[argyllcms] Re: Fluorescent patches in a profile target?
- From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 20 Mar 2010 08:44:31 -0700
Hello (Hello (Hello?)?)?
Is there anybody out there?
Cheers,
b&
On 2010 Mar 18, at 8:22 PM, Ben Goren wrote:
> I'm still working on a less-un-ideal target for profiling cameras, and I've
> been thinking about things a lot.
>
> I've recently realized, in one of those mind-twisting kinds of ways, just how
> many things in a typical photographic scene are likely to be brighter than a
> 100% reflective target (such as the Tyvek I discovered or the PTFE that Ernst
> is collecting data on). Of course, there're emissive objects and specular
> reflections...but there're also fluorescent objects. Some cheap office
> papers, for example, have OBAs that push the short-wavelength brightness well
> over 100%. I haven't gone searching for any DayGlo things to check, but it
> wouldn't surprise me if some of them have peaks over 100% (at different
> wavelengths, of course) as well.
>
> Adobe Camera Raw, with its flattest settings and the ``Camera Faithful''
> color profile is actually a not-too-miserable colorimetric match for a scene,
> provided you start with a correct incident exposure and apply the proper
> white balance. The caveat is that a 100% white target will get rendered as L*
> = 90 (or thereabouts) and the rest of the highlights will be scaled
> accordingly. I haven't tried to determine the shape of the curve; instead,
> I've just been using the results as a starting point to feed to Argyll.
>
> I'm therefore wondering about the wisdom of including fluorescent patches in
> a profile target in an attempt to characterize the 100%+ range.
>
> Obviously, different lighting conditions will produce different amounts of
> fluorescence. I mainly intend to use this target with studio strobes, which I
> hope have a similar enough spectrum to the illumination source in an i1 to
> produce useful results.
>
> But I'm also wondering about how well Argyll would deal with the math...as
> well as, of course, whether or not it's even a good idea in the first place.
> And, if it *is* a good idea, what kinds of fluorescent materials to look
> for....
>
> Thanks,
>
> b&
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