Am 04.01.2014 19:47, schrieb Cousin Ricky:
> clipka <ano### [at] anonymousorg> wrote:
>>   The problem is that the human eye's sensors for long wavelengths
>> (red) are also sensitive to very short wavelengths (violet); thus, when
>> translating a very short wavelength to an RGB colour you do get a deal
>> of R in there (about 24% of the B channel at 400 nm, at least with the
>> table POV-Ray is currently using).
>
> Is this really the eye's sensors?  It seems obvious to me that POV-Ray uses the
> color matching function, where the red component does show up in the violet
> region.  But this doesn't appear to be reflected in our eye's cone cells;
> rather, it seems that the CMF is an outcome of the brain's /interpretation/ of
> the signals from the cone cells, or perhaps some preprocessing done in the
> retina.

The retina does indeed perform some comparatively heavy preprocessing of 
the colour stimulus, and may play an important role in the mangling of 
the R and B channels. Unfortunately that knowledge doesn't help us solve 
the underlying problem.

Using a color space with a B closer to the violet end of the spectrum 
might make the problem less prominent. However, it should be noted that 
similar shifts in hue happen at all wavelengths, and what happens at the 
purple line is only the tip of the iceberg. The only solution is to use 
more color channels. Enter spectral rendering.

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