration for negatives?
========================================================
Date: Mon, 7 Apr 2003 18:37 +0100 (BST)
From: TonySleep@halftone.co.uk (Tony Sleep)
----------------------------------------
simpy wrote:

> 1) I usually use negative film. Does IT8 calibration make a difference
> for negatives as well? I can imagine that the difference will be less
> obvious than for slides, because the color-cast removal messes up the
> colors anyway. On the other hand, a calibrated scanner could give a
> better starting position for vuescan to remove the color cast...

Vuescan bases its knowledge of each device's (scanner's) colourspace on the 
IT8 Q60. This is generic and individual scanners of the same model will 
vary a little, but nothing like as much as film types. The point is, 
though, is that what needs to be applied to the raw data is a composite of 
scanner+film type.

Where colour neg is concerned, there are too many variables for film  
characterisation to  get you very far. Exposure, colour temp. and  
processing each have a much wider range than slide films, and consequently 
there's too a wide range for profiling to be any help. Besides, with slide 
you'll generally be aiming at a scan that is the best approximation to 
what's on the film. This isn't possible with  neg, where almost everything 
is a matter of interpretation and judgement/intent. There's a 3-D magnitude 
of freedom which just doesn't apply to slides, but that's partly  why many 
choose to use it. Having got all that extra information onto film, 
there's often far more than will make a satisfactory picture without 
working on levels and curves.  Hue and luminance correction by profile 
would be a straitjacket, even if it did work.

> 2) I found that you can usually buy different types of IT8 reference
> targets; one for every major type of film (ektachrome/velvia/other
> fuji...). Why would you need a different target for every type of film?
> I would assume that there is only one `correct' calibration, regardless
> of the film material. What am I missing?

As mentioned, what needs to be applied to the raw data is a profile that 
characterises the scanner's response to coloured dyes  of different 
densities. The trouble is that different films use different dye sets which 
the scanner sees differently, and not necessarily in the same way that the 
eye works. Two different dye images that appear similar to the eye may 
'look' completely different to the scanner's different chromatic response - 
 which extends into IR, and often UV as well, I believe. So each mfr. 
produces an IT80 which uses their dyes, and each requires a different  
profile.

> 3) IF IT8 calibration is useful for negatives and there IS a difference
> between target types, which one would be the best?

It isn't, none are, and AFAIK no IT8's on colour neg exist. Really you have 
 to approach each colour neg image (or at least subject) as a new colour 
correction challenge. You can make this easier by photographing a greycard 
a white card and a black card, for each set of subject conditions you 
encounter on each roll. Sometimes that will give a good basis for colour 
correction using the PS levels eyedroppers. But other times it won't, not 
least because you don't want the result to be quite like the original 
scene anyway. EG neutralise the warmth in a sunset, and it no longer 
looks like a sunset anymore but a mistake. Our eye/brain is subtler than a 
colorimeter, or profiles.


Regards 

Tony Sleep - http://www.halftone.co.uk
Online portfolio & exhibit + film scanner info & comparisons

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Topic: vuescan: IT8 calibration for negatives?
=========================================
Date: Mon, 07 Apr 2003 17:42:09 +0200
From: simpy <simpy@xs4all.nl>
----------------------------------------
Hello all,

I recently started scanning using a Minolta Scan Dual II. I am 
reasonably satisfied with the results, but I am seriously considering 
using Vuescan to bring out some more details. I am reasonably fussy 
about color so I am tempted to try the professional version with support 
for ICC profiles + IT8 calibration.

However, I do have a few questions about an IT8-calibrated workflow. I
hope someone can help me out...

1) I usually use negative film. Does IT8 calibration make a difference
for negatives as well? I can imagine that the difference will be less
obvious than for slides, because the color-cast removal messes up the
colors anyway. On the other hand, a calibrated scanner could give a
better starting position for vuescan to remove the color cast...

2) I found that you can usually buy different types of IT8 reference
targets; one for every major type of film (ektachrome/velvia/other
fuji...). Why would you need a different target for every type of film?
I would assume that there is only one `correct' calibration, regardless
of the film material. What am I missing?

3) IF IT8 calibration is useful for negatives and there IS a difference
between target types, which one would be the best?

Thanks in advance!

Simon Tindemans



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