Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast

[RogerMillerPhoto@aol.com]

Rob, I want IT-8 calibration because I'm color blind and I want to reduce the 
number of variables I have to deal with.  In theory, any of my calibrated 
scanners can be used to scan the same slide and the final files will all be 
nearly identical.  As you imply, IT-8 calibration has its limitations because 
a given target slide can only represent one type of transparency film.  With 
the exception of a gadget film like Velvia, most transparency films are 
fairly similar and have less variability between them than you might find 
between different brands of scanners.  So IT-8 calibration can help with 
consistent scanning of transparency film and get things a lot closer to a 
common starting point for someone like me with poor color vision.

For negatives, I believe it was Ian Lyons who said that calibrating the 
SS4000 and SilverFast with an IT-8 slide also had benefits for negatives.  I 
don't know why.  But I can certainly see how information from an IT-8 slide 
could be used to characterize the scanner's deviation from some norm so that 
software could improve (make more consistent) negative scanning as well.  For 
example, if IT-8 calibration finds that the scanner's red channel has a weak 
response when scanning transparency film and then makes an appropriate 
correction, then it seems the red channel gain would have to be boosted just 
as much when scanning negative film in order to get a "normal" scan.  This is 
speculation on my part.

Once again, my goal is to keep things as consistent as possible so that I can 
do the final tweaking "by the numbers" without having to start with files in 
which the color balance differs greatly from one another.  That might not be 
as important to someone with perfect color vision, but even they would 
probably benefit from it if they had more than one film scanner since scans 
from each scanner would have a starting point closer to one another.  
Otherwise, each scan would be an adventure.  I don't have time, nor the color 
vision, for such adventures.  

Someday I'd like to see the randomness taken out of the photo process and 
brought under control so the photographer doesn't have to worry about it or 
fight it all of the time.  IT-8 calibration and color management are steps in 
the right direction, but we've got a long way to go.  Only when the 
randomness from the scanning process is brought under control will the weenie 
work be taken out of scanning and the photographer allowed to concentrate his 
creative efforts on the task at hand.

Now that I've said all of that, I have to admit that I've been considering 
buying Vuescan just to see if I could live with it.  I'm not real happy with 
SilverFast's price gouging.

In a message dated 8/5/2001 4:21:41 PM Pacific Daylight Time, 
harper@wordweb.com writes:


> Roger wrote:
> > Too bad Insight and Vuescan don't support IT-8 calibration.
> > That's the only reason I've tolerating this SilverFast
>
> For the purchase price of Vuescan it might be worth trying with the SS4000
> just to see how much difference calibration really makes?
>
> It occurs to me to wonder how much difference IT8 calibration on a film
> scanner makes?  Presumably the IT8 target is an ektachrome slide, so you'd
> be calibrating for that type of film.  What about negs?  What about other
> brands of slide?  Is the calibration just introducing colour shifts that
> will have to be corrected anyway?
>
> Rob