POV-Ray : Newsgroups : povray.binaries.animations : CIELCHuv D65 gamut sphere : Re: CIELCHuv D65 gamut sphere Server Time
22 Feb 2024 07:09:21 EST (-0500)
  Re: CIELCHuv D65 gamut sphere  
From: clipka
Date: 25 Mar 2017 11:38:19
Message: <58d68eeb$1@news.povray.org>
Am 25.03.2017 um 16:09 schrieb Mike Horvath:
> On 3/25/2017 9:46 AM, clipka wrote:
>> Am 25.03.2017 um 12:22 schrieb Mike Horvath:
>>> On 3/25/2017 5:21 AM, clipka wrote:
>>>> Am 25.03.2017 um 09:19 schrieb Mike Horvath:
>>>>> The visible gamut under D65 illumination mapped to spherical CIELCHuv
>>>>> coordinates.
>>>>
>>>> You seem to be interpreting L as a polar coordinate, which is rather
>>>> unconventional -- and as a matter of fact doesn't make much sense,
>>>> since
>>>> it causes all grey tones to collapse into the center.
>>>>
>>>> The official CIE LCh colout space is cylindrical in nature, not
>>>> spherical (though the visible gamut under D65 might take on a somewhat
>>>> spherical shape).
>>>>
>>>
>>> Yes, I know. Adding a bit to the beginning of the radius creates a hole
>>> that keeps the gray values from collapsing.
>>
>> Why use this non-canonical representation of CIE LCh/Luv in the first
>> place?
>>
> 
> Back when I was learning how to use paint programs, before I learned
> what a color solid was, I came up with a spherical representation of the
> HSL color model (see attachment). I always liked the shape, and it stuck
> with me.

Beware that the parameterization of that color solid differs
significantly from that of your CIE LCh animation: In this HSL solid, S
is quite clearly measured radially from the vertical axis. In your CIE
LCh animation, the corresponding parameter C seems to be measured
radially from the center.


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