[filmscanners] Re: Colour management on Negatives

["Bob Shomler" <bobf2@shomler.com>]

>I suppose one could approximate what one can do with
>transparency film by shooting a Macbeth color chart and gray scale on
>the particular negative stock one wants to use, have the film processed,
>and then scan the film and have the software perform its reversal
>operation along with its accounting for the orange masking and its
>effect on the color rendition.  One could then compare the result in
>output of the finished scan with the original Macbeth color chart so as
>to determin what sorts of color corrections one needs to make to bring
>the finished scan into line with the original given the negative film
>being used.

Would this work through a range of different lighting color temperatures?  You 
might get a good usable set of color correction factors for a test case; but 
unless one is working in studio environment or under controleld lighting 
conditions it seems likely that subject incident light could vary from the test 
environment such that those adjustments may well not produce color fidelity 
through a range of lighting conditions.

Consider difference in conventional print color adjustments needed when 
negative film subjects are illuminated by bright sunlight, deep shade within 
bright sunlight (blue cast), and various indoor lighting (red cast from 
tungsten).  Perhaps a good white balance algorithm supplemented with white and 
gray picker points would yield better results.

Bob Shomler



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