[argyllcms] Re: Metameric Mismatch
- From: "Brad Funkhouser" <brad.funkhouser@xxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Mon, 13 Oct 2014 09:49:02 -0500
Interesting problem.
And a very practical issue for me.
I don't want to go through the effort of building custom input targets using
actual art colors just for fun. It seems like color science utilities
together with the measurement capabilities of my Eye-One Pro and
pre-existing spectral data for the art colors should somehow allow me to
compute delta Es for my current profiles on those colors.
I wonder what targets camera manufacturers use for testing the spectral
response curves of their sensors?
Thanks.
- Brad
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Graeme Gill
Sent: Monday, October 13, 2014 1:22 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Metameric Mismatch
Brad Funkhouser wrote:
> So, is there any realistic way to approximate my camera's spectral
response
> curves? Can some fancy color science math utility take RGB values for a
> measured ptfe white patch shot under 4 or 5 significantly different
measured
> illuminants and somehow glean a close approximation? If this is possible,
> is there a utility to feed D50 spectral color data through an illuminant
> then through a set of response curves to get expected RGB values?
Hi,
such things have been done, but the problem tends to be
under-constrained,
so a lot of assumptions need to be made, resulting in curves that are often
quite sensitive to measurement noise and not very accurate overall.
To get greater accuracy you really need a target with finely spaced
transitions throughout the wavelength range.
I have had a play with some code that does this, using the i1d3
spectral sensitivities as an example "ground truth" set, but something
like the ColorCheckerDC really doesn't seem to have the range of spectral
shapes to give dependable real world results.
Graeme Gill.
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