POV-Ray : Newsgroups : povray.binaries.images : Calibrated spectral colors : Re: Calibrated spectral colors Server Time
28 Nov 2023 15:30:30 EST (-0500)
  Re: Calibrated spectral colors  
From: BayashiPascal
Date: 7 Aug 2023 06:40:00
Message: <web.64d0c9006ed655f18f8c74531749e915@news.povray.org>
Thanks for your reply.

> I had two issues with D_RGB().  The first, as Ive made clear in the
> documentation, is that it does not match the RGB colors that we are used
> to.  This makes matching colors more difficult, and this task is indeed
> the reason I held up publishing MakeSpectrum for so long.

I think I see what you mean: Ive's D_RGB() function's arguments represents a
combination of the SPDs for the D_CC_A3, D_CC_B3, D_CC_C3 color patches (used as
proxy for red, green, blue), while in your approach the RGB values in argument
stand for the 'pure' red, green, blue of "pigment {rgb <red,green,blue>}" that
POV-Ray users are used too. Right?

> The second issue is that some RGB combinations create pigments that
> reflect/transmit more light than than they receive at some wavelengths.
> This can be seen in the attached illustration.


> I am currently looking at a potential third issue: whether or not
> generating SPDs by naively combining primary colors will lead to the
> same fade_color/absorption primary color bias than RGB rendering has,
> but I do not have results on that yet.

I don't understand what you mean here, but I guess you'll share here your
results about it, so wait-and-see.

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