[argyllcms] Re: Convert D50 ti3 file to A ti3 file
- From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 23 Oct 2017 08:53:36 -0700
On Oct 22, 2017, at 9:52 PM, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
Mike Tough (Redacted sender mike.tough for DMARC) wrote:
Is it possible to either generate a ti3 file or utilise the the spectral
data to
generate a camera profile for the type A illuminant in Argyll cms? If not,
is there any
other open source software that could do the job?
you should be able to use spec2cie
<http://www.argyllcms.com/doc/spec2cie.html>
to do this, using the -i parameter.
I'd add: commercial charts rarely have enough patches for good camera
profiles...and, as you're clearly aware, the actual illuminant in the scene is
a critical element with potentially huge variability. At best, a profile will
only be valid for the exact same conditions as the chart was photographed under.
If you're working with a digital camera, you can create a spectral model of the
camera's sensor; from that model, you can create profiles on the fly for any
conditions. You need to know the scene's illuminant, but that's typically
trivial: in the studio, measure with a spectrophotometer; outdoors, assume D??
and get the ?? from a chart; same story with incandescent sources. (In
uncontrolled mixed lighting you can't sample, colorimetry is a fool's errand.)
...but you indicate you're shooting a transparency chart. A resulting profile
will only make sense if you're using it to digitize film slides with the exact
same chemistry...but, even then, is the goal to replicate the color of the
slide or of the original scene? The former is more practical but more
subjective and something of a moving target. How are the slides being presented
to the viewer -- projector, print, light table...? The latter...is an exercise
in futility; far, far better to re-shoot with a colorimetric workflow from the
start.
Cheers,
b&
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