Re: The color of gray
Re: The color of gray
- Subject: Re: The color of gray
- From: Mark Stegman <email@hidden>
- Date: Tue, 02 Sep 2014 12:50:41 +1000
Ben,
Am I reading this right?
...A reflective object that's gray has a flat spectral response; whatever
> the spectrum of the illuminant, that's the spectrum of the object.
>
If the illuminant has a restricted, non uniform, spectrum how can the
spectral response of the object be flat?
How can an object reflect parts of the spectrum that are not present?
What colour is a 'grey' object under a red light?
Mark
On Tue, Sep 2, 2014 at 4:07 AM, Ben Goren <email@hidden> wrote:
> On Aug 31, 2014, at 11:20 PM, Peter Miles <email@hidden> wrote:
>
> > What I don't understand is WHY the grays print with an identical hues.
>
> It goes back to my earlier post. A reflective object that's gray has a
> flat spectral response; whatever the spectrum of the illuminant, that's the
> spectrum of the object. An emissive source that's gray has the same
> chromaticity coordinates as the source's white point.
>
> You can probably figure out some way to create a profile that will print
> with a simulation of a different illuminant than the one you're actually
> viewing the print with, but that's never going to be useful outside of a
> classroom -- and, even then, it'd require quite a bit of setup to properly
> illustrate the phenomenon.
>
> Rather, the whole profiling process is built such that grays are as I
> described. Reflective grays are assumed to be spectrally flat, and emissive
> grays are assumed to lie on the chromaticity coordinates.
>
> It's a complicated and confusing subject that took me quite a while to
> warp my brain 'round -- and there're people subscribed to this list who've
> forgotten more than I'll ever know. That's to say...don't be shy about
> asking for more clarification if I'm still not making sense to you....
>
> Cheers,
>
> b&
>
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