[argyllcms] Re: How to go from negative scan > darkroom reproduction (with spectral reading of darkroom print)

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 28 Jan 2015 14:18:09 +1100

Derin Korman wrote:


> Can I use device link profiles, or some other way, to go from the scan of a
> negative to an approximation of what I get in the darkroom?

I'm not clear on what you mean by "in the darkroom". You could
characterize a negative by it's device independent appearance,
but I'm not sure what the point would be. You could probably
do that with existing Argyll tools, as long as you chose the
device space appropriately. i.e. for a film printer that has
RGB input and a negative output, you would have to call it
a CMY device. It's generally hard to measure negatives without
using something like a SpectroScanD and a lot of patience.
But I'm not sure what use such a profile would be.

> I had the idea that I could photograph colorchecker sg,
> scan that negative using a characterized device,
> print the same negative in the darkroom and read it with i1pro
> and then here on I am a bit lost as to how to proceed.

Profiling photographic processes generally doesn't work well,
because they are too variable. Per photo or batch adjustments need
to be made for the variations in the film, processing, exposure etc.
You could certainly attempt to characterize the photographic
process from a shot of a test chart through to a film scanner
positive (i.e. RGB) output, but would it be useful, given that
you would have to lock down the film, film processing and the
scanner settings ?

In my view, it would take a carefully designed workflow and
associated tools to manage such a process, one that captured
colorimetric behaviour and provided the adjustment mechanisms
to work while maintaining the validity of the colorimetric
characterization. Given the small usage of film now, it hardly
seems worth the effort of creating such a suite of tools to
support such a workflow.

Graeme Gill.

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