Re: Negative IT8 profile
Re: Negative IT8 profile
- Subject: Re: Negative IT8 profile
- From: Chris Protopapas <email@hidden>
- Date: Tue, 28 Feb 2006 17:48:06 -0500
Sounds interesting, but my experience with scanning color negatives tells be that there are too many variables in the mix to make profiling negatives a viable process in the real world.
Aside from all the possible film emulsions, there are the variations in lighting (color temperature and contrast), variations in exposure, variations in processing (not simply push-pull, but chemistry), plus the tendency of photographers and art directors to choose sub-optimal exposures as their "selects". One of the reasons photographers love negative film is exactly because it enables them to salvage marginal exposures under difficult lighting conditions.
This
might be useful in a tightly controlled workflow, where every one of the preceding variables is locked down, but that rarely happens in reality.
Color Management is all about profiling repeatable conditions and stable devices, exactly what color negatives are not. From a CM point of view, every transparency is the same (Kodachrome excepted), but every negative is different. The negative is not an image that needs to be reproduced, but merely a means of creating a final image.
The color negative's enormous exposure range (compared to transparencies) is coupled with an extremely compressed density range, which in practice means that very small variations in density and color in the shadow end are magnified by the expansion of the scanning process, and may make correct profiling of the shadow range problematic. The rule with profiles is that the more work they have to do to produce a "corrected" image, the more errors they will deliver. In the case of an inverted negative, flat, thin and very cyan, the profile will have to do an enormous amount of work to bring the image into some sort of acceptable state.
All that said, I wish you luck. This sounds like it could be a fascinating experiment, nevertheless...
Chris Protopapas
Fuel Digital Inc.
New York City
email@hidden
From: Walker Blackwell <email@hidden>
Subject: Negative IT8 profile
I'm working with a new drum scanner and I'm in the beginning stages
of building a set of IT8 profiles that will convert a positive IT8
calibrated scan of a color negative that has been inverted in
Photoshop (and thus is very cyan indeed) into a neutral balanced image.
Is this possible?
This is what I will be doing. Give me word if this just won't work
and if I'm wasting my time.
1. 3 rolls of 6x7 film of a reflective IT8 scan under x lighting
conditions with 3 stop bracket.
2. Develop 1 stop pull 1 stop normal 1 stop push.
3. For starters, drum scan the middle exposure and normal development
as positive.
4. Invert in Photoshop.
5. Import and calibrate with Monaco.
The hope is that this RGB profile will correct for the histrogram and
any color crossovers that I wouldn't be able to correct for via
levels or negative "Color" layer overlay.
Hopefully one profile would also be able to correct for a series of
different exposures via the same film (if everything else works.)
Anyone here who has experience in Color Neg profiling? I'm interested
in this because I think this entire area of color theory has, in a
way, been shoved to the way-side and under-investigated.
all the best, Walker Blackwell
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