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On 3/25/2017 11:38 AM, clipka wrote:
> In this HSL solid, S
> is quite clearly measured radially from the vertical axis.
>
Nope. It is from the center point too.
Mike
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Am 25.03.2017 um 18:36 schrieb Mike Horvath:
> On 3/25/2017 11:38 AM, clipka wrote:
>> In this HSL solid, S
>> is quite clearly measured radially from the vertical axis.
>>
>
> Nope. It is from the center point too.
Just read up on HSL, and you are right: In your spherical HSL diagram,
the distance from the center of the spehere does indeed correspond to
the parameter called "Saturation" in the HSL model.
*BUT* that "Saturation" parameter differs significantly from what I'd
consider the physical definition of saturation, where only monochromatic
light would be defined as fully saturated, while white light (at any
brightness, i.e. any shade of grey if you will) would be considered
fully unsaturated, which is what the "Chroma" parameter in the CIE LCh
model corresponds to.
If you want to get anywhere close to your HSL sphere with the CIE LCh
model, you have to represent the "Chroma" parameter as distance from the
vertical axis, otherwise you'll get a torus-ish shape instead of a
sphere-ish one. I also /think/ you'd get closer to your ideal by
sticking to the fully canonical rendering, with the "Lightness"
parameter represented as distance from the bottom plane.
At any rate, publishing a non-canonical representation of the CIE LCh
model will certainly do more to confuse people about the colour model
than to educate them.
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On 3/25/2017 4:19 PM, clipka wrote:
> Am 25.03.2017 um 18:36 schrieb Mike Horvath:
>> On 3/25/2017 11:38 AM, clipka wrote:
>>> In this HSL solid, S
>>> is quite clearly measured radially from the vertical axis.
>>>
>>
>> Nope. It is from the center point too.
>
> Just read up on HSL, and you are right: In your spherical HSL diagram,
> the distance from the center of the spehere does indeed correspond to
> the parameter called "Saturation" in the HSL model.
>
https://commons.wikimedia.org/wiki/File:HSLSphere.svg
Is this image easier to understand? It is missing the "donut hole" in
the middle, however. So all the grays collapse to a point, unfortunately.
> *BUT* that "Saturation" parameter differs significantly from what I'd
> consider the physical definition of saturation, where only monochromatic
> light would be defined as fully saturated, while white light (at any
> brightness, i.e. any shade of grey if you will) would be considered
> fully unsaturated, which is what the "Chroma" parameter in the CIE LCh
> model corresponds to.
>
Do these figures show what you are talking about?
https://en.wikipedia.org/wiki/File:Hsl-hsv_saturation-lightness_slices.svg
It seems "chroma" needs to be converted to "saturation first". Not sure
the best way to do this, as I haven't thought of it before.
>
> If you want to get anywhere close to your HSL sphere with the CIE LCh
> model, you have to represent the "Chroma" parameter as distance from the
> vertical axis, otherwise you'll get a torus-ish shape instead of a
> sphere-ish one. I also /think/ you'd get closer to your ideal by
> sticking to the fully canonical rendering, with the "Lightness"
> parameter represented as distance from the bottom plane.
>
I'm not concerned so much with the outer shape. The spherical
parameterization is what's important to me. But "chroma" needs to be
converted to "saturation" first, as in the above image.
> At any rate, publishing a non-canonical representation of the CIE LCh
> model will certainly do more to confuse people about the colour model
> than to educate them.
>
I labeled all the images as "original research", and nothing links to
them except a user page.
Mike
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Am 25.03.2017 um 22:38 schrieb Mike Horvath:
> On 3/25/2017 4:19 PM, clipka wrote:
>> Am 25.03.2017 um 18:36 schrieb Mike Horvath:
>>> On 3/25/2017 11:38 AM, clipka wrote:
>>>> In this HSL solid, S
>>>> is quite clearly measured radially from the vertical axis.
>>>>
>>>
>>> Nope. It is from the center point too.
>>
>> Just read up on HSL, and you are right: In your spherical HSL diagram,
>> the distance from the center of the spehere does indeed correspond to
>> the parameter called "Saturation" in the HSL model.
>>
>
> https://commons.wikimedia.org/wiki/File:HSLSphere.svg
>
> Is this image easier to understand? It is missing the "donut hole" in
> the middle, however. So all the grays collapse to a point, unfortunately.
No, it's the HSL model's definition of "Saturation" in general that I
find counter-intuitive, not your visual representations of the HSL
colour solids.
> I labeled all the images as "original research", and nothing links to
> them except a user page.
Fair enough.
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On 3/25/2017 6:14 PM, clipka wrote:
> No, it's the HSL model's definition of "Saturation" in general that I
> find counter-intuitive, not your visual representations of the HSL
> colour solids.
>
This article explains several definitions/methods to convert "chroma" to
"saturation".
https://en.wikipedia.org/wiki/HSL_and_HSV
Not sure if one of these methods is good to use, or if CIELCHab &
CIELCHuv need something custom tailored for them. (Which is beyond me.)
Mike
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Hi(gh)!
On 25.03.2017 09:19, Mike Horvath wrote:
> The visible gamut under D65 illumination mapped to spherical CIELCHuv
> coordinates.
Sweet! May I C64ize/AtariSTize and re-publish it (of course crediting you)?
See you in Khyberspace!
Yadgar
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On 3/28/2017 2:27 PM, Jörg "Yadgar" Bleimann wrote:
> Hi(gh)!
>
> On 25.03.2017 09:19, Mike Horvath wrote:
>> The visible gamut under D65 illumination mapped to spherical CIELCHuv
>> coordinates.
>
> Sweet! May I C64ize/AtariSTize and re-publish it (of course crediting you)?
>
> See you in Khyberspace!
>
> Yadgar
You may. But as clipka has pointed out, in its current form it is not
useful to anyone at all and should be forgotten.
Mike
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There are some nicer animations here:
https://commons.wikimedia.org/wiki/User:SharkD
such as one of these:
https://commons.wikimedia.org/wiki/File:Visible_gamut_within_CIELUV_color_space_D65_whitepoint_mesh.webm
https://commons.wikimedia.org/wiki/File:Visible_gamut_within_CIELCHuv_color_space_D65_whitepoint_mesh.webm
I can provide the individual uncompressed frames of the animation if needed.
Mike
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On 3/28/2017 2:27 PM, Jörg "Yadgar" Bleimann wrote:
> Hi(gh)!
>
> On 25.03.2017 09:19, Mike Horvath wrote:
>> The visible gamut under D65 illumination mapped to spherical CIELCHuv
>> coordinates.
>
> Sweet! May I C64ize/AtariSTize and re-publish it (of course crediting you)?
>
> See you in Khyberspace!
>
> Yadgar
Here's a nice animation too, though I can only claim partial credit.
https://commons.wikimedia.org/wiki/File:Pyramid_35_spheres.gif
Mike
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On 3/29/2017 12:35 AM, Mike Horvath wrote:
> Here's a nice animation too, though I can only claim partial credit.
>
> https://commons.wikimedia.org/wiki/File:Pyramid_35_spheres.gif
>
>
> Mike
ONCE AGAIN, I can only claim partial credit, rather.
;)
Mike
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