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The tone compression also allows room on a negative for larger exposure latitute than reversal film. The possibility that a particular negative frame being scanned may be under- or over-exposed by a stop or two, but still have some detail in the heavily compressed shadows or highlights, makes coming up with a calibration process difficult without analyzing the frame in question for film base color/density, exposure and color balance. Scott -----Original Message----- From: Ernst Dinkla [mailto:E.Dinkla@chello.nl] Sent: Wednesday, March 13, 2002 2:50 PM To: firstname.lastname@example.org Subject: Re: SilverFast (negafix) ----- Original Message ----- From: "Paul D. DeRocco" <email@example.com> To: <firstname.lastname@example.org> Sent: Wednesday, March 13, 2002 7:56 PM Subject: RE: SilverFast (negafix) > I have trouble understanding why a negative should be intrinsically more > variable than a transparency, given that the latter had a negative in it at > one point, using chemistry that had way more constraints on it (e.g., the > ability to wash those dyes out) than any negative film. > > But most scanner software doesn't attempt to do anything more with a > negative than apply a fixed negative to postive transformation, using curves > built into the software. This just duplicates the sort of table > interpolation calculations that a color management engine does under control > of an ICC profile. And using an ICC profile would allow something like > standard tools to be used to build such profiles. This may not compensate > for the lot-to-lot variability of negatives, but then neither does anything > else--except perhaps NegaFix, and people are saying that that doesn't > eliminate the need for tweaks, either. The negative film has a more compressed character as a first step to the final image on paper that will never have the contrast of a slide. With the knowledge that only the positive paper print would be viewed by eye they also did some other tricks that resulted in an even more off colour negative. That off colour is then corrected in the print. As a total it is the right approach. For scanning it is nice that there is some compression done already. But if there never will be a conventional positive print from that negative made it would be sensible to make a film that has the compression but not the mask etc. Or make a slide film that has more compression if it has to be scanned only. The extra mask(s) + any difference in development that has more influence on the compressed image colours may be the cause of the variation I guess. And maybe that part of the process never was considered that important because the other step after it would compensate the variation. Ernst - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions. - Turn off HTML mail features. Keep quoted material short. Use accurate subject lines. http://www.leben.com/lists for list instructions.