On 3/20/2017 11:48 AM, clipka wrote:
> Am 20.03.2017 um 14:52 schrieb Mike Horvath:
>> On 3/20/2017 8:21 AM, clipka wrote:
>>> Am 20.03.2017 um 02:21 schrieb Mike Horvath:
>>>> On 11/29/2016 10:56 PM, clipka wrote:
>>>>> Gamut of all theoretically possible surface colours, under D65 (noon
>>>>> daylight) illumination, in CIE 1931 xyY space.
>>>>>
>>>>
>>>> Here's my version, thanks to clipka and Bruce Lindbloom.
>>>
>>> That looks about right now.
>>>
>>> You seem to have a gap between the shape and the "black pane" though,
>>> which is particularly noticeable in the yellow and green regions.
>>>
>>> I'd therefore recommend investing a bit of extra work to make the shape
>>> extend to the black point -- or, more precisely, the locus of
>>> infinitesimally dark spectral colours.
>>>
>>
>> I'm not sure what to do with black. It's degenerate in xyY space, isn't
>> it? I get divide-by-zero errors when converting from XYZ.
>
> That's why you need to go for infinitesimally dark colours instead: Set
> all wavelengths to zero, except for a single wavelength which you set to
> a darn small power like, say, 1e-3.
>

I ended up just replacing that bottom row with the standard 2D xy 
chromaticity diagram, but colored black.

Thanks for catching the issue! I would not have noticed it myself.


Mike

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